Institute of Biomedical Engineering, Boğaziçi University, Istanbul, Turkey.
Istanbul Faculty of Medicine, Department of Orthopaedics and Traumatology, Istanbul University, Istanbul, Turkey.
J Biomech. 2020 Apr 16;103:109755. doi: 10.1016/j.jbiomech.2020.109755. Epub 2020 Mar 17.
In cerebral palsy (CP) patients suffering pathological knee joint motion, spastic muscle's passive state forces have not been quantified intraoperatively. Besides, assessment of spastic muscle's active state forces in conditions involving intermuscular mechanical interactions and gait relevant joint positions is lacking. Therefore, the source of flexor forces limiting joint motion remains unclear. The aim was to test the following hypotheses: (i) in both passive and active states, spastic semitendinosus (ST) per se shows its highest forces within gait relevant knee angle (KA) range and (ii) due to intermuscular mechanical interactions, the active state forces elevate. Isometric forces (seven children with CP, GMFCS-II) were measured during surgery over a range of KA from flexion to full extension, at hip angle (HA) = 45° and 20°, in four conditions: (I) passive state, (II) individual stimulation of the ST, simultaneous stimulation of the ST (III) with its synergists, and (IV) also with an antagonist. Gait analyses: intraoperative data for KA = 17-61° (HA = 45°) and KA = 0-33° (HA = 20°) represent the loading response and terminal swing, and mid/terminal stance phases of gait, respectively. Intraoperative tests: Passive forces maximally approximated half of peak force in condition II (HA = 45°). Added muscle activations did increase muscle forces significantly (HA = 45°: on average by 42.0% and 72.5%; HA = 20°: maximally by 131.8% and 123.7%, respectively in conditions III and IV, p < 0.01). In conclusion, intermuscular mechanical interactions yield elevated active state forces, which are well above passive state forces. This indicates that intermuscular mechanical interactions may be a source of high flexor forces in CP.
在患有病理性膝关节运动障碍的脑瘫（CP）患者中，痉挛肌肉的被动状态力在手术中尚未被量化。此外，在涉及肌肉间力学相互作用和与步态相关的关节位置的情况下，痉挛肌肉的主动状态力的评估也缺乏。因此，限制关节运动的屈肌力的来源尚不清楚。目的是检验以下假设：（i）在被动和主动状态下，痉挛性半腱肌（ST）本身在与步态相关的膝关节角度（KA）范围内显示出最高的力；（ii）由于肌肉间力学相互作用，主动状态力会升高。在髋关节角度（HA）= 45°和 20°的情况下，在膝关节从屈曲到完全伸展的范围内，对 7 名 CP 患儿（GMFCS-II）进行了术中等长力测量，共分为 4 种情况：（I）被动状态，（ii）单独刺激 ST，（iii）同时刺激 ST 及其协同肌，（iv）还刺激拮抗剂。步态分析：KA=17-61°（HA=45°）和 KA=0-33°（HA=20°）的术中数据分别代表了步态的加载反应和终末摆动以及中/终末站立阶段。术中测试：在条件 II（HA=45°）中，被动力最大接近峰值力的一半。增加肌肉激活可显著增加肌肉力（HA=45°：平均增加 42.0%和 72.5%；HA=20°：最大增加 131.8%和 123.7%，分别在条件 iii 和 iv 中，p<0.01）。总之，肌肉间力学相互作用产生了更高的主动状态力，远高于被动状态力。这表明肌肉间力学相互作用可能是 CP 中高屈肌力的一个来源。
