Background

This study aimed to investigate the structural, morphological and passive mechanical properties of the medial gastrocnemius muscle among ambulating chronic stroke survivors using a computational model previously established in healthy individuals without stroke.

Methods

Individuals with chronic stroke (n = 14, age = 63.4 ± 6.0 years) and healthy controls (n = 15, age = 59.6 ± 8.4 years) participated in the study. The mechanical properties of the medial gastrocnemius were measured during continuous passive ankle motion using ultrasound elastography and a corresponding muscle mechanical property-angle curve was estimated where slack angle and elasticity were determined. Muscle thickness, fascicle length, pennation angle, and echo intensity were also assessed using B-mode ultrasound.

Findings

No significant differences in slack angle (paretic: −16.2° ± 6.13°, non-paretic: −16.93° ± 6.80°, p = 0.82), or slack elasticity (paretic: 4.36 ± 1.94 kPa, non-paretic: 4.54 ± 1.24 kPa, p = 0.64) were found between sides or groups. Lower muscle pennation angle (paretic: 13.6 ± 2.9°, non-paretic: 15.9 ± 2.0°, p = 0.019) and higher echo intensity (paretic: 80.5 ± 13.6, non-paretic: 63.4 ± 17.1, p = 0.003) were observed for paretic muscles. No significant between-sides differences were found for muscle thickness (paretic: 1.5 ± 0.3 cm, non-paretic: 1.6 ± 0.2 cm, p = 0.255) or fascicle length (paretic: 6.6 ± 1.9 cm, non-paretic: 7.1 ± 2.2 cm, p = 0.216). Significant between-groups difference was also observed for fascicle length [non-dominant side (control): 6.2 ± 0.8 cm, paretic side (stroke): 6.6 ± 1.9 cm, p = 0.017].

Interpretation

Although muscle mechanical properties increased exponentially over the slack ankle, measures between paretic and non-paretic sides were similar in ambulating participants with chronic stroke. Side-to-side differences in structural and morphological measures suggest the impact of stroke was relatively more pronounced for these muscle parameters than for passive mechanical properties.

中文翻译：

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慢性卒中患者腓肠肌内侧的结构和被动力学特性

背景

本研究旨在使用先前在没有中风的健康个体中建立的计算模型，研究行走的慢性中风幸存者中腓肠肌内侧的结构、形态和被动机械特性。

方法

患有慢性中风的个体（n  = 14，年龄 = 63.4 ± 6.0 岁）和健康对照者（n  = 15，年龄 = 59.6 ± 8.4 岁）参与了这项研究。在连续被动踝关节运动期间使用超声弹性成像测量内侧腓肠肌的力学性能，并估计相应的肌肉力学性能-角度曲线，其中确定松弛角和弹性。还使用 B 型超声评估了肌肉厚度、肌束长度、羽状角和回声强度。

发现

松弛角（偏侧：-16.2° ± 6.13°，非偏侧：-16.93° ± 6.80°，p  = 0.82）或松弛弹性（偏侧：4.36 ± 1.94 kPa，非偏侧：4.54 ± 1.24）没有显着差异kPa，p  = 0.64）在两侧或组之间发现。观察到较低的肌肉羽状角（麻痹：13.6 ± 2.9°，非麻痹：15.9 ± 2.0°，p  = 0.019）和较高的回波强度（麻痹：80.5 ± 13.6，非麻痹：63.4 ± 17.1，p  = 0.003）用于麻痹肌肉。肌肉厚度（麻痹：1.5 ± 0.3 cm，非麻痹：1.6 ± 0.2 cm，p  = 0.255）或肌束长度（麻痹：6.6 ± 1.9 cm，非麻痹：7.1 ± 2.2）未发现显着的两侧差异厘米，p = 0.216)。束长度也观察到显着的组间差异[非优势侧（对照）：6.2 ± 0.8 cm，麻痹侧（中风）：6.6 ± 1.9 cm，p  = 0.017]。

解释

尽管肌肉力学性能在脚踝松弛时呈指数增长，但在行走的慢性中风参与者中，麻痹侧和非麻痹侧之间的测量值相似。结构和形态测量的左右差异表明，中风对这些肌肉参数的影响比对被动机械性能的影响相对更明显。