Language：Japanese   Publisher：(一社)日本関節病学会  

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Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s11548-024-03087-1

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

AIMS: This study aimed to investigate the incidence of ≥ 5 mm asymmetry in lower and whole leg lengths (LLs) in patients with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH-OA) and primary hip osteoarthritis (PHOA), and the relationship between lower and whole LL asymmetries and femoral length asymmetry. METHODS: In total, 116 patients who underwent unilateral total hip arthroplasty were included in this study. Of these, 93 had DDH-OA and 23 had PHOA. Patients with DDH-OA were categorized into three groups: Crowe grade I, II/III, and IV. Anatomical femoral length, femoral length greater trochanter (GT), femoral length lesser trochanter (LT), tibial length, foot height, lower LL, and whole LL were evaluated using preoperative CT data of the whole leg in the supine position. Asymmetry was evaluated in the Crowe I, II/III, IV, and PHOA groups. RESULTS: The incidences of whole and lower LL asymmetries were 40%, 62.5%, 66.7%, and 26.1%, and 21.7%, 20.8%, 55.6%, and 8.7% in the Crowe I, II/III, and IV, and PHOA groups, respectively. The incidence of tibial length asymmetry was significantly higher in the Crowe IV group (44.4%) than that in the PHOA group (4.4%). In all, 50% of patients with DDH-OA with femoral length GT and LT asymmetries had lower LL asymmetry, and 75% had whole LL asymmetry. The incidences of lower and whole LL asymmetries were 20% and 42.9%, respectively, even in the absence of femoral length GT and LT asymmetries. CONCLUSION: Overall, 43% of patients with unilateral DDH-OA without femoral length asymmetry had whole LL asymmetry of ≥ 5 mm. Thus, both the femur length and whole LL should be measured to accurately assess LL discrepancy in patients with unilateral DDH-OA.

DOI： 10.1302/2633-1462.52.BJO-2023-0152.R1

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DOI： 10.48550/arXiv.2401.00159

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Osteophyte formation is attracting attention as an early-stage pathology of knee osteoarthritis (OA). Although osteophyte formation is understood as a defense response to joint instability, its role and impact on OA remain largely unknown. Many studies have been conducted using the surgical destabilization of the medial meniscus (DMM) mouse model, but there are few standard evaluation methods, especially in the histological evaluation of early-stage osteophytes. The purpose of this study was to establish a reproducible and uniform method for histological evaluation of characteristics of early osteophyte formation in the DMM mouse model. METHODS: Male mice were operated with DMM at 12 weeks old and histologically evaluated at 4 days and 1, 2 and 4 weeks after DMM. Osteophyte Width, Osteophyte Area, and Original and Modified Maturity Scores were used to evaluate osteophytes for all sections. RESULTS: Osteophyte Width, Osteophyte Area and Maturity Scores were all greater anteriorly than posteriorly in the knee joint. The Modified Maturity Score was more strongly correlated with position than the Original Maturity Score, and could be used to evaluate early-stage osteophyte formation. CONCLUSION: The Modified Maturity Score as well as Osteophyte Width and Area at the section of the anterior cruciate ligament (ACL) attachment site can provide a reproducible evaluation method to histologically assess the early-stage osteophyte formation in the DMM mouse model.

DOI： 10.1016/j.ocarto.2023.100409

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Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.media.2023.102970

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Language：English   Publishing type：Research paper (scientific journal)  

AIMS: This study aimed to develop and validate a fully automated system that quantifies proximal femoral bone mineral density (BMD) from CT images. METHODS: The study analyzed 978 pairs of hip CT and dual-energy X-ray absorptiometry (DXA) measurements of the proximal femur (DXA-BMD) collected from three institutions. From the CT images, the femur and a calibration phantom were automatically segmented using previously trained deep-learning models. The Hounsfield units of each voxel were converted into density (mg/cm3). Then, a deep-learning model trained by manual landmark selection of 315 cases was developed to select the landmarks at the proximal femur to rotate the CT volume to the neutral position. Finally, the CT volume of the femur was projected onto the coronal plane, and the areal BMD of the proximal femur (CT-aBMD) was quantified. CT-aBMD correlated to DXA-BMD, and a receiver operating characteristic (ROC) analysis quantified the accuracy in diagnosing osteoporosis. RESULTS: CT-aBMD was successfully measured in 976/978 hips (99.8%). A significant correlation was found between CT-aBMD and DXA-BMD (r = 0.941; p < 0.001). In the ROC analysis, the area under the curve to diagnose osteoporosis was 0.976. The diagnostic sensitivity and specificity were 88.9% and 96%, respectively, with the cutoff set at 0.625 g/cm2. CONCLUSION: Accurate DXA-BMD measurements and diagnosis of osteoporosis were performed from CT images using the system developed herein. As the models are open-source, clinicians can use the proposed system to screen osteoporosis and determine the surgical strategy for hip surgery.

DOI： 10.1302/2046-3758.129.BJR-2023-0115.R1

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: The purpose of this study was to investigate the position of the femur relative to the tibia throughout range of motion in the osteoarthritic knee to evaluate knee kinematics and assess its relationship with the degree of varus deformity. METHODS: In this study, 116 preoperative knees with varus deformity were evaluated using a navigation system. The internal-external, anteroposterior, and mediolateral positions of the femur relative to the tibia were measured at maximum extension, 15°, 30°, 45°, 60°, 90°, 105°, and 120°, and maximum flexion angles. From these parameters, two-dimensional translation of the surgical epicondylar axis was projected onto the tibial axial plane, and the femoral movement was evaluated relative to the tibia. In addition, the knees were retrospectively classified into three groups according to their degrees of preoperative hip-knee-ankle angle: mild (< 10°), moderate (10°-20°), and severe (> 20°). Then, the differences in each parameter between these groups were investigated. The Steel-Dwass test was performed to identify the difference among three groups. Statistical significance was set at p values < 0.05. RESULTS: There was a significant difference in the anteroposterior position of the femur relative to the tibia among the three groups, especially from extension to early flexion (p < 0.05). The anteroposterior position at knee extension deviated posteriorly according to the progression of varus deformity. Rotational and mediolateral translation were not significantly different among the groups. Normal knee kinematics were diminished in almost all cases in each group. In addition, anterior paradoxical motion of the femur during early knee flexion was observed in 45.6% (n = 26), 57.1% (n = 28), and 80.0% (n = 8) of cases in the mild, moderate, and severe groups, respectively. The anteroposterior position of the femur relative to the tibia at knee extension was significantly more posterior in patients with than in those without anterior paradoxical motion (p < 0.0001). CONCLUSION: The anteroposterior position of the femur relative to the tibia changed according to the progression of varus deformity in osteoarthritic knees, especially from knee extension to early flexion. Posterior deviation of the femur at knee extension induced its anteroposterior movement relative to the tibia, resulting in anterior paradoxical motion. LEVEL OF EVIDENCE: III.

DOI： 10.1007/s00167-023-07363-6

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: This study aimed to compare midflexion rotational laxity between two different design concept models of cruciate-retaining total knee arthroplasty: symmetrical surface design of neutral joint line obliquity and asymmetrical surface design of varus joint line obliquity. METHODS: Sixty-three knees that underwent cruciate-retaining total knee arthroplasty were evaluated. Manual maximum passive rotational stress without acceleration was applied to the knees under navigation monitoring. Pre-operative and post-operative internal and external rotational angles were measured at 30°, 45°, 60°, and 90° knee flexion. RESULTS: The post-operative internal rotational laxity was significantly increased compared with pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 9.7° vs 11.1°, 10.6° vs 11.6°, 11.2° vs 12.9°, and 13.2° vs 14.9°; p = 0.01, 0.04, 0.001, and 0.008, respectively). The post-operative external rotational laxity was significantly decreased compared to pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 10.8° vs 6.8°, 12.5° vs 9.4°, 12.8° vs 10.0°, and 11.3° vs 9.5°; p < 0.0001, < 0.0001, < 0.0001, and 0.0008, respectively). The post-operative total rotational laxity significantly decreased, compared with pre-operative levels, at 30° and 45° flexion among all subjects (mean 20.4° vs 17.9°, and 23.1° vs 21.1°; p = 0.002 and 0.04, respectively). The post-operative total rotational laxity was significantly smaller in asymmetrically designed total knee arthroplasty than in symmetrically designed total knee arthroplasty at 30°, 45°, and 60° flexion (mean 19.3° vs 15.8°, 22.8° vs 18.7°, and 24.4° vs 20.8°; p = 0.03, 0.03, and 0.02, respectively), whereas no significant difference was observed at 90° flexion. CONCLUSION: Compared to symmetrical surface design, asymmetrical surface design resulted in lower rotational laxity at the midflexion range in cruciate-retaining total knee arthroplasty. LEVEL OF EVIDENCE: III.

DOI： 10.1186/s40634-023-00652-6

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Language：Japanese   Publisher：(一社)日本医用画像工学会  

超音波画像診断装置は,非侵襲・短時間で撮影可能であり高時間高分解能な画像が取得できるため,筋肉の解析に適したモダリティである.しかし,撮影範囲には制限があり,3次元的な解析が困難である.そこで本研究では下肢を撮像した複数のパノラマ超音波断面を用いて,下肢全体の筋骨格の形状を予測することを目的とする.具体的には,パノラマ超音波の複数断面の撮像には,モーションキャプチャーを用いて,パノラマ断面とそれに対応する位置情報を取得する.筋骨格の形状予測には,CTデータベースを用いて統計形状モデルを構築し,構築したモデルと取得したデータを用いることで,筋骨格の形状を予測し,推定精度を求めるため,1人の被験者から得られた同一箇所の3次元MRI画像と複数の超音波パノラマ断面を用いて,定量的な評価を行う.この手法により,パノラマ超音波画像を複数取得するだけで,広範囲の筋骨格形状を取得することが可能となる.(著者抄録)

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Language：Japanese   Publisher：(一社)日本医用画像工学会  

体幹部筋骨格モデルを構築し,加齢変化に基づく,体幹部筋骨格の変形過程を理解することは,手術計画や生体力学解析に重要である.本研究では,大規模なCTデータベースを用いて,連続的な各年齢の男女別の体幹部筋骨格の統計形状モデル(SSM)を構築する.J-MIDデータベースと共同研究施設で収集した4万症例以上のデータを活用し,従来は部分的な骨格形状に限定されていたSSM構築を,本研究では体幹部の複数の筋骨格構造を含めたSSMの構築を行う.構築された各年齢の統計形状モデルの性能評価を行い,筋骨格形状の加齢変化について調査する.(著者抄録)

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Language：English   Publishing type：Research paper (scientific journal)  

This paper presents methods of decomposition of musculoskeletal structures from radiographs into multiple individual muscle and bone structures. While existing solutions require dual-energy scan for the training dataset and are mainly applied to structures with high-intensity contrast, such as bones, we focused on multiple superimposed muscles with subtle contrast in addition to bones. The decomposition problem is formulated as an image translation problem between (1) a real X-ray image and (2) multiple digitally reconstructed radiographs, each of which contains a single muscle or bone structure, and solved using unpaired training based on the CycleGAN framework. The training dataset was created via automatic computed tomography (CT) segmentation of muscle/bone regions and virtually projecting them with geometric parameters similar to the real X-ray images. Two additional features were incorporated into the CycleGAN framework to achieve a high-resolution and accurate decomposition: hierarchical learning and reconstruction loss with the gradient correlation similarity metric. Furthermore, we introduced a new diagnostic metric for muscle asymmetry directly measured from a plain X-ray image to validate the proposed method. Our simulation and real-image experiments using real X-ray and CT images of 475 patients with hip diseases suggested that each additional feature significantly enhanced the decomposition accuracy. The experiments also evaluated the accuracy of muscle volume ratio measurement, which suggested a potential application to muscle asymmetry assessment from an X-ray image for diagnostic and therapeutic assistance. The improved CycleGAN framework can be applied for investigating the decomposition of musculoskeletal structures from single radiographs.

DOI： 10.1038/s41598-023-35075-x

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1097/CORR.0000000000002690

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

UNLABELLED: The patient's position may affect the bone mineral density (BMD) measurements; however, the extent of this effect is undefined. This CT image-based simulation study quantified changes in BMD induced by hip flexion, adduction, and rotations to recommend appropriate patient positioning when acquiring dual-energy x-ray absorptiometry images. PURPOSE: Several studies have analyzed the effect of hip rotation on the measurement of bone mineral density (BMD) of the proximal femur by dual-energy x-ray absorptiometry (DXA). However, as the effects of hip flexion and abduction on BMD measurements remain uncertain, a computational simulation study using CT images was performed in this study. METHODS: Hip CT images of 120 patients (33 men and 87 women; mean age, 82.1 ± 9.4 years) were used for analysis. Digitally reconstructed radiographs of the proximal femur region were generated from CT images to calculate the BMD of the proximal femur region. BMD at the neutral position was quantified, and the percent changes in BMD when hip internal rotation was altered from -30° to 15°, when hip flexion was altered from 0° to 30°, and when hip abduction was altered from -15° to 30° were quantified. Analyses were automatically performed with a 1° increment in each direction using computer programming. RESULTS: The alteration of hip angles in each direction affected BMD measurements, with the largest changes found for hip flexion (maximum change of 17.7% at 30° flexion) and the smallest changes found for hip rotation (maximum change of 2.2% at 15° internal rotation). The BMD measurements increased by 0.34% for each 1° of hip abduction, and the maximum change was 12.3% at 30° abduction. CONCLUSION: This simulation study quantified the amount of BMD change induced by altering the hip position. Based on these results, we recommend that patients be positioned carefully when acquiring DXA images.

DOI： 10.1007/s11657-023-01225-x

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: The sacroiliac joint (SIJ) has attracted increasing attention as a source of low back and groin pain, but the kinematics of SIJ against standing load and its sex difference remain unclear due to the difficulty of in vivo load study. An upright magnetic resonance imaging (MRI) system can provide in vivo imaging both in the supine and standing positions. The reliability of the mobility of SIJ against the standing load was evaluated and its sex difference was examined in healthy young volunteers using an upright MRI. METHOD: Static (reliability) and kinematic studies were performed. In the static study, a dry bone of pelvic ring embedded in gel form and frozen in the plastic box was used. In the kinematic study, 19 volunteers (10 males, 9 females) with a mean age of 23.9 years were included. The ilium positions for the sacrum in supine and standing positions were measured against the pelvic coordinates to evaluate the mobility of the SIJ. RESULTS: In the static study, the residual error of the rotation of the SIJ study was < 0.2°. In the kinematic study, the mean values of SIJ sagittal rotation from supine to standing position in males and females were - 0.9° ± 0.7° (mean ± standard deviation) and - 1.7° ± 0.8°, respectively. The sex difference was statistically significant (p = 0.04). The sagittal rotation of the SIJ showed a significant correlation with the sacral slope. CONCLUSION: The residual error for measuring the SIJ rotation using the upright MRI was < 0.2°. The young healthy participants showed sex differences in the sagittal rotation of the SIJ against the standing load and the females showed a larger posterior rotation of the ilium against the sacrum from the supine to standing position than the males. Therefore, upright MRI is useful to investigate SIJ motion.

DOI： 10.1007/s11548-022-02806-w

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: Artificial intelligence (AI) technologies have enabled precise three-dimensional analysis of individual muscles on computed tomography (CT) or magnetic resonance images via automatic segmentation. This study aimed to perform three-dimensional assessments of pelvic and thigh muscle atrophy and fatty degeneration in patients with unilateral hip osteoarthritis using CT and to evaluate the correlation with health-related quality of life (HRQoL). METHODS: The study included one man and 43 women. Six muscle groups were segmented, and the muscle atrophy ratio was calculated volumetrically. The degree of fatty degeneration was defined as the difference between the mean CT values (Hounsfield units [HU]) of the healthy and affected sides. HRQoL was evaluated using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). RESULTS: The mean muscle atrophy rate was 16.3%, and the mean degree of muscle fatty degeneration was 7.9 HU. Multivariate correlation analysis revealed that the WOMAC stiffness subscale was significantly related to fatty degeneration of the hamstrings, the WOMAC physical function subscale was significantly related to fatty degeneration of the iliopsoas muscle, and the JHEQ movement subscale was significantly related to fatty degeneration of the hip adductors. CONCLUSION: We found that fatty degeneration of the hamstrings, iliopsoas, and hip adductor muscles was significantly related to HRQoL in patients with hip osteoarthritis. These findings suggest that these muscles should be targeted during conservative rehabilitation for HOA and perioperative rehabilitation for THA.

DOI： 10.1007/s11548-022-02797-8

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Language：Japanese   Publisher：(一社)日本医用画像工学会  

医用画像から得られる被験者個別の解剖構造に忠実な筋骨格モデルは,運動障害の原因の解明用途において重要である.一方,体位によって運動器の力学的・動態的な条件は異なるため,立位で行う動作における筋骨格モデルは,臥位において撮影された医用画像ではなく立位において撮影された医用画像から作成されることが望ましい.しかし,立位における医用画像は臥位における医用画像ほど普及しておらず,扱えるデータの数は限定的である.そのためわれわれは,一般に広く普及している臥位による医用画像を有効利用するため,立位時の筋骨格変形を定量化し,臥位の医用画像から立位の医用画像を予測することを目指している.本稿ではその第一段階として,同一被験者により撮影された臥位・立位CT画像を自動セグメンテーションし,その精度を検証した結果を報告する.(著者抄録)

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Language：Japanese   Publisher：(一社)日本医用画像工学会  

医用画像から得られる被験者個別の解剖構造に忠実な筋骨格モデルは,運動障害の原因の解明用途において重要である.一方,体位によって運動器の力学的・動態的な条件は異なるため,立位で行う動作における筋骨格モデルは,臥位において撮影された医用画像ではなく立位において撮影された医用画像から作成されることが望ましい.しかし,立位における医用画像は臥位における医用画像ほど普及しておらず,扱えるデータの数は限定的である.そのためわれわれは,一般に広く普及している臥位による医用画像を有効利用するため,立位時の筋骨格変形を定量化し,臥位の医用画像から立位の医用画像を予測することを目指している.本稿ではその第一段階として,同一被験者により撮影された臥位・立位CT画像を自動セグメンテーションし,その精度を検証した結果を報告する.(著者抄録)

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Other Link： https://search.jamas.or.jp/default/link?pub_year=2023&ichushi_jid=J02087&link_issn=&doc_id=20231010050004&doc_link_id=10.11409%2Fmit.41.21&url=https%3A%2F%2Fdoi.org%2F10.11409%2Fmit.41.21&type=J-STAGE&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00007_2.gif

Publishing type：Research paper (scientific journal)  

DOI： 10.48550/arXiv.2305.19920

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Publishing type：Research paper (international conference proceedings)  

DOI： 10.1007/978-3-031-43990-2_47

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Other Link： https://dblp.uni-trier.de/db/conf/miccai/miccai2023-7.html#GuOUTSHTOSS23

Publishing type：Research paper (scientific journal)  

DOI： 10.48550/arXiv.2307.11513

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Language：Japanese   Publisher：(一社)日本人工関節学会  

対象は2015年1月～2019年9月の34例38関節(男性13例、女性21例、手術時平均年齢63.6歳)。JOAスコアは術前平均51.9点から最終観察時平均83.1点と改善を認めた。Initial gapは5関節においていずれもZone IIで認めたが、全例術後6ヵ月レントゲンでは消失していた。Radiolucent lineの出現は、術後6ヵ月ではZone IIIに4関節、術後1年ではZone IIに6関節、術後2年ではZone IIIに3関節に認めた。ゆるみや再置換を要した症例はなく、短期の臨床経過は良好であった。

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Language：Japanese   Publisher：(一社)日本人工関節学会  

ロボティックアーム手術支援システムMako THA症例112例132関節を対象に、術中のenhance modeとexpress modeの脚延長量計測の精度について、術後のCTで計測した脚延長量と比較検討した。Enhance mode施行は47例57関節、Express mode施行は65例75関節であった。Enhance modeは脚延長量の平均絶対値差がExpress modeより有意に小さく73.3%が1mm以下で精度が高かった。

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Language：English   Publishing type：Research paper (scientific journal)  

Pelvic incidence (PI) is often quantified in patients undergoing total hip arthroplasty. Errors in radiographic PI measurements can affect clinical outcomes. The purposes of this study were (1) to evaluate the error in radiographic PI measurement in patients with hip osteoarthritis (OA) and (2) to analyze the factors related to the error. Radiographs and computer tomography (CT) images of 100 patients (24 men and 76 women; mean age 63.7 years) with unilateral OA were reviewed. The error in radiographic PI measurement was defined as the difference between the radiographic measurement of the PI (rPI) and the accurate value of PI measured using CT images (cPI). Factors related to the error in the rPI were analyzed, including the coronal and axial rotation of the pelvis on lateral radiographs. The degree of coronal and axial rotation was expressed as the angle of rotation around the anteroposterior and craniocaudal axes. The mean rPI was significantly larger than the cPI (57.8° and 54.1°, p < 0.01). The error in the rPI was 3.6° on average and 15.8° at maximum. The mean coronal and axial rotation of the pelvis was 9.6° and 4.4°, respectively. The error in the rPI positively correlated with coronal pelvic rotation and rPI, and negatively correlated with axial pelvic rotation (p < 0.01, r = 0.35, 0.43, and -0.45, respectively). The rPI was 3.6° larger on average than the cPI in patients with hip OA. Coronal and axial rotation of the pelvis and a large PI were related to the error in the rPI.

DOI： 10.1002/jor.25477

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Language：Japanese   Publisher：(株)医学書院  

＜文献概要＞人工知能の医療への応用は,整形外科においては画像診断を中心に2019年以降報告が増え,股関節外科領域においても近年報告が増えている.単純X線画像自動診断,予後予測,3次元画像解析などに応用されている.われわれは,CTデータから筋骨格モデルを抽出するAIを開発し,骨格では表面距離誤差0.1mm,筋肉では表面距離誤差0.9mmの精度を達成した.術後CT画像評価のための金属アーチファクト低減,CT/MRI画像変換,単純X線骨盤正面像からの3次元筋骨格構造の再現や骨粗鬆症診断,サルコペニア診断などにも取り組んでいる.

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: The Japanese Orthopaedic Association National Registry (JOANR) was recently launched in Japan and is expected to improve the quality of medical care. However, surgeons must register ten detailed features for total hip arthroplasty, which is labor intensive. One possible solution is to use a system that automatically extracts information about the surgeries. Although it is not easy to extract features from an operative record consisting of free-text data, natural language processing has been used to extract features from operative records. This study aimed to evaluate the best natural language processing method for building a system that automatically detects some elements in the JOANR from the operative records of total hip arthroplasty. METHODS: We obtained operative records of total hip arthroplasty (n = 2574) in three hospitals and targeted two items: surgical approach and fixation technique. We compared the accuracy of three natural language processing methods: rule-based algorithms, machine learning, and bidirectional encoder representations from transformers (BERT). RESULTS: In the surgical approach task, the accuracy of BERT was superior to that of the rule-based algorithm (99.6% vs. 93.6%, p < 0.001), comparable to machine learning. In the fixation technique task, the accuracy of BERT was superior to the rule-based algorithm and machine learning (96% vs. 74%, p < 0.0001 and 94%, p = 0.0004). CONCLUSIONS: BERT is the most appropriate method for building a system that automatically detects the surgical approach and fixation technique.

DOI： 10.1016/j.jos.2022.09.003

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Osteonecrosis of the femoral head (ONFH) classification systems are based on the size, volume, and location of necrotic lesions. Often-but not always-ONFH results in femoral head collapse. Because acetabular coverage is associated with mechanical stress on the femoral head, it might also be associated with femoral head collapse in patients with ONFH. However, the association between acetabular coverage and femoral head collapse in these patients has not been established. QUESTIONS/PURPOSES: (1) Is femoral head collapse associated with acetabular coverage or pelvic incidence (PI) in patients with ONFH? (2) Are established predictors of femoral head collapse in ONFH classification systems associated with acetabular coverage? METHODS: Between 2008 and 2018, we evaluated 343 hips in 218 patients with ONFH. We considered all patients with ONFH except for those with a traumatic etiology, a history of surgical treatment before collapse, or those with collapse at initial presentation as potentially eligible for this study. Of those, 101 hips with ONFH (50% [50] were in males with a mean age of 44 ± 15 years) met our inclusion criteria. These patients were subsequently divided into two groups: those with femoral head collapse within 12 months (collapse group, 35 hips) and those without femoral head collapse (noncollapse group, 66 hips). No differences in patient demographics were observed between the two groups. CT images were used to measure the PI and acetabular coverage in three planes: the lateral center-edge angle (LCEA) in the coronal plane, the anterior and posterior center-edge angle in the sagittal plane, and the anterior and posterior acetabular sector angle in the axial plane; in addition, the difference between these parameters was investigated between the groups. The thresholds for femoral head collapse in the parameters that showed differences were investigated. Necrotic location and size were evaluated using the Japanese Investigation Committee (JIC) classification and the Steinberg grade classification, respectively. We examined the relationship between these parameters and classifications. RESULTS: The mean LCEA was slightly greater in the noncollapse group than in the collapse group (32° ± 6° versus 28° ± 7°; mean difference 4° [95% CI 1.15° to 6.46°]; p = 0.005); the clinical importance of this small difference is uncertain. There were no differences in PI between the two groups. After accounting for sex, age, BMI, and etiology as confounding factors, as well as acetabular coverage parameters and PI, we found a lower LCEA to be independently associated with increased odds of collapse, although the effect size is small and of questionable importance (OR 1.18 [95% CI 1.06 to 1.33]; p = 0.001). The threshold of LCEA for femoral head collapse was 28° (sensitivity = 0.79, specificity = 0.60, area under the curve = 0.73). The percentage of patients with an LCEA less than 28° was larger in JIC Type C1 (OR 6.52 [95% CI 1.64 to 43.83]; p = 0.006) and C2 (OR 9.84 [95% CI 2.34 to 68.38]; p = 0.001) than in patients with both Type A and Type B. The acetabular coverage data for the excluded patients did not differ from those of the patients included in the analysis. CONCLUSION: Our findings suggest that acetabular coverage appears to have little, if any, association with the likelihood of collapse in patients with ONFH. We found a small association between a lower LCEA and a higher odds of collapse, but the effect size may not be clinically important. Factors other than acetabular coverage need to be considered, and if our findings are verified by other investigators, osteotomy is unlikely to have a protective role. As the patients in our study were fairly homogeneous in terms of ethnicity and BMI, these factors need to be further investigated to determine whether they are associated with femoral head collapse in ONFH. LEVEL OF EVIDENCE: Level III, prognostic study.

DOI： 10.1097/CORR.0000000000002363

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: The functional pelvic plane (FPP), which adopts the natural pelvic sagittal tilt in the supine position, is a good reference for determining the cup angle in total hip arthroplasty (THA). However, hip flexion contracture may change pelvic tilt post-operatively by the release of contracture. This study investigated the influence of hip flexion contracture on pelvic sagittal tilt in the supine position. METHODS: This study included 300 patients who underwent primary unilateral THA. We divided the participants into two groups: with preoperative hip extension angle <0° (hip flexion contracture group) and without (non-contracture group). The pelvic sagittal tilt and femoral flexion angle were investigated using computed tomography (CT) or pelvic radiographs performed preoperatively and postoperatively. RESULTS: The femoral flexion angle had significantly reduced postoperatively in the hip flexion contracture group but remained unchanged in the non-contracture group. The preoperative and postoperative pelvic sagittal tilt showed no significant differences between the two groups up to 1 year postoperatively. CONCLUSION: The influence of hip flexion contracture on the pelvic sagittal tilt in the supine position was minimal. The FPP in the supine position could be a good reference to ascertain the cup orientation, even in hip flexion contracture cases.

