Move Research Institute Amsterdam, and Faculteit der Bewegingswetenschappen, Vrije Universiteit Amsterdam, Van de Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands.
BMC Musculoskelet Disord. 2013 Dec 23;14:365. doi: 10.1186/1471-2474-14-365.
In spastic cerebral palsy (SCP), a limited range of motion of the foot (ROM), limits gait and other activities. Assessment of this limitation of ROM and knowledge of active mechanisms is of crucial importance for clinical treatment.
For a comparison between spastic cerebral palsy (SCP) children and typically developing children (TD), medial gastrocnemius muscle-tendon complex length was assessed using 3-D ultrasound imaging techniques, while exerting externally standardized moments via a hand-held dynamometer. Exemplary X-ray imaging of ankle and foot was used to confirm possible TD-SCP differences in foot deformation.
SCP and TD did not differ in normalized level of excitation (EMG) of muscles studied. For given moments exerted in SCP, foot plate angles were all more towards plantar flexion than in TD. However, foot plate angle proved to be an invalid estimator of talocrural joint angle, since at equal foot plate angles, GM muscle-tendon complex was shorter in SCP (corresponding to an equivalent of 1 cm). A substantial difference remained even after normalizing for individual differences in tibia length. X-ray imaging of ankle and foot of one SCP child and two typically developed adults, confirmed that in SCP that of total footplate angle changes (0-4 Nm: 15°), the contribution of foot deformation to changes in foot plate angle (8) were as big as the contribution of dorsal flexion at the talocrural joint (7°). In typically developed individuals there were relatively smaller contributions (10 -11%) by foot deformation to changes in foot plate angle, indicating that the contribution of talocrural angle changes was most important. Using a new estimate for position at the talocrural joint (the difference between GM muscle-tendon complex length and tibia length, GM relative length) removed this effect, thus allowing more fair comparison of SCP and TD data. On the basis of analysis of foot plate angle and GM relative length as a function of externally applied moments, it is concluded that foot plate angle measurements underestimate angular changes at the talocrural joint when moving in dorsal flexion direction and overestimate them when moving in plantar flexion direction, with concomitant effects on triceps surae lengths.
In SCP children diagnosed with decreased dorsal ROM of the ankle joint, the commonly used measure (i.e. range of foot plate angle), is not a good estimate of rotation at the talocrural joint. since a sizable part of the movement of the foot (or foot plate) derives from internal deformation of the foot.
在痉挛性脑瘫（SCP）中，足部的活动范围（ROM）受限，限制了步态和其他活动。评估这种 ROM 的限制以及对主动机制的了解对临床治疗至关重要。
为了比较痉挛性脑瘫（SCP）儿童和典型发育儿童（TD），使用 3D 超声成像技术评估内侧腓肠肌-肌腱复合体的长度，同时通过手持测力计施加外部标准化力矩。对踝关节和足部的典型 X 射线成像用于确认足部变形方面可能存在的 TD-SCP 差异。
研究的肌肉的 SCP 和 TD 在归一化激发水平（EMG）上没有差异。对于在 SCP 中施加的给定力矩，足板角度都比 TD 更向跖屈方向。然而，足板角度被证明是距下关节角度的无效估计器，因为在相等的足板角度下，GM 肌肉-肌腱复合体在 SCP 中更短（相当于 1 厘米）。即使在考虑胫骨长度个体差异后进行归一化，仍存在显著差异。对一名 SCP 儿童和两名典型发育成人的踝关节和足部的 X 射线成像证实，在 SCP 中，整个足板角度变化（0-4 Nm：15°）中，足部变形对足板角度变化的贡献（8°）与距下关节背屈的贡献（7°）一样大。在典型发育的个体中，足部变形对足板角度变化的贡献相对较小（10-11%），这表明距下关节角度变化的贡献最为重要。使用距下关节位置的新估计值（GM 肌肉-肌腱复合体长度与胫骨长度之间的差异，GM 相对长度）消除了这种影响，从而可以更公平地比较 SCP 和 TD 数据。基于对外施力矩的足板角度和 GM 相对长度的分析，结论是当向背屈方向移动时，足板角度测量值低估了距下关节的角度变化，当向跖屈方向移动时，高估了距下关节的角度变化，同时对三头肌长度产生影响。
在诊断为踝关节背屈 ROM 降低的 SCP 儿童中，常用的测量方法（即足板角度范围）不能很好地估计距下关节的旋转。因为足部（或足板）的大部分运动都来自于足部的内部变形。
