Background. Anatomical studies and the mechanical property studies showed that there is a strong correlation between Achilles tendon (AT) elasticity and individual gastrocnemius muscle (the medial head of gastrocnemius (MG) and the lateral head of gastrocnemius (LG)) elasticity. Limited ankle dorsiflexion range of motion has been correlated with decreased flexibility of the MG/LG/AT complex. However, no studies have been conducted to examine the exact correlation between the Achilles tendon and the individual muscle of the gastrocnemius. Purposes. The purposes of the present study were (1) to evaluate intra- and interoperator reliabilities of elastic property measurements in the gastrocnemius muscle-Achilles tendon complex by using the shear wave elastography (SWE) and (2) to examine the correlation between the regional elastic properties of the AT and the individual muscle of the gastrocnemius. Methods. Twenty healthy subjects (mean age: 22.50 (3.02) years) were recruited in this study. The elastic properties of the AT and the individual muscle of the gastrocnemius were quantified using the SWE. Findings. The SWE has comparatively high reliability in quantifying the elastic properties of the muscle-tendon range from good to excellent. The intraoperator ICC of the gastrocnemius muscle-Achilles tendon complex was 0.77 to 0.95, while the interoperator ICC was 0.76 to 0.94. The minimal detectable change (MDC) of the muscle was 1.72 kPa, while the AT was 32.90 kPa. A significant correlation was found between the elastic modulus of AT and the elastic modulus of the MG ( and at the relaxing position and and at the neutral position). Conclusions. The SWE has the potential to assess localized changes in muscle-tendon elastic properties, provide more intuitive relations between elastic properties of the muscle tendon and function, and evaluate the therapeutic effect of the muscle tendon. A significant correlation between the AT and the MG was found, and it may provide a new treatment idea (targeted to the tight muscle heads) for the clinical setting to treat subjects with AT disorders.

中文翻译：

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跟腱的区域弹性特性受到腓肠肌个体肌肉的异质性影响。

背景。解剖学研究和力学性能研究表明，跟腱（AT）弹性与个体腓肠肌（腓肠肌内侧头（MG）和腓肠肌外侧头（LG））弹性之间存在很强的相关性。有限的踝关节背屈活动范围与 MG/LG/AT 复合体的灵活性降低有关。然而，尚未进行研究来检查跟腱与腓肠肌的单个肌肉之间的确切相关性。目的. 本研究的目的是 (1) 通过使用剪切波弹性成像 (SWE) 评估腓肠肌-跟腱复合体中弹性特性测量的内部和操作者间的可靠性和 (2) 检查区域弹性之间的相关性AT 和腓肠肌单个肌肉的特性。方法。本研究招募了 20 名健康受试者（平均年龄：22.50 (3.02) 岁）。使用 SWE 量化 AT 和腓肠肌单个肌肉的弹性特性。发现. SWE 在量化肌腱弹性特性方面具有较高的可靠性，范围从良好到优秀。腓肠肌-跟腱复合体的术内 ICC 为 0.77 至 0.95，而术间 ICC 为 0.76 至 0.94。肌肉的最小可检测变化 (MDC) 为 1.72 kPa，而 AT 为 32.90 kPa。AT的弹性模量与MG的弹性模量之间存在显着相关性（和在放松的位置和和在中立位置）。结论。SWE有可能评估肌腱弹性特性的局部变化，提供肌腱弹性特性与功能之间更直观的关系，并评估肌腱的治疗效果。发现 AT 和 MG 之间存在显着相关性，它可能为临床治疗 AT 障碍患者提供一种新的治疗思路（针对紧张的肌肉头部）。