DOI： 10.1093/mr/roac110

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Language：Japanese   Publisher：(公社)日本整形外科学会  

人工知能の医療への応用範囲は,疾患診断,予後予測,発症リスク評価,治療法選択と幅広い.整形外科においては画像診断を中心に2019年以降報告が増え,股関節外科領域においても近年報告が増えている.単純X線画像診断では,大腿骨頸部骨折,変形性股関節症,大腿骨頭壊死症診断,インプラント機種推定などが報告されている.予後予測としては変形性股関節症の進行予測,人工関節感染の洗浄掻爬術の成功率予測,THA(total hip arthroplasty)の機能予測や,短期合併症予測,入院期間予測,股関節鏡術後の機能予測,大腿骨頸部骨折後の骨頭壊死症の発生予測,大腿骨近位部骨折後の死亡予測をするAI(artificial intelligence)が報告されている.三次元画像ではCT(computed tomography)での大腿骨カム変形の自動検出,delayed gadolinium-enhanced MRI(magnetic resonance imaging)での軟骨自動抽出などが報告されている.われわれは,CTデータから筋骨格モデルを抽出するAIを開発し,骨格では表面距離誤差0.1mm,筋肉では表面距離誤差0.9mmの精度を達成した.術後CT画像評価のための金属アーチファクト低減,CT/MRI画像変換,単純X線骨盤正面像からの三次元筋骨格構造の再現などにも取り組んでいる.(著者抄録)

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：Japanese   Publisher：(一社)日本関節病学会  

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Cup orientation in THA in the supine, standing, and sitting positions is affected by pelvic sagittal tilt (PT). Patterns of PT shift between these positions may increase the risk of dislocation and edge loading. The PT has also been reported to change during the aging process; however, there is limited research regarding long-term changes in PT and PT shifts after THA. QUESTIONS/PURPOSES: (1) What changes occur in PT in the supine, standing, and sitting positions during 20 years of follow-up after THA in patients who have not had revision or dislocation? (2) What factors are associated with the differences between preoperative supine PT and postoperative sitting or standing PT (Δ sitting and Δ standing, respectively) 20 years postoperatively? METHODS: Between January 1998 and December 1999, 101 consecutive patients underwent THA for appropriate indications. AP radiographs of the pelvis in the supine, standing, and sitting positions preoperatively and at 1, 10, and 20 years after THA were longitudinally performed to evaluate changes in PT. Fifty-nine percent (60 of 101) of patients were lost before 20 years of follow-up or had incomplete sets of imaging tests, leaving 41% (41 of 101) eligible for analysis here. There were no patients who had recurrent dislocation or underwent revision arthroplasty in the cohort; therefore, this analysis regarding postoperative changes in PT indicates the natural course of the change in PT during follow-up of THA. PT was measured based on the anterior pelvic plane. PT shifts with positional changes, Δ standing, and Δ sitting during the follow-up period were calculated. Posterior changes and shifts are represented by negative values. To analyze the factors associated with Δ standing and Δ sitting after 20 years, the correlations between these parameters and preoperative factors (including sex, age, pelvic incidence [PI], lumbar lordosis [LL], preoperative PT, and preoperative PT shift) and postoperative factors (including the occurrence of new lumbar vertebral fractures, lumbar spondylolisthesis, contralateral THA) performed during follow-up, and PI-LL 20 years after THA were determined. RESULTS: Median (IQR) supine and standing PTs changed (moved posteriorly) by -5° (-11° to -2°; p < 0.01) and -10° (-15° to -7°; p < 0.01), respectively. Sitting PT did not change during the 20-year follow-up period. Median (IQR) PT shift from standing to sitting changed from -34° preoperatively (-40° to -28°) to -23° after 20 years (-28° to -20°). There were posterior changes in median (range) Δ standing (median -12° at 20 years [-19° to -7°]); Δ sitting did not change during the follow-up period (median -36° at 20 years [-40° to -29°]). Patients with a large preoperative posterior PT shift from supine to standing demonstrated larger posterior tilt of Δ standing at 20 years. Patients with lumbar vertebral fractures during follow-up demonstrated larger posterior tilt of Δ standing at 20 years. CONCLUSION: Patients who demonstrate a large preoperative posterior shift from supine to standing deserve special consideration when undergoing THA. In such circumstances, we recommend that the anteversion of the cup not be excessive, given that there is a relatively high risk of further posterior tilt in PT, which may lead to anterior dislocation and edge loading. Further longitudinal study in a larger cohort of patients with complications including postoperative dislocation and revision, as well as older patients, is needed to verify these assumptions on the potential risk for dislocation and edge loading after THA. LEVEL OF EVIDENCE: Level III, therapeutic study.

DOI： 10.1097/CORR.0000000000002382

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Language：Japanese   Publisher：(一社)日本筋学会  

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Language：Japanese   Publisher：(一社)日本骨粗鬆症学会  

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Language：English   Publishing type：Research paper (scientific journal)  

While accurate measurement of bone mineral density (BMD) is essential in the diagnosis of osteoporosis and in evaluating the treatment of osteoporosis, it is unclear how region of interest (ROI) settings affect measurement of BMD at the total proximal femur region. In this study, we performed a simulation analysis to clarify the effect on BMD measurement of changing the ROI using hip computed tomography (CT) images of 75 females (mean age, 62.4 years). Digitally reconstructed radiographs of the proximal femur region were generated from CT images to calculate the change in BMD when the proximal boundary of the ROI was altered by 0-10 mm, and when the distal boundary of the ROI was altered by 0-30 mm. Further, changes in BMD were compared across BMD classification groups. A mean BMD increase of 0.62% was found for each 1-mm extension of the distal boundary. A mean BMD decrease of 0.18% was found for each 1-mm alteration of the proximal boundary. Comparing BMD classification groups, patients with osteoporosis and osteopenia demonstrated greater BMD changes than patients with normal BMD for the distal boundary (0.68%, 0.64%, and 0.54%, respectively) and patients with osteoporosis demonstrated greater BMD changes than patients with osteoporosis and normal BMD for the proximal boundary (0.37%, 0.13%, and 0.03%, respectively). In conclusion, our study found that a consistent ROI setting, especially on the distal boundary, is necessary for the accurate measurement of total proximal femur BMD. Based on the findings, we recommend confirming that the ROI setting shown on the BMD result form is consistent with changes in serial BMD.

DOI： 10.1007/s00223-022-01012-9

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Language：Japanese   Publisher：(一社)日本医用画像工学会  

人体に忠実な全身骨格モデルは,人体の骨格構造解析や動作解析において重要である.現在,骨格の表現方法の一つとして,複数人の臓器の形状データを統計的に解析した統計形状モデル(SSM)が用いられている.しかし,従来研究では一部の骨格形状のみのSSMを構築しており,全身骨格の構築は行われていない.そのため,我々は日本医学放射線学会が収集しているJ-MIDデータベースと,共同研究施設で収集する4万症例以上の大規模なCTデータベースを用いた全身骨格のSSM構築を目指している.本研究ではその第一歩として,下肢(骨盤から足部まで)の大規模CT画像データベースから骨格上のランドマークを抽出し,そのランドマークを用いて下肢骨格の解析を行った.下肢のランドマークデータを年齢・性別ごとに分け,骨格形状の加齢変化について調査を行ったので報告する.(著者抄録)

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Language：English   Publishing type：Research paper (scientific journal)  

This study used a rabbit model to investigate the osteocompatibility of Si3N4-coated carbon fiber-reinforced polyetheretherketone (CFRP) and hydroxyapatite (HA)-coated CFRP with antibiotics (vancomycin [VCM]) and antithrombotic drugs (polyvinylpyrrolidone [PVP]). HA-coated cylindrical CFRP implants were used as the controls (HA), and HA-coated implants treated with VCM and PVP were prepared (HA-VP) as the test groups; a cylindrical CFRP coated with Si3N4 was also prepared (SiN). Ten implants from each group were randomly inserted into the femoral diaphysis of rabbits. The pull-out test, radiological analysis using micro-computed tomography (µ-CT), and histological analysis were performed. The pull-out strength of the SiN group was lower than that of the HA group. µ-CT analysis revealed that the amount of bone formation around the implant in the SiN group was inferior to that in the HA group. Conversely, the HA-VP group had equivalent pull-out strength and bone formation as analyzed by µ-CT compared to the HA group. In conclusion, the additional surface treatment of the HA-coated CFRP with VCM and PVP provided sufficient bone fixation and formation.

DOI： 10.1007/s10047-022-01340-5

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：English   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(株)南江堂  

＜文献概要＞はじめに 世界保健機関(WHO)および多くのガイドラインは,骨粗鬆症や骨量減少の診断の際にdual-energy X-ray absorptiometry(DXA)を用い腰椎,大腿骨近位部の骨密度を計測することを推奨している.骨粗鬆症とそれに続発する脆弱性骨折の予防は高齢者の日常生活動作(ADL)の維持に重要な役割をはたすものの,骨粗鬆症自体には一般に症状がないために骨密度測定の機会を逸し,診断が正しく行われない症例も多い.そのため,近年では骨粗鬆症や骨量減少が正しく診断できるようにDXA以外の装置を用いて骨密度を計測し,診断の機会を向上させる試み(opportunistic screening)がなされてきた.本稿では臨床用に撮影されたCTから骨密度を計測する手法(quantitative CT:QCT)による大腿骨近位部の計測を中心に現状と課題に関して報告する.

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Other Link： https://search.jamas.or.jp/default/link?pub_year=2022&ichushi_jid=J00764&link_issn=&doc_id=20220527300011&doc_link_id=10.15106%2Fj_seikei73_557&url=https%3A%2F%2Fdoi.org%2F10.15106%2Fj_seikei73_557&type=%E5%8C%BB%E6%9B%B8.jp_%E3%82%AA%E3%83%BC%E3%83%AB%E3%82%A2%E3%82%AF%E3%82%BB%E3%82%B9&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00024_2.gif

Language：Japanese   Publisher：(株)南江堂  

＜文献概要＞はじめに 医療における人工知能(AI)に対する期待は高まる一方である.自動診断や予後予測による医療の効率化に加え,大量の診療データの自動解析による新しい医学的発見が期待されており,AIを利用した医学論文は指数関数的に増えている.整形外科においても,まだ数は少ないがAIを活用した論文報告が増えている.CTやMRIなどの三次元画像解析は時間を要する作業で,実臨床での応用や大量のデータの解析には限界があり,AI技術の応用が期待される領域である.AI技術を用いてCTやMRIから筋骨格モデルを抽出することができれば,手術計画や骨形態計測,骨格アライメント計測,筋肉の定量評価,生体力学計算に活用することが可能である.従来抽出が困難であった個別筋肉の抽出を行い,より精密な筋骨格評価が可能となりつつある.

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Other Link： https://search.jamas.or.jp/default/link?pub_year=2022&ichushi_jid=J00764&link_issn=&doc_id=20220527300043&doc_link_id=10.15106%2Fj_seikei73_721&url=https%3A%2F%2Fdoi.org%2F10.15106%2Fj_seikei73_721&type=%E5%8C%BB%E6%9B%B8.jp_%E3%82%AA%E3%83%BC%E3%83%AB%E3%82%A2%E3%82%AF%E3%82%BB%E3%82%B9&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00024_2.gif

Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVES: The magnitude of femoral head collapse (MFHC) is one of the criteria for staging osteonecrosis of the femoral head (ONFH). The present study aimed to clarify the relationship between MFHC and hip pain or functional quality of life (QOL) scores in patients with ONFH. METHODS: Seventy patients with ONFH who had femoral head collapse without osteoarthritic changes were divided into four groups based on MFHC by 1 mm. Pain was assessed using the visual analogue scale (VAS). QOL was evaluated using patient-reported outcome measures, such as the Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ), Oxford Hip Score (OHS), and Short Form-12 Health Survey, version 2 (SF-12v2). We also explored the relationship between MFHC and QOL. RESULTS: Pain score and satisfaction score in the VAS, JHEQ pain subscale, JHEQ movement subscale, and JHEQ total score were significantly associated with MFHC, and no significant differences were found between groups in any subscale or total score for OHS and SF-12v2. CONCLUSION: In patients with ONFH, differences in MFHC by 1 mm were associated with deterioration of some pain VAS and QOL outcomes.

DOI： 10.1093/mr/roac023

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(一社)日本リウマチ学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(NPO)日本CT検診学会  

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Language：Japanese   Publisher：(株)メジカルビュー社  

＜文献概要＞寛骨臼骨折後の外傷性股関節症に対する人工股関節全置換術は,偽関節や骨欠損,金属プレートやスクリューの存在,軟部組織癒着などの状態が症例により異なり,手術の難易度の幅が広い。CTを撮影し3次元計画を立案することが望ましい。特に寛骨臼の上下で骨盤が不連続となったpelvic discontinuityになっていないかの確認が重要である。再THAと寛骨臼骨折骨接合術の両方の知識と技術を要する場合があり,術者の経験が少ないときは両方に精通する医師に相談することも重要である。

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Other Link： https://search.jamas.or.jp/default/link?pub_year=2022&ichushi_jid=J00282&link_issn=&doc_id=20220126080017&doc_link_id=%2Fap4kange%2F2022%2F004102%2F016%2F0200-0205%26dl%3D0&url=https%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Fap4kange%2F2022%2F004102%2F016%2F0200-0205%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

Language：English   Publishing type：Research paper (scientific journal)  

Commercial software is generally needed to measure the areal bone mineral density (aBMD) of the proximal femur from clinical computed tomography (CT) images. This study developed and verified an open-source reproducible system to quantify CT-aBMD to screen osteoporosis using clinical CT images. PURPOSE: For existing CT images acquired for various reasons other than osteoporosis, it might be beneficial to estimate areal BMD as assessed by dual-energy X-ray absorptiometry (DXA-based BMD) to ascertain the bone status based on DXA. In this study, we aimed to (1) develop an open-source reproducible measurement system to quantify DXA-based BMD from CT images and (2) validate its accuracy. METHODS: This study analyzed 75 pairs of hip CT and DXA images of women that were acquired for the preoperative assessment of total hip arthroplasty. From the CT images, the femur and a calibration phantom were automatically segmented using pre-trained codes/models available at https://github.com/keisuke-uemura . The proximal femoral region was isolated by manually selected landmarks and was projected onto the coronal plane to measure the areal density (CT-aHU). The calibration phantom was employed to convert the CT-aHU into CT-aBMD. Each parameter was correlated with DXA-based BMD, and the residual errors of CT images to estimate the T-scores in DXA were calculated using the standard error of estimate (SEE). RESULTS: The correlation coefficients of DXA-based BMD with CT-aHU and CT-aBMD were 0.947 and 0.950, respectively (both p < 0.001). The SEE for quantifying the T-scores in DXA were 0.51 and 0.50 for CT-aHU and CT-aBMD, respectively. CONCLUSION: With the method developed herein, CT permits estimation of the DXA-based BMD of the proximal femur within the standard DXA total hip region of interest with an SEE of 0.5 in T-scores. The radiation dose for CT acquisition needs consideration; therefore, our data do not provide a rationale for performing CT for screening osteoporosis. However, on CT images already acquired for clinical indications other than osteoporosis, researchers may use this open-source system to investigate osteoporosis status through the estimated DXA-based BMD of the proximal femur.

DOI： 10.1007/s11657-022-01063-3

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Publishing type：Research paper (scientific journal)  

DOI： 10.48550/arXiv.2207.03210

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Publishing type：Research paper (international conference proceedings)   Publisher：Springer  

DOI： 10.1007/978-3-031-16446-0_61

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Other Link： https://dblp.uni-trier.de/db/conf/miccai/miccai2022-6.html#GuOUSTSS22

Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

AIMS: Pelvic incidence (PI) is considered an important anatomical parameter for determining the sagittal balance of the spine. The contribution of an abnormal PI to hip osteoarthritis (OA) remains controversial. In this study, we aimed to investigate the relationship between PI and hip OA, and the difference in PI between hip OA without anatomical abnormalities (primary OA) and hip OA with developmental dysplasia of the hip (DDH-OA). METHODS: In this study, 100 patients each of primary OA, DDH-OA, and control subjects with no history of hip disease were included. CT images were used to measure PI, sagittal femoral head coverage, α angle, and acetabular anteversion. PI was also subdivided into three categories: high PI (larger than 64.0°), medium PI (42.0° to 64.0°), and low PI (less than 42.0°). The anterior centre edge angles, posterior centre edge angles, and total sagittal femoral head coverage were measured. The correlations between PI and sagittal femoral head coverage, α angle, and acetabular anteversion were examined. RESULTS: No significant difference in PI was observed between the three groups. There was no significant difference between the groups in terms of the category distribution of PI. The DDH-OA group had lower mean sagittal femoral head coverage than the other groups. There were no significant correlations between PI and other anatomical factors, including sagittal femoral head coverage, α angle, and acetabular anteversion. CONCLUSION: No associations were found between mean PI values or PI categories and hip OA. Furthermore, there was no difference in PI between patients with primary OA and DDH-OA. From our evaluation, we found no evidence of PI being an independent factor associated with the development of hip OA. Cite this article: Bone Joint J 2021;103-B(11):1656-1661.

DOI： 10.1302/0301-620X.103B11.BJJ-2021-0472.R1

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVES: Osteonecrosis of the femoral head (ONFH) is a designated intractable disease (DID) in Japan. The Ministry of Health, Labour, and Welfare launched an online registry system for DIDs. We aimed to investigate the epidemiological characteristics of patients with ONFH using the DID database. METHODS: Data of patients with ONFH registered in the DID database between January 2004 and December 2013 were extracted. The incidence of new cases and distributions of sex, age, and associated risk factors were investigated. The prevalence of the two categories, 'steroid-associated' and 'alcohol-associated' risk factors, was estimated for each prefecture. RESULTS: New 15,049 cases of ONFH were investigated. The mean registration rate-corrected annual ONFH incidence per 100,000 individuals was 1.77. The male-to-female ratio was 1.33. Age distribution peaked in the 40s and 50s for male and 60s for female. The prevalence of steroid-associated ONFH was lower in males (28.6%) than in females (49.8%), while that of alcohol-associated ONFH was higher in males (47.2%) than in females (9.3%). No clear region was identified for the steroids. The incidence of alcohol-associated ONFH was significantly higher in Tokyo and Okinawa, regardless of sex. CONCLUSIONS: Alcohol-associated ONFH incidence varies geographically across Japan, suggesting that it has regional characteristics.

DOI： 10.1093/mr/roab065

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Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVES: The CentPillar stem (Stryker Orthopaedics), an anatomical short stem, was designed to match the proximal femoral canal shape in both patients with normal hips and those with developmental dysplasia of the hip (DDH). The long-term outcomes of the CentPillar stem was examined herein. METHODS: In total, 222 hips that underwent total hip arthroplasty using the CentPillar stem were analyzed. DDH was the main reason for surgery (79.3%). Implant survivorship was assessed using Kaplan-Meier analysis. For radiographic evaluation, stress shielding was assessed using the Engh classification. For functional evaluation, patients' ability to perform deep hip bending activities (sit on the floor, squat, and sit straight) was assessed. RESULTS: During a median follow-up of 13.1 years, 2 stem revisions were performed (aseptic loosening and late hematogenous periprosthetic infection), and the overall cumulative implant survival rate was 99.0% at 15 years. In the radiographic evaluation, grade >3 stress shielding was found in only one hip. More than 80% of the patients were able to perform each of the three deep hip bending activities. CONCLUSIONS: Good fixation at the proximal part of the femur was obtained, and the implant survival rate of the CentPillar stem was excellent during a long-term follow-up.

DOI： 10.1080/14397595.2020.1868129

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Language：Japanese   Publisher：(一社)日本骨粗鬆症学会  

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OBJECTIVES: We aimed to investigate the epidemiological characteristics of osteonecrosis of the femoral head (ONFH) using the designated intractable diseases (DID) database in Japan. METHODS: Data on patients who had received public subsidies for medical costs due to ONFH from 2012 to 2013 were extracted from the DID database. The incidence and prevalence of ONFH, distribution of gender, age, and the prevalence of associated risk factors were assessed. These epidemiological characteristics were compared with those of another nationwide ONFH survey conducted during a similar period. RESULTS: Data on 3264 newly diagnosed patients (incident cases) and 20,042 patients registered until 2013 (prevalent cases) were evaluated. The corrected annual incidence and prevalence of ONFH per 100,000 were 3.0 and 18.2-19.2, respectively. The ratio of males to females was 1.4 in 2012 and 1.2 in 2013, respectively. Peak distribution was observed at ages 40s and 60s in males and females, respectively. The prevalence of the risk factors were steroid-associated: 39%, alcohol-associated: 30%, both: 4%, and none: 27%. CONCLUSIONS: The DID database data showed a similar distribution of gender and age to that in other nationwide surveys but lower incidence and prevalence of ONFH. Sampling bias may affect the epidemiological characteristics of ONFH.

DOI： 10.1093/mr/roab047

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Language：Japanese   Publisher：(株)医学書院  

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Other Link： https://search.jamas.or.jp/default/link?pub_year=2021&ichushi_jid=J01554&link_issn=&doc_id=20210813090020&doc_link_id=10.11477%2Fmf.1408202121&url=https%3A%2F%2Fdoi.org%2F10.11477%2Fmf.1408202121&type=%E5%8C%BB%E6%9B%B8.jp_%E3%82%AA%E3%83%BC%E3%83%AB%E3%82%A2%E3%82%AF%E3%82%BB%E3%82%B9&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00024_2.gif

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INTRODUCTION: To evaluate the advantages of a carbon fiber-reinforced polyetheretherketone (CFR/PEEK) intramedullary nail on the diagnosis of fracture healing because of its radiolucency, we retrospectively reviewed radiographs and computed tomography (CT) images of trochanteric femoral fractures that underwent internal fixation with the CFR/PEEK intramedullary nail or a traditional metallic intramedullary nail. METHODS: Radiographs and CT images from 20 patients with intertrochanteric femoral fractures treated with a CFR/PEEK intramedullary nail and 20 similar patients treated with a metallic intramedullary nail were reviewed. After division of the intertrochanteric region into three zones on anteroposterior and lateral views of the radiographs, the visibilities of the fracture site, fracture line, and bone formation were evaluated in each zone. A three-grade assessment for existence of scattering and effect of scattering on diagnosis of the surrounding bone was performed on three axial slices of the CT images. RESULTS: In the CFR/PEEK group, the fracture site was visible in all zones for all cases except for the posterior zone on the lateral view in one case. In the cranial and middle zones on anteroposterior views and the middle zone on lateral views of the radiographs, the visible fracture site rates in the CFR/PEEK group were significantly higher than those in the metal group. The grades for existence of scattering and effect of scattering on diagnosis of surrounding bone on the CT images were significantly lower in the CFR/PEEK group compared with the metal group. CONCLUSION: Superior fracture site visibility on radiographs was demonstrated in cases treated with the CFR/PEEK intramedullary nail compared with cases treated with the traditional metallic intramedullary nail, thereby confirming the advantages of the CFR/PEEK intramedullary nail for evaluation of fracture reduction and bone formation. The CFR/PEEK nail evoked little scattering on CT images, leading to higher diagnostic values for the peri-prosthetic cancellous and cortical bone compared with the metallic nail.

DOI： 10.1016/j.injury.2021.03.048

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Language：Japanese   Publisher：日本股関節学会  

大腿骨転子部骨折に対し、炭素線維強化PEEK樹脂複合材(CFR/PEEK)を用いた大腿骨近位部固定ネイルで骨接合術を行った20例(A群)と、金属ネイルで骨接合術を行い、A群と年齢、性別、BMI、骨折型が同等の20例(B群)を対象とした。術後3ヵ月で撮像した股関節CTをコンピューターソウトウェアを用いてインプラント軸を基準に座標系を統一し、ラグスクリュー・ネイル接合部、2cm上下方高位での横断像で金属散乱線に阻害されない骨・軟部・インプラントの視認性を群間比較した。その結果、A群はX線CTでの診断特性が良好で、ラグスクリュー・ネイル接合部より2cm下方では、全例で金属散乱線の影響がなかった。また、同一横断面にラグスクリューとネイルが存在する接合部付近においての視認性が特に優れていた。CFR/PEEKネイルは金属ネイルに比べ、X線CTでの診断特性が良好と考えられた。

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Language：Japanese   Publisher：日本股関節学会  

大腿骨転子部骨折に対し、炭素線維強化PEEK樹脂複合材(CFR/PEEK)を用いた大腿骨近位部固定ネイルで骨接合術を行い、術後半年に骨癒合を獲得できなかった2例を対象とした。臨床評価としてHarris hip score、NRS、骨癒合獲得時期、X線学的評価、合併症(インプラント破損やカットアウト)を調査した。手術時年齢は平均82歳で、全例が女性であった。骨折型は全例がAO-OTA分類の不安定型であった。その結果、2例とも最終的に10〜24ヵ月に骨癒合を獲得できた。術後1ヵ月以降のラグスクリューのテレスコープを認めず、経過観察期間中に骨折部の転位、カットアウト、インプラントの変形・破損も生じなかった。術後経過および最終観察時においても疼痛や活動制限はなかった。CFR/PEEKインプラントは最長24ヵ月の骨癒合不全の状態で荷重条件下でも、ネイルが疲労破綻することなく骨癒合を獲得でき、優れた耐疲労特性があると考えられた。

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: We investigated the accuracy of the acetabular cup position and orientation in robotic-assisted total hip arthroplasty (rTHA) compared to navigated THA (nTHA) using computed tomography (CT) for patients with osteoarthritis secondary to developmental dysplasia of the hip (DDH). METHODS: We studied 31 hips of 28 patients who underwent rTHA and 119 hips of 112 patients who underwent nTHA with the same target cup orientation. After propensity score matching, each group comprised 29 hips. Post-operative cup position and orientation were measured from the postoperative CT data. Errors from the target cup position and orientation were compared between the two groups. RESULTS: Post-operatively, the absolute error of the anteroposterior and superoinferior cup positions from the target position was significantly lower in the rTHA group than in the nTHA group. The change in the post-operative radiographic inclination from the target orientation was lower in the rTHA group than in the nTHA group. Screw fixation for cup implantation was required for three hips in the nTHA group but not in the rTHA group. CONCLUSION: rTHA achieved more precise cup implantation with reduced variation from the target orientation compared to nTHA in patients with osteoarthritis secondary to DDH.

DOI： 10.1007/s00264-021-05015-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

BACKGROUND: This study aimed to compare the clinical and radiographic outcomes of using two different oversized rasps in total hip arthroplasty (THA) with a composite beam cemented stem (DCM-J). METHODS: A consecutive series of 105 hips underwent hybrid THA using the DCM-J stem between 2006 and 2010. Among the patients with a minimum 10-year follow-up, a 1.5-mm oversized rasp was used in 38 hips (group S), whereas a 0.5-mm oversized rasp was used in 36 hips (group M). The Japanese Orthopedic Association hip score and radiographic findings were evaluated, including cement mantle thickness, stress shielding, and cortical hypertrophy. RESULTS: The Japanese Orthopedic Association hip score was significantly improved postoperatively with 100% of the implant survival rate in both groups when septic loosening was excluded. Radiographic assessment performed immediately postoperatively revealed that the cement mantle thickness was significantly larger in group M than group S in Gruen zone 1 but did not differ between groups in zones 2-7. Stress shielding was significantly more frequent in group M than group S at 2 years (P = .011), 5 years (P = .012), and ≥10 years postoperatively (P = .038). Cortical hypertrophy appeared in a time-dependent manner; however, the prevalence did not significantly differ between groups at final follow-up at a mean of 11.7 years (range 10-14 years) postoperatively. CONCLUSIONS: The DCM-J stem achieved good clinical results in both groups. Stress shielding was significantly more frequent in THA using the 0.5-mm rasp than the 1.5-mm rasp, indicating that sufficient cement mantle room should be prepared for the cemented stem.

DOI： 10.1016/j.arth.2021.01.044

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Language：English   Publishing type：Research paper (scientific journal)  

Aim: This study aimed to evaluate the 2-year outcomes from a clinical trial of recombinant human FGF-2 (rhFGF-2) for osteonecrosis of the femoral head (ONFH). Patients & methods: Sixty-four patients with nontraumatic, precollapse and large ONFHs were percutaneously administered with 800 μg rhFGF-2 contained in gelatin hydrogel. Setting the end point of radiological collapse, we analyzed the joint preservation period of the historical control. Changes in two validated clinical scores, bone regeneration and safety were evaluated. Results: Radiological joint preservation time was significantly higher in the rhFGF-2 group than in the control group. The ONFHs tended to improve to smaller ONFHs. The postoperative clinical scores significantly improved. Thirteen serious adverse events showed recovery. Conclusion: rhFGF-2 treatment increases joint preservation time with clinical efficacy, radiological bone regeneration and safety.

