Chesworth B M, Vandervoort A A
Physiotherapy Department, Victoria Hospital, London, Ontario, Canada.
Phys Ther. 1995 Apr;75(4):253-61. doi: 10.1093/ptj/75.4.253.
The purpose of this study was to quantify several variables of ankle stiffness and dorsiflexion (DF) range of motion (ROM) in the casted (fractured) and noncasted ankles of humans after cast removal.
Thirty subjects (mean age = 32.4 years, SD = 15.8) with malleolar ankle fractures were tested within 4 days of cast removal but before they began physical therapy.
A torque motor system generated torque-versus-displacement graphs by recording angular displacement and resistive torque during a 6 0/s passive cycling of the ankle from 10 degrees of plantar flexion to the limit of DF ROM: Maximum passive DF ROM, passive torque, and passive elastic stiffness at the neutral position and energy loss were measured. Testing was performed in the absence of triceps surae muscle electromyographic activity. For analysis, subjects were separated into two groups based on fracture severity.
There was no difference in passive torque between the fractured ankles and the matched noncasted ankles. There was a small difference in passive elastic stiffness between the more severely fractured ankles and the matched noncasted ankles. The fractured ankles were different in terms of energy loss from the matched noncasted ankles. For maximum passive DF ROM, there was a large difference between the fractured ankles (more severe: mean = 4.4 degrees; less severe: mean = 6.8 degrees) and the matched noncasted ankles (more severe: mean = 15.1 degrees; less severe: mean = 19.1 degrees).
Altered length-tension relationships and neuromuscular mechanisms have been suggested to produce postimmobilization joint contractures. The results of this study on humans are consistent with both possibilities and support the theory that changes that occur during immobilization result in protection from overstretching of the fragile calf musculature after a period of ankle fixation. The time course of normalization of stretch reflexes warrants investigation.
本研究旨在对去除石膏后人类打石膏（骨折）和未打石膏脚踝的踝关节僵硬度及背屈（DF）活动范围（ROM）的多个变量进行量化。
30名踝关节骨折患者（平均年龄 = 32.4岁，标准差 = 15.8）在去除石膏后4天内但在开始物理治疗前接受测试。
一个扭矩电机系统通过记录踝关节从跖屈10度至DF ROM极限以60°/秒进行被动循环时的角位移和阻力扭矩，生成扭矩-位移图：测量最大被动DF ROM、被动扭矩、中立位的被动弹性僵硬度以及能量损失。测试在腓肠肌无肌电图活动的情况下进行。为进行分析，根据骨折严重程度将受试者分为两组。
骨折脚踝与匹配的未打石膏脚踝之间的被动扭矩无差异。骨折更严重的脚踝与匹配的未打石膏脚踝之间的被动弹性僵硬度存在微小差异。骨折脚踝与匹配的未打石膏脚踝在能量损失方面存在差异。对于最大被动DF ROM，骨折脚踝（更严重：平均 = 4.4度；不太严重：平均 = 6.8度）与匹配的未打石膏脚踝（更严重：平均 = 15.1度；不太严重：平均 = 19.1度）之间存在较大差异。
有人提出长度-张力关系和神经肌肉机制的改变会导致固定后关节挛缩。本研究对人类的结果与这两种可能性均相符，并支持这样一种理论，即固定期间发生的变化可在一段时间的踝关节固定后保护脆弱的小腿肌肉组织免受过度拉伸。牵张反射恢复正常的时间进程值得研究。
