Yucesoy Can A, Temelli Yener, Ateş Filiz
Institute of Biomedical Engineering, Boğaziçi University, Istanbul, Turkey.
Istanbul School of Medicine, Department of Orthopaedics and Traumatology, Istanbul University, Istanbul, Turkey.
J Electromyogr Kinesiol. 2017 Oct;36:49-55. doi: 10.1016/j.jelekin.2017.07.003. Epub 2017 Jul 12.
The knee kept forcibly in a flexed position is typical in cerebral palsy. Using a benchmark, we investigate intra-operatively if peak spastic hamstring force is measured in flexed knee positions. This tests the assumed shift of optimal length due to adaptation of spastic muscle and a decreasing force trend towards extension. Previously we measured spastic gracilis (GRA) and semitendinosus (ST) forces. Presently, we studied spastic semimembranosus (SM) and tested the following hypotheses: spastic SM forces are (1) high in flexed and (2) low in extended positions. We compared the data to those of GRA and ST to test (3) if percentages of peak force produced in flexed positions are different. During muscle lengthening surgery of 8 CP patients (9years, 4months; GMFCS levels=II-IV; limbs tested=13) isometric SM forces were measured from flexion (120°) to full extension (0°). Spastic SM forces were low in flexed knee positions (only 4.2% (3.4%) and 10.7% (9.7%) of peak force at KA=120° and KA=90° respectively, indicating less force production compared to the GRA or ST) and high in extended knee positions (even 100% of peak force at KA=0°). This indicates an absence of strong evidence for a shift of optimal muscle length of SM towards flexion.
膝关节持续强行处于屈曲位在脑瘫中很典型。我们采用一个基准，在术中研究屈膝位时是否能测到腘绳肌痉挛峰值力。这检验了由于痉挛肌肉适应性改变导致的最佳长度假定变化以及伸膝时力的下降趋势。此前我们测量了股薄肌（GRA）和半腱肌（ST）的力量。目前，我们研究了半膜肌（SM）痉挛情况并检验了以下假设：痉挛性SM力量（1）在屈膝位时较高，（2）在伸膝位时较低。我们将数据与GRA和ST的数据进行比较，以检验（3）屈膝位产生的峰值力百分比是否不同。在8例脑瘫患者（9岁4个月；GMFCS分级=II-IV级；测试肢体=13个）的肌肉延长手术过程中，测量了从屈曲（120°）到完全伸直（0°）时等长的SM力量。痉挛性SM力量在屈膝位时较低（在KA = 120°和KA = 90°时分别仅为峰值力的4.2%（3.4%）和10.7%（9.7%），表明与GRA或ST相比产生的力量较小），而在伸膝位时较高（在KA = 0°时甚至达到峰值力的100%）。这表明没有有力证据支持SM最佳肌肉长度向屈曲方向偏移。