DOI： 10.2217/rme-2021-0049

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OBJECTIVES: Alcohol intake and smoking are modifiable lifestyle-related risk factors for osteonecrosis of the femoral head (ONFH). We investigated geographic differences in ONFH incidence in Japan and the correlation with alcohol intake and smoking to develop prevention strategies for ONFH in Japan. METHODS: This ecological study was conducted in Japan primarily using the following data sources: nationwide epidemiological survey and national survey. We estimated the annual ONFH incidence and the prevalence of alcohol drinking and smoking in each prefecture. Prefectural incidence and prevalence were calculated by sex and age-standardization. RESULTS: The mean annual ONFH incidence per 100,000 population was 3.08 in men and 1.63 in women, respectively. There was no significant correlation between ONFH incidence and the prevalence of any levels of alcohol intake, while smoking ≥20 cigarettes/day showed a significant and moderate correlation in men (r = 0.47, p = .01). This correlation remained significant after adjustment for the prevalence of any levels of alcohol intake (standardized partial regression coefficient = 0.47-0.49, p = .009-.01). CONCLUSION: ONFH incidence is geographically variable in Japan, and this may be partly explained by the distribution of smoking prevalence. Smoking cessation may contribute to an effective decline in the overall ONFH incidence in Japan.

DOI： 10.1080/14397595.2021.1899452

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Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVES: Alcohol intake and smoking are modifiable lifestyle-related risk factors for osteonecrosis of the femoral head (ONFH). We investigated geographic differences in ONFH incidence in Japan and the correlation with alcohol intake and smoking to develop prevention strategies for ONFH in Japan. METHODS: This ecological study was conducted in Japan primarily using the following data sources: nationwide epidemiological survey and national survey. We estimated the annual ONFH incidence and the prevalence of alcohol drinking and smoking in each prefecture. Prefectural incidence and prevalence were calculated by sex and age-standardization. RESULTS: The mean annual ONFH incidence per 100,000 population was 3.08 in men and 1.63 in women, respectively. There was no significant correlation between ONFH incidence and the prevalence of any levels of alcohol intake, while smoking ≥20 cigarettes/day showed a significant and moderate correlation in men (r = 0.47, p = .01). This correlation remained significant after adjustment for the prevalence of any levels of alcohol intake (standardized partial regression coefficient = 0.47-0.49, p = .009-.01). CONCLUSION: ONFH incidence is geographically variable in Japan, and this may be partly explained by the distribution of smoking prevalence. Smoking cessation may contribute to an effective decline in the overall ONFH incidence in Japan.

DOI： 10.1080/14397595.2021.1899452

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: In quantitative computed tomography (CT), manual selection of the intensity calibration phantom's region of interest is necessary for calculating density (mg/cm3) from the radiodensity values (Hounsfield units: HU). However, as this manual process requires effort and time, the purposes of this study were to develop a system that applies a convolutional neural network (CNN) to automatically segment intensity calibration phantom regions in CT images and to test the system in a large cohort to evaluate its robustness. METHODS: This cross-sectional, retrospective study included 1040 cases (520 each from two institutions) in which an intensity calibration phantom (B-MAS200, Kyoto Kagaku, Kyoto, Japan) was used. A training dataset was created by manually segmenting the phantom regions for 40 cases (20 cases for each institution). The CNN model's segmentation accuracy was assessed with the Dice coefficient, and the average symmetric surface distance was assessed through fourfold cross-validation. Further, absolute difference of HU was compared between manually and automatically segmented regions. The system was tested on the remaining 1000 cases. For each institution, linear regression was applied to calculate the correlation coefficients between HU and phantom density. RESULTS: The source code and the model used for phantom segmentation can be accessed at https://github.com/keisuke-uemura/CT-Intensity-Calibration-Phantom-Segmentation . The median Dice coefficient was 0.977, and the median average symmetric surface distance was 0.116 mm. The median absolute difference of the segmented regions between manual and automated segmentation was 0.114 HU. For the test cases, the median correlation coefficients were 0.9998 and 0.999 for the two institutions, with a minimum value of 0.9863. CONCLUSION: The proposed CNN model successfully segmented the calibration phantom regions in CT images with excellent accuracy.

DOI： 10.1007/s11548-021-02345-w

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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AIMS: Alcohol intake is one of the factors associated with the occurrence of osteonecrosis of the femoral head (ONFH), and its epidemiological information regarding alcohol intake depends on patients' self-reports. Therefore, we analysed the efficacy of laboratory tests as an objective diagnostic tool to indicate habitual drinking in patients with alcohol-associated ONFH. METHODS: This study included 109 consecutive patients diagnosed with ONFH who underwent primary hip surgery in our institution between 2010 and 2018. The patients were classified into group AL (alcohol-associated ONFH; n = 26) and group NO (alcohol-unassociated ONFH; n = 83), based on their self-reported information. Serum levels of gamma-glutamyl transferase (GGT), mean corpuscular volume (MCV), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol and triglycerides were compared between both groups. The sensitivities and specificities with the optimal cut-off values for detecting alcohol-associated ONFH were compared among these markers. RESULTS: The median serum levels of GGT, AST and ALT were significantly higher in the AL group than in the NO group. The receiver operating characteristic curve analysis demonstrated an area under the curve of 0.795 for GGT, 0.731 for AST and 0.709 for ALT. The optimal cut-off level of GGT as a marker for alcohol-associated ONFH was 36.5 units/L, with a sensitivity of 76% and specificity of 80%, and it was found to be the best marker among the other examined laboratory markers. CONCLUSION: Serum GGT level is a useful laboratory marker with moderate accuracy that indicates habitual drinking in patients with alcohol-associated ONFH.

DOI： 10.1093/alcalc/agaa117

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Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVES: This study aimed to investigate differences in lower limb alignment and the prevalence of knee osteoarthritis (OA) among patients with primary hip osteoarthritis (PHOA) versus those with hip osteoarthritis secondary to developmental dysplasia of the hip (DDH-OA). METHODS: We compared 83 patients who underwent primary total hip arthroplasty for unilateral PHOA or DDH-OA after performing propensity score matching. The prevalence of knee OA and lower limb alignment were evaluated on preoperative plain radiographs. RESULTS: The prevalence of knee OA on the ipsilateral side was significantly higher in the PHOA group than in the DDH-OA group (p =.019), whereas there was no difference between the groups on the contralateral side (p = .631). Lower-limb alignment was more valgus on the ipsilateral side in the DDH-OA group than the PHOA group, whereas it was not significantly different on the contralateral side between groups. CONCLUSION: The prevalence of knee OA and lower-limb malalignment on the ipsilateral side of hip OA were different for PHOA and DDH-OA patients. Shifting the mechanical axis of lower limbs might be associated with the prevalence of knee OA and lower limb malalignment in the presence of unilateral hip OA.

DOI： 10.1080/14397595.2021.1883261

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Coronal hip contracture induces pelvic obliquity in the presence of hip osteoarthritis (HOA), followed by the functional leg-length discrepancy. To promote accurate diagnosis of contracture and proper management of soft tissue release in total hip arthroplasty (THA), this study aimed to clarify the morphological features on plain radiographs that are related to contracture in patients with HOA. Two hundred forty-three hips of 231 patients with HOA who underwent primary THA were included in this study. Preoperative pelvic radiographs of the bilateral hips in maximum adduction and abduction were used to quantify contracture. Patients were grouped according to their contracture as having abduction contracture, adduction contracture, or minimal contracture. We investigated HOA, subluxation, anatomical factors, spinal factors, and the morphology of osteophytes at the inferomedial femoral head and compared parameters among groups to clarify the predictors of contracture. Eighteen hips (7.6%) were classified as having adduction contracture and 23 (9.4%) as having abduction contracture. Crowe classification, leg-length discrepancy, and osteophyte morphology showed significant correlations with adduction contracture. Factors significantly correlated with abduction contracture were offset difference, pelvic obliquity, functional femoral anteversion, and osteophyte morphology. Multivariate logistic regression analysis showed that the factor most strongly related to adduction contracture was Crowe III classification, whereas the strongest predictor of abduction contracture was osteophyte morphology. In conclusion, hip subluxation was related to the adduction contracture of the hip, whereas osteophyte morphology was related to abduction contracture.

DOI： 10.1002/jor.24891

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Language：Japanese   Publisher：日本医用画像工学会  

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Language：English   Publisher：日本医用画像工学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：日本医用画像工学会  

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Language：Japanese   Publisher：日本医用画像工学会  

新学術領域「多元計算解剖学」A01-3班:多元計算解剖学における機能情報統合の基盤技術においては,運動器機能解析を目指した筋骨格計算解剖モデルの開発を行った.本プロジェクトでは,医学・バイオメカニクス・スポーツ科学を含む,さまざまな運動器科学領域での応用を目的とし,医用画像に基づいた被験者個別の筋骨格解剖を忠実に再現したモデルを簡便かつ高精度に構築する手法を検討した.本稿では,プロジェクトの成果である1)深層学習を用いた筋骨格セグメンテーション,2)CT-MRIモダリティー変換,3)X線画像とCT画像の位置合わせによる骨格運動・姿勢推定,4)高精細遺体凍結画像と臨床画像の統合による筋線維走行推定,について紹介する.(著者抄録)

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2020&ichushi_jid=J02087&link_issn=&doc_id=20200728050005&doc_link_id=10.11409%2Fmit.38.108&url=https%3A%2F%2Fdoi.org%2F10.11409%2Fmit.38.108&type=J-STAGE&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00007_2.gif

Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

Total hip arthroplasty (THA) is often required to decrease the excessive anatomical femoral anteversion (AA) in developmental dysplasia of the hip. Studies have recommended decreasing the AA via the use of a retroverted modular neck. However, hip rotation after THA may strengthen or weaken the effect of changing the AA. Thus, the present study analyzed the effect of a retroverted neck on AA and hip rotation. Patients who underwent THA using a straight neck (ST group) or a 15° retroverted neck (RV group) in a version changeable dual modular system (Mainstay stem, Kyocera, Kyoto, Japan) were retrospectively reviewed. After matching for age, body mass index, and surgical approach, 44 patients were included in each group. The AA and hip rotation (femoral rotational angle: FRA) were measured on CT images acquired preoperatively and 1 month after THA, and were compared between the groups. The mean ± standard deviation preoperative AA of the ST group (26.1 ± 10.7°) was significantly smaller than that of the RV group (44.2 ± 7.8°) (p < 0.001). In contrast, the postoperative AA did not significantly differ between the groups (ST group 27.5 ± 9.8°, RV group 25.1 ± 8.3°, p = 0.406). The change in FRA after THA did not significantly differ between the groups (ST group - 3.8 ± 9.9°, RV group - 3.5 ± 9.1°, p = 0.841). In conclusion, a 15° retroverted neck was useful in controlling AA in hips with excessive AA, and the change in FRA after THA did not differ between the ST group and the RV group.

DOI： 10.1007/s10047-020-01162-3

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Language：Japanese   Publisher：金原出版(株)  

＜文献概要＞炭素繊維強化樹脂(CFRP)は,高い強度で剛性を下げられ,優れた耐疲労特性,X線透過性から,金属に代わる骨折治療用具の材料として期待されている。生体適合性に優れたpolyetheretherketone(PEEK)が樹脂材料の主流で,海外ではCFR-PEEK製の骨折治療用具が既に臨床応用されている。本邦でもCFR-PEEK製髄内釘の治験が完了し,本邦初のCFR-PEEK骨折治療用具が臨床応用目前である。

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：金原出版(株)  

＜文献概要＞炭素繊維強化樹脂(CFRP)は,高い強度で剛性を下げられ,優れた耐疲労特性,X線透過性から,金属に代わる骨折治療用具の材料として期待されている。生体適合性に優れたpolyetheretherketone(PEEK)が樹脂材料の主流で,海外ではCFR-PEEK製の骨折治療用具が既に臨床応用されている。本邦でもCFR-PEEK製髄内釘の治験が完了し,本邦初のCFR-PEEK骨折治療用具が臨床応用目前である。

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Language：English   Publishing type：Research paper (scientific journal)  

Pelvic sagittal inclination (PSI) significantly affects the femoral head coverage by the acetabulum in patients with developmental dysplasia of the hip (DDH), while no reports have quantified PSI in DDH patients in the supine and standing positions. Furthermore, little is known about how PSI changes after periacetabular osteotomies. Herein, PSI in the supine and standing positions was quantified in DDH patients preoperatively and postoperatively. Twenty-five patients with DDH who had undergone periacetabular osteotomies were analyzed. The preoperative PSI and the PSI 2 years after surgery were measured in the supine and standing positions using the image registration technique between radiographs and computed tomographic images. The percentage of patients who showed PSI changes of more than 10° from the supine to the standing position was quantified. PSI changed 8.2 ± 5.0° posteriorly from the supine to the standing position during the preoperative period. Posterior pelvic tilt of more than 10° was found in nine cases (36%). Two years after periacetabular osteotomies, the postural PSI change was 7.1 ± 3.9° posteriorly. When the preoperative and postoperative PSI values were compared, PSI in the standing position did not differ (p = 0.20). Similarly, the amount of PSI change from the supine to standing position was not significantly different (p = 0.26). In conclusion, posterior pelvic tilt in the standing position was found preoperatively in symptomatic DDH patients, and it remained for 2 years after periacetabular osteotomies. This postural change in PSI does not seem to influence the outcome of periacetabular osteotomy. However, during preoperative planning, surgeons should recognize that acetabular anteversion or anterior acetabular coverage differs between the supine and standing positions in some patients with DDH. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:578-587, 2020.

DOI： 10.1002/jor.24484

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INTRODUCTION: We developed a new carbon fiber-reinforced polyetheretherketone (CFR/PEEK) intramedullary nail for proximal femoral fractures. This study aimed to examine the efficacy and safety of the CFR/PEEK intramedullary nail for use in the treatment of patients with proximal femoral fractures. METHODS: This multicentre single-arm clinical trial enrolled 20 patients (3 men, 17 women; mean age 85.0 years, range 72-95 years) with proximal femoral fractures treated with the CFR/PEEK intramedullary nail. The follow-up period was >4 months. Primary outcomes were union of the bone fracture, time to bone union, bone nonunion, complications, implant failure, and the reoperation rate. Secondary outcomes were fracture reduction success, and clinical scores using the Harris hip score, Barthel index, Vitality index, Mini-Mental State Examination, and Numerical Rating Scale. RESULTS: Among the 20 patients with proximal femoral fractures treated with CFR/PEEK intramedullary nails, 19 (95%) were confirmed to display bone union within 3.7 months (range 2.8-10.0 months). One patient was diagnosed as having bone nonunion, although the patient did not complain any pain, and there was no radiological evidence of failure after a follow-up period of >18 months. There were no complications (e.g., cut out, infection, hardware failure), and reoperation was not required. Fracture reduction was good and acceptable in all cases, and the mean tip-apex distance was 13.5 mm (range 9.0-19.1 mm). The results indicated that preoperative activity was maintained (preoperative and postoperative Harris hip scores were 73.2 and 71.0 points, respectively; p = 0.61). CONCLUSION: There were no adverse reactions or failures related to the CFR/PEEK implant, and it provided satisfactory clinical results and a high union rate. Thus, use of the novel CFR/PEEK intramedullary nail is feasible.

DOI： 10.1016/j.injury.2020.01.007

PubMed

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This study aimed to investigate whether use of a computed tomography (CT)-based navigation system reduce the risk of dislocation after total hip arthroplasty (THA) in patients with osteonecrosis of the femoral head (ONFH). A total of 271 hips from 192 consecutive patients that underwent primary THA for ONFH were included. There were 110 hips in non-navigation group, and 161 hips in navigation group. After applying exclusion criteria, 209 hips from 149 patients were selected for analysis. Clinical outcomes and complication rates were evaluated, and implant alignments were also calculated. To identify whether the navigation system was useful to prevent dislocation, the inverse probability of treatment-weighted Cox regression analysis using a propensity score in relationship to sex, age at surgery, body mass index, and femoral head size was performed. No significant difference was observed in clinical scores between both groups. Dislocation was significantly lower in the navigation group (3 hips, 2.7%) than in the non-navigation group (11 hips, 11.2%; p = 0.012), whereas periprosthetic joint infection and aseptic loosening did not differ between the groups. Variance of cup inclination and anteversion angles was smaller in the navigation group than in the non-navigation group (p < 0.001). Use of the CT-based navigation system (hazard ratio; 0.26, 95% confidence interval, 0.07-0.98; p = 0.047) turned out to be the predictor for preventing dislocation. In conclusion, use of the CT-based navigation system provided a precise placement of components, and thus helps to prevent dislocation in patients with ONFH in the propensity score analysis.

DOI： 10.1007/s10047-020-01158-z

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This study aimed to identify the incidence of anteflexion impairment after rotational acetabular osteotomy based on patient-reported outcome measures, and the morphological factors and postoperative bony range of motion associated with anteflexion impairment at 2 years postoperatively. We analyzed 26 patients with developmental dysplasia of the hip who underwent rotational acetabular osteotomy at our institution. Using questionnaires, we defined anteflexion impairment as difficulty in clipping toenails and pulling up and removing socks. Morphological parameters and bony range of motion measured using a postoperative three-dimensional surface model, were compared between the subjects with and without anteflexion impairment. The incidence of anteflexion impairment was 69% at 6 months, 35% at 1 year, and 12% at 2 years after rotational acetabular osteotomy. The mean bony flexion angle was smaller in subjects with impairment than in those without impairment. The mean internal rotation (IR) angle at 90° of flexion was smaller in subjects with impairment than in those without impairment. The incidence of impairment was significantly higher in subjects with both less than or equal to 105° of bony flexion and less than or equal to 20° of IR at 90° of flexion than in the remaining subjects. No significant difference was observed in postoperative femoral head coverage and preoperative morphological parameters including spinal condition between the two groups. To prevent femoroacetabular impingement after rotational acetabular osteotomy, surgeons need to reorient the acetabulum to restore postoperative bony flexion to more than or equal to 105° and/or postoperative IR range of motion to more than or equal to 20° at 90° of flexion.

DOI： 10.1002/jor.24600

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DOI： 10.1007/s11265-019-01507-z

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Language：Japanese   Publisher：(一社)日本人工関節学会  

当科では人工股関節再置換術において、寛骨臼骨欠損の大きいPaprosky分類Type3BとPelvic discontinuityに対しては同種骨移植に加えBurch-Schneider Reinforcement cage(BS cage)を用いる方針としている。今回、2013〜2017年に本法を施行した15例16股の短期成績を報告した。男性3例、女性12例、手術時年齢は59〜91歳、術後観察期間は平均2.4年(0.1〜4.1年)であった。JOAスコアは術前平均42点が術後80点に改善した。術後合併症として脱臼を1股(6%)に認め、この症例は認知症を有する90歳の患者であった。また一過性の大腿神経麻痺を1股に認めたが、術後1年で改善した。BS cageの破損や再置換例はなかった。代表例2例を提示した。

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BACKGROUND: The identification and precise removal of bony impingement lesions during arthroscopic débridement arthroplasty for elbow osteoarthritis is technically difficult. Surgical navigation systems, combined with preoperative 3-dimensional (3D) assessment of bony impingements, can provide real-time tracking of the surgical instruments and impingement lesions. This study aims to determine the registration accuracy of the navigation system for the humerus and ulna during elbow arthroscopy. METHODS: We tested the registration procedure using resin bone models of 3 actual patients with elbow osteoarthritis. We digitized bone surface points using navigation pointers under arthroscopy. We initially performed paired-point registration, digitizing 6 preset anatomical landmarks, and then refined the initial alignment with surface matching registration, digitizing 30 points. The registration accuracy for each trial was evaluated as the mean target registration error in each reference marker. Three observers repeated the registration procedure 5 times each with the 3 specimens (total, 45 trials). The median of the registration accuracy was evaluated in total (45 trials) as the accuracy of the registration procedure. The differences in the registration accuracy among the 3 observers (median of 15 trials) were also examined. RESULTS: The total registration accuracies were 0.96 mm for the humerus and 0.85 mm for the ulna. No significant differences were found in the registration accuracy for the humerus and ulna among the 3 observers. CONCLUSIONS: This arthroscopic-assisted registration procedure is sufficiently feasible and accurate for application of the navigation system to arthroscopic débridement arthroplasty in clinical settings.

DOI： 10.1016/j.jse.2019.06.009

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND AND OBJECTIVE: Malposition of the acetabular component causes dislocation and prosthetic impingement after Total Hip Arthroplasty (THA), which significantly affects the postoperative quality of life and implant longevity. The position of the acetabular component is determined by the Pelvic Sagittal Inclination (PSI), which not only varies among different people but also changes in different positions. It is important to recognize individual dynamic changes of the PSI for patient-specific planning of the THA. Previously PSI was estimated by registering the CT and radiography images. In this study, we introduce a new method for accurate estimation of functional PSI without requiring CT image in order to lower radiation exposure of the patient which opens up the possibility of increasing its application in a larger number of hospitals where CT is not acquired as a routine protocol. METHODS: The proposed method consists of two main steps: First, the Mask R-CNN framework was employed to segment the pelvic shape from the background in the radiography images. Then, following the segmentation network, another convolutional network regressed the PSI angle. We employed a transfer learning paradigm where the network weights were initialized by non-medical images followed by fine-tuning using radiography images. Furthermore, in the training process, augmented data was generated to improve the performance of both networks. We analyzed the role of segmentation network in our system and investigated the Mask R-CNN performance in comparison with the U-Net, which is commonly used for the medical image segmentation. RESULTS: In this study, the Mask R-CNN utilizing multi-task learning, transfer learning, and data augmentation techniques achieve 0.960 ± 0.008 DICE coefficient, which significantly outperforms the U-Net. The cascaded system is capable of estimating the PSI with 4.04° ± 3.39° error for the radiography images. CONCLUSIONS: The proposed framework suggests a fully automatic and robust estimation of the PSI using only an anterior-posterior radiography image.

DOI： 10.1016/j.cmpb.2019.105282

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: The Association Research Circulation Osseous (ARCO) presents the 2019 revised staging system of osteonecrosis of the femoral head (ONFH) based on the 1994 ARCO classification. METHODS: In October 2018, ARCO established a task force to revise the staging system of ONFH. The task force involved 29 experts who used a web-based survey for international collaboration. Content validity ratios for each answer were calculated to identify the levels of agreement. For the rating queries, a consensus was defined when more than 70% of the panel members scored a 4 or 5 rating on a 5-point scale. RESULTS: Response rates were 93.1%-100%, and through the 4-round Delphi study, the 1994 ARCO classification for ONFH was successfully revised. The final consensus resulted in the following 4-staged system: stage I-X-ray is normal, but either magnetic resonance imaging or bone scan is positive; stage II-X-ray is abnormal (subtle signs of osteosclerosis, focal osteoporosis, or cystic change in the femoral head) but without any evidence of subchondral fracture, fracture in the necrotic portion, or flattening of the femoral head; stage III-fracture in the subchondral or necrotic zone as seen on X-ray or computed tomography scans. This stage is further divided into stage IIIA (early, femoral head depression ≤2 mm) and stage IIIB (late, femoral head depression >2 mm); and stage IV-X-ray evidence of osteoarthritis with accompanying joint space narrowing, acetabular changes, and/or joint destruction. This revised staging system does not incorporate the previous subclassification or quantitation parameters, but the panels agreed on the future development of a separate grading system for predicting disease progression. CONCLUSION: A staging system has been developed to revise the 1994 ARCO classification for ONFH by an expert panel-based Delphi survey. ARCO approved and recommends this revised system as a universal staging of ONFH.

DOI： 10.1016/j.arth.2019.11.029

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(一社)日本関節病学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

We propose a method for automatic segmentation of individual muscles from a clinical CT. The method uses Bayesian convolutional neural networks with the U-Net architecture, using Monte Carlo dropout that infers an uncertainty metric in addition to the segmentation label. We evaluated the performance of the proposed method using two data sets: 20 fully annotated CTs of the hip and thigh regions and 18 partially annotated CTs that are publicly available from The Cancer Imaging Archive (TCIA) database. The experiments showed a Dice coefficient (DC) of 0.891±0.016 (mean±std) and an average symmetric surface distance (ASD) of 0.994±0.230 mm over 19 muscles in the set of 20 CTs. These results were statistically significant improvements compared to the state-of-the-art hierarchical multi-atlas method which resulted in 0.845 ± 0.031 DC and 1.556 ± 0.444 mm ASD. We evaluated validity of the uncertainty metric in the multi-class organ segmentation problem and demonstrated a correlation between the pixels with high uncertainty and the segmentation failure. One application of the uncertainty metric in active-learning is demonstrated, and the proposed query pixel selection method considerably reduced the manual annotation cost for expanding the training data set. The proposed method allows an accurate patient-specific analysis of individual muscle shapes in a clinical routine. This would open up various applications including personalization of biomechanical simulation and quantitative evaluation of muscle atrophy.

DOI： 10.1109/TMI.2019.2940555

PubMed

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: It is not clear how to treat asymptomatic deep venous thromboses (DVTs) following elective hip arthroplasty because the natural course of DVTs is unclear. It is therefore valuable to understand the natural course of DVTs and their relation to thromboprophylactic methods. METHODS: We followed 742 consecutive patients who underwent elective hip arthroplasty followed by mechanical or chemical prophylaxis of a DVT. All patients underwent preoperative and postoperative duplex ultrasonography of both limbs. Patients who developed postoperative DVT in the popliteal or calf vein were followed without thromboprophylaxis. DVT-positive patients were prospectively followed up with duplex ultrasonography at 3, 6, 12, and 24 months postoperatively. RESULTS: Incidences of preoperative and postoperative DVTs were 3.9% and 33.0%, respectively. Nonfatal pulmonary embolism (PE) occurred in 1 patient after negative echography. All DVTs that developed in the calf vein postoperatively and without anticoagulation remained benign, and 93% of the DVTs ultimately disappeared. CONCLUSION: These results confirmed that the natural course of asymptomatic distal DVTs is benign, with no risk of leading to PE. Thus, distal DVTs could be allowed to remain untreated without chemical prophylaxis to prevent PE in Asian populations.

DOI： 10.1016/j.arth.2019.08.062

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Language：Japanese   Publisher：(株)医学書院  

＜文献概要＞はじめに 人工股関節全置換術(total hip arthroplasty:THA)のロボット支援手術は,手術の一部を自動で行うactive systemであるROBODOC(Integrated Surgical Systems, Inc.)が最初のシステムで,セメントレスステム設置の骨母床作成において,術前CTによる手術計画どおりに大腿骨髄腔をロボットアームで制御したミリングバーにより掘削するというものであった.Active systemでは,外科医がロボットの動きを熟知していないとロボットアームの動作に対する適切な対応ができないため,軟部組織損傷のリスクがある.一方で,外科医がロボットアームを手で動かして骨掘削をするsemi-active systemが開発された.その1つであるMakoシステム(日本ストライカー)は,膝関節単顆置換術(unicompartmental knee arthroplasty:UKA)に応用され,その後,寛骨臼リーミングやカップ設置角度の支援ができるようになっている.Makoシステムを使用したTHAでは,カップ設置角度の精度が高く,手術手技の習得は術中X線透視法よりも容易で,脱臼などの合併症を減らし,術後の機能評価も優れていることが報告されている.MakoシステムでのTHAは,2017年10月5日に薬事承認され,2018年8月から評価医療として臨床応用が始まった.筆者はMakoシステムでのTHAを経験したので,その手技や初期の臨床経過について紹介する.

