Background

The permanence of neuromuscular adaptations following anterior cruciate ligament reconstruction is not known. The aim of this study was to compare bilateral muscle co-contraction indices, time to peak ground reaction force, and timing of muscle onset between anterior cruciate ligament reconstruction subjects 10–15 years post reconstruction with those of matched uninjured controls during a one-leg hop landing.

Methods

Nine healthy controls and 9 reconstruction subjects were recruited. Clinical and functional knee exams were administered. Lower limb co-contraction indices, time to peak ground reaction force, and muscle onset times were measured bilaterally. Differences in clinical and functional outcomes were assessed with unpaired t-tests, and mixed model repeated measures were used to examine effects of group, limb and interaction terms in electromyography measures.

Findings

89% of control knees were clinically “normal”, whereas only 33% of reconstructed knees were “normal”. Anterior cruciate ligament-reconstructed subjects tended to achieve shorter functional hop distances but demonstrated symmetrical lower limb electromyography measures that were no different from those of controls' with the exception that biceps femoris activation was delayed bilaterally prior to ground contact but was greater during the injury risk phase of landing.

Interpretation

With the exception of hamstring activation, lower limb electromyography measures were largely similar between ACLR and matched control subjects, which was in contrast to the clinical findings. This result brings into question the significance of neuromuscular function at this long-term follow-up but raises new questions regarding the role of symmetry and pre-injury risk.

中文翻译：

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长期随访前交叉韧带重建患者的神经肌肉功能

背景

前交叉韧带重建后神经肌肉适应性的持久性尚不清楚。本研究的目的是比较重建后 10-15 年前交叉韧带重建受试者的双侧肌肉共同收缩指数、达到地面反作用力峰值的时间和肌肉开始时间与匹配的未受伤对照组在单腿训练期间跳跃着陆。

方法

招募了 9 名健康对照者和 9 名重建受试者。进行了临床和功能性膝关节检查。双侧测量下肢共同收缩指数、达到地面反作用力峰值的时间和肌肉开始时间。使用非配对t检验评估临床和功能结果的差异，并使用混合模型重复测量来检查肌电图测量中组、肢体和交互项的影响。

发现

89% 的对照膝在临床上“正常”，而只有 33% 的重建膝“正常”。前交叉韧带重建的受试者倾向于实现更短的功能性跳跃距离，但表现出对称的下肢肌电图测量，与对照组的测量结果没有什么不同，除了股二头肌激活在触地前双侧延迟，但在受伤风险期间更大着陆阶段。

解释

除了腘绳肌激活外，ACLR 和匹配的对照受试者的下肢肌电图测量结果基本相似，这与临床发现相反。这一结果对长期随访中神经肌肉功能的重要性提出了质疑，但也提出了关于对称性和损伤前风险的作用的新问题。