Department of Physical Therapy, Creighton University, Omaha, Nebraska, U.S.A..
Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California, U.S.A.
Arthroscopy. 2017 Oct;33(10):1797-1803. doi: 10.1016/j.arthro.2017.03.018.
To evaluate the effect of varying degrees of simulated cam morphology on acetabular stress magnitude and location using a finite element model with 1 subject that incorporates population-specific hip/pelvis kinematics during a squat task.
A reference model of the hip joint was created from magnetic resonance images obtained from 1 asymptomatic 28-year-old man without femoroacetabular impingement (FAI) morphology or hip dysplasia (alpha angle 41.9°, lateral center edge angle 34.0°, neck-shaft angle 137°, and no visible articular cartilage lesions or bone marrow edema on magnetic resonance). The femoral head/neck geometry was manipulated to mimic different cam morphology severities as reported in a previous study (minimum, moderate, and large). Peak hip and pelvis squat kinematics from healthy individuals (hip flexion 112.6°, abduction 10.5°, internal rotation 14.8°) and persons with FAI (hip flexion 106.3°, abduction 10.5°, internal rotation 8.9°) were applied to the control and cam models. Relative acetabular joint stress values and location of contact were the variables of interest.
Average von Mises stress values for control, minimum, moderate, and large cam models were 9.64, 9.27, 11.36, and 28.43 MPa, respectively. Contact in the control and minimum cam models occurred within the acetabular cup. In the moderate and large cam models, contact shifted anterosuperiorly within the acetabular cup and to anterosuperior acetabular rim, respectively.
Despite simulating lower degrees of hip flexion and internal rotation, increased stress and a shift in contact location were observed in the simulated models of FAI. This finding suggests that decreased hip internal rotation in this population during functional tasks may be the result of bony abutment.
Clinicians should be cautious about prescribing deep squats for persons with cam morphology. Performing squat exercises with neutral or external hip rotation may limit bony abutment at high hip flexion angles.
使用包含特定人群髋关节/骨盆运动学的 1 名无症状 28 岁男性的参考模型，评估不同程度模拟凸轮形态对髋臼应力大小和位置的影响，该患者在深蹲任务中无股骨髋臼撞击（FAI）形态或髋关节发育不良（阿尔法角 41.9°，外侧中心边缘角 34.0°，颈干角 137°，磁共振上未见关节软骨损伤或骨髓水肿）。通过模拟先前研究中报道的不同凸轮形态严重程度（最小、中度和最大）来操纵股骨头/颈几何形状。将健康个体（髋关节屈曲 112.6°，外展 10.5°，内旋 14.8°）和 FAI 个体（髋关节屈曲 106.3°，外展 10.5°，内旋 8.9°）的峰值髋关节和骨盆深蹲运动学应用于对照和凸轮模型。髋臼关节的相对关节应力值和接触位置是感兴趣的变量。
对照、最小、中度和最大凸轮模型的平均 von Mises 应力值分别为 9.64、9.27、11.36 和 28.43 MPa。在对照和最小凸轮模型中，接触发生在髋臼杯内。在中度和最大凸轮模型中，接触分别向前上转移至髋臼杯内和髋臼前上边缘。
尽管模拟的髋关节屈曲和内旋程度较低，但在模拟的 FAI 模型中观察到了更高的应力和接触位置的变化。这一发现表明，在功能任务中，该人群的髋关节内旋减少可能是骨性撞击的结果。
临床医生在为凸轮形态患者开深蹲处方时应谨慎。在深蹲练习中进行中立或外旋髋关节的动作可能会限制在髋关节高屈曲角度时的骨性撞击。