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2019&ichushi_jid=J01554&link_issn=&doc_id=20190814080016&doc_link_id=10.11477%2Fmf.1408201445&url=https%3A%2F%2Fdoi.org%2F10.11477%2Fmf.1408201445&type=%88%E3%8F%91.jp_%83I%81%5B%83%8B%83A%83N%83Z%83X&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00024_2.gif

Language：Japanese   Publisher：日本股関節学会  

特発性大腿骨頭壊死(ONFH)の連続症例109例109関節を対象に、アルコール関連ONFH26例(A群)とアルコール非関連ONFH83例(B群)に分け、術前1〜3週間の血液検査におけるGGT、MCV、ALT、AST、T-Cho、TGを比較した。アルコール関連ONFHは、1週間のアルコール摂取量(g)と飲酒年数の積が3032(drink-year)以上となる症例と定義した。その結果、A群はB群に比べGGT、AST、ALTが有意に高値であった。性別、年齢、BMIをマッチさせた2群間で比較すると、A群でGGT、AST、MCVが有意に高値であった。各検査値とアルコール関連ONFH診断の関係を示すROC曲線を作成したところ、GGTの予測能が最も高かった。ONFHの関連因子が習慣性飲酒であると予測するGGTの特異度と感度は、カットオフ値を36.5U/Lとすると80%/76%、100U/Lとすると94%/38%で、その精度は中等度であった。

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Language：Japanese   Publisher：日本股関節学会  

当院で2007〜2017年にTHA後頻回脱臼に対して再置換術を行った19例の成績を調査した。再置換術後に17例(98%)で脱臼は制動されていた。再置換術後も脱臼を認めた2例はいずれも再置換術後アライメント不良かつ36mm骨頭使用例であった。脱臼を制動するためには、インプラントアライメントがcombined anteversion theoryに基づく目標設置角度の前後5°以内であることと、骨頭径36mm以上の大径骨頭を使用することが必要と考えられた。

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We evaluated the course of the femoral blood vessels of patients with acetabular dysplasia. Patients were divided into five groups: those with Crowe type I, II, III, and IV dysplastic hips and those with normal hips. A computed tomography-based hip navigation software was used to measure the distance between the femoral blood vessels and the anterior pelvic wall in four axial planes located 10-40 mm proximal to the pelvic teardrop. In Crowe Groups I through IV, the distance was shortest at a point 20 mm proximal to the pelvic teardrop. Furthermore, the distance decreased as the Crowe classification grade increased. Because the femoral blood vessels pass close to the pelvis in many patients in Crowe III and IV hips, caution is required during surgery in these patients.

DOI： 10.1007/s10047-019-01116-4

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Immunosuppressive therapy for renal allograft recipients has changed substantially since the introduction of the anti-CD25 monoclonal antibody, basiliximab. We hypothesized that recent improvements in immunosuppressive treatment may reduce the incidence of osteonecrosis of the femoral head (ONFH). This study aimed to investigate transitional changes in the incidence of OFNH among renal transplant recipients by MRI. METHODS: Participants comprised 110 patients who had undergone renal transplantation from 2003 to 2012, during which time basiliximab was in regular use at our institute (Recent group), and 232 patients who had undergone RT between 1986 and 2003 (Past group). We compared ONFH incidence between the two groups and evaluated risk factors for ONFH, including immunosuppressants (calcineurin inhibitors, basiliximab, and/or steroids) and postoperative renal function. RESULTS: Incidence of ONFH was lower in the Recent group (0%) than in the Past group (3.4%; p = 0.043). In the Recent group, age was greater, ABO/human leukocyte antigen incompatibility was worse, while steroid dose was decreased and post-transplant renal function was improved. Cumulative methylprednisolone dose at postoperative week 2 and delayed graft function were identified as risk factors for ONFH. CONCLUSION: Risk of ONFH after renal transplantation has fallen with the advent of regular use of basiliximab, although this agent does not appear to be a factor directly associated with the incidence of ONFH. STUDY DESIGN: Clinical prognostic study (Level III case control study).

DOI： 10.1016/j.jos.2019.06.009

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Language：Japanese   Publisher：日本医用画像工学会  

大規模医用画像データベースに対する病態解析の必要性が高まっている.そこで我々は変形性股関節症に着目し,大規模医用画像データベースに対する変形性股関節症の分類である一次性と二次性の自動分類を目標とする.本研究ではそのための第一歩として三次元CT画像からConvolutional Neural Network(CNN)を用いて解剖学的特徴点を特定し,臨床で用いられているCenter Edge Angle(CEA)を自動で計測する.また診療科を問わず網羅的に収集された約一万症例のCTデータベースから変形性股関節症の有病率の測定に利用できるかを検討する.(著者抄録)

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Language：Japanese   Publisher：日本医用画像工学会  

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Language：Japanese   Publisher：The Japanese Society of Medical Imaging Technology  

Medical images depict organs with different contrasts depending on their measurement techniques. In a clinical setting, patients may undergo multiple types of modalities for certain purposes. However, image acquisition by multiple types of modalities is time-consuming and not cost-effective. In this research, we address image synthesis, i.e. translating images such that they resemble the contrast of target modality. Image synthesis have long required “paired” training data, i.e. images of the same patients acquired with multiple modalities in the same postures, until CycleGAN has recently resolved this deficiency. CycleGAN enables Image Synthesis without paired data, learning synthesis toward each modality. Although CT-MR synthesis methods have been proposed so far, these only take into account MR images of single sequence. However, it is often the case that MR images of multiple sequences in the same posture are available. In this paper, we examine image synthesis between MR images of three types of sequences and CT around hip region using CycleGAN.

DOI： 10.11409/mit.37.130

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Language：Japanese   Publisher：(一社)中部日本整形外科災害外科学会  

対象は2013年10月〜2017年12月の128関節(男31関節、女97関節、手術時平均年齢82歳)、観察期間は平均14ヵ月であった。骨折型はAO分類で31-A1.1:38関節、A1.2:36関節、A2.1:15関節、A2.2:23関節、A2.3:8関節、A3.1:1関節、A3.2:3関節、頸基部:4関節であった。術後整復位は、正面像では内方型:44関節、解剖型:77関節、外方型:7関節で、側面像ではsubtype P:23関節、subtype N:86関節、subtype A:19関節であった。Tip Apex Distance(TAD)は平均15.9mm、最終観察時のsliding量は3.9mmであった。ラグスクリューのcut outは3関節(2.3%)に認め、うち2関節は術後3ヵ月以内であった。骨癒合は123関節(96%)で得られた。Cut outを生じた3関節は、骨癒合を得た123関節と比較し、術後整復位が正面像で外方型、TADとsliding量が大きく、骨折部の整復、ラグスクリュー刺入位置が不良であった。

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2019&ichushi_jid=J00831&link_issn=&doc_id=20190710180088&doc_link_id=10.11359%2Fchubu.2019.587&url=https%3A%2F%2Fdoi.org%2F10.11359%2Fchubu.2019.587&type=J-STAGE&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00007_2.gif

Language：English   Publishing type：Research paper (scientific journal)  

In this computed tomography (CT) morphological study we describe the way the proximal femoral morphology differs with worsening degrees of developmental dysplasia of the hip (DDH) and describe gender differences in patients with DDH. Forty-nine male patients with DDH were matched with 49 females with DDH, using age and the Crowe classification of DDH severity. The femoral length, anteversion, neck-shaft angle, offset, neck length, canal-calcar ratio, canal flare index, lateral center-edge angle, alpha angle, pelvic tilt, and pelvic incidence were measured for each patient on their pre-operative CT scans, prior to total hip arthroplasty surgery. Femoral anteversion and neck length were 16° and 47 mm, 25°and 36 mm, 26° and 43 mm, and 44° and 36 mm, for Crowe I and III males and Crowe I and III females, respectively. The mean male anteversion was 22° (±14), compared to 30° (±15.5) in females (p = 0.02, Confidence Interval: 1.6-14.9). Gender differences in femoral length, neck length and offset lost significance when height-normalized and no other significant gender differences were found. In conclusion, femoral neck length reduces with increasing DDH severity, whilst anteversion tends to increase. Male patients with DDH have significantly less femoral anteversion, which has important implications for osteotomy and arthroplasty surgery in DDH. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

DOI： 10.1002/jor.24272

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Language：Japanese   Publisher：(一社)日本医用画像工学会  

医用画像は、撮像モダリティーによって異なるコントラスト特徴を示す。臨床では一般に、用途に応じて異なる複数のモダリティーの画像が撮影されるが、複数モダリティーでの撮影は時間やコストがかかる。本研究では、1つのモダリティーの画像から、別のモダリティーと同様のコントラスト特徴を有する画像を生成することを目的とする。従来、異種モダリティー画像生成には、同一患者を同一肢位で、複数モダリティーで撮影した「対応あり」の学習データが必要であったが、近年CycleGANとよばれる。対応なしの学習データでも画像生成が可能で、かつ双方向の生成が可能な手法が提案された。これまでに報告されているCycleGANを用いたCT-MR間の画像生成技術は、1種類のシーケンスで撮影されたMR画像のみを扱っていた。本稿では、CycleGANを用いて、3種類のシーケンスで撮影された股関節周辺のMR画像とCT画像の相互変換を行うアルゴリズムについて報告する。(著者抄録)

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Language：Japanese   Publisher：金原出版(株)  

＜文献概要＞骨盤輪骨折は高所転落や交通事故など高エネルギー外傷で発生するが,近年は加齢に伴う骨脆弱性により軽微な外傷で発生する脆弱性骨盤輪骨折が増加している。いずれも早期に低侵襲に骨盤輪を再建することができれば,その後の良好な機能回復が期待できる。損傷骨盤輪の安定化において後方骨盤輪の固定が重要で,様々な固定方法が考案されている。経皮的仙腸関節スクリュー固定,経皮的経腸骨経仙骨スクリュー固定は最も低侵襲な方法であるが,X線透視下に安全なスクリュー経路を見いだし,そこにスクリューを刺入することは容易ではない。術前にCTを用いて三次元計画を立案し,疑似X線像を作成して術中参照する方法は有用である。また,さらに安全性を高めるためナビゲーションシステムを用いる方法が開発されている。特に術中整復後に三次元X線像を撮像し,その画像に対してガイドワイヤーの方向をリアルタイムに確認できる3D fluoroscopic navigationの有用性が近年多く報告され,注目されている。

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Language：English   Publishing type：Research paper (scientific journal)  

The aim was to elucidate the differences in activities of daily living (ADL) after hip arthroplasty among hip resurfacing (HRA), anterolateral total hip arthroplasty (AL-THA), and posterolateral THA (PL-THA) patients after age, sex, body mass index, bilateral/unilateral hip arthroplasty, and postoperative duration were matched using propensity scores. A total of 673 hips from 540 consecutive patients who underwent hip arthroplasty were included. A self-completed questionnaire on preoperative and postoperative ADLs was administered during postsurgical visits at least ≥ 4 years postoperatively. Between HRA and PL-THA patients, the numbers of patients who performed heels-down squatting was significantly more in HRA than in PL-THA. Between AL-THA and PL-THA patients, there were significant differences in postoperative ADLs including bathing in a bathtub, riding on a train/bus, cutting toenails, bowing while straight sitting, heels-up/down squatting, riding on a bicycle, driving a car, and domestic travel. There were no significant differences in postoperative ADLs between ≥ 36 mm head and ≤ 32 mm head PL-THA patients, and between AL-THA and HRA patients. This propensity score matched study indicated that AL-THA and HRA patients were more active postoperatively than PL-THA patients.

DOI： 10.1007/s10047-018-1069-7

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: Pelvic position on the sagittal plane is usually evaluated with the pelvic sagittal inclination (PSI) angle from a single radiograph. However, the reproducibility of pelvic positioning has not been investigated, and thus, the validity of measuring the PSI from a single film/time point is not understood. Herein, the reproducibility of a patient's pelvic positions in supine and standing postures was analyzed. METHODS: A total of 34 patients who underwent either a pelvic osteotomy or total hip arthroplasty were enrolled in this study. Preoperative radiographs in both supine and standing postures were acquired twice (first X-ray and second X-ray) within 6 months; preoperative computed tomography (CT) images of the full pelvis were also acquired in a supine posture (preop-CT). To eliminate measurement variability, each PSI was automatically measured from radiographs and CT images through the use of CT segmentation and landmark localization followed by intensity-based 2D-3D registration. The absolute difference of PSI among each image was calculated and the intra-class correlation coefficient (ICC) in each posture was also analyzed. RESULTS: The median absolute differences of PSI in the supine posture were 1.3° between the first and second X-rays, 1.2° between the first X-ray and preop-CT, and 1.3° between the second X-ray and preop-CT. The median absolute difference of PSI in the standing posture was 1.5°. The ICC was 0.965 (95% CI: 0.939-0.981) in supine and 0.977 (95% CI: 0.954-0.988) during standing. CONCLUSIONS: Pelvic positions in supine and standing postures are reproducible. Thus, measuring the PSI from a single radiograph is reliable.

DOI： 10.1177/2309499019828515

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BACKGROUND: Muscle atrophy and degeneration around hip joint have been evaluated using computer tomography (CT) or magnetic resonance imaging two-dimensionally (2D). However, it is unclear how these 2D measurements of muscle atrophy and degeneration reflect their three-dimensional (3D) measurements. The purpose of this study is to examine the validity of the 2D evaluation of muscular atrophy and fatty degeneration compared to 3D evaluation. METHODS: The study included computed tomography (CT) images of 20 patients with unilateral hip joint disorders. We manually segmented the edges of 14 muscles around the pelvis and the femur. The correlation coefficient between the 3D and 2D measurements at the anatomic landmarks was calculated. Furthermore, the 2D evaluation was performed at 1 cm interval from each anatomic landmark to determine the cross-section that correlated most strongly with the 3D measurements. A strong correlation in Spearman's rank correlation coefficient (r) was defined as r > 0.7. RESULTS: Nine (64%) and 10 (71%) muscles had a strong correlation coefficient between the 3D and 2D anatomic landmark measurements of muscular atrophy and degeneration, respectively. The maximum distance between the cross-section with the highest correlation coefficient and the anatomical landmark was 11 cm. CONCLUSIONS: More than half of muscles exhibited a strong correlation between the 3D and 2D anatomic landmark measurements of muscular atrophy and degeneration. To improve the correlation coefficient, the position of the cross-section was needed to be changed.

DOI： 10.1016/j.jos.2019.02.004

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: The Dorr classification is widely used to evaluate femoral bone quality, but it has no clear quantitative criteria. This study aimed to evaluate the reproducibility of the Dorr classification and examine its quantitative indices on plain radiographs, which are suitable for objective classification. HYPOTHESIS: Reproducibility of the Dorr classification is influenced by the clinical experience of the examiners, and radiographic indices are required for this classification. MATERIALS AND METHODS: One hundred and one patients were examined using their preoperative plain antero-posterior and lateral radiographs. To evaluate the reproducibility of the Dorr classification, the Dorr type of each patient was judged twice each by three expert hip surgeons and three junior hip surgeons. Indices measured using the plain radiographs were canal-to-calcar ratio, cortical index (CI), and canal flare index. A receiver operating characteristic curve was used to evaluate which measured parameters were suitable as indices for the Dorr classification which was determined by the consultation among three expert hip surgeons. RESULTS: Regarding intra-examiner reproducibility, kappa coefficients for the three junior hip surgeons were 0.36, 0.62, and 0.65, whereas those for the three expert hip surgeons were 0.70, 0.86, and 0.87. Regarding inter-examiner reproducibility, the kappa coefficient for the junior hip surgeons was 0.32, whereas that for the expert hip surgeons was 0.52. The CI on the lateral radiograph had the largest area under the curve (AUC) between types A and B, whereas the CI on the anteroposterior radiograph had the largest AUC between types B and C. The respective cutoff points of the CI on the anteroposterior radiograph were 0.58 between types A and B and 0.49 between types B and C. The respective cutoff points of CI on the lateral radiograph were 0.45 between types A and B and 0.28 between types B and C. CONCLUSION: The intra-examiner reproducibility of the Dorr classification ranged from "fair" to "almost perfect", whereas the inter-examiner reproducibility ranged from "fair" to "moderate". Both were influenced by the level of clinical experience of the examiners. The most suitable index for classification using plain radiographs of the hip is the CI on anteroposterior and lateral radiographs. LEVEL OF EVIDENCE: IV, retrospective study.

DOI： 10.1016/j.otsr.2018.11.008

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Bone is in a continuous state of remodeling whereby old bone is absorbed and new bone is formed in its place. During this process, new formations reinforce the bone in the direction of the dominant stress trajectories through a functional adaptation. In normal aging, the balance between bone resorption and formation can be shifted. How this affects the functional adaptation remains to be investigated. Furthermore, how or whether the bone continues to change beyond the age of 85 is not yet studied in detail. In this study we examined the age-related changes in the cortical and trabecular bone in old age, and assessed whether we can find evidence of the presence of functional adaptation. We measured cortical and trabecular parameters from micro-computed tomography scans of the femoral head extracted from hip fracture patients between the age of 70 and 93 years. A significant decrease in global trabecular bone mineral density (38.1%) and cortical thickness (13.0%) was seen from the 9th to the 10th decade of life. The degree of anisotropy was maintained globally as well as locally in both high and low stress regions. The local trabecular bone mineral density decreased in both high stress and low stress regions between the 9th and 10th decade of life with similar trends. This suggests that the role of functional adaptation in maintaining the bone structural integrity in old age may be limited. This study highlights the need for a controlled clinical trial examining the cause of the continued bone degradation throughout old age.

DOI： 10.1038/s41598-018-36299-y

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Publishing type：Research paper (scientific journal)  

© The Author(s) 2019. Purpose: Pelvic position on the sagittal plane is usually evaluated with the pelvic sagittal inclination (PSI) angle from a single radiograph. However, the reproducibility of pelvic positioning has not been investigated, and thus, the validity of measuring the PSI from a single film/time point is not understood. Herein, the reproducibility of a patient’s pelvic positions in supine and standing postures was analyzed. Methods: A total of 34 patients who underwent either a pelvic osteotomy or total hip arthroplasty were enrolled in this study. Preoperative radiographs in both supine and standing postures were acquired twice (first X-ray and second X-ray) within 6 months; preoperative computed tomography (CT) images of the full pelvis were also acquired in a supine posture (preop-CT). To eliminate measurement variability, each PSI was automatically measured from radiographs and CT images through the use of CT segmentation and landmark localization followed by intensity-based 2D-3D registration. The absolute difference of PSI among each image was calculated and the intra-class correlation coefficient (ICC) in each posture was also analyzed. Results: The median absolute differences of PSI in the supine posture were 1.3° between the first and second X-rays, 1.2° between the first X-ray and preop-CT, and 1.3° between the second X-ray and preop-CT. The median absolute difference of PSI in the standing posture was 1.5°. The ICC was 0.965 (95% CI: 0.939–0.981) in supine and 0.977 (95% CI: 0.954–0.988) during standing. Conclusions: Pelvic positions in supine and standing postures are reproducible. Thus, measuring the PSI from a single radiograph is reliable.

DOI： 10.1177/2309499019828515

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Language：Japanese   Publisher：(公社)日本理学療法士協会-近畿ブロック  

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Publishing type：Research paper (international conference proceedings)  

© 2019 SPIE. In total hip arthroplasty, analysis of postoperative images is important to evaluate surgical outcome. Since CT is most prevalent modality in orthopedic surgery, we aimed at the analysis of CT image. The challenge in this work is the metal artifact in postoperative CT caused by the metallic implant, which reduces the accuracy of segmentation especially in the vicinity of the implant. Our goal was to develop an automated segmentation method of the muscles in the postoperative CT images. In this paper, we propose a method that combines Normalized Metal Artifact Reduction (NMAR), which is one of the state-of-the-art metal artifact reduction methods, and a CNN- based segmentation using the U-Net architecture. We conducted experiments using simulated images and real images of the lower extremity to evaluate the segmentation accuracy of 19 muscles that are contaminated with metallic artifact. The training dataset we used is 20 CTs that were manually traced by an expert surgeon. In simulation study, the proposed method improved the average symmetric surface distance (ASD) from 1.85 ± 1.63 mm to 1.24 ± 0.67 mm (mean ± std). The real image study using two CTs with the ground truth of gluteus maximus, medius and minimus muscles showed the reduction of ASD from 1.67 ± 0.40 mm to 1.52 ± 0.47 mm. Our future work includes the end-to-end convolutional neural network for metal artifact reduction and musculoskeltal segmentation and to establish a ground truth dataset by performing non-rigid registration between the postoperative and preoperative CT of the same patient.

DOI： 10.1117/12.2521440

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Language：Japanese   Publisher：日本バイオマテリアル学会  

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DOI： 10.1111/aor.13388

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

INTRODUCTION: The purpose of the present study was to determine which factors affect the positional accuracy of iliosacral screws inserted using 3D fluoroscopic navigation. Specifically, we asked: (1) does the screw insertion angle in the coronal and axial planes affect the positional accuracy of iliosacral screw insertion using 3D fluoroscopic navigation? (2) Is the positional accuracy of iliosacral screw insertion using 3D fluoroscopic navigation affected by the type of screw (transsacral versus standard iliosacral), site of screw insertion (S1 versus S2), patient position (supine versus prone), presence of a dysmorphic sacrum, or AO/OTA classification (type B versus C)? MATERIALS AND METHODS: Twenty-seven patients with AO/OTA type B or C pelvic ring fracture were treated by percutaneous iliosacral screw fixation. A total of 55 screws were inserted into S1 or S2 using 3D fluoroscopic navigation combined with preoperative CT-based planning. The positional accuracy of screw placement was assessed by matching postoperative CT images with preoperative CT images. The distance between the central axis of the inserted screw and that of the planned screw placement was measured in the sagittal plane passing through the center of the vertebral body. RESULTS: The mean deviation between the planned and the inserted screw position was 2.9 ± 1.7 mm (range 0-8.5 mm) at the vertebral body center. Multiple regression analysis showed that the screw insertion angle relative to the vertical line of the bone surface in the axial plane (β = 0.354, p = 0.013) and the use of a transsacral screw (β = 0.317, p = 0.017) were correlated with the positional accuracy of screw placement (adjusted R2 = 0.276, p = 0.002). CONCLUSIONS: A greater screw insertion angle relative to the vertical line on the bone surface and the use of transsacral screws increases the positional error of iliosacral screws inserted using 3D fluoroscopic navigation. LEVEL OF EVIDENCE: Level IV, therapeutic study.

DOI： 10.1007/s00402-018-3055-1

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：(一社)日本コンピュータ外科学会  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

炭素繊維強化PEEK樹脂複合材(CF/PEEK)は、金属材料のような疲労現象がなく、炭素繊維の配列により剛性設計が自由にできることから、整形外科インプラント材料として導入されてきている。我々はCF/PEEKで大腿骨近位部固定ネイルを開発しており、従来のγ型金属ネイルから2ヶ所のデザイン改良をCF/PEEKで試みた。第一に、髄腔狭小例でも挿入時の干渉を減弱できるようネイル中間部をスリムダウンし、第二に、ラグスクリュー近位で回旋止めスクリュー挿入溝を前後面に作成した。この新規デザインCF/PEEKネイルと従来のγ型金属ネイルの有限要素解析モデルを作成し、ラグスクリュー近位端に1000Nの垂直荷重を加え、最大応力値と設計許容値に関する強度率を計算した。最大応力値は、従来のγ型ネイルで、金属が712MPa、CF/PEEKが453MPaと同形状ではCF/PEEKが低く、新規デザインCF/PEEKは更に353MPaと低かった。強度率は、それぞれ0.79、0.66、0.51と新規デザインCF/PEEKが最も低く、安全強度に余裕が十分にあることが明らかとなった。(著者抄録)

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Other Link： https://search-tp.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2018&ichushi_jid=J05471&link_issn=&doc_id=20181011070029&doc_link_id=%2Fcx9biomc%2F2018%2F003900%2F029%2F0181-0186%26dl%3D0&url=https%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Fcx9biomc%2F2018%2F003900%2F029%2F0181-0186%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

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BACKGROUND: Although alcohol is a leading risk factor for osteonecrosis of the femoral head (ONFH) and its prevalence reportedly ranges from 20% to 45%, there are no unified classification criteria for this subpopulation. In 2015, Association Research Circulation Osseous decided to develop classification criteria for alcohol-associated ONFH. METHODS: In June of 2017, Association Research Circulation Osseous formed a task force to conduct a Delphi survey. The task force invited 28 experts in osteonecrosis/bone circulation from 8 countries. Each round of the Delphi survey included questionnaires, analysis of replies, and feedback reports to the panel. After 3 rounds of the survey, consensus was reached on the classification criteria. The response rates for the 3 Delphi rounds were 100% (round 1), 96% (round 2), and 100% (round 3). RESULTS: The consensus on the classification criteria of alcohol-associated ONFH included the following: (1) patients should have a history of alcohol intake >400 mL/wk (320 g/wk, any type of alcoholic beverage) of pure ethanol for more than 6 months; (2) ONFH should be diagnosed within 1 year after alcohol intake of this dose; and (3) patients should not have other risk factor(s). CONCLUSION: ARCO-established classification criteria to standardize clinical studies concerning AA-ONFH.

DOI： 10.1016/j.arth.2018.09.006

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BACKGROUND: Glucocorticoid usage, a leading cause of osteonecrosis of the femoral head (ONFH), and its prevalence was reported in 25%-50% of non-traumatic ONFH patients. Nevertheless, there have been no unified criteria to classify glucocorticoid-associated ONFH (GA-ONFH). In 2015, the Association Research Circulation Osseous addressed the issue of developing a classification scheme. METHODS: In June 2017, a task force was set up to conduct a Delphi survey concerning ONFH. The task force invited 28 experts in osteonecrosis/bone circulation from 8 countries. Each round of the Delphi survey consists of questionnaires, analysis of replies, and feedback reports to the panel. After 3 rounds of the survey, the panel reached a consensus on the classification criteria. The response rates were 100% (Round 1), 96% (Round 2), and 100% (Round 3), respectively. RESULTS: The consensus on the classification criteria of GA-ONFH included the following: (1) patients should have a history of glucocorticoid use >2 g of prednisolone or its equivalent within a 3-month period; (2) osteonecrosis should be diagnosed within 2 years after glucocorticoid usage, and (3) patients should not have other risk factor(s) besides glucocorticoids. CONCLUSION: Association Research Circulation Osseous established classification criteria to standardize clinical studies concerning GA-ONFH.

DOI： 10.1016/j.arth.2018.09.005

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: To avoid malalignment of components during hip resurfacing arthroplasty (HRA), we used a computed tomography (CT)-based navigation system for guidance. This study aimed to evaluate the clinical accuracy and precision of HRA performed using the CT-based navigation systems. METHODS: HRA was performed on 17 hips guided by the CT-based navigation systems. We measured cup alignment deviation, deviation of the stem position, and alignment from the plan by image matching between pre-operative and post-operative CT images. RESULTS: Cup anteversion was within 5° of that in the plan in all cases. Cup inclination was within 5° of that in the plan in 82.4% and within 10° in all cases. The angular difference of the stem was within 5° in all cases, and the entry point of the stem was within 4 mm in all cases. CONCLUSION: The CT-based navigation system for HRA guided accurate component placement according to the plan.

DOI： 10.1007/s00264-018-4113-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Verlag  

The original publication of this paper contain an error for the first name and last name of the second author have been mixed up as “Wenliang, Z.”.

DOI： 10.1007/s00264-018-3948-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Verlag  

Purpose: For successful joint preservation in osteonecrosis of the femoral head (ONFH), it is important to understand the mechanism of collapse. The purpose of this study was to investigate the initiation of subchondral fracture in ONFH by using micro-CT imaging of the whole femoral head, focusing on the three-dimensional relationship between the subchondral fracture and the bone resorption area. Methods: A total of 40 femoral heads from 37 patients retrieved during total hip arthroplasty for stage 3A or 3B ONFH by Japanese Investigation Committee criteria were scanned using micro-CT with a 0.146-mm thickness cuts. We divided the cohort into early and late collapsed stages according to a threshold of 3 mm of collapse as measured by micro-CT. Results: According to the analysis on multiple radial plane views in the whole femoral head, there were two interesting findings. First, the initial fracture cracks ran between separated bone resorption areas at the anterosuperior portions of all 18 femoral heads in the early collapsed stage. Second, fractures of the necrotic bone at the sclerotic boundary and a fibrous, granulation-like, low-density tissue along the necrotic side of the sclerotic boundary were seen in 19 of the 22 in the late collapsed stage. After bone resorption around the retinaculum and teres insertion initiates the subchondral fracture, bone resorption expanding at the anterosuperior portion of the femoral head may result in the spread of fracture and the potential for massive collapse. Conclusions: Three-dimensional micro-CT showed bone resorption around the reparative zone initiates the subchondral fracture in ONFH.

