Harris Michael D, MacWilliams Bruce A, Bo Foreman K, Peters Christopher L, Weiss Jeffrey A, Anderson Andrew E
Program in Physical Therapy, Washington University School of Medicine, St Louis, MO 63108, United States; Department of Orthopaedic Surgery, Washington University School of Medicine, St Louis, MO 63108, United States.
Department of Orthopaedics, University of Utah, Salt Lake City, UT 84108, United States; Shriners Hospitals for Children, Salt Lake City, UT 84103, United States; Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, United States.
J Biomech. 2017 Mar 21;54:80-87. doi: 10.1016/j.jbiomech.2017.01.040. Epub 2017 Feb 7.
Acetabular dysplasia is a known cause of hip osteoarthritis. In addition to abnormal anatomy, changes in kinematics, joint reaction forces (JRFs), and muscle forces could cause tissue damage to the cartilage and labrum, and may contribute to pain and fatigue. The objective of this study was to compare lower extremity joint angles, moments, hip JRFs and muscle forces during gait between patients with symptomatic acetabular dysplasia and healthy controls. Marker trajectories and ground reaction forces were measured in 10 dysplasia patients and 10 typically developing control subjects. A musculoskeletal model was scaled in OpenSim to each subject and subject-specific hip joint centers were determined using reconstructions from CT images. Joint kinematics and moments were calculated using inverse kinematics and inverse dynamics, respectively. Muscle forces and hip JRFs were estimated with static optimization. Inter-group differences were tested for statistical significance (p≤0.05) and large effect sizes (d≥0.8). Results demonstrated that dysplasia patients had higher medially directed JRFs. Joint angles and moments were mostly similar between the groups, but large inter-group effect sizes suggested some restriction in range of motion by patients at the hip and ankle. Higher medially-directed JRFs and inter-group differences in hip muscle forces likely stem from lateralization of the hip joint center in dysplastic patients. Joint force differences, combined with reductions in range of motion at the hip and ankle may also indicate compensatory strategies by patients with dysplasia to maintain joint stability.
髋臼发育不良是髋关节骨关节炎的已知病因。除了解剖结构异常外，运动学、关节反应力（JRFs）和肌肉力量的变化可能会导致软骨和盂唇的组织损伤，并可能导致疼痛和疲劳。本研究的目的是比较有症状的髋臼发育不良患者与健康对照者在步态过程中的下肢关节角度、力矩、髋关节JRFs和肌肉力量。在10名发育不良患者和10名正常发育的对照受试者中测量了标记轨迹和地面反作用力。在OpenSim中为每个受试者缩放了一个肌肉骨骼模型，并使用CT图像重建确定了受试者特定的髋关节中心。分别使用逆运动学和逆动力学计算关节运动学和力矩。通过静态优化估计肌肉力量和髋关节JRFs。对组间差异进行统计学显著性检验（p≤0.05）和大效应量检验（d≥0.8）。结果表明，发育不良患者的JRFs向内方向更高。两组之间的关节角度和力矩大多相似，但较大的组间效应量表明发育不良患者在髋关节和踝关节的活动范围存在一定限制。较高的向内方向JRFs以及髋关节肌肉力量的组间差异可能源于发育不良患者髋关节中心的外移。关节力差异，再加上髋关节和踝关节活动范围的减小，也可能表明发育不良患者为维持关节稳定性而采取的代偿策略。
