Data_Sheet_1_Subject-Specific Modeling of Femoral Torsion Influences the Prediction of Hip Loading During Gait in Asymptomatic Adults.pdf

Hip osteoarthritis may be caused by increased or abnormal intra-articular forces, which are known to be related to structural articular cartilage damage. Femoral torsional deformities have previously been correlated with hip pain and labral damage, and they may contribute to the onset of hip osteoarthritis by exacerbating the effects of existing pathoanatomies, such as cam and pincer morphologies. A comprehensive understanding of the influence of femoral morphotypes on hip joint loading requires subject-specific morphometric and biomechanical data on the movement characteristics of individuals exhibiting varying degrees of femoral torsion. The aim of this study was to evaluate hip kinematics and kinetics as well as muscle and joint loads during gait in a group of adult subjects presenting a heterogeneous range of femoral torsion by means of personalized musculoskeletal models. Thirty-seven healthy volunteers underwent a 3D gait analysis at a self-selected walking speed. Femoral torsion was evaluated with low-dosage biplanar radiography. The collected motion capture data were used as input for an inverse dynamics analysis. Personalized musculoskeletal models were created by including femoral geometries that matched each subject’s radiographically measured femoral torsion. Correlations between femoral torsion and hip kinematics and kinetics, hip contact forces (HCFs), and muscle forces were analyzed. Within the investigated cohort, higher femoral antetorsion led to significantly higher anteromedial HCFs during gait (medial during loaded stance phase and anterior during swing phase). Most of the loads during gait are transmitted through the anterior/superolateral quadrant of the acetabulum. Correlations with hip kinematics and muscle forces were also observed. Femoral antetorsion, through altered kinematic strategies and different muscle activations and forces, may therefore lead to altered joint mechanics and pose a risk for articular damage. The method proposed in this study, which accounts for both morphological and kinematic characteristics, might help in identifying in a clinical setting patients who, as a consequence of altered femoral torsional alignment, present more severe functional impairments and altered joint mechanics and are therefore at a higher risk for cartilage damage and early onset of hip osteoarthritis.

髋骨关节炎（Hip osteoarthritis）可由关节内应力（intra-articular forces）升高或异常引发，这类异常应力已被证实与关节软骨结构性损伤相关。此前已有研究表明，股骨扭转畸形（femoral torsional deformities）与髋部疼痛及盂唇损伤存在关联，其可通过加重现有病理解剖结构（如凸轮型与钳夹型形态（cam and pincer morphologies））的不良影响，进而诱发髋骨关节炎。

要全面厘清股骨表型对髋关节载荷的影响，需获取不同股骨扭转程度个体的运动特征相关的个体特异性形态计量学与生物力学数据。本研究旨在借助个性化肌肉骨骼模型，对一组股骨扭转程度异质性的成年受试者开展步态分析，评估其步态过程中的髋关节运动学、动力学指标以及肌肉与关节载荷情况。

本研究纳入37名健康志愿者，令其以自主选择的步行速度完成三维步态分析，并采用低剂量双平面X线摄影（low-dosage biplanar radiography）评估股骨扭转角度。采集所得的运动捕捉（motion capture）数据被用作逆向动力学分析（inverse dynamics analysis）的输入参数。研究团队通过匹配每位受试者影像学测量所得的股骨扭转角度的股骨几何结构，构建了个性化肌肉骨骼模型，并分析了股骨扭转与髋关节运动学、动力学、髋关节接触力（hip contact forces, HCFs）以及肌肉力量之间的相关性。

在本次研究的受试队列中，股骨前扭转程度越高，步态过程中的前内侧髋关节接触力显著越高：负重站立相为内侧方向载荷，摆动相为前方方向载荷。步态过程中的大部分关节载荷通过髋臼前上外侧象限传递。同时研究还观察到股骨扭转与髋关节运动学及肌肉力量存在相关性。

综上，股骨前扭转可通过改变运动策略、调整肌肉激活模式与肌肉力量，进而改变关节力学特性，增加关节软骨损伤风险。本研究提出的方法同时兼顾了形态学与运动学特征，有望在临床场景中识别出因股骨扭转对线异常而出现更严重功能障碍、关节力学特性改变的患者——这类群体的软骨损伤与髋骨关节炎早发风险显著更高。