DOI： 10.1007/s00264-018-3879-x

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Language：Japanese   Publisher：(一社)日本医用画像工学会  

医用画像からのセグメンテーションは、定量的な診断や患者個別のシミュレーションのため重要である。医用画像は、その撮像モダリティにより異なる特徴をもつ。CTは骨の構造を明瞭に撮影することができるのに対して、MRは軟組織の構造を明瞭に撮影することができる。このような違いはセグメンテーションにおいても考慮する必要がある。そこで本研究では、CycleGANを用いてMRIから同患者同姿勢のCT画像を生成することにより、セグメンテーションに活用する手法を提案する。本稿では、生成前後の画像の類似度を考慮した手法とラベルデータを用いた制約を用いる手法の比較検討を行った。(著者抄録)

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PURPOSE: The purposes of this study were to document novel Raman spectroscopic findings in femoral heads affected by osteonecrosis and to identify molecular structure differences based on aetiology. METHODS: We obtained 13 femoral heads with osteonecrosis from 13 different patients who underwent total hip arthroplasty. Comparisons were made between the viable zones of each femoral head examined. The samples were scanned with X-ray micro-CT for structural mapping and a central coronal section slab was prepared for Raman spectroscopy and histological analyses. Raman spectra were collected at different locations, including the viable and necrotic zones of the femoral head, using a highly spectrally resolved Raman microprobe. RESULTS: Significant alterations in the spectral morphology in the high wavenumber region were found, with a pronounced inhibition of peculiar lipid signals in the frequency interval 2851 ~ 2890 cm-1 and at ~ 1750 cm-1. The necrotic zone in steroid-associated osteonecrosis showed an increase in the ratio of lipid-related bands to protein-related bands, while alcohol-associated osteonecrosis exhibited a decrease in this ratio. CONCLUSIONS: We systematically found a decrease in Raman intensity for sphingomyelin and phenylalanine fingerprint bands in the necrotic zones, and these differences may be related to the etiology of osteonecrosis.

DOI： 10.1007/s00264-018-3898-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Verlag  

Purpose: Reduced range of motion (ROM) in flexion and internal rotation are associated with impaired activities of daily living (ADL) after rotational acetabular osteotomy (RAO). This study focused on the morphological variation of the anterior inferior iliac spine in developmental dysplasia of the hip (DDH) and its impact on post-operative bony ROM after RAO. This study aimed to investigate the association between bony ROM after RAO and pre-operative morphological factors of the pelvis and femur, including a positional variation of the anterior inferior iliac spine. Methods: Bony ROM in 52 patients with DDH was assessed after virtual RAO using computed tomography (CT). Post-operative acetabular coverage was set at lateral and anterior centre-edge angles of 30° and 55°, respectively. The position of the anterior inferior iliac spine was classified as higher or lower. Results: Multiple regression analysis revealed that the lower anterior inferior iliac spine and higher femoral neck shaft angle were significantly associated with the lower flexion angle after RAO. Lower femoral anteversion, higher femoral neck shaft angle and higher alpha angle at the anterosuperior part were significantly associated with lower internal rotation angle at 90° flexion after RAO. Conclusion: Therefore, morphological variation of the anterior inferior iliac spine affected bony ROM in flexion and that of the femoral neck affected bony ROM in internal rotation at flexion after RAO.

DOI： 10.1007/s00264-017-3673-1

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BACKGROUND: Many studies have confirmed that the size and location of necrotic lesions are major factors that affect the prevalence of collapse and prognosis in patients with osteonecrosis of the femoral head (ONFH). Although several classification systems categorize and quantify ONFH, there is no agreement on which one is most useful for the purpose. QUESTIONS/PURPOSES: We compared the Steinberg, modified Kerboul, and Japanese Investigation Committee (JIC) classifications of ONFH in terms of (1) the correlation among the three different classification systems. We further examined (2) the inter- and intraobserver reliability of the three classification systems and (3) the association of higher grades within each classification and the risk of subsequent collapse. METHODS: Between January 2000 and December 2014, we treated 101 hips in 74 patients for precollapse ONFH, diagnosed either on plain radiographs or MRI. Of those, one patient (1%) died, six patients (8%) were lost to followup, and two patients (3%) underwent osteotomy before 2 years, leaving 86 hips in 65 patients (88%) for analysis here. Three-dimensional spoiled gradient-echo sequence (3D-SPGR) MRI was performed for all hips, and the presence of ONFH was determined by finding the area surrounded by the outer margin of the low-signal-intensity band on 3D-SPGR MRI. Patients with ONFH were categorized using the Steinberg, modified Kerboul, and JIC classification systems, and correlations among these three classification systems were investigated. Inter- and intraobserver reliability was assessed by 10 orthopaedic surgeons using 40 sets of 3D-SPGR MR images. The reliability of each system was evaluated using the kappa coefficient. The cumulative survival rate with collapse and undergoing hip arthroplasty as the endpoints was evaluated for each of the three classification systems (mean followup, 9 years; range, 2-16 years), and the association of higher grades within each classification and the risk of subsequent collapse were also evaluated. RESULTS: We found strong correlations between the Steinberg and modified Kerboul classifications (ρ = 0.83, p < 0.001), the Steinberg and JIC classifications (ρ = 0.77, p < 0.001), and the modified Kerboul and JIC classifications (ρ = 0.80, p < 0.001). Interobserver reliability in the JIC classification (0.72; range, 0.30-0.90) was higher than that in the Steinberg classification (0.56; range, 0.24-0.84; p < 0.001) and the modified Kerboul classification (0.57; range, 0.35-0.80; p < 0.001). The cumulative survival rate with collapse as the endpoint after a minimum of 2 years of followup in the Steinberg classification differed between Grades A (82%; 95% confidence interval [CI], 66%-97%) and B (43%; 95% CI, 21.9%-64.8%; p = 0.007), Grades A and C (20%; 95% CI, 4.3%-35.7%; p < 0.001), and Grades B and C (p = 0.029). Survival was lower for modified Kerboul Grade 4 hips (12%; 95% CI, 0%-27.1%) than for Steinberg Grade C hips (20%; 95% CI, 4.3%-35.7%) and JIC Type C2 hips (18%; 95% CI, 2.8%-34.0%). The JIC classification was best able to identify hips at low risk of collapse because no JIC Type A hips collapsed. CONCLUSIONS: The JIC classification was more reliable and effective, at least for early-stage ONFH, than the Steinberg or modified Kerboul classifications. Further investigation might be useful to identify whether each classification system emphasizes specific risk factors for collapse. LEVEL OF EVIDENCE: Level III, diagnostic study.

DOI： 10.1007/s11999.0000000000000245

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For three-dimensional study of total hip arthroplasty, including preoperative planning and biomechanical studies, it is important to indicate the systems used to define the cup and stem alignment and the pelvic and femoral coordinate systems that are used. Cup alignment may be represented radiographically, operatively, or anatomically. Stem alignment is based on the representation of stem anteversion. The pelvis may be defined using the anatomical coordinate system, the functional coordinate system, or the coordinate system recommended by the International Society of Biomechanics (ISB). The anatomical coordinate system uses the anterior pelvic plane as the reference plane, which consists of the bilateral anterosuperior iliac spines and the midpoint of the bilateral pubic tubercles. The functional coordinate system incorporates the pelvic sagittal inclination, or pelvic tilt, in the supine position. The ISB pelvic coordinate system uses the plane consisting of the bilateral anterosuperior iliac spines and the midpoint of the bilateral posterosuperior iliac spines. The two major femoral coordinate systems are the femoral retrocondylar coordinate system and the ISB femoral coordinate system. The femoral retrocondylar coordinate system uses the retrocondylar plane as a reference plane, which consists of the posterior edge of the great trochanter and the bilateral posterior condyles. The ISB femoral coordinate system uses the plane consisting of the femoral head center and the bilateral femoral epicondyles as a reference plane. We must recognize that these differences in the representation of cup and stem alignment and the reference bone coordinate system significantly influence the clinical outcome of total hip arthroplasty whether using three-dimensional planning, navigation, or robotics. Such misunderstanding could result in an incorrect clinical interpretation of biomechanical analysis results.

DOI： 10.1007/978-981-10-5245-3_7

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Developmental dysplasia of the hip (DDH) is a common cause of secondary osteoarthritis. Various types of periacetabular osteotomy that reorient the dysplastic acetabulum have been developed to prevent the early onset of secondary osteoarthritis. Bernese periacetabular osteotomy and rotational acetabular osteotomy are now commonly used as surgical treatments for symptomatic DDH. Periacetabular osteotomies are technically demanding procedures that require detailed anatomical knowledge of the pelvic anatomy and three-dimensional (3D) cognitive skills because surgeons must avoid intra-articular perforation of chisels, thin acetabular fragments, posterior column fracture, and vascular and nerve injury. Preoperative 3D simulation of the osteotomy would be useful to avoid these perioperative complications. Computer-assisted systems such as navigation and custom cutting guides would be powerful tools with which to accurately execute the 3D osteotomy plan. A few reports have described the clinical application of a navigation system or custom cutting guide for periacetabular osteotomy. However, no navigation system that can track movement of the acetabular fragment has been developed. Some researchers have been developing such navigation systems with a focus on tracking the acetabular fragment.

DOI： 10.1007/978-981-10-5245-3_12

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Purpose: Patient-specific quantitative assessments of muscle mass and biomechanical musculoskeletal simulations require segmentation of the muscles from medical images. The objective of this work is to automate muscle segmentation from CT data of the hip and thigh. Method: We propose a hierarchical multi-atlas method in which each hierarchy includes spatial normalization using simpler pre-segmented structures in order to reduce the inter-patient variability of more complex target structures. Results: The proposed hierarchical method was evaluated with 19 muscles from 20 CT images of the hip and thigh using the manual segmentation by expert orthopedic surgeons as ground truth. The average symmetric surface distance was significantly reduced in the proposed method (1.53 mm) in comparison with the conventional method (2.65 mm). Conclusion: We demonstrated that the proposed hierarchical multi-atlas method improved the accuracy of muscle segmentation from CT images, in which large inter-patient variability and insufficient contrast were involved.

DOI： 10.1007/s11548-018-1758-y

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Purpose: In total hip arthroplasty, prediction of the optimal implant size is important in order to prevent perioperative complications. However, it is not easy to achieve complete agreement between the planned size and the actual size required appropriate implant fit. No previous report has adequately discussed the factors related to mismatch between predicted and actual implant sizes. The purpose was to report the results of a single surgeon case series of patients undergoing THA using computed tomography (CT)-based templating and the possible factors related to implant size mismatch. Methods: The study included 141 hips of 126 patients who underwent primary total hip arthroplasty with CT-based navigation. We retrospectively reviewed the planned and actual implant sizes used in these patients. Cup position, cup orientation and stem alignment were evaluated as surgical factors that could possibly be related to mismatch in implant size. Cortical index and canal flare index were also evaluated as morphological factors. Results: The final inclusions in this study were 124 hips of 111 patients including 82% of those were developmental dysplasia of the hip. Agreement in implant size was seen for 94.4% of cups and 85.5% of stems, respectively. No related factors were found for cup size mismatch. Stem alignment in the sagittal and coronal planes showed significant differences between the size-matched stem group and the smaller stem group (p&lt
0.05). Conclusions: Implant size agreement rates between the three-dimensional plan and the actual implants used intraoperatively were high. However, broach alignment should be checked in the coronal and sagittal planes if the intraoperative broach is smaller than the planned size.

DOI： 10.1007/s11548-017-1693-3

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© Springer Nature Singapore Pte Ltd. 2018. All rights reserved. Databases of medical images are valuable resources not only for clinical studies such as the analysis of disease progression or a large-scale population analysis of morphological characteristics but also for those engaged in image analysis. Databases can serve as a compendium against which newly developed algorithms can be tested and a common platform for performance comparisons with existing state-of-the-art algorithms. Several database projects that have focused on certain target modalities and diseases have been successful, including the Cancer Imaging Archive, the Alzheimer's Disease Neuroimaging Initiative, and the Osteoarthritis Initiative. Here, we introduce our efforts to construct a database of medical images and treatment records of Japanese patients who underwent hip surgery. This database currently contains computed tomography images, radiographs, and the log files of a surgical navigation system, including preoperative plans, intraoperative procedures, and postoperative outcomes (alignment). Herein, we also introduce our attempts in three applications: statistical analysis of the alignment in functional (standing) position, muscle function, and statistical analysis of surgeons' expertise from the surgical log. Open access is an important aspect for the research community, but privacy is a concern, especially for large-scale databases where per-patient consent is difficult to obtain as well as with images of patients with specific diseases wherein complete de-identification is extremely difficult. We believe our effort serves as a step toward augmentation of social acceptability of the strength of medical image databases for accelerating advanced medical treatment.

DOI： 10.1007/978-981-10-5245-3_16

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Purpose: The aim was to compare patients who suffered recurrent dislocation following total hip arthroplasty (THA) with those who did not to clarify the degree of soft tissue tension in dislocation patients. Methods: The subjects were 18 hips with recurrent dislocation (unstable THA group) and 37 hips without dislocation (stable THA group). To evaluate soft tissue tension, radiographs were taken while applying distal traction at traction forces of 40, 30, and 20% of the body weight (BW) and femoral head displacement was measured. Acetabular offset, femoral offset, limb offset, and leg length discrepancy were measured in patients with a normal contralateral hip joint. Results: The mean femoral head displacement in the unstable THA group was 5.6 mm at 40% of the BW, 4.6 mm at 30% of the BW, and 3.5 mm at 20% of the BW. In the stable THA group, the mean femoral head displacement was 1.4 mm at 40% of the BW, 1.1 mm at 30% of the BW, and 0.9 mm at 20% of the BW. Significant differences were seen between the groups at all traction forces. Furthermore, on comparing the unstable and stable THA groups, femoral offset was found to significantly be smaller in the affected side than in the healthy side in the unstable THA group. Conclusions: We found that soft tissue tension is approximately fourfold lower in patients exhibiting recurrent dislocations following THA than in patients exhibiting no dislocations and that femoral offset was related to decreased soft tissue tension.

DOI： 10.1007/s00264-018-3908-9

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Several reports have shown good long-term results with the Birmingham hip resurfacing (BHR) arthroplasty, but little is known about the results in Asian countries where there is a high prevalence of osteonecrosis and developmental dysplasia of the hip, and many females with small femoral head sizes. Therefore, we retrospectively evaluated the long-term clinical results of the BHR in 112 Japanese patients (53 males and 59 females-130 hips) with an average age of 52 years. Implant survivorship was analyzed using the Kaplan-Meier method with the endpoint being revision for any reason. Factors such as sex, femoral component size, and type of hip disease were analyzed as predictors of implant survivorship. With a median follow-up of 12 years, six cases were revised (two for femoral component aseptic loosening, two for infection, one for cup aseptic loosening, and one for femoral neck fracture), and the overall survival rate was 96.5% (95% CI 90.9-98.7) at 10 years and 93.6% (95% CI 83.4-97.7) at 15 years. When septic revisions were excluded, the implant survival rate was 98.2% (95% CI 92.9-99.6) at 10 years and 95.3% (95% CI 83.9-98.7) at 15 years. Sex, femoral component size, and type of hip disease were not predictors of implant survivorship. In conclusion, good clinical results were obtained with the BHR at 10- and 15-year follow-up in Japanese patients who have different stature and types of hip diseases as compared with patients in Western countries.

DOI： 10.1007/s10047-017-0981-6

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Stem anteversion in the setting of total hip arthroplasty (THA) is usually measured by referencing the posterior condylar line (PCL). However, stem anteversion may not express the functional torsion of the femur if a consistent horizontal tilt in the PCL is observed after THA. Herein, the horizontal tilt of the PCL at the resting neutral position of the hip was retrospectively measured in 53 THA patients from three computed tomography (CT) datasets: (i) preoperative (preop-CT), (ii) 3 weeks after THA (1st postop-CT), and (iii) more than 2 years after THA (2nd postop-CT). Factors including sex, surgical approach, change in femoral anteversion, leg length, leg lateral length, and pelvic sagittal tilt, were analyzed to determine if they were predictors for the rotational change in PCL, and the number of cases in which the horizontal tilt of the PCL remained within 10° in the three CT images was calculated. Comparing the preop-CT to the 1st postop-CT demonstrated that the PCL underwent internal rotation by (mean ± standard deviation) 13.1° ± 8.6°; only leg lateralization was significantly correlated to the change in PCL (β = 0.278, P = 0.046). Comparing the preop-CT to the 2nd postop-CT demonstrated that the PCL was internally rotated by 9.7° ± 9.3°; no factors were correlated to the change in PCL. There were only 12 hips (23%) in which the horizontal tilt of the PCL remained within 10°. In conclusion, the PCL in the resting position was internally rotated shortly after THA and remained internally rotated from the preoperative position at two or more years following THA. Thus, stem anteversion measured by referencing the PCL may not represent functional torsion of the femur.

DOI： 10.1111/aor.12998

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BACKGROUND: Stem anteversion angle is important in the combined anteversion theory to avoid implant impingement after total hip arthroplasty (THA). However, anatomic measurements of stem anteversion angle may not represent functional anteversion of the femur if the femur undergoes axial rotation. Herein, the femoral rotational angle (FRA) was measured in supine and standing positions before and after THA to evaluate the difference between anatomic and functional measurements. METHODS: A total of 191 hips (174 patients) treated with THA for osteoarthritis were analyzed in this retrospective, case-controlled study. The FRA was measured as the angle between the posterior condylar line and the line through the bilateral anterior superior iliac spines (positive for external rotation) and was measured preoperatively and postoperatively in supine and standing positions with computed tomography segmentation and landmark localization of the pelvis and the femur followed by intensity-based 2D-3D registration. The number of cases in which the absolute FRA remained <15° in both positions was also calculated. RESULTS: The average ± standard deviation preoperative FRA was 0.3° ± 8.3° in the supine position and -4.5° ± 8.8° during standing; the postoperative FRA was -3.8° ± 9.0° in supine and -14.3° ± 8.3° during standing. There were 134 cases (70%) in which the preoperative absolute FRA remained <15° in both positions while only 85 hips (45%) remained <15°, postoperatively. CONCLUSION: Substantial variability was seen in the FRA, especially during the postoperative period. These results suggest that the anatomic stem anteversion angle may not represent the functional anteversion of the femur.

DOI： 10.1016/j.arth.2017.09.027

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There have been many reports of increasing numbers of resurfacing hip arthroplasty revisions because of unexplained pain and adverse local tissue reactions, especially with the Articular Surface Replacement system. Thus, the use of many resurfacing hip replacements has been declining. In contrast, the Birmingham Hip Resurfacing system has shown excellent long-term survivorship compared with other resurfacing prostheses, especially for young and active patients with osteoarthritis. Some reports on primary total resurfacing hip arthroplasty for developmental dysplasia of the hip (DDH) showed a higher rate of revision than primary osteoarthritis, but it is controversial whether a diagnosis of DDH itself is an independent risk factor for failure of hip resurfacing or it is related to its characteristics of female dominant gender and smaller component size. With most resurfacing prostheses, small components have a small coverage arc, indicating that small acetabular components have a narrower safe zone for the alignment against edge loading. Thus, strict control of acetabular component alignment is essential to prevent adverse wear for patients with DDH. It also requires surgical skill to fix an acetabular component using the press-fit technique alone. With a severely deformed femoral head, it is technically demanding to determine the proper insertion position and alignment of the guidewire while avoiding notch formation and preparing a healthy host bone with sufficient stability for the femoral components. Sufficient surgical experience, a properly designed prosthesis, and dedicated alignment control via intraoperative radiographic checks and/or computer technology (e.g., navigation or a patient-specific surgical guidance) would be required to improve implant survival of hip resurfacing for patients with DDH. We believe that DDH itself is not a contraindication for primary total hip resurfacing arthroplasty.

DOI： 10.1007/978-981-13-0414-9_3

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DOI： 10.1007/978-981-13-1396-7_22

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© The Author(s) 2018. Purpose: Intertrochanteric fractures are usually treated with open reduction and internal fixation, but controversy still remains regarding the proper placement of the lag screw on the anteroposterior view. The stability of the lag screw has been shown to correlate with the bone quality around the screw, but the three-dimensional distribution of the bone mineral density (BMD) in the femoral head has not been studied in detail. Herein, the BMD along the femoral neck axis was measured to clarify the recommended position of the lag screw. Methods: Ten femoral heads acquired from intertrochanteric fractures were evaluated in this study. Each femoral head was scanned with micro computed tomography and the BMD along the femoral neck axis was measured in five regions: center, anterior, posterior, superior, and inferior. The BMD on the anteroposterior view (superior, center, and inferior) and the BMD on the lateral view (anterior, center, and posterior) were compared. Results: The BMD of the center region (173.0 ± 50.6 mg/cm3) was significantly higher than that of the inferior region (139.7 ± 50.1 mg/cm3) on the anteroposterior view (p < 0.01). On the lateral view, the BMD was lower than the center region in the anterior region (165.7 ± 52.8 mg/cm3) and in the posterior region (157.5 ± 42.3 mg/cm3), but the difference was not significant. Conclusion: The BMD was higher in the center region of the femoral head than in the inferior region. Therefore, lag screws are recommended to be inserted into the center of the femoral head.

DOI： 10.1177/2309499018778325

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DOI： 10.1007/978-3-030-00928-1_79

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Three-dimensional (3D) muscle fiber architecture is important in patient-specific biomechanical simulation. While several in-vivo methods using diffusion tensor imaging and ultrasound have been demonstrated their feasibility in reconstruction of the fiber architecture, the main challenge is the lack of gold standard. Although physical measurement from cadavers has been considered as the accurate way of determining 3D muscle fiber architecture, its downsides include error in the manual tracing and the labor intensive process allowing only sparse sampling of a particular muscle. We propose an alternative method of obtaining a dense fiber architecture of multiple muscles in close proximity using high resolution cryosectioned images. Similar to the diffusion tensor imaging, we first extract the local orientation at each voxel using the structure tensor analysis and then tractography algorithm is applied to obtain stream lines. The proposed method was applied to all muscles around the hip joint and the masticatory muscles. Qualitative comparison with the anatomy textbook indicated that the proposed method reconstructed a plausible muscle fiber architecture. We plan to make the reconstructed fiber architecture of whole body muscles publicly available in order to serve for the biomechanics community.

DOI： 10.1007/978-3-319-74113-0_8

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CT is commonly used in orthopedic procedures. MRI is used along with CT to identify muscle structures and diagnose osteonecrosis due to its superior soft tissue contrast. However, MRI has poor contrast for bone structures. Clearly, it would be helpful if a corresponding CT were available, as bone boundaries are more clearly seen and CT has a standardized (i.e., Hounsfield) unit. Therefore, we aim at MR-to-CT synthesis. While the CycleGAN was successfully applied to unpaired CT and MR images of the head, these images do not have as much variation of intensity pairs as do images in the pelvic region due to the presence of joints and muscles. In this paper, we extended the CycleGAN approach by adding the gradient consistency loss to improve the accuracy at the boundaries. We conducted two experiments. To evaluate image synthesis, we investigated dependency of image synthesis accuracy on (1) the number of training data and (2) incorporation of the gradient consistency loss. To demonstrate the applicability of our method, we also investigated segmentation accuracy on synthesized images.

DOI： 10.1007/978-3-030-00536-8_4

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© 2018 SPIE. High-resolution medical images are crucial for medical diagnosis, and for planning and assisting surgery. Micro computed tomography (micro CT) can generate high-resolution 3D images and analyze internal micro-structures. However, micro CT scanners can only scan small objects and cannot be used for in-vivo clinical imaging and diagnosis. In this paper, we propose a super-resolution method to reconstruct micro CT-like images from clinical CT images based on learning a mapping function or relationship between the micro CT and clinical CT. The proposed method consists of following three steps: (1) Pre-processing: This involves the collection of pairs of clinical CT images and micro CT images for training and the registration and normalization of each pair. (2) Training: This involves learning a non-linear mapping function between the micro CT and clinical CT by using training pairs. (3) Processing (testing) step: This involves enhancing a new CT image, which is not included in the training data set, by using the learned mapping function.

DOI： 10.1117/12.2293443

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CT is commonly used in orthopedic procedures. MRI is used along with CT to identify muscle structures and diagnose osteonecrosis due to its superior soft tissue contrast. However, MRI has poor contrast for bone structures. Clearly, it would be helpful if a corresponding CT were available, as bone boundaries are more clearly seen and CT has a standardized (i.e., Hounsfield) unit. Therefore, we aim at MR-to-CT synthesis. While the CycleGAN was successfully applied to unpaired CT and MR images of the head, these images do not have as much variation of intensity pairs as do images in the pelvic region due to the presence of joints and muscles. In this paper, we extended the CycleGAN approach by adding the gradient consistency loss to improve the accuracy at the boundaries. We conducted two experiments. To evaluate image synthesis, we investigated dependency of image synthesis accuracy on (1) the number of training data and (2) incorporation of the gradient consistency loss. To demonstrate the applicability of our method, we also investigated segmentation accuracy on synthesized images.

DOI： 10.1007/978-3-030-00536-8_4

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The purpose of this preliminary study was to determine the error range compared with preoperative plans in proximal femoral osteotomy conducted using a computed tomography (CT)-based navigation system.
Four patients (four hips) underwent transtrochanteric rotational osteotomy (TRO), and three patients (four hips) underwent curved varus osteotomy (CVO) using CT-based navigation. Volume registration of pre- and postoperative CT was performed for error assessment.
In TRO, the mean osteotomy angle error was (range ) in the valgus direction and (range ) in the retroversion direction. The mean osteotomy position error, with the femoral head side as positive, was -0.4 mm (range -1.4 to 0 mm). The bone fragment rotational movement error was (range ). In CVO, the mean osteotomy position error, with the femoral head side as positive, was -0.2 mm (range -2.0 to 1.7 mm) at the level of the lesser trochanter and 0.8 mm (range 0-3.2 mm) at the level of the greater trochanter. Bone fragment varus accuracy was (range ).
In proximal femoral osteotomy using CT-based navigation, the angle error of osteotomy was within and the positional error was within 4 mm. The rotational movement error of the proximal fragment was within . These margins of error should be considered in preoperative planning. To improve surgical accuracy, it would be necessary to develop a computer-assisted device which can track the osteotomized fragment.

DOI： 10.1007/s11548-017-1577-6

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DOI： 10.1016/j.arth.2017.10.026

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BackgroundThe aim of this study was to validate the effectiveness of neck-cut patient-specific surgical guides (PSGs) for femoral component implantation in total hip arthroplasty (THA) through the anterolateral approach compared with that without PSG.
MethodsA total of 32 fresh cadaveric hips were included. Anatomical stem implantation with wide-base-contact PSG (AWP group) and without PSG (control group) were compared. The absolute errors between preoperative planning and PSG setting (E1), as well as those between preoperative planning and postoperative component implantation (E2) were evaluated using CT.
ResultsThe E1/E2 values of AWP were 0.90.3 degrees/0.6 +/- 0.6 degrees in the coronal plane, and 1.7 +/- 0.8 degrees/1.0 +/- 0.9 degrees in the sagittal plane, and 1.0 +/- 0.6 mm/1.0 +/- 1.1 mm for the medial height. The E2 value in the sagittal plane (P=0.037) and the medial height (P=0.011) of AWP were significantly smaller than those of control group.
ConclusionsThe neck-cut PSG through the anterolateral approach is effective for femoral component implantation.

DOI： 10.1002/rcs.1830

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BACKGROUND: Cup anteversion and inclination are important for avoiding implant impingement and dislocation in total hip arthroplasty. However, functional cup anteversion and cup inclination also change as the pelvic sagittal inclination (PSI) changes. Therefore, PSI in both supine and standing positions was measured in a large cohort in this study. METHODS: A total of 422 patients (median age, 61; range, 15-87) who underwent total hip arthroplasty were the subjects of this study. There were 83 patients with primary osteoarthritis (OA), 274 patients with developmental dysplasia-derived secondary OA, 48 patients with osteonecrosis, and 17 patients with rapidly destructive coxopathy (RDC). Preoperative PSI in supine and standing positions was measured by automated computed topography segmentation and landmark localization of the pelvis followed by intensity-based 2D-3D registration, and the number of cases in which PSI changed more than 10° posteriorly was calculated. Hip disease, sex, and age were analyzed if they were related to a PSI change of more than 10°. RESULTS: The median PSI was 5.1° (interquartile range, 0.4°-9.4°) in supine and -1.3° (interquartile range, -6.5° to 4.2°) in standing position. There were 79 cases (19%) in which the PSI changed more than 10° posteriorly from supine to standing. Elder age and patients with primary OA and RDC were revealed to be the related factors. CONCLUSION: PSI changed more than 10° posteriorly from supine to standing in 19% of cases. Age and diagnosis of primary OA and RDC were the significant factors for the posterior rotation.

