Exercise Science Program, School of Exercise and Rehabilitation Sciences, University of Toledo, 2801 W. Bancroft St., Toledo, OH, USA.
Department of Kinesiology, College of Agriculture, Health and Natural Resources, University of Connecticut, Storrs, CT, USA.
Sports Med. 2021 May;51(5):961-990. doi: 10.1007/s40279-020-01403-8. Epub 2021 Jan 5.
Differences in the excitability of motor generating neural pathways are reported following anterior cruciate ligament reconstruction (ACLR) that is associated with quadriceps dysfunction and theorized to prevent the full recovery of muscle function.
The aims of this systematic review and meta-analysis were to compare quadriceps neural excitability between the involved ACLR limb, the uninvolved limb, and uninjured controls, and to determine at what time intervals these differences are present after surgery.
We conducted a search of PubMed, SPORTDiscus, Embase, and Web of Science, and extracted measures assessing difference of quadriceps spinal-reflexive, corticospinal, and intracortical excitability from studies that compared (1) involved limb to the uninvolved limb, (2) involved limb to a control limb, or (3) uninvolved limb to a control limb. We stratified time at 24 months, since this represents a period of heightened risk for reinjury. A modified Downs and Black checklist and Egger's test were used to determine the methodological quality of individual studies and risk of bias between studies.
Fourteen studies comprising 611 participants (371 individuals with a history of ACLR; median time from surgery: 31.5 months; range 0.5-221.1 months) were included in the review. Overall, the involved (g = 0.60, 95% CI [0.24, 0.96]) and uninvolved (g = 0.49, 95% CI [0.00, 0.98]) limbs exhibited greater motor threshold (MT) in comparison to uninjured controls. Motor-evoked potential (MEP) amplitudes were greater in the uninvolved limb in comparison to uninjured controls (g = 0.31, 95% CI [0.03, 0.59]). Lesser intracortical inhibition was exhibited in the uninvolved limb compared to uninjured controls (g = 0.54, 95% CI [0.14, 0.93]). When stratified by time from surgery, MEP amplitudes were greater in the uninvolved limb compared to uninjured controls (g = 0.33, 95% CI [0.03, 0.63]) within the first 24 months after surgery. When evaluated more than 24 months after surgery, the involved limb exhibited greater Hoffmann reflex (H-reflex) compared to uninjured controls (g = 0.38, 95% CI [0.00, 0.77]). MT were greater in the involved limb (g = 0.93, 95% CI [- 0.01, 1.88]) and uninvolved limb (g = 0.57, 95% CI [0.13, 1.02]) compared to uninjured controls. MEP amplitudes in the involved limb were lesser compared to uninjured controls when evaluated more than 24 months after ACLR (g = -1.11, 95% CI [- 2.03, - 0.20]).
The available evidence supports that there are neural excitability differences within the corticospinal tract in individuals with ACLR when compared to uninjured controls. Future research should focus further on longitudinal assessments of neural excitability prior to and following ACLR. Identifying interventions aimed to facilitate corticospinal excitability after ACLR appears to be warranted to improve quadriceps function.
Registered through PROSPERO CRD42020158714.
前交叉韧带重建（ACLR）后，运动产生神经通路的兴奋性存在差异，这与股四头肌功能障碍有关，并被认为会阻止肌肉功能的完全恢复。
本系统评价和荟萃分析的目的是比较 ACLR 受累肢体、未受累肢体和未受伤对照组之间的股四头肌神经兴奋性，并确定手术后何时存在这些差异。
我们对 PubMed、SPORTDiscus、Embase 和 Web of Science 进行了检索，并提取了评估股四头肌脊髓反射性、皮质脊髓性和皮质内兴奋性差异的测量值，这些研究比较了（1）受累肢体与未受累肢体，（2）受累肢体与对照肢体，或（3）未受累肢体与对照肢体。我们将时间分层为 24 个月，因为这是受伤再次发生的高风险期。采用改良的 Downs 和 Black 清单和 Egger 检验来确定个体研究的方法学质量和研究之间的偏倚风险。
共有 14 项研究，包括 611 名参与者（371 名有 ACLR 病史；手术中位时间：31.5 个月；范围 0.5-221.1 个月）纳入了综述。总体而言，与未受伤的对照组相比，受累（g=0.60，95%CI [0.24，0.96]）和未受累（g=0.49，95%CI [0.00，0.98]）肢体的运动阈值（MT）更高。与未受伤的对照组相比，未受累肢体的运动诱发电位（MEP）幅度更大（g=0.31，95%CI [0.03，0.59]）。与未受伤的对照组相比，未受累肢体的皮质内抑制作用较弱（g=0.54，95%CI [0.14，0.93]）。按手术时间分层，未受累肢体的 MEP 幅度在术后 24 个月内大于未受伤对照组（g=0.33，95%CI [0.03，0.63]）。在术后超过 24 个月评估时，受累肢体的 Hoffmann 反射（H 反射）大于未受伤对照组（g=0.38，95%CI [0.00，0.77]）。受累肢体（g=0.93，95%CI [-0.01，1.88]）和未受累肢体（g=0.57，95%CI [0.13，1.02]）的 MT 均高于未受伤对照组。与未受伤的对照组相比，受累肢体的 MEP 幅度在 ACLR 后超过 24 个月时较小（g=-1.11，95%CI [-2.03，-0.20]）。
现有证据支持，与未受伤的对照组相比，ACL 重建患者的皮质脊髓束内存在神经兴奋性差异。未来的研究应进一步关注 ACLR 前后神经兴奋性的纵向评估。确定旨在促进 ACLR 后皮质脊髓兴奋性的干预措施似乎是合理的，以改善股四头肌功能。
通过 PROSPERO CRD42020158714 进行注册。
