Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado, Aurora, Colorado.
Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, Utah.
J Bone Joint Surg Am. 2019 Sep 4;101(17):1539-1545. doi: 10.2106/JBJS.18.01457.
Quadriceps weakness is a hallmark of total knee arthroplasty and is driven by reduced voluntary muscle activation following the surgical procedure. The mechanisms underlying postoperative activation deficits are not well established, although nociception has been implicated via both spinal reflex and supraspinal pathways. The purpose of this study was to assess the role of nociception in postoperative recovery of strength and activation.
A total of 53 participants were assessed prior to total knee arthroplasty and at 6 weeks postoperatively. Quadriceps strength was measured by maximum voluntary isometric contraction, and activation was measured by the doublet interpolation technique. The pressure-pain threshold was used to measure local sensitization (at the knee joint) and systemic sensitization (at the forearm). Changes in outcomes (strength and activation) were regressed against pressure-pain threshold measurements. Mediation analyses were planned for significant associations to investigate whether deficits in voluntary activation were implicated on a causal pathway between pressure-pain threshold measures and postoperative strength loss.
Knee pressure-pain threshold measures were significantly associated with reduced voluntary quadriceps activation (beta = -0.04; p = 0.009) and diminished quadriceps strength after total knee arthroplasty (beta = -0.07; p = 0.001). There was also a mediation effect of voluntary activation on the relationship between the knee pressure-pain threshold and quadriceps strength. After correcting for multiple comparisons, relationships between the forearm pressure-pain threshold and strength and activation did not reach significance.
The measures of local nociceptor sensitization were related to reduced strength and activation following total knee arthroplasty. This is consistent with a causal pathway linking increased firing of knee joint nociceptors to reduced activation and reduced strength. Future randomized studies should investigate whether peripherally directed pain therapies reduce pain while also promoting the recovery of quadriceps strength via an improved capacity for voluntary activation.
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
股四头肌无力是全膝关节置换术的一个标志，术后由于自愿肌肉激活减少而导致。术后激活缺陷的机制尚不清楚，尽管通过脊髓反射和皮质上途径已经涉及到伤害感受。本研究的目的是评估伤害感受在术后力量和激活恢复中的作用。
共有 53 名参与者在全膝关节置换术前和术后 6 周进行评估。股四头肌力量通过最大自愿等长收缩测量，激活通过双脉冲插值技术测量。压痛阈值用于测量局部敏化（在膝关节）和全身敏化（在前臂）。结果（力量和激活）的变化与压痛阈值测量值相关。对于显著关联，计划进行中介分析，以调查自愿激活缺陷是否涉及压痛阈值测量值与术后力量丧失之间的因果途径。
膝关节压痛阈值测量值与术后全膝关节置换后自愿股四头肌激活减少（β = -0.04；p = 0.009）和股四头肌力量减弱显著相关（β = -0.07；p = 0.001）。自愿激活对膝关节压痛阈值与股四头肌力量之间的关系也存在中介效应。在纠正多重比较后，前臂压痛阈值与力量和激活之间的关系没有达到显著性。
局部伤害感受器敏化的测量值与全膝关节置换术后力量和激活减少有关。这与一种因果途径一致，即膝关节伤害感受器的放电增加与激活和力量减少有关。未来的随机研究应调查是否外周导向的疼痛疗法在减轻疼痛的同时，通过改善自愿激活能力来促进股四头肌力量的恢复。
治疗学 IV 级。有关证据水平的完整描述，请参见作者说明。
