Arnold Allison S, Liu May Q, Schwartz Michael H, Ounpuu Sylvia, Delp Scott L
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305-5450, USA.
Gait Posture. 2006 Apr;23(3):273-81. doi: 10.1016/j.gaitpost.2005.03.003. Epub 2005 Jun 17.
Persons with cerebral palsy frequently walk with excessive knee flexion during terminal swing and stance. This gait abnormality is often attributed to "short" or "spastic" hamstrings that restrict knee extension, and is often treated by hamstrings lengthening surgery. At present, the outcomes of these procedures are inconsistent. This study examined whether analyses of the muscle-tendon lengths and lengthening velocities of patients' hamstrings during walking may be helpful when deciding whether a candidate is likely to benefit from hamstrings surgery. One hundred and fifty-two subjects were cross-classified in a series of multi-way contingency tables based on their pre- and postoperative gait kinematics, muscle-tendon lengths, muscle-tendon velocities, and hamstrings surgeries. The lengths and velocities of the subjects' semimembranosus muscles were estimated by combining kinematic data from gait analysis with a three-dimensional computer model of the lower extremity. Log-linear analysis revealed that the subjects who walked with abnormally "short" or "slow" hamstrings preoperatively, and whose hamstrings did not operate at longer lengths or faster velocities postoperatively, were unlikely to walk with improved knee extension after treatment (p < 0.05). Subjects who did not walk with abnormally short or slow hamstrings preoperatively, and whose hamstrings did operate at longer lengths or faster velocities postoperatively, tended to exhibit unimproved or worsened anterior pelvic tilt after treatment (p < 0.05). Examination of the muscle-tendon lengths and velocities allows individuals who walk with abnormally short or slow hamstrings to be distinguished from those who do not, and thus may help to identify patients who are at risk for unsatisfactory postsurgical changes in knee extension or anterior pelvic tilt.
患有脑瘫的人在摆动末期和站立期行走时，膝关节常常过度屈曲。这种步态异常通常归因于限制膝关节伸展的“短缩”或“痉挛”的腘绳肌，并且常常通过腘绳肌延长手术来治疗。目前，这些手术的结果并不一致。本研究探讨了在决定患者是否可能从腘绳肌手术中获益时，分析患者行走过程中腘绳肌的肌腱长度和延长速度是否有帮助。152名受试者根据其术前和术后的步态运动学、肌腱长度、肌腱速度以及腘绳肌手术情况，在一系列多向列联表中进行交叉分类。通过将步态分析的运动学数据与下肢三维计算机模型相结合，估计受试者半膜肌的长度和速度。对数线性分析显示，术前腘绳肌异常“短缩”或“缓慢”且术后腘绳肌未以更长的长度或更快的速度运作的受试者，治疗后膝关节伸展改善的可能性不大（p < 0.05）。术前腘绳肌无异常短缩或缓慢且术后腘绳肌确实以更长的长度或更快的速度运作的受试者，治疗后往往表现出未改善或加重的骨盆前倾（p < 0.05）。对肌腱长度和速度的检查能够区分腘绳肌异常短缩或缓慢的行走者与正常者，因此可能有助于识别那些术后膝关节伸展或骨盆前倾变化不理想的风险患者。