DOI： 10.1016/j.arth.2017.03.015

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The purpose of this study was to clarify bone turnover marker levels in rapidly destructive coxopathy (RDC). Twenty patients with RDC (mean age, 72 +/- A 11 years; 3 men, 17 postmenopausal women), 111 with osteoarthritis (OA) (age, 60 +/- A 10 years; 15 men, 13 premenopausal women, 83 postmenopausal women), and 18 with osteonecrosis of femoral head (ON) (55 +/- A 14 years; 11 men, 3 premenopausal women, 4 postmenopausal women), and 100 patients with femoral neck fracture (FNF) (81 +/- A 10 years; 27 men, 73 postmenopausal women) were included. Serum tartrate-resistant acid phosphatase 5b (TRACP-5b), bone alkaline phosphatase (BAP), matrix metalloproteinase-3 (MMP-3) levels, and bone mineral density (BMD) of proximal femur and lumbar spine were investigated. TRACP-5b levels were significantly higher in RDC than in OA and ON, whereas BAP levels were higher in RDC than in OA (P &lt; 0.05). MMP-3 levels were higher in RDC and ON than in OA (P &lt; 0.05). TRACP-5b were higher in RDC than OA (P &lt; 0.05) and FNF (P &lt; 0.05) in performing propensity score matching; there were no differences in BMD between RDC and OA. TRACP-5b showed the largest area under the curve (AUC, 0.82) according to receiver operating characteristic (ROC) curve analysis for diagnosing RDC against OA and ON. AUCs of BAP and MMP-3 were 0.78 and 0.74. The respective sensitivities and specificities were 70.0 % and 85.3 % for TRACP-5b (cutoff, 623 mU/dl), 95.0 % and 57.1 % for BAP (13.8 U/l), and 70.0 % and 76.4 % for MMP-3 (52.7 ng/ml). The lack of differences in BMD suggested that high bone turnover marker levels may reflect osteoclast cell activation in RDC hips. Serum TRACP-5b and BAP could be RDC markers.

DOI： 10.1007/s00774-016-0769-4

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Rotational acetabular osteotomy (RAO) is used to treat developmental hip dysplasia (DDH). It requires detailed anatomical knowledge of the pelvic anatomy and three-dimensional cognitive skills. We addressed whether a computer navigation system combined with a preoperative computed tomography-based plan enabled surgeons to perform RAO safely and reliably through a mini-incision regardless of their level of experience with performing osteotomies.
We enrolled 24 patients (25 hips) with DDH (radiographic grade 0 or 1 osteoarthritic changes: Tonnis classification). Using the navigation system, four surgeons performed RAO via a mini-incision transtrochanteric approach. Two experienced surgeons treated 15 patients (16 hips). Two surgeons with low-level RAO experience treated nine patients (9 hips). Operative data and clinical and radiographic outcomes were compared. Average follow-up was 3.2 years.
There were no significant differences in the (1) incision length, operation time, or intraoperative blood loss; (2) numerical pain rating scale score and Western Ontario and McMaster Universities Osteoarthritis Index Scale score at 1, 2 years, and at the latest follow-up; (3) preoperative and postoperative acetabular coverage of the femoral head, postoperative joint congruency, postoperative medial and distal femoral head displacement, or acetabular thickness; and (4) positional accuracy of iliac, pubic, and ischial osteotomy and accuracy of acetabular coverage of the femoral head.
Clinical and radiographic outcomes of RAO with navigation were not influenced by the surgeons' level of osteotomy experience.

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PURPOSE: Patient-specific musculoskeletal biomechanical simulation is useful in preoperative surgical planning and postoperative assessment in orthopedic surgery and rehabilitation medicine. A difficulty in application of the patient-specific musculoskeletal modeling comes from the fact that the muscle attachment regions are typically invisible in CT and MRI. Our purpose is to develop a method for estimating patient-specific muscle attachment regions from 3D medical images and to validate with cadaver experiments. METHODS: Eight fresh cadaver specimens of the lower extremity were used in the experiments. Before dissection, CT images of all the specimens were acquired and the bone regions in CT images were extracted using an automated segmentation method to reconstruct the bone shape models. During dissection, ten different muscle attachment regions were recorded with an optical motion tracker. Then, these regions obtained from eight cadavers were integrated on an average bone surface via non-rigid registration, and muscle attachment probabilistic atlases (PAs) were constructed. An average muscle attachment region derived from the PA was non-rigidly mapped to the patients bone surface to estimate the patient-specific muscle attachment region. RESULTS: Average Dice similarity coefficient between the true and estimated attachment areas computed by the proposed method was more than 10% higher than the one computed by a previous method in most cases and the average boundary distance error of the proposed method was 1.1 mm smaller than the previous method on average. CONCLUSION: We conducted cadaver experiments to measure the attachment regions of the hip muscles and constructed PAs of the muscle attachment regions. The muscle attachment PA clarified the variations of the location of the muscle attachments and allowed us to estimate the patient-specific attachment area more accurately based on the patient bone shape derived from CT.

DOI： 10.1007/s11548-016-1519-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

Background: Functional anteversion and inclination of the cup change as the pelvic sagittal inclination (PSI) changes. The purposes of this study were to investigate the chronological changes of PSI during a 10-year follow-up period after total hip arthroplasty (THA) and to report the characteristics of patients who showed a greater than 10 degrees change in the PSI from the supine to the standing position.
Methods: The subjects were 70 patients who were followed up for 10 years after THA. PSI values in the supine and standing positions were measured by 2D-3D matching using computed tomography images and pelvic radiographs. PSI values before THA and 1, 5, and 10 years after THA were compared in both the supine and standing positions.
Results: Supine PSI showed less than 5 degrees of change, whereas standing PSI showed a significant decrease with time over the 10-year period. Although 43% of patients with less than 10 degrees of difference in the PSI between the supine and standing positions before THA increased PSI posteriorly (reclining) more than 10 degrees in standing from the supine position at 10 years, no late dislocation was observed.
Conclusion: Supine PSI showed no significant change, but standing PSI showed a significant increase posteriorly with time over a 10-year period. However, this PSI change did not reach the level that it caused negative consequences such as late dislocation. The pelvic position in the supine position might still be a good functional reference position of the pelvis for aiming to achieve proper cup alignment at 10 years. (C) 2016 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.arth.2016.08.035

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Study Design: Reliability and agreement study.
Objective: To assess the reliability of intraoperative 3-dimensional imaging with a mobile C-arm (3D C-arm) equipped with a flat-panel detector.
Summary of Background Data: Pedicle screws are widely used in spinal surgery. Postoperative computed tomography (CT) is the most reliable method to detect screw misplacement. Recent advances in imaging devices have enabled surgeons to acquire 3D images of the spine during surgery. However, the reliability of these imaging devices is not known.
Methods: A total of 203 screws were used in 22 consecutive patients who underwent surgery for scoliosis. Screw position was read twice with a 3D C-arm and twice with CT in a blinded manner by 2 independent observers. Screw positions were classified into 4 categories at every 2mm and then into 2 simpler categories of acceptable or unacceptable. The degree of agreement with respect to screw positions between the double readings was evaluated by kappa value. With unanimous agreement between 2 observers regarding postoperative CT readings considered the gold standard, the sensitivity of the 3D C-arm for determining screw misplacement was calculated.
Results: A total 804 readings were performed. For the 4-category classification, the mean k value for the 2 interobserver readings was 0.52 for the 3D C-arm and 0.46 for CT. For the 2-category classification, the mean k value for the 2 interobserver readings was 0.80 for the 3D C-arm and 0.66 for CT. The sensitivity, specificity, positive predictive value, and negative predictive value of intraoperative imaging with the 3D C-arm were 70%, 95%, 44%, and 98%, respectively. With respect to screws with perforation &gt;= 4 mm, the sensitivity was 83%. No revision surgery was performed.
Conclusions: Intraoperative imaging with a 3D C-arm was reliable for detecting screw misplacement and helpful in decreasing the rate of revision surgery for screw misplacement.

DOI： 10.1097/BSD.0b013e3182a357ad

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Springer Verlag  

We propose an optimization method for estimating patient-specific muscle fiber arrangement from clinical CT. Our approach first computes the structure tensor field to estimate local orientation, then a geometric template representing fiber arrangement is fitted using a B-spline deformation by maximizing fitness of the local orientation using a smoothness penalty. The initialization is computed with a previously proposed algorithm that takes account of only the muscle’s surface shape. Evaluation was performed using a CT volume (1.0 mm3/voxel) and high resolution optical images of a serial cryo-section (0.1 mm3/voxel). The mean fiber distance error at the initialization of 6.00 mm was decreased to 2.78 mm after the proposed optimization for the gluteus maximus muscle, and from 5.28 mm to 3.09 mm for the gluteus medius muscle. The result from 20 patient CT images suggested that the proposed algorithm reconstructed an anatomically more plausible fiber arrangement than the previous method.

DOI： 10.1007/978-3-319-66182-7_75

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Churchill Livingstone Inc.  

The authors regret that there was an error in figure 4 of their published article. Although the error does not change the data and conclusion of the paper, this error may cause misunderstanding of the conclusion for reader. The authors apologise for any inconvenience caused. The purpose of the study was to investigate the effects of different surgical approaches, the posterolateral approach and the direct anterior approach, on postoperative femoral anteversion and stem coronal and sagittal alignment in total hip arthroplasty, and to identify the factors related to postoperative femoral anteversion and stem alignment. The stem sagittal alignment in the manuscript was defined as follows: “The sagittal alignment of the femoral stem was defined as the difference between femoral tilt and the stem sagittal tilt, using the following formula: stem sagittal alignment (°) = stem sagittal tilt (°) – femoral tilt (°). A negative value less than -3° was defined as flexed implantation, and a positive value more than 3° was defined as extended implantation (Fig. 4).” However, in Figure 4, the middle figure labeled as “extended implantation” showed flexed implantation, and the lower figure labeled as “flexed implantation” showed extended implantation. The corrected figure is provided below.

DOI： 10.1016/j.arth.2016.03.052

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER HEIDELBERG  

This study describes the use of CT images in atlas-based automated planning methods for acetabular cup implants in total hip arthroplasty (THA). The objective of this study is to develop an automated cup planning method considering the statistical distribution of the residual thickness.
From a number of past THA planning datasets, we construct two statistical atlases that represent the surgeon's expertise. The first atlas is a pelvis-cup merged statistical shape model (PC-SSM), which encodes global spatial relationships between the patient anatomy and implant. The other is a statistical residual thickness map (SRTM) of the implant surface, which encodes local spatial constraints of the anatomy and implant. In addition to PC-SSM and SRTM, we utilized the minimum thickness as a threshold constraint to prevent penetration.
The proposed method was applied to the pelvis shapes segmented from CT images of 37 datasets of osteoarthritis patients. Automated planning results with manual segmentation were compared to the plans prepared by an experienced surgeon. There was no significant difference in the average cup size error between the two methods (1.1 and 1.2 mm, respectively). The average positional error obtained by the proposed method, which integrates the two atlases, was significantly smaller (3.2 mm) than the previous method, which uses single atlas (3.9 mm). In the proposed method with automated segmentation, the size error of the proposed method for automated segmentation was comparable (1.1 mm) to that for manual segmentation (1.1 mm). The average positional error was significantly worse (4.2 mm) than that using manual segmentation (3.2 mm). If we only consider mildly diseased cases, however, there was no significance between them (3.2 mm in automated and 2.6 mm in manual segmentation).
We infer that integrating PC-SSM and SRTM is a useful approach for modeling experienced surgeon's preference during cup planning.

DOI： 10.1007/s11548-016-1428-x

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：電気学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL BONE JOINT SURGERY  

Background: Inadequate soft-tissue tension in total hip arthroplasty is regarded as one cause of dislocation or abductor muscle weakness. The purpose of the present study was to assess how the postoperative discrepancy in limb offset (consisting of both femoral offset and acetabular offset) affects soft-tissue tension compared with other factors among patients with unilateral hip disease undergoing total hip arthroplasty.
Methods: A total of 89 consecutive patients underwent mini-incision total hip arthroplasty involving an anterolateral or posterior approach and with use of a computer navigation system. Soft-tissue tension was measured by applying traction amounting to 40% of body weight with the joint positioned at 0 degrees, 15 degrees, 30 degrees, and 45 degrees of flexion. The separation between the cup and the prosthetic head was measured using the navigation system.
Results: The cup-head separation differed significantly for varying angles of flexion (p &lt; 0.001), with the greatest distance noted at 15 degrees of flexion (mean and standard deviation, 11 +/- 5 mm). Stepwise multiple regression analysis showed that postoperative limb-offset discrepancy, an anterolateral approach, and preoperative abduction range of motion were correlated with the cup-head separation at 15 degrees of flexion. Postoperative limb-offset discrepancy was negatively correlated with the cup-head separation at 0 degrees, 15 degrees, and 30 degrees of flexion.
Conclusions: Postoperative limb-offset discrepancy significantly affected the soft-tissue tension in total hip arthroplasty at varying degrees of flexion. This indicated that it is important to restore normal limb offset without overlengthening to obtain adequate soft-tissue tension in total hip arthroplasty.

DOI： 10.2106/JBJS.15.01073

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Some studies have cautioned about the possibility of bleeding complications with routine use of anticoagulants like fondaparinux (FPX) for thrombophylaxis after elective hip surgery. Overdosing or prolonged periods of anticoagulant use should be avoided. We trialed a new regimen using FPX and tranexamic acid (TA) to reduce the risk of bleeding complications while maintaining efficacy in preventing deep vein thrombosis (DVT). The present study evaluated the effectiveness and safety of this regimen in 391 consecutive patients. Each patient was assigned either the FPX group, administered a once-daily subcutaneous injection of 1.5 mg of FPX on postoperative days 2, 3, and 4; or the intermittent pneumatic compression (IPC) group, which used an IPC device continuously for 1-2 days with no administration of any anticoagulant drugs. Ultrasonography was performed to diagnose DVT in all patients. No cases of fatal or symptomatic pulmonary embolism were encountered in either group, but six patients (3.1 %) in the FPX group and nine patients (6.0 %) in the IPC group showed asymptomatic distal DVT. The incidence of DVT tended to be lower (p = 0.19), volumes of intraoperative (p &lt; 0.01) and postoperative (p &lt; 0.01) blood loss were significantly smaller, and hemoglobin level was significantly higher in the FPX group than in the IPC group (p &lt; 0.01). Our new thrombophylactic regimen using FPX and TA appears effective and safe for use after elective hip surgery.

DOI： 10.1007/s11239-015-1249-8

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BACKGROUND: Muscle atrophy in osteoarthritis (OA) patients is expected to recover after total hip arthroplasty (THA) because of the increase in activity levels. Although some reports have shown an increase in the thigh muscles (Th) after THA, no reports of increases in the gluteal muscles and of analyses of the factors related to muscle recovery have been published. In this study, the changes in the gluteal and Th volumes after THA were quantitatively evaluated using computed tomography (CT) images, and the factors related to muscle recovery were analyzed. METHODS: The subjects were 40 OA hips with CT images taken 3 weeks after THA (first postoperative [postop] CT) and more than 2 years after THA (second postop CT). The cross-sectional areas of gluteus maximus (G-max), gluteus medius (G-med), and Th were measured in both CT images. The factors related to muscle recovery that were measured and evaluated were age, gender, days from operation, surgical approach, Kellgren-Lawrence grades, and hip functional score (Japanese Orthopaedics Association hip score). RESULTS: All measured cross-sectional areas of the operated side increased significantly from the first postop CT to the second postop CT (G-max, 40%; G-med, 11%; and Th, 20%). In the analysis of the factors related to muscle recovery, the increase rate of G-max correlated significantly with patient age, and the increase rate of G-med correlated significantly with the increase in Japanese Orthopaedics Association hip score. CONCLUSIONS: Hip OA can lead to atrophy of the gluteal and Th, but the muscle volume can recover more than 2 years after THA.

DOI： 10.1016/j.arth.2015.10.036

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

The optimal reorientation of the acetabulum for developmental dysplasia of the hip (DDH) is unknown in terms of hip range-of-motion (ROM). The simulated ROMs of 52 DDHs after rotational acetabular osteotomy (RAO) with several patterns of femoral head coverage and those of 73 normal hips were analyzed using computer models reconstructed from CT images. After RAO with a lateral center edge angle (LCEA) of 30 degrees and an anterior center edge angle (ACEA) of 55 degrees producing coverage similar to that of normal hips, the maximal flexion and maximal internal rotation at 110 degrees flexion with 20 degrees adduction were significantly smaller than those of the normal group. To achieve ROMs after RAO similar to those of the normal group, an LCEA of 30 degrees with an ACEA of 45 degrees, an LCEA of 25 degrees with an ACEA of 45 degrees to 50 degrees, and an LCEA of 20 degrees with an ACEA of 50 degrees could be preferred angles to target, even though they provided smaller coverage than that of normal hips. After RAO producing femoral head coverage similar to that of normal hips, the maximal flexion and the maximal internal rotation at 110 degrees flexion with 20 degrees adduction were significantly smaller than those of the normal group. (c) 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:217-223, 2016.

DOI： 10.1002/jor.23024

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Rotation of the femur is usually measured by the posterior condylar line (PCL). However, the functional position of the PCL has not been studied well. The angles between the PCL and the horizontal body line (HBL) were measured on preoperative computed tomographic (CT) images of 324 hips with osteoarthritis and compared with the CT images taken after hip arthroplasty. The PCL rotated 0.4° (±10.9° SD) internally from the HBL on preoperative CT images and was significantly correlated with femoral anteversion, Kellgren-Lawrence grade, and sex. On postoperative CT images, the PCL rotated 10.1° (interquartile range, 1.7°-15.5°) internally from the HBL. There was individual variance in the position of the PCL, and caution may be needed when using it as a rotational reference.

DOI： 10.1016/j.arth.2015.08.038

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Accurate 3D models of lower extremity are required for model-based simulations in kinematic analysis of musculoskeletal (MS) system. In this paper, we present a modeling framework which combines a hybrid registration scheme with an articulated statistical shape model (aSSM) construction technique. The present modeling framework is used to develop an aSSM of compound MS structures based on a training set of 12 single side CT images with the associated ground-truth segmentation of 7 structures around the thigh region. By incorporating 90% of the training set variations, the model exhibits a generalization ability of 2.77 +/- 0.48 mm and specificity of 2.87 +/- 0.43 mm. The constructed aSSM has potential applications in model-based 2D-3D construction, 3D medical image segmentation, and kinematic analysis of MS system. To the best of our knowledge, this is the first 3D aSSM of compound MS structures around the thigh region.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

Goal: In the following, we will present a newly developed X-ray calibration phantom and its integration for 2-D/3-D pelvis reconstruction and subsequent automatic cup planning. Two different planning strategies were applied and evaluated with clinical data. Methods: Two different cup planning methods were investigated: The first planning strategy is based on a combined pelvis and cup statistical atlas. Thereby, the pelvis part of the combined atlas is matched to the reconstructed pelvis model, resulting in an optimized cup planning. The second planning strategy analyzes the morphology of the reconstructed pelvis model to determine the best fitting cup implant. Results: The first planning strategy was compared to 3-D CT-based planning. Digitally reconstructed radiographs of THA patients with differently severe pathologies were used to evaluate the accuracy of predicting the cup size and position. Within a discrepancy of one cup size, the size was correctly identified in 100% of the cases for Crowe type I datasets and in 77.8% of the cases for Crowe type II, III, and IV datasets. The second planning strategy was analyzed with respect to the eventually implanted cup size. In seven patients, the estimated cup diameter was correct within one cup size, while the estimation for the remaining five patients differed by two cup sizes. Conclusion: While both planning strategies showed the same prediction rate with a discrepancy of one cup size (87.5%), the prediction of the exact cup size was increased for the statistical atlas-based strategy (56%) in contrast to the anatomically driven approach (37.5%). Significance: The proposed approach demonstrated the clinical validity of using 2-D/3-D reconstruction technique for cup planning.

DOI： 10.1109/TBME.2015.2441378

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

We evaluated real-time angular changes during press-fit cup insertion in 70 total hip arthroplasties. Inclination and anteversion cup angles on navigation system were recorded after each procedure of five hammer blows during cup insertion, and maximum deviated inclination (MDI) and anteversion (MDA) angles until the cup was fully seated were measured. We found 1 (1%) and 29 (41%) hips with increases and decreases in MDI of 5 degrees or more, and 13 (19%) and 6 (8%) hips with increases and decreases in MDA of 5 degrees or more, respectively. The MDI in men was significantly lower and the MDA for left-side surgery was significantly higher. Surgeons should pay attention to fluctuation in angular changes during cup insertion and may consider countermeasures to minimize cup malpositioning. (c) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.arth.2015.04.037

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

The purpose of this study was to investigate the effects of different surgical approaches, the posterolateral approach (PLA) and the direct anterior approach (DAA), on postoperative femoral anteversion and stem coronal and sagittal alignment in total hip arthroplasty (THA), and to identify the factors related to postoperative femoral anteversion and stem alignment. A total of 209 hips of 181 patients were evaluated. THA was performed through the PLA in 80 hips and through the DAA in 129 hips. Femoral anteversion and stem alignment were measured on postoperative computed tomography images. The factor related to postoperative anteversion change was pre-operative femoral anteversion, and the surgical approaches did not affect the postoperative anteversion change, while surgical approach did have an effect on stem sagittal alignment. (c) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.arth.2015.04.026

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Language：Japanese   Publishing type：Research paper (other academic)  

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Language：Japanese   Publishing type：Research paper (other academic)  

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

In most patients with hip disorders, the anterior pelvic plane (APP) sagittal tilt does not change from supine to standing position. However, in some patients, APP sagittal tilt changes more than 10 degrees posteriorly from supine to standing position. The purpose of this study was to both examine APP sagittal tilt and investigate the hip flexion and extension range of motion (ROM) required during daily activities in these atypical patients. Patient-specific 4-dimensional (4D) motion analysis was performed for 50 hips from 44 patients who had undergone total hip arthroplasty. All patients divided into two categories, such as atypical patients for whom the pelvis tilted more than 10 degrees posteriorly from supine to standing position preoperatively (19 hips from 18 patients) and the remaining typical patients (31 hips from 26 patients). The required hip flexion and extension angles did not differ significantly between atypical patients and typical patients. In conclusion, the hip flexion ROM during deep bending activities and hip extension ROM during extension activities required in those atypical patients with pelvic tilt more than 10 degrees backward from supine to standing position did not shift in the direction of extension. (c) 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:542-547, 2015.

DOI： 10.1002/jor.22799

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

In some atypical patients, pelvic sagittal inclination (PSI) changes posteriorly by &gt; 10 degrees from supine to standing position before total hip arthroplasty (THA). Several studies have suggested PSI in standing position is related to lumbar degeneration. The purpose of this study was to investigate spinal factors influencing changes in PSI from supine to standing position before THA. Participants comprised 163 consecutive patients who had undergone THA. Presence of compression fractures, presence of lumbar spondylolisthesis, thoracic kyphosis angle, lumbar lordosis angle, S1 anterior tilt angle and T4 plumb line position were investigated as spinal factors. Presence of compression fractures, age, presence of lumbar spondylolisthesis and small S1 anterior tilt angle were independently associated with posterior change in PSI from supine to standing position in patients before THA. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.arth.2013.11.014

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

There is increasing awareness of prevalence of adverse local tissue reaction (ALTR) surrounding metal-on-metal (MoM) and highly cross-linked polyethylene (HXLPE) bearings, and sensitive and simple screening modalities for ALTR are required. We examined reliability of ultrasound screening for ALTR in 131 hips of 105 patients who received both ultrasound and MRI examinations after hip arthroplasty with MoM or HXLPE bearings. Using the MRI results as reference, sensitivity, specificity and accuracy of ultrasound were 74%, 92% and 84% around MoM bearings, and 90%, 83%, and 85% around HXLPE bearings. Ultrasound detected ALTR in 11 hips that were not shown with MRI. Ultrasound examination is assumed to be a reliable screening tool for detecting clinically important ALTR lesions developing in the anterior region around MoM or HXLPE bearings. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.arth.2014.04.030

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Carbon fiber-reinforced polyetheretherketone (CFR-PEEK) hip prostheses possess numerous advantages over metal prostheses; however, the security of the taper connection between the CFR-PEEK stem and the modular femoral head in vivo has not been verified. Therefore, we mechanically examined the taper connection of retrieved in vivo loaded CFR-PEEK stems in comparison with in vivo loaded titanium alloy stems. CFR-PEEK and titanium alloy femoral stems with a 12/14 taper trunnion were implanted in ovine hips. A 22-mm ceramic head was intraoperatively impacted to the stem. Retrieved specimens were obtained following weight-bearing conditions for up to 39 postoperative weeks and taper junction pull-off tests were conducted. Postoperative retrieved CFR-PEEK stem pull-off strength was significantly greater than that at time zero. Postoperative retrieved CFR-PEEK stem pull-off strength was also significantly higher than that of postoperative retrieved titanium alloy stem. Microscopic findings of the taper surface revealed no obvious damage in the retrieved CFR-PEEK stems, whereas fretting and corrosion were observed in the retrieved titanium alloy stems. The present findings suggest that the taper connection between the ceramic head and the 12/14 CFR-PEEK stem trunnion is more secure than that between the ceramic head and the titanium alloy trunnion.

DOI： 10.1007/s10047-014-0789-6

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：日本コンピュータ外科学会  

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：日本コンピュータ外科学会  

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：日本コンピュータ外科学会  

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：日本コンピュータ外科学会  

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：日本医用画像工学会  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ISCIE  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Background: Percutaneous iliosacral screw insertion requires substantial experience and detailed anatomical knowledge to find the proper entry point and trajectory even with the use of a navigation system. Our hypothesis was that three-dimensional (3D) fluoroscopic navigation combined with a preoperative computed tomography (CT)-based plan could enable surgeons to perform safe and reliable iliosacral screw insertion. The purpose of the current study is two-fold: (1) to demonstrate the navigation accuracy for sacral fractures and sacroiliac dislocations on widely displaced cadaveric pelves; and (2) to report the technical and clinical aspects of percutaneous iliosacral screw insertion using the CT-3D-fluoroscopy matching navigation system.
Methods: We simulated three types of posterior pelvic ring disruptions with vertical displacements of 0, 1, 2 and 3 cm using cadaveric pelvic rings. A total of six fiducial markers were fixed to the anterior surface of the sacrum. Target registration error over the sacrum was assessed with the fluoroscopic imaging centre on the second sacral vertebral body. Six patients with pelvic ring fractures underwent percutaneous iliosacral screw placement using the CT-3D-fluoroscopy matching navigation. Three pelvic ring fractures were classified as type B2 and three were classified as type C1 according to the AO-OTA classification. Iliosacral screws for the S1 and S2 vertebra were inserted.
Results: The mean target registration error over the sacrum was 1.2 mm (0.5-1.9 mm) in the experimental study. Fracture type and amount of vertical displacement did not affect the target registration error. All 12 screws were positioned correctly in the clinical series. There were no postoperative complications including nerve palsy. The mean deviation between the planned and the inserted screw position was 2.5 mm at the screw entry point, 1.8 mm at the area around the nerve root tunnels and 2.2 mm at the tip of the screw.
Conclusion: The CT-3D-fluoroscopy matching navigation system was accurate and robust regardless of pelvic ring fracture type and fragment displacement. Percutaneous iliosacral screw insertion with the navigation system is clinically feasible. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.injury.2014.01.015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

BackgroundAnterior sacroiliac joint plate fixation for unstable pelvic ring fractures avoids soft tissue problems in the buttocks; however, the lumbosacral nerves lie in close proximity to the sacroiliac joint and may be injured during the procedure. MethodsA 49 year-old woman with a type C pelvic ring fracture was treated with an anterior sacroiliac plate using a computed tomography (CT)-three-dimensional (3D)-fluoroscopy matching navigation system, which visualized the lumbosacral nerves as well as the iliac and sacral bones. We used a flat panel detector 3D C-arm, which made it possible to superimpose our preoperative CT-based plan on the intra-operative 3D-fluoroscopic images. ResultsNo postoperative complications were noted. ConclusionsIntra-operative lumbosacral nerve visualization using computer navigation was useful to recognize the 'at-risk' area for nerve injury during anterior sacroiliac plate fixation. Copyright (c) 2013 John Wiley & Sons, Ltd.

