Stevens Jennifer E, Mizner Ryan L, Snyder-Mackler Lynn
Department of Physical Therapy and Graduate Program in Biomechanics and Movement Sciences, University of Delaware, Newark, DE 19716, USA.
J Orthop Res. 2003 Sep;21(5):775-9. doi: 10.1016/S0736-0266(03)00052-4.
Patients with osteoarthritis (OA) of the knee have quadriceps weakness and arthrogenous muscle inhibition (AMI). While total knee arthroplasty (TKA) reliably reduces pain and improves function in patients with knee OA, quadriceps weakness persists after surgery. The purpose of this investigation was to assess contributions of AMI to quadriceps weakness before and after TKA and to assess the effect of pain on AMI.
Twenty-eight patients with unilateral, end-stage, primary knee OA were tested an average of 10 days before and 26 days after TKA. The mean age at time of operation was 63 years (range 49-82 years). Measurements on the involved and uninvolved knees were performed using the burst-superimposition technique, where supramaximal electrical stimulation is superimposed on a voluntary contraction. Knee pain during contraction was measured using a numeric rating scale.
The involved quadriceps were significantly weaker than the uninvolved prior to TKA (p<0.05). Quadriceps strength decreased by 60% (p<0.001) and activation decreased 17% (p<0.001) after TKA. Changes in muscle activation accounted for 65% of the variability in the change in quadriceps strength (r(2)=0.65) (p<0.001). Knee pain during muscle contraction accounted for a small, but significant portion of the change in voluntary activation (r(2)=0.22) (p=0.006).
Exercise regimens that emphasize strong muscle contraction and clinical tools that facilitate muscle activation like biofeedback and neuromuscular electrical stimulation may be necessary to reverse the quadriceps activation failure and weakness in the patients with knee OA that worsens after TKA. The failure of current rehabilitation regimens to directly address activation deficits within the first months after surgery may explain the persistent quadriceps weakness in patients after TKA.
膝关节骨关节炎（OA）患者存在股四头肌无力和关节源性肌肉抑制（AMI）。虽然全膝关节置换术（TKA）能可靠地减轻膝关节OA患者的疼痛并改善功能，但术后股四头肌无力仍然存在。本研究的目的是评估AMI对TKA前后股四头肌无力的影响，并评估疼痛对AMI的作用。
28名单侧、终末期、原发性膝关节OA患者在TKA前平均10天和术后26天接受测试。手术时的平均年龄为63岁（范围49 - 82岁）。使用爆发叠加技术对患侧和未患侧膝关节进行测量，即将超强电刺激叠加在自主收缩上。使用数字评分量表测量收缩时的膝关节疼痛。
TKA前，患侧股四头肌明显比未患侧弱（p<0.05）。TKA后，股四头肌力量下降了60%（p<0.001），激活率下降了17%（p<0.001）。肌肉激活的变化占股四头肌力量变化变异性的65%（r(2)=0.65）（p<0.001）。肌肉收缩时的膝关节疼痛占自主激活变化的一小部分，但具有显著意义（r(2)=0.22）（p=0.006）。
对于膝关节OA患者，在TKA后病情恶化的情况下，可能需要强调强力肌肉收缩的运动方案以及诸如生物反馈和神经肌肉电刺激等促进肌肉激活的临床工具，以扭转股四头肌激活失败和无力的状况。目前的康复方案未能在术后头几个月直接解决激活缺陷问题，这可能解释了TKA患者股四头肌持续无力的原因。
