Influence of patellar position on the knee extensor mechanism in normal and crouched walking
Influence of patellar position on the knee extensor mechanism in normal and crouched walking
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DOI：
10.1016/j.jbiomech.2016.11.052
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发表时间：
2017-01-25
影响因子：
2.4
通讯作者：
Thelen, Darryl G.
中科院分区：
文献类型：
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作者：
Lenhart, Rachel L.;Brandon, Scott C. E.;Thelen, Darryl G.
髌骨上翘在脑瘫中很常见，尤其是在蹲伏步态的患者中。在治疗蹲姿时，一直提倡髌骨上矫正，但矫正的适当程度及其对膝关节伸肌功能的影响尚不清楚。因此，本研究的目的是评估正常步态和蹲姿时髌骨位置对股四头肌和髌骨肌腱力的影响。为此，使用具有新型12自由度膝关节的下肢肌肉骨骼模型来模拟健康儿童的正常步态，以及三名脑瘫儿童的轻度（站立时膝关节弯曲23度）、中度（41度）和重度（67度）蹲伏步态。模拟结果表明，股四头肌和髌骨肌腱的力量随着蹲伏而急剧增加，并受髌骨位置的调节。例如，在正常髌骨肌腱位置时，正常行走时髌骨肌腱力峰值为体重的0.7倍，而在轻度、中度和重度蹲伏时达到体重的2.2、3.2和5.4倍。适度的髌骨上翘可以减少蹲姿时股四头肌和髌骨肌腱的负荷，这是由于膝关节屈曲时髌骨肌腱力矩臂的增强。相反，下颚髌骨减少了屈曲膝关节的髌骨肌腱矩臂，从而增加了屈膝行走所需的髌骨肌腱负荷。从功能上讲，这些结果表明，膝盖骨下陷也可能损害其他屈曲膝关节活动（如椅子上升和爬楼梯）的膝关节伸肌功能。当使用手术方法矫正表现为蹲姿的儿童髌骨上翘时，研究结果是重要的考虑因素。(C) 2016 Elsevier Ltd.版权所有。
Patella alta is common in cerebral palsy, especially in patients with crouch gait. Correction of patella alta has been advocated in the treatment of crouch, however the appropriate degree of correction and the implications for knee extensor function remain unclear. Therefore, the goal of this study was to assess the impact of patellar position on quadriceps and patellar tendon forces during normal and crouch gait. To this end, a lower extremity musculoskeletal model with a novel 12 degree of freedom knee joint was used to simulate normal gait in a healthy child, as well as mild (23 deg min knee flexion in stance), moderate (41 deg), and severe (67 deg) crouch gait in three children with cerebral palsy. The simulations revealed that quadriceps and patellar tendon forces increase dramatically with crouch, and are modulated by patellar position. For example with a normal patellar tendon position, peak patellar tendon forces were 0.7 times body weight in normal walking, but reached 2.2,3.2and5.4times body weight in mild, moderate and severe crouch. Moderate patella alta acted to reduce quadriceps and patellar tendon loads in crouch gait, due to an enhancement of the patellar tendon moment arms with alta in a flexed knee. In contrast, patella baja reduced the patellar tendon moment arm in a flexed knee and thus induced an increase in the patellar tendon loads needed to walk in crouch. Functionally, these results suggest that patella baja could also compromise knee extensor function for other flexed knee activities such as chair rise and stair climbing. The findings are important to consider when using surgical approaches for correcting patella alta in children who exhibit crouch gait patterns. (C) 2016 Elsevier Ltd. All rights reserved.