DOI： 10.1002/rcs.1556

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

To confirm whether developmental dysplasia of the hip has a risk of hip impingement, we analysed maximum ranges of movement to the point of bony impingement, and impingement location using three-dimensional (3D) surface models of the pelvis and femur in combination with 3D morphology of the hip joint using computer-assisted methods. Results of computed tomography were examined for 52 hip joints with DDH and 73 normal healthy hip joints. DDH shows larger maximum extension (p = 0.001) and internal rotation at 90 flexion ( p &lt; 0.001). Similar maximum flexion (p = 0.835) and external rotation (p = 0.713) were observed between groups, while high rates of extra- articular impingement were noticed in these directions in DDH (p &lt; 0.001). Smaller cranial acetabular anteversion (p = 0.048), centre-edge angles (p &lt; 0.001), a circumferentially shallower acetabulum, larger femoral neck anteversion (p &lt; 0.001), and larger alpha angle were identified in DDH. Risk of anterior impingement in retroverted DDH hips is similar to that in retroverted normal hips in excessive adduction but minimal in less adduction. These findings might be borne in mind when considering the possibility of extra-articular posterior impingement in DDH being a source of pain, particularly for patients with a highly anteverted femoral neck.

DOI： 10.1302/0301-620X.96B5.32503

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A preliminary investigation into the diagnostic potential of Raman spectroscopy for assessing pathological articular cartilage was conducted. Five arthritic human tibial cartilages retrieved after total knee arthroplasty were examined using near-infrared (NIR) Raman spectroscopy excited with 647.1nm lines of a Kr-ion laser. A "healthy" cartilage obtained from cadaver donor was also examined as a control sample. Degradation severity was first visually classified into five grades (Grade 0-VI) on the surface of both medial and lateral zones in each tibial plateau, according to the Collins scale. Raman spectra were then collected from selected zones with different damage severity. A systematic increase in relative intensity ratio between the Raman bands located at 1241 and 1269cm-1 (amide III doublet) was observed with increasing degradation grades, which could be related to structural changes under loading in type II collagen. This finding suggests that the present spectroscopic approach might be useful for recognizing and quantitatively assessing the degree of osteoarthritis (OA) in its early manifestation stage. © 2013 Elsevier Ltd.

DOI： 10.1016/j.jmbbm.2013.02.014

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Language：Japanese   Publishing type：Research paper (other academic)   Publisher：The Japan Society of Mechanical Engineers  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Objective. The purpose of this study was to evaluate cytokine level characteristics in the hip joint fluid, including rapidly destructive coxopathy (RDC), OA, osteonecrosis (ON) of the femoral head and RA.
Methods. Thirty-three hips with RDC, 57 with OA, 36 with ON and 10 with RA were included in the study. OA hips were divided into two groups: 20 hips with early OA without joint space narrowing and 37 hips with terminal OA. ON hips were divided into three groups: 13 hips with &lt; 3 mm collapse, 14 hips with &gt; 3 mm collapse and 9 hips with terminal ON. Joint fluid was collected during surgery. Cytokine levels including IL-1 beta, IL-6, IL-8 and TNF-alpha were measured using homogeneous time-resolved fluorescence.
Results. All measured cytokine levels in RDC were significantly higher than those in OA (P &lt; 0.05). Terminal OA showed higher cytokine levels than those in early OA (P &lt; 0.05). IL-6 and TNF-alpha levels in the ON group with &gt; 3 mm collapse were higher than those found in the ON group with &lt; 3 mm collapse. In comparing cytokine levels between RDC, terminal OA, RA and terminal ON, RDC showed significantly higher IL-8 levels than terminal OA and RA (P &lt; 0.05).
Conclusion. IL-8 levels in RDC were higher than in the other hip diseases. The IL-8 level may reflect the aggressiveness of joint destruction in RDC, and IL-6 and TNF-alpha levels may also reflect ongoing destruction in OA and ON.

DOI： 10.1093/rheumatology/ket334

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：The Institute of Electronics, Information and Communication Engineers  

In order to adapt automated total hip arthroplasty planning to different types of femoral stem efficiently, we constructed statistical atlas for different stem with representative cases which contribute to planning performance and evaluated performance of planning using that atlas. As a result of cross-validation between two types of femoral stem, anatomical type and flat type, while planning with anatomical type stem using representative cases selection in cases of flat type stem operated, the reverse didn't.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SAGE PUBLICATIONS INC  

Background: Jogging has been classified as a high-impact sport, and jogging after total hip arthroplasty (THA) has not been well documented.
Purpose: To investigate the participation rate for postoperative jogging as well as jogging parameters and the influence of jogging on implant stability and bearing wear.
Study Design: Case-control study; Level of evidence, 3.
Methods: Included in this study were 804 hips in 608 patients (85 men, 523 women) who underwent THA between 2005 and 2011 with follow-up longer than 1 year. The mean patient age was 62 years (range, 26-98 years), and mean follow-up duration was 4.8 years (range, 2.3-7.8 years). Hip resurfacing arthroplasty (HRA) was performed in 81 patients and conventional THA in 527 patients. During routine postsurgical visits, patients were given a questionnaire concerning preoperative and postoperative jogging routines. For joggers, frequency, distance, duration, and velocity of jogging were recorded. Patients who did not jog postoperatively were asked to provide reasons for not jogging. Radiographs concerning implant migration and polyethylene wear were evaluated with specialized software, and serum cobalt and chromium ion concentrations were investigated for patients with metal-on-metal articulation.
Results: A total of 33 patients (5.4%) performed jogging preoperatively, and 23 patients (3.8%) performed jogging postoperatively. Of the 23 who jogged postoperatively, conventional THA was performed in 13 patients and HRA in 10 patients. Postoperatively, joggers trained a mean of 4 times (range, 1-7 times) per week, covering a mean distance of 3.6 km (range, 0.5-15 km) in a mean time of 29 minutes (range, 5-90 minutes) per session and at a mean speed of 7.7 km/h (range, 3-18 km/h). No patient complained of pain or showed serum cobalt and chromium ion elevation greater than 7 ppb. No hip showed loosening, abnormal component migration, or excessive wear at a mean 5-year follow-up. There were 74 postoperative non-joggers with an interest in jogging. The reasons given for avoiding jogging included anxiety (45 patients; 61%); impossible because of several reasons, including pain, decreased range of motion, and muscle weakness (18 patients; 24%); and lumbar or knee pain (11 patients; 15%). Multivariate analysis revealed that male sex and a history of preoperative jogging demonstrated significant relationships with postoperative jogging.
Conclusion: A total of 3.8% of THA patients participated in postoperative jogging. Short-term postoperative follow-up did not identify any negative influence of jogging on implant survival.

DOI： 10.1177/0363546513506866

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Objectives:The aim of the present study was to determine whether 3-dimensional (3D) fluoroscopic navigation combined with a preoperative computer tomography (CT)-based plan could enable surgeons to perform safe and reliable iliosacral screw insertion despite their limited experience.Methods:Eight pelvises with surrounding soft tissue donated from embalmed cadavers were used. Kirschner wires with a diameter of 3 mm were placed across the ilia bilaterally into the S1 and S2 vertebrae by 4 orthopaedic trainees. In 4 specimens, wires were placed across the right ilium using conventional technique and the left ilium using the CT-3D-fluoroscopy matching navigation system. In 4 other specimens, wires were placed across the right ilium using the 3D-fluoroscopic navigation system and the left ilium using the CT-3D-fluoroscopy matching navigation system. A postoperative CT-based analysis of wire localization was performed. The number of wire insertions until the final position check, operation duration, and radiation time and dose were also evaluated.Results:The percentage of wires inserted correctly was higher in the CT-3D-fluoroscopy matching navigated group (100%) than in the conventional technique group (50%) and 3D-fluoroscopic navigation group (50%). The number of wire insertions and radiation time were significantly lower with both navigation systems than with the conventional technique, whereas there was no significant difference between the navigation systems. There were no significant differences in operation time and radiation dose among the 3 groups.Conclusions:The CT-3D-fluoroscopy matching navigation system reduced the malposition rate of percutaneous iliosacral screw insertion when performed by less experienced surgeons.

DOI： 10.1097/BOT.0b013e31828fc4a5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

We investigated differences in the location and mode of labral tears between dysplastic hips and hips with femoroacetabular impingement (FAI). We also investigated the relationship between labral tear and adjacent cartilage damage. We retrospectively studied 72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological evidence of dysplasia or FAI on high-resolution CT arthrography. The incidence and location of labral tears and modes of tear associated with the base of the labrum (Mode 1) or body of the labrum (Mode 2) were compared among FAI, mildly dysplastic and severely dysplastic hips. The locations predominantly involved with labral tears were different in FAI and mild dysplastic hips (anterior and anterosuperior zones) and in severely dysplastic hips (anterosuperior and superior zones) around the acetabulum. Significant differences were observed in the prevalence of Mode 1 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)).
Hip pathology is significantly related to the locations and modes of labral tears. Mode 1 tears may be a risk factor for the development of adjacent acetabular cartilage damage.

DOI： 10.1302/0301-620X.95B10.31647

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DOI： 10.1097/BSD.0b013e3182a357ad

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Language：English   Publishing type：Research paper (scientific journal)  

Background: The effect of the extent of osteonecrosis on the survival of hip resurfacing for osteonecrosis of the femoral head (ONFH) has not been well documented, but is a potentially important variable in the decision to perform resurfacing. Questions/purposes: We examined (1) the relationship between the volume of osteonecrosis in the femoral head before surgery and the extent of the residual necrotic bone after femoral head machining, (2) how the extent of the residual necrotic bone relative to the resurfaced femoral head (after femoral head machining) affected the survival of total hip resurfacing for patients with ONFH, and (3) how the extent of the necrotic bone relative to the entire femoral head (before femoral head machining) affected the survival and clinical outcome scores of patients who underwent total hip resurfacing. Methods: Thirty-three patients (39 hips) who underwent hip resurfacing were reviewed after a mean followup of 8 years. The extent of osteonecrosis in the femoral head and residual osteonecrosis in the implant bony bed after femoral head machining were estimated using a three-dimensional MRI-based templating system. Results: There was a statistically significant difference in the extent of osteonecrosis before and after femoral head machining, although the two were well correlated (r = 0.97). The mean percentage of osteonecrosis in the implant bony bed after femoral head machining was 5% smaller than that relative to the entire femoral head (range, -9% to 15%). There were no significant differences in implant survival between groups with small and large osteonecrosis classified by either the total amount of osteonecrosis before surgery or residual osteonecrosis after femoral head machining. Conclusion: The extent of osteonecrosis in the femoral head significantly decreased after femoral head machining. Neither the residual osteonecrosis volume in the implant bony bed after femoral head machining nor the total amount of osteonecrosis before femoral head machining had significant influence on the survival of hip resurfacing. Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence. © 2013 The Association of Bone and Joint Surgeons®.

DOI： 10.1007/s11999-013-2833-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases.
We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky's type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips).
Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81-98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening.
The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.

DOI： 10.1007/s00264-013-1818-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Carbon fiber-reinforced polyetheretherketone (CFR/PEEK) is theoretically suitable as a material for use in hip prostheses, offering excellent biocompatibility, mechanical properties, and the absence of metal ions. To evaluate in vivo fixation methods of CFR/PEEK hip prostheses in bone, we examined radiographic and histological results for cementless or cemented CFR/PEEK hip prostheses in an ovine model with implantation up to 52 weeks. CFR/PEEK cups and stems with rough-textured surfaces plus hydroxyapatite (HA) coatings for cementless fixation and CFR/PEEK cups and stems without HA coating for cement fixation were manufactured based on ovine computed tomography (CT) data. Unilateral total hip arthroplasty was performed using cementless or cemented CFR/PEEK hip prostheses. Five cementless cups and stems and six cemented cups and stems were evaluated. On the femoral side, all cementless stems demonstrated bony ongrowth fixation and all cemented stems demonstrated stable fixation without any gaps at both the bone-cement and cement-stem interfaces. All cementless cases and four of the six cemented cases showed minimal stress shielding. On the acetabular side, two of the five cementless cups demonstrated bony ongrowth fixation. Our results suggest that both cementless and cemented CFR/PEEK stems work well for fixation. Cup fixation may be difficult for both cementless and cemented types in this ovine model, but bone ongrowth fixation on the cup was first seen in two cementless cases. Cementless fixation can be achieved using HA-coated CFR/PEEK implants, even under load-bearing conditions. (C) 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 485492, 2013

DOI： 10.1002/jor.22251

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：計測自動制御学会  

DOI： 10.9746/sicetr.49.78

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG BERLIN  

Segmentation of the femur and pelvis is a prerequisite for patient-specific planning and simulation for hip surgery. Accurate boundary determination of the femoral head and acetabulum is the primary challenge in diseased hip joints because of deformed shapes and extreme narrowness of the joint space. To overcome this difficulty, we investigated a multi-stage method in which the hierarchical hip statistical shape model (SSM) is initially utilized to complete segmentation of the pelvis and distal femur, and then the conditional femoral head SSM is used under the condition that the regions segmented during the previous stage are known. CT data from 100 diseased patients categorized on the basis of their disease type and severity, which included 200 hemi-hips, were used to validate the method, which delivered significantly increased segmentation accuracy for the femoral head.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：British Editorial Society of Bone and Joint Surgery  

We investigated differences in the location and mode of labral tears between dysplastic hips and hips with femoroacetabular impingement (FAI). We also investigated the relationship between labral tear and adjacent cartilage damage. We retrospectively studied 72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological evidence of dysplasia or FAI on high-resolution CT arthrography. The incidence and location of labral tears and modes of tear associated with the base of the labrum (Mode 1) or body of the labrum (Mode 2) were compared among FAI, mildly dysplastic and severely dysplastic hips. The locations predominantly involved with labral tears were different in FAI and mild dysplastic hips (anterior and anterosuperior zones) and in severely dysplastic hips (anterosuperior and superior zones) around the acetabulum. Significant differences were observed in the prevalence of Mode 1 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)). Hip pathology is significantly related to the locations and modes of labral tears. Mode 1 tears may be a risk factor for the development of adjacent acetabular cartilage damage. © 2013 The British Editorial Society of Bone &amp
Joint Surgery.

DOI： 10.1302/0301-620X.95B10.31647

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper describes a method for automated optimization of total hip arthroplasty (THA) planning incorporating joint functionalities. The optimal planning is formulated as maximum a posterior (MAP) estimation, which ensures the best-balance of joint functionalities and bone-implant spatial relations based on their statistical models derived from the training datasets prepared by an experienced surgeon. According to the performance evaluation, four of the six functionalities of the automatically optimized plans were almost equivalent to those of surgeon's plans, and two of them were improved. We consider these results showed a potential usefulness of the proposed method.

DOI： 10.1109/EMBC.2013.6610166

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The reparative reaction including angiogenesis and osteogenesis in human bone after an ischemic event remains unknown. To investigate the reparative reaction in human bone, the distribution of tartrate resistant acid phosphatase (TRAP)-positive cells and the expressions of hypoxia inducible factor-1 alpha (HIF-1 alpha), vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), and CD31 were observed around the fracture site in 101 hips in 100 patients with femoral neck fracture. These 17 men and 83 women had a mean age of 80 years (range, 58-97 years). Of the hips, 17 were Garden stage 3, and 84 were Garden stage 4. The mean duration from fracture to surgery was 6.3 days (range, 1-14 days). Hematoxylin-eosin staining, TRAP staining, and immunohistochemistry using anti-HIF-1 alpha, anti-VEGF anti-FGF-2, and anti-CD31 antibodies were performed for the coronal section of the retrieved whole femoral heads. TRAP-positive cells were detected near the trabecular bone around the fracture site in ten hips (10 %). HIF-1 alpha expression was detected in 41 hips (41 %), mainly in the endothelial cells of the vessels. VEGF showed diffuse cytoplasmic staining of the mononuclear cells in the edematous area in 39 hips (39 %) while FGF-2 was detected in the cytoplasm of mononuclear cells in the bone marrow in 82 hips (82 %). CD31 was expressed in the bone marrow vessels in 35 hips (35 %). There were significant differences in HIF-1 alpha expression relative to the duration between the fracture and the surgery, and in CD31 expression relative to Garden stage. HIF-1 alpha expression was detected around the fracture site in the early period after fracture and CD31 expression was detected more frequently in Garden 3 hips while VEGF and FGF-2 expressions were detected regardless of Garden classification.

DOI： 10.1007/s00428-012-1331-y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Background Although navigated THA provides improved precision in implant positioning and alignment, it is unclear whether these translate into long-term implant survival. Questions/Purposes We compared survivorship, dislocation rate, and incidence of radiographic failures such as loosening and bearing breakage after THA with and without navigation at a minimum 10-year followup.
Methods We retrospectively reviewed 46 patients (60 hips) and 97 patients (120 hips) receiving THA with or without a CT-based navigation system, respectively, using cementless THA ceramic-on-ceramic bearing couples. There were no differences in age, sex, diagnosis, height, weight, BMI, or preoperative clinical score between groups. We evaluated survivorship, mode of acetabular and femoral component fixation, osteolysis, and implant wear or breakage at a minimum followup of 10 years (average, 11 years; range, 10-13 years).
Results Survival at 13 years was 100% with navigation and 95.6% (95% CI, 88.4%-98.4%) without navigation. With navigation, all cups were placed within a zone of 40 degrees (range, 30 degrees-50 degrees) of radiographic inclination and 15 degrees (range, 5 degrees-15 degrees) of radiographic anteversion; without navigation, 31 cups (26%) were placed outside this zone. Hips treated without navigation had a higher rate of dislocation (8%) than the navigated cases (0%). Revision was performed in four nonnavigated cases, all of which showed evidence of neck impingement on the ceramic liner. Moreover, seven other cases without navigation showed posterior neck erosion on radiographs. These 11 impingement-related mechanical complications correlated with cup malorientation, and the incidence of impingement-related complications was higher in nonnavigated cases.
Conclusions Navigation reduced the rates of dislocation and impingement-related mechanical complications leading to revision in cementless THA using ceramic-on-ceramic bearing couples over a minimum 10-year followup.
Level of Evidence Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

DOI： 10.1007/s11999-012-2378-4

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Language：Japanese   Publishing type：Research paper (other academic)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENDOCRINE SOC  

Context: Slipped capital femoral epiphysis is a well-recognized skeletal complication of renal osteodystrophy in adolescence, which is distinct from idiopathic slipped capital femoral epiphysis in its etiology.
Objective: We report a case of severe mixed-type renal osteodystrophy with metaphyseal bone collapse that mimicked slipped capital femoral epiphyses.
Methods: Case history, laboratory and radiological evaluation, and bone biopsies are discussed.
Results: A 14-yr-old girl presented with left hip pain showing bilateral metaphyseal bone collapse accompanied with posterior-inferior displacement of capital femoral epiphyses after 2.5 yr of GH treatment. Blood chemistry, showing high levels of alkaline phosphatase and PTH, and a transiliac bone biopsy, indicating severe osteomalacia with osteitis fibrosa, along with serial computed tomography images of the hips from the presymptomatic stage, led to accurate diagnosis and successful treatment by administration of high-dose vitamin D.
Conclusion: This case emphasizes the importance of controlling hyperparathyroidism well in children with chronic renal insufficiency, particularly at adolescence before initiating GH treatment. When children with renal insufficiency present with displacement of capital femoral epiphysis, it is necessary to evaluate the serum levels of alkaline phosphatase and PTH and metaphyseal bone quality below the physis. (J Clin Endocrinol Metab 97: 3851-3856, 2012)

DOI： 10.1210/jc.2012-2739

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Language：Japanese   Publisher：(一社)日本脊椎脊髄病学会  

フラットパネル検出器搭載モバイルC-armによる側彎症手術における椎弓根スクリュー位置評価の信頼性を検討した。合計202本の椎弓根スクリューを術中3Dイメージング画像と術後CTでそれぞれ評価、比較した。術中3Dイメージングの検者内一致度はカッパ係数で0.82と良好で、感度70%、陽性的中率44%であった。本装置は、スクリュー位置評価において、通常CTに代わる有用な機器となる。(著者抄録)

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2012&ichushi_jid=J05510&link_issn=&doc_id=20121130030009&doc_link_id=%2Ffg7spine%2F2012%2F000311%2F010%2F1461-1464%26dl%3D0&url=http%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Ffg7spine%2F2012%2F000311%2F010%2F1461-1464%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INFORMA HEALTHCARE  

Background and purpose It is controversial whether the transverse acetabular ligament (TAL) is a reliable guide for determining the cup orientation during total hip arthroplasty (THA). We investigated the variations in TAL anatomy and the TAL-guided cup orientation.
Methods 80 hips with osteoarthritis secondary to hip dysplasia (OA) and 80 hips with osteonecrosis of the femoral head (ON) were examined. We compared the anatomical anteversion of TAL and the TAL-guided cup orientation in relation to both disease and gender using 3D reconstruction of computed tomography (CT) images.
Results Mean TAL anteversion was 11 degrees (SD 10, range -12 to 35). The OA group (least-square mean 16 degrees, 95% confidence interval (CI): 14-18) had larger anteversion than the ON group (least-square mean 6.2 degrees, CI: 3.8 - 7.5). Females (least-square mean 20 degrees, CI: 17-23) had larger anteversion than males (least-square mean 7.0 degrees, CI: 4.6-9.3) in the OA group, while there were no differences between the sexes in the ON group. When TAL was used for anteversion guidance with the radiographic cup inclination fixed at 40 degrees, 39% of OA hips and 9% of ON hips had more than 10 degrees variance from the target anteversion, which was 15 degrees.
Interpretation In ON hips, TAL is a good guide for determining cup orientation during THA, although it is not a reliable guide in hips with OA secondary to dysplasia. This is because TAL orientation has large individual variation and is influenced by disease and gender.

DOI： 10.3109/17453674.2012.727077

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Despite the excellent osseointegration of carbon-fiber-reinforced polyetheretherketone (CFR/PEEK) with a surface hydroxyapatite (HA) coating, the bone-implant interfacial shear strength of HA-coated CFR/PEEK after osseointegration is unclear. We examined the interfacial shear strength of HA-coated CFR/PEEK implants after in vivo implantation in a rabbit femur-implant pull-out test model. HA coating was performed by a newly developed method. Uncoated CFR/PEEK, HA-coated blasted titanium alloy, and uncoated blasted titanium alloy were used as control implants. The implants were inserted into drilled femoral cortex, and pull-out tests were conducted after 6 and 12 weeks of implantation to determine maximum interfacial shear strength. The HA-coated CFR/PEEK (15.7?+/-?4.5?MPa) and HA-coated titanium alloy (14.1?+/-?6.0?MPa) exhibited significantly larger interfacial shear strengths than the uncoated CFR/PEEK (7.7?+/-?1.8?MPa) and the uncoated titanium alloy (7.8?+/-?2.1?MPa) at 6 weeks. At 12 weeks, only the uncoated CFR/PEEK (8.3?+/-?3.0?MPa) exhibited a significantly smaller interfacial shear strength, as compared to the HA-coated CFR/PEEK (17.4?+/-?3.6?MPa), HA-coated titanium alloy (14.2?+/-?4.8?MPa), and uncoated titanium alloy (15.0?+/-?2.6?MPa). Surface analysis of the removed implants revealed detachment of the HA layer in both the HA-coated CFR/PEEK and titanium alloy implants. The proposed novel HA coating method of CFR/PEEK significantly increased interfacial shear strength between bone and CFR/PEEK. The achieved interfacial shear strength of the HA-coated CFR/PEEK implant is of the same level as that of grit-blasted titanium alloy with HA. (c) 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:16181625, 2012

DOI： 10.1002/jor.22115

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

The purpose of this study was to retrospectively investigate the incidence of initial polar gaps and their effect on clinical results in Birmingham Hip Resurfacing cups. A total of 151 hips in 134 patients who underwent hip resurfacing at a mean age of 50 years were examined. The mean follow-up period was 7 years. A polar gap was identified in 47 hips (31%) with a mean width of 2.1 mm. Gaps of 2 mm or more were identified in 21 hips, 6 of which showed reductions in cup inclination during the initial 3 months. After 3 months, no progressive cup migration was observed. There was no cup revision. All gaps were filled with bone within 2 years of surgery. The initial polar gaps had no significant influence on the stability of hydroxyapatite-coated Porocast cobalt-chromium hemispherical monoblock cups (Midland Medical Technologies Ltd, Birmingham, UK), although gaps of 2 mm or more had a higher risk of early migration.

DOI： 10.1016/j.arth.2012.02.028

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The Chiari osteotomy reportedly has a 60% to 91% survival rate at a minimum 20 years followup. The dome pelvic osteotomy (DPO) has the advantage of allowing a larger weightbearing surface, and congruity in the sagittal plane presumably would reduce the joint contact stress and perhaps increase longevity.
We determined: (1) the survival after DPO at a minimum 25-year followup, (2) patient function, (3) acetabular coverage, and (4) factors influencing conversion to THA.
We retrospectively reviewed 50 patients (59 hips) with developmental dysplasia of the hip (DDH) treated with DPO. The preoperative radiographic stages were graded as prearthritis (18 hips), early osteoarthritis (25 hips), and advanced osteoarthritis (16 hips). We performed a Kaplan-Meier survival analysis with THA conversion as the end point. We determined various radiographic parameters reflecting coverage, and compared demographic information for hips without and with THA conversion using multivariate logistic regression analysis. The minimum followup was 25 years (mean, 27.5 years; range, 25-32 years).
Survival for all hips was 63.6% (95% CI, 51-76) at 27.5 years and that for hips with prearthritis and early osteoarthritis before the surgery was 79.1% (95% CI, 63-91). Twenty-one hips (36%) had undergone THAs at a mean 18.3 years (range, 2.5-25 years). At the last followup, pain, walking ability, and acetabular coverage improved. We identified four factors predicting THA conversion: greater age, presence of a preoperative Trendelenburg sign, higher preoperative radiographic osteoarthritis grade, and smaller postoperative acetabular head index (AHI) predicted conversion to THA.
DPO is a reasonable treatment option for patients with DDH and prearthritis or early osteoarthritis, with high survival at greater than 25 years.
Level IV, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

DOI： 10.1007/s11999-012-2282-y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

Although deep hip bending activities are often required in Asian populations because of traditional lifestyles and religious practices, few have examined the required hip range of motion (ROM) in these activities after total hip arthroplasty (THA). We performed postoperative motion analysis to evaluate the differences in required ROMs between Japanese-style and Western-style deep hip bending activities, to investigate Whether prosthetic impingement would occur during these activities and to clarify the necessity for precautions in these activities after THA. Japanese-style activities did not require larger hip ROMs than Western-style ones, and all required hip flexion angles were less than 120 degrees. Prosthetic impingement was not observed, with a safety margin 10 degrees or higher until impingement in any directions of flexion, adduction, or internal rotation for any activities. Thus, particular postoperative precautions for Japanese-style activities are not required.

