Research Department of Orthopaedics and Musculoskeletal Science, University College London, Royal National Orthopaedic Hospital, Stanmore, United Kingdom.
Department of Mechanical Engineering, University College London, London, United Kingdom.
Elife. 2021 Feb 16;10:e63204. doi: 10.7554/eLife.63204.
The unique structure of the Achilles tendon, combining three smaller sub-tendons, enhances movement efficiency by allowing individual control from connected muscles. This requires compliant interfaces between sub-tendons, but compliance decreases with age and may account for increased injury frequency. Current understanding of sub-tendon sliding and its role in the whole Achilles tendon function is limited. Here we show changing the degree of sliding greatly affects the tendon mechanical behaviour. Our in vitro testing discovered distinct sub-tendon mechanical properties in keeping with their mechanical demands. In silico study based on measured properties, subject-specific tendon geometry, and modified sliding capacity demonstrated age-related displacement reduction similar to our in vivo ultrasonography measurements. Peak stress magnitude and distribution within the whole Achilles tendon are affected by individual tendon geometries, the sliding capacity between sub-tendons, and different muscle loading conditions. These results suggest clinical possibilities to identify patients at risk and design personalised rehabilitation protocols.
跟腱的独特结构由三个较小的子腱组成，通过允许连接的肌肉进行单独控制，从而提高运动效率。这需要子腱之间具有顺应性界面，但顺应性会随着年龄的增长而降低，这可能是受伤频率增加的原因。目前对子腱滑动及其在整个跟腱功能中的作用的了解有限。在这里，我们展示了改变滑动程度会极大地影响肌腱的机械性能。我们的体外测试发现，不同的子腱具有与其力学需求相适应的机械特性。基于测量的特性、特定于个体的肌腱几何形状和修改后的滑动能力的计算研究表明，与我们的体内超声测量结果相似，存在与年龄相关的位移减少。整个跟腱内的峰值应力大小和分布受到个体肌腱几何形状、子腱之间的滑动能力以及不同肌肉加载条件的影响。这些结果表明，临床上有可能识别出有风险的患者，并设计个性化的康复方案。