DOI： 10.1016/j.arth.2012.01.029

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Language：Japanese   Publisher：日本股関節学会  

大腿骨頭軟骨下骨折(SFFH)10例と急速破壊型股関節症(RDC)45例および関節リウマチ(RA)股12例のTHA施行時に摘出した大腿骨頭を試料として組織学的検討を行い、疾患別で比較した。結果、TRAP染色により、SFFH群では8例(80%)が陽性を示し、TRAP陽性細胞は軟骨下骨梁骨折周囲の仮骨に沿って存在していた。RDC群では35例(78%)が陽性を示し、TRAP陽性細胞はいずれも集簇していた。RA群では11例(92%)が陽性を示し、TRAP陽性細胞は3例で集簇していた。SFFH群ではTRAP細胞の集簇は認められなかった。RANKL染色により、SFFH群では2例(20%)、RDC群では35例(78%)、RA群では3例(25%)が陽性を示した。このうちRDC群ではRANKLが骨梁周囲や線維性組織内に多く発現しており、骨破壊に関与している可能性が示唆された。

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：日本股関節学会  

表面置換型人工股関節全置換術(RHA)は、「骨温存」「脱臼抵抗性」「低摩耗」という点で魅力的と考えられるが、「耐用性」については、従来型THAと比べて有利であるか議論が分かれている。そこで今回、自施設で1998〜2008年に特発性大腿骨頭壊死症に対しRHAを行った35例と従来型THAを行った74例の中期成績を群間比較した。術後経過期間は両群とも平均7年で、評価項目は「最終観察時のWOMACスコア」「人工関節の生存率」とした。患者背景をみるとRHA群で若年の男性が有意に多かったが、「WOMACスコア」「生存率」は従来型THA群と同等であり、良好であった。

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：The Institute of Electronics, Information and Communication Engineers  

Segmentation of the musculo-skeletal from 3D images is needed for patient-specific musculo-skeletal simulation. We proposed automated musculoskeletal segmentation from CT data of the hip using hierarchical multi-atlas method. The proposed method will be potentially utilized for different populations, modalities, and muscles. If segmentation accuracy will keep good when the amount of the preparation is limited, it becomes that much easier to prepare dataset. So, we performed an experimental study on the relationship between training set size and segmentation accuracy. We provide an indication of new dataset preparations.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The International Society for Computer Assisted Orthopaedic Surgery  

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

Although metal hypersensitivity or pseudotumors are concerns for metal-on-metal (MOM) bearings, detailed pathologies of patterns, severity, and incidence of periprosthetic soft tissue lesions are incompletely understood. We examined the potential of ultrasound for screening of periarticular soft tissue lesions around MoM bearings. Ultrasound examinations were conducted in 88 hips (79 patients) with MoM hip resurfacings or MoM total hip arthroplasties with a large femoral head. Four qualitative ultrasound patterns were shown, including normal pattern in 69 hips, joint-expansion pattern in 11 hips, cystic pattern in 5 hips, and mass pattern in 3 hips. Hips with the latter 3 abnormal patterns showed significantly higher frequency of clinical symptoms, without significant differences of sex, duration of implantation, head sizes, and cup abduction/anteversion angles, compared with hips with normal pattern. Ultrasound examination provides sensitive screening of soft tissue reactions around MoM bearings and may be useful in monitoring progression and defining treatment for periarticular soft tissue abnormalities.

DOI： 10.1016/j.arth.2011.09.015

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The International Society for Computer Assisted Orthopaedic Surgery  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we describe methods for automated bone segmentation and THA planning. The automated planning is formulated as maximum a posterior (MAP) estimation with statistical atlases of implants, bone models, joint functionalities which are modeled with training datasets prepared by an experienced surgeon. In the experiment, we performed the evaluation of the proposed method and obtained a result that there was no significance between the proposed method and surgeon's plans. We considered this showed a potential usefulness of our method with automated segmentation.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

To analyze long-term survivorship of cementless total hip arthroplasties (THAs) with the third-generation alumina ceramic-on-ceramic bearing, 100 consecutive THAs between 1996 and 1998 were reviewed. One cup and 2 stems were revised due to aseptic loosening. Another cup showed chipping of the acetabular liner at 8 years and required cup revision. The remaining hips showed stable bone ingrowth fixation with no osteolysis at the final follow-up. The 14-year survivorship as the end point of revision was 97.9% for the cup, 97.8% for the stem, and 95.7% for the overall implants, respectively. We conclude that cementless THA with the third-generation ceramic-on-ceramic hip bearing provided an excellent survivorship and eliminated periprosthetic osteolysis for 11 to 14 years. (C) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.arth.2011.08.017

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Joint space width (JSW) of hip joints on radiographs in normal population may vary by related factors, but previous investigations were insufficient due to limitations of sources of radiographs, inclusion of subjects with osteoarthritis, and manual measurement techniques. We investigated influential factors on JSW using semiautomatic computational software on pelvic radiographs in asymptomatic subjects without radiological osteoarthritic findings.
Global and local JSW at the medial, middle, and lateral compartments, and the hip structural parameters were measured in asymptomatic, normal 150 cases (300 hips), using a customized computational software.
Reliability of measurement in global and local JSWs was high with intraobserver reproducibility (intraclass correlation coefficient) ranging from 0.957 to 0.993 and interobserver reproducibility ranging from 0.925 to 0.985. There were significant differences among three local JSWs, with the largest JSW at the lateral compartment. Global and medial local JSWs were significantly larger in the right hip, and global, medial and middle local JSWs were significantly smaller in women. Global and local JSWs were inversely correlated with CE angle and positively correlated with horizontal distance of the head center, but not correlated with body mass index in men and women. They were positively correlated with age and inversely correlated with vertical distance of the head center only in men.
There were interindividual variations of JSW in normal population, depending on sites of the weight-bearing area, side, gender, age, and hip structural parameters. For accurate diagnosis and assessment of hip osteoarthritis, consideration of those influential factors other than degenerative change is important.

DOI： 10.1007/s00402-012-1463-1

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Atlas-based methods for automated preoperative planning of the femoral stem implant in total hip arthroplasty are described. Statistical atlases are constructed from a number of past preoperative plans prepared by experienced surgeons in order to represent the surgeon's expertise of the planning. Two types of atlases are considered. One is a statistical distance map atlas, which represents surgeon's preference of the contact pattern between the femoral canal (host bone) and stem (implant) surfaces. The other is an optimal reference plan, which is selected as the best representative plan expected to minimize the deviation from the surgeon's preferred contact pattern. These atlases are fitted to the patient data to automatically generate the preoperative plan of the femoral stem. In this paper, we formulate a general framework of atlas-based implant planning, and then describe the methods for construction and utilization of the two proposed atlases. In the experiments, we used 40 cases to evaluate the proposed methods and compare them with previous methods by defining the errors as differences between automated and surgeon's plans. By using the proposed methods, the positional and orientation errors were significantly reduced compared with the previous methods and the size error was superior to inter-surgeon variability in size selection using 2D templates on an X-ray image reported in previous work. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.media.2011.10.005

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The wear behavior of alumina femoral heads was examined at follow-up periods between 7.7 and 10.7 years. Four head retrievals of the same size (28 mm in diameter) were divided into two groups with different design characteristics. Systematically using scanning electron and atomic force microscopy procedures, wear characteristics could be classified on the entire heads according to five zones with increasing degrees of wear damage (Grade 1-5), in addition to one zone of stripe wear (Grade SW). The stripe wear zone showed quite different topographical features as compared to frictionally worn zones. Furthermore, hip implants designed with different clearances are shown to lead to different wear patterns on the femoral head surface, the smaller the clearance the wider the worn surface area. Cathodoluminescence piezo-spectroscopy provided information about the residual stress state in surfaces worn to different degrees and helped clarifying the wear mechanisms on the microscopic scale.

DOI： 10.1007/s10856-011-4502-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

A carbon fiber-reinforced polymer (CFRP) is theoretically a suitable material for use in an uncemented hip prosthesis considering it can provide isoelastic environment with the surrounding bone, adequate fatigue strength, and a metal-free radiographic evaluation. To date, the selection of polymer material and optimization of both design and surface finish of the prostheses for osseointegration has not been accomplished. This study examined radiographic and histologic results of an uncemented CFRP stem manufactured from carbon fiber-reinforced polyetheretherketone (CFR/PEEK) with a roughened surface and a bioactive treatment in an adult ovine model following a 12-month implantation period. A unilateral hemiarthroplasty of the hip was performed using the CFRP stem or a titanium stem as a control. Four cases with the CFRP stem and five cases with titanium stem were evaluated. Bone on-growth fixation was achieved in two cases with the CFRP stem and in all the cases with the titanium stem. The CFRP cases showed minimal stress shielding while three of five cases with the titanium stem demonstrated typical osteopenia associated with stiff metal stems. Bone on-growth to the uncemented CFRP stem was achieved by using the CFR/PEEK for the material and modifying the surface design and the bioactive surface finish. Bone resorption and osteopenia observed with the Ti stems was not found with the CFRP design.

DOI： 10.1111/j.1525-1594.2011.01275.x

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Diagnostic modeling based on computational anatomy is an important topic. In previous work, discrimination method using support vector machine based on principal component analysis of the hippocampus shapes have been proposed. However, disease-specific component was not considered explicitly. In this paper, we propose a method for constructing the disease subspace using orthogonal complement of the normal subspace. The proposed method was tested using the hepatic cirrhosis and hip osteoarthritis datasets and was compared to a previous method. In our experiments, the proposed method was effective for disease discrimination based on organ shapes.
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6528676

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INFORMA HEALTHCARE  

Objective: The aim of this study was to find the proper location of the fluoroscopic imaging center in order to apply a CT-based 3D fluoroscopy matching navigation system in the pelvic and femoral regions.
Materials and methods: To simulate surgeries around the hip joint, a dry human pelvis and femur were used. A total of 16 fiducial markers, each consisting of a metal ball 1.5 mm in diameter, were fixed to the pelvis and femur. For the pelvis, the pubic symphysis, the acetabular fossa, and a site on the ilium 3 cm above the acetabular roof were selected as fluoroscopic imaging centers. For the proximal femur, the base of the femoral neck, the femoral shaft at the level of the lesser trochanter, and the inferior border of the great trochanter were selected as fluoroscopic imaging centers.
Results: Target registration error (TRE) differed significantly among the selected fluoroscopic imaging centers. The best mean TRE for the pelvis was 0.8 mm (range: 0.2 to 1.6 mm) with the imaging center on the ilium (3 cm above the acetabular roof). The best mean TRE for the proximal femur was 1.1 mm (range: 0.2 to 2.0 mm) with the imaging center on the femoral shaft at the lesser trochanter level.
Conclusion: Fluoroscopic imaging center location had a significant effect on the accuracy of the CT-based 3D fluoroscopy matching navigation system in the pelvic and femoral regions. The proper fluoroscopic imaging centers for CT-3D fluoroscopic matching were, for the pelvis, a site on the ilium 3 cm above the acetabular roof, and for the proximal femur, the femoral shaft at the level of the lesser trochanter.

DOI： 10.3109/10929088.2012.654823

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Publisher：The Japanese Society of Medical Imaging Technology  

Localization of the pelvic anatomical coordinate system is a prerequisite for patient-specific preoperative planning and joint motion simulation for hip surgery. Our aim is to automate localization of the pelvic anatomical coordinate system from 3D CT data. In this paper, we propose a statistical atlas-based method that consists of three steps. The first step is spatial normalization using a probabilistic atlas. The second step is feature point recognition using a statistical landmark model. The final step is coordinate system refinement using a standard CT atlas. We applied the proposed method to 39 datasets. Compared to manual localization by an experienced surgeon, the average positional error was 2.37 ± 1.30 mm and the average orientation error was 1.07 ± 0.50 degrees. These results demonstrate the usefulness of the proposed method.

DOI： 10.11409/mit.30.43

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Other Link： http://search.jamas.or.jp/link/ui/2012220714

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Although wear reduction of highly cross-linked polyethylene has been demonstrated to be independent of femoral head diameter in some simulation studies, the clinical effects of femoral head diameter on wear of highly cross-linked polyethylene sockets remain unclear. We compared the in vivo wear of Longevity highly cross-linked polyethylene liners at 8-year follow-up using 26- or 32-mm cobalt-chromium heads.
A retrospective cohort study was performed on 90 cementless total hip arthroplasties (THAs) using Longevity highly cross-linked polyethylene liners combined with 26- (45 THAs) or 32-mm (45 THAs) cobalt-chromium heads. Annual radiographs were analyzed using PolyWare computer-assisted methods and linear and volumetric total head penetration rates and linear and volumetric steady-state wear rates were compared.
The two groups showed similar background data, and no significant differences were identified between groups in total head penetration rate or steady-state wear rate. Steady-state wear rates were negligible. Osteolysis was not observed in any hips in either group.
At the 8-year follow-up, wear of the Longevity was the same irrespective of the use 26- or 32-mm heads.

DOI： 10.1007/s00402-011-1360-z

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Language：Japanese   Publisher：(一社)日本人工関節学会  

Birmingham Hip Resurfacingを用いて表面置換型人工股関節全置換術を施行した特発性大腿骨頭壊死症(ION)37例43関節(男32例、女11例、平均38.3歳)の成績を、変形性股関節症(OA)99例112関節(男44例、女68例、平均54.2歳)と比較した。観察期間2〜11年で、JOAスコアはION群平均96点、OA群94点、WOMACスコアはそれぞれ4.7点、4.5点と有意差はなかった。再置換は5関節に行い、カップがION群0関節、OA群2関節、大腿コンポーネントがそれぞれ2関節、3関節であった。再置換の理由は、ION群は術後9ヵ月と10年に生じた大腿コンポーネントの弛みであった。OA群は術後3週に頸部骨折、2.5年に感染を各1例認め、カップと大腿コンポーネントの再置換を行い、術後11年に大腿コンポーネントの弛みが認められた。エンドポイントを再置換としたカップの術後7年の生存率はION群100%、OA群98%、大腿コンポーネントはいずれも98%で、両群間に有意差はなかった。

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Language：Japanese   Publisher：日本股関節学会  

表面置換型人工股関節全置換術50例57股(男23股、女34股、平均49歳)を対象に、二次元デジタル術前計画(2D法)と三次元術前計画(3D法)のコンポーネントサイズ選択の一致率について検討した。2D法はStryker社製のCase plan、3D法は3D-CTデータを用いて独自開発した3Dデジタルテンプレートソフトで行った。対象の疾患は一次性OAが2股、DDH由来OAが41股、ONが12股、RAが1股、外傷性OAが1股で、Bombelli分類や骨頭の圧潰などで分類した骨頭変形の程度は軽度群34股、高度群23股であった。カップサイズの完全一致率は2D法74%、3D法90%、大腿コンポーネントはそれぞれ77%、93%と両法間に有意差が認められた。骨頭変形程度では、2D法のカップサイズ完全一致率が軽度群88%、高度群52%、大腿コンポーネントはそれぞれ94%、52%と有意差が認められた。3D法ではカップサイズ完全一致率が軽度群94%、高度群83%、大腿コンポーネントはそれぞれ100%、83%であった。

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Language：Japanese   Publisher：(株)メジカルビュー社  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

The purpose of the present study was to evaluate the 6- to 11-year follow-up results of hemispherical porous-coated cups implanted into dysplastic hips using press-fit technique without screws focusing on the amount of host bone coverage. There were 87 patients who underwent 98 primary total hip arthroplasties. Bony coverage was measured as the angle between the vertical line and the line drawn from the cup center to the lateral edge of the acetabulum, which was named the cup center-edge angle (cup-CE angle). All 98 cups were judged to be bone ingrown. The minimum cup-CE angle was 8.4 degrees (mean, 26.3 degrees). Bone-cup contact of more than 8.4 degrees of the cup-CE angle was large enough for press-fit cups to resist superior directed loads during this follow-up period.

DOI： 10.1016/j.arth.2010.05.025

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL PUBLISHING, INC  

For the proper diagnosis or treatment of hip joint disorders caused by anatomical abnormalities, the normal hip joint morphology must be studied to understand its influence on the maximum range of motion (ROM) until bony impingement by focusing on gender differences. Acetabular and femoral morphologies were analyzed from 3D CT images of 106 normal hip joints from elderly men (n = 36 joints) and women (n = 70 joints), and measurements of ROM until bony impingement were made in four directions (flexion, extension, and external and internal rotation at 90 degrees flexion) using surface models of the pelvis and femur reconstructed from the CT data. Gender differences were found not only in joint orientation, including anteversion and inclination of the acetabulum and femoral neck anteversion, but also in the shape around the joint, including the acetabular rim and the femoral neck. This ROM study also showed gender differences in all four standard directions. In conclusion, significant gender differences were observed in the acetabular and femoral morphology, which led to significant gender differences in ROM until bony impingement. (C) 2010 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:333-339, 2011

DOI： 10.1002/jor.21265

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL BONE JOINT SURGERY INC  

Background: The purpose of this retrospective study was to analyze the functional and radiographic results of cementless, modular total hip arthroplasty combined with subtrochanteric osteotomy for the treatment of patients who had had Crowe Group-IV developmental dysplasia of the hip as a child.
Methods: Twenty-five consecutive patients (thirty-three hips) who had previously had Crowe Group-IV developmental dysplasia of the hip were treated with a modular cementless prosthesis at a mean age of sixty years. The mean follow-up period was eight years (range, five to eleven years). The acetabular cup was placed in the position of the anatomical hip center in every patient. Subtrochanteric femoral shortening osteotomy was performed with use of a step-, cut design.
Results: The mean Merle d'Aubigne and Postel hip score improved from 9 to 16 points (out of a maximum of 18 points). The mean limb-length discrepancy in seventeen patients with unilateral involvement was reduced from 5.1 cm (range, 3.7 to 6.5 cm) to 2.8 cm (range, 1.4 to 4.6 cm). Two,patients had a positive Trendelenburg sign, and three had a slight limp at the time of the latest follow-up. No cases of nonunion or nerve palsy were encountered. Postoperative dislocations occurred in two hips. One hip showed progressive radiolucent lines around the proximal femoral sleeve within two years after the surgery, and this was followed by progressive stem subsidence. Only one femoral stem was revised.
Conclusions: Cementless, modular total hip arthroplasty combined with subtrochanteric osteotomy for the treatment of patients with prior Crowe Group-IV developmental dysplasia of the hip resulted in satisfactory outcomes. Hips with poor bone quality and a developmentally short femoral neck present technical challenges with regard to achieving sufficient rotatory stability, following osteotomy, for osseointegration of the modular implants.

DOI： 10.2106/JBJS.I.01619

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER HEIDELBERG  

The aim of this study was to investigate the incidence of osteonecrosis of the hip and knee among renal allograft recipients treated with cyclosporin- or tacrolimus-based immunosuppressive regimens and its predictors focusing on the first 8 weeks after transplantation. The subjects were 232 renal allograft recipients who had MRI for osteonecrosis of the hip and knee 3 months or longer after transplant. The following potential predictors of osteonecrosis were tested using univariate and multivariate logistic regression analyses: age, gender, body weight, body mass index, duration on dialysis before transplant, number of human leukocyte antigen mismatches, ABO mismatches, type of transplanted kidney, immunosuppressive regimen, cumulative steroid dose and steroid pulses, incidence of acute rejection, and delayed graft function, defined as requiring dialyses in the first week. Evidence of osteonecrosis was visible on the MRI of 11 recipients (4.7%, 95% confidence interval 2.4-8.3). Univariate and multivariate logistic regression analyses indicated that delayed graft function was the most important predictor of osteonecrosis. In conclusion, we found a lower incidence of osteonecrosis of the hip and knee in renal allograft recipients treated with cyclosporin or tacrolimus. In the patients treated with improved immunosuppressive regimens, delayed graft function was a significant early predictor of osteonecrosis.

DOI： 10.1007/s00296-009-1241-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INFORMA HEALTHCARE  

Objective: The aim of this study was to evaluate the accuracy of a novel 3-dimensional (3D) fluoroscopic navigation system using a flat-panel detector-equipped C-arm, focusing on the influence of the distance from the center of fluoroscopic imaging on navigation accuracy.
Materials and Methods: A geometric phantom was made using a Styrofoam cube with 25 markers, each consisting of a metal ball 1.5 mm in diameter, fixed in a cross arrangement at 1-cm intervals. Hip joint surgery was simulated using a set of dry pelvic and femoral bones. A total of eight markers were fixed to the acetabulum and proximal femur.
Results: In the geometric phantom study, mean target registration error (TRE) was 0.7 mm (range: 0.1-1.5). The TRE of markers located at 5 cm from the imaging center was significantly higher than the TRE of markers located at 1 and 2 cm. However, the TRE was &lt;1 mm in 90% of the overall trials and &lt;1.5 mm in 100%. In the dry bone study, the mean TRE was 0.9 mm (range: 0.7-1.5) over the acetabulum and 1.0 mm (range: 0.5-1.4) over the femur. No significant difference in TRE was seen between the acetabulum and proximal femur.
Conclusion: The accuracy of this novel 3D fluoroscopic navigation system was considered acceptable for clinical application. A 3D C-arm equipped with a flat-panel detector could increase the feasibility of 3D fluoroscopic navigation by reducing the effects of image distortion on navigation accuracy.

DOI： 10.3109/10929088.2011.602117

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Language：Japanese   Publisher：(一社)日本人工関節学会  

大腿骨頭壊死症に対して表面置換型人工股関節全置換術を施行した症例に対して、術前に撮影した3D-MRIを用いて大腿コンポーネントに対するリーミング後の残存壊死体積の比を計測し、臨床成績との関連性を検討した。大腿骨頭壊死症に対してRHAを施行し、2年以上の経過観察が可能で、かつ術前3D-MRIデータが得られた31例36股を対象とした。骨頭壊死面積比は平均37.1%で、コンポーネント内壊死面積比は平均27.4%であった。コンポーネント内壊死体積比は、平均26.8%であった。壊死範囲が0〜25%未満には術後8年で大腿コンポーネントの弛み例を認め、50%以上には臨床不良例を認めなかった。臨床不良例を認めた25%未満と25〜50%未満の症例の間に臨床不良例の明らかな有意差はなかった。

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Language：Japanese   Publisher：日本股関節学会  

表面置換型人工股関節全置換術(以下RHA)に用いられるカップは、摺動面とカップ本体が一体のモノブロックとなっているため、dysplastic用の特殊タイプ以外はスクリュー固定ができず、確実なプレスフィット固定が必要である。セメントレスカップのプレスフィット固定は、導入初期にはカップと臼底部の間にgapが発生し、骨との接触面積が低下することや臼蓋骨折をきたすことなど、その固定性を危惧する報告があった。しかし、適切なアンダーリーミングやインプラントデザインなどの研究により近年良好な中長期成績が報告されており、gapも臨床成績に影響しないとの報告が多いが、その詳細は不明である。そこで今回、当院と関連施設で1998〜2007年にRHAを施行された166例を対象に、gapの発生率・程度・X線学的経時変化や、gapが臨床成績に与えた影響などについて検討した。その結果、gapは21例(13%)に認め、gapの幅は0.6〜4.5mm(平均2.4m)であった。gap幅が3mm以上であった9例中6例では術後3ヵ月以内にカップ外転角度の3°以上の減少とカップの3mm以上の移動を認めたが、いずれもその後は安定し、最終観察時には全例でgapは消失もしくはfillingしており、臨床成績不良例はなかった。

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

The long-term results of grafting with hydroxyapatite granules for acetabular deficiency in revision total hip replacement are not well known. We have evaluated the results of revision using a modular cup with hydroxyapatite grafting for Paprosky type 2 and 3 acetabular defects at a minimum of ten years&apos; follow-up. We retrospectively reviewed 49 acetabular revisions at a mean of 135 months (120 to 178). There was one type 2B, ten 2C, 28 3A and ten 3B hips. With loosening as the endpoint, the survival rate was 74.2% (95% confidence interval 58.3 to 90.1). Radiologically, four of the type 3A hips (14%) and six of the type 3B hips (60%) showed aseptic loosening with collapse of the hydroxyapatite layer, whereas no loosening occurred in type 2 hips. There was consolidation of the hydroxyapatite layer in 33 hips (66%). Loosening was detected in nine of 29 hips (31%) without cement and in one of 20 hips (5%) with cement (p = 0.03, Fisher&apos;s exact probability test). The linear wear and annual wear rate did not correlate with loosening.
These results suggest that the long-term results of hydroxyapatite grafting with cement for type 2 and 3A hips are encouraging.

DOI： 10.1302/0301-620X.92B9.24555

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER LONDON LTD  

The purpose of this study was to evaluate retrospectively the progression of reparative changes in osteonecrosis of the femoral head over a long period of time, using both serial plain films and magnetic resonance (MR) images. The subjects were 25 patients with 33 hips affected by osteonecrosis, followed conservatively for more than 10 years (mean, 14.1; range, 10 to 23.4). At the latest follow-up examination, there were 11 hips at the non-collapse stage, 17 hips at the collapse stage where collapse has ceased, and five hips at the osteoarthritic stage. An increase in radiographic sclerosis of the lesion area was seen in 14 of 17 hips which showed cessation of collapse, 13 of which showed an intralesional area with intermediate signal intensity on fat suppression MR images. Four of five hips at the osteoarthritic stage also showed an intralesional area with intermediate signal intensity on fat suppression MR images. Ten of 11 hips at the non-collapse stage showed a normal fat signal intensity area demarcated with a low-signal-intensity band on T1-weighted MR images. In the 24 hips followed for more than 5 years with MR imaging (mean, 9.2; range, 5.9 to 13.8), changes of lesion size of abnormal signal intensity on T1-weighted MR images were not observed. In conclusion, reparative process was limited to the periphery of osteonecrosis over a long period of time unless collapse had occurred. If collapse had ceased minimally, the reconstructive repair process could be facilitated.

DOI： 10.1007/s10067-010-1404-8

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

We compared a modular neck system with a non-modular system in a cementless anatomical total hip replacement (THR). Each group consisted of 74 hips with developmental hip dysplasia. Both groups had the same cementless acetabular component and the same articulation, which consisted of a conventional polyethylene liner and a 28 mm alumina head. The mean follow-up was 14.5 years (13 to 15), at which point there were significant differences in the mean total Harris hip score (modular/non-modular: 98.6 (64 to 100)/93.8 (68 to 100)), the mean range of abduction (32 degrees (15 degrees to 40 degrees)/28 (0 degrees to 40 degrees)), use of a 10 elevated liner (31%/100%), the incidence of osteolysis (27%/79.7%) and the incidence of equal leg lengths (&gt;= 6 mm, 92%/61%). There was no disassociation or fracture of the modular neck.
The modular system reduces the need for an elevated liner, thereby reducing the incidence of osteolysis. It gives a better range of movement and allows the surgeon to make an accurate adjustment of leg length.

DOI： 10.1302/0301-620X.92B6.23001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：W B SAUNDERS CO-ELSEVIER INC  

This study reports on differences in the use of minimally invasive surgery for total hip arthroplasty related to the direction of cup insertion against the operating table, intraoperative hip range of motion, stability, and a choice of cup liners for both a mini-incision posterior approach (MPA) and a mini-incision anterior approach (MAA) using Stryker Navigation&apos;s CT-Hip system. The MPA group consisted of 39 consecutive patients and the MAA group consisted of 33 consecutive patients. Clinically, there was no significant difference in the average Japanese Orthopedic Association hip score or the Oxford hip score preoperatively and at 6 months and 2 years follow-up. The intraoperative joint stability measurements showed no large difference between the two groups when malpositioning of . the cup was eliminated.

DOI： 10.1016/j.ocl.2009.04.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Osteogenesis and angiogenesis are closely associated with the reparative process in bone. In osteonecrosis of the femoral head (ONFH), although the progression of bone resorption by osteoclasts is considered to be followed by femoral head collapse, the reparative reaction remains unknown. In order to investigate the reparative reaction in patients with ONFH, the distribution of`TRAP-positive cells and expression of HIF-1 alpha, VEGF, and FGF-2 were observed in 51 hips in 42 patients. TRAP-positive cells were detected around the teres insertion and retinaculum in the early radiologic stage, and increased around the new trabecular bone throughput the reparative interface zone in the late collapsed stage. HIF-1 alpha expression was detected at the fibrosis area and the transitional area, which included the proximal area of the reparative interface zone adjacent to the necrotic zone. VEGF was expressed at the edematous area of the reparative interface zone, while FGF-2 was detected widely in the reparative interface zone and the normal zone. In the late radiologic stages, HIF-1 alpha, VEGF, and FGF-2 were not detected in the necrotic zone, and they acted in angiogenesis in the reparative interface zone, while TRAP-positive cells increased around the new bone formation in response to remodeling after the collapse. (C) 2008 Orthopaedic Research Society. Published by Wiley Periodicals Inc. J Orthop Res 27:694-700, 2009

DOI： 10.1002/jor.20802

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