Division of Physical Therapy Education, University of Nebraska Medical Center, Omaha, NE 68198-4420, USA.
J Geriatr Phys Ther. 2012 Apr-Jun;35(2):62-71. doi: 10.1519/JPT.0b013e3182353ee4.
Persons with total knee arthroplasty (TKA) have many impairments that may compromise postural control. Most work examining postural control following TKA has focused on static and reactive postural control.
The purpose of this study was to (1) compare anticipatory postural adjustments (APAs) between individuals with TKA and healthy controls; and (2) identify possible pre- to postoperative changes in APAs in those undergoing TKA.
Ten individuals planning TKA and 10 healthy age- and sex-matched controls were recruited. During a standing reaching task, lower extremity muscle activity was measured using electromyography (EMG) onsets and normalized EMG amplitudes, and center of pressure (COP) excursion was measured via a force platform. Other outcome measures included isometric strength of the knee flexors and extensors. Individuals in the TKA group were tested preoperatively, and at 3 and 6 months postoperatively. Controls were also measured 3 times over 6 months.
There were no pre- to postoperative differences in lower extremity EMG onsets, normalized EMG amplitudes, or COP excursion in those with TKA. When compared to controls, individuals with TKA demonstrated lower EMG amplitudes of the vastus lateralis and biceps femoris, whereas EMG onsets and COP excursion did not differ. Individuals with TKA demonstrated lower knee extension torque.
It seems that the surgery itself did not alter APAs among individuals with TKA. Potential contributors to the differences in EMG amplitudes in those with TKA compared to controls, such as impaired neural activation or efforts to reduce stress on the involved knee joint, need further investigation.
全膝关节置换术（TKA）患者有许多可能影响姿势控制的障碍。大多数研究TKA 后姿势控制的工作都集中在静态和反应性姿势控制上。
本研究的目的是：（1）比较 TKA 患者和健康对照者的预期姿势调整（APA）；（2）确定接受 TKA 的患者 APA 可能的术前到术后变化。
招募了 10 名计划接受 TKA 的患者和 10 名年龄和性别匹配的健康对照者。在站立伸展任务中，使用肌电图（EMG）起始和归一化 EMG 幅度测量下肢肌肉活动，并通过力平台测量中心压力（COP）偏移。其他结果测量包括膝关节屈肌和伸肌的等长强度。TKA 组患者在术前、术后 3 个月和 6 个月进行测试。对照组也在 6 个月内测量了 3 次。
TKA 患者的下肢 EMG 起始、归一化 EMG 幅度或 COP 偏移均无术前到术后差异。与对照组相比，TKA 患者的股外侧肌和股二头肌的 EMG 幅度较低，而 EMG 起始和 COP 偏移则没有差异。TKA 患者的膝关节伸肌扭矩较低。
似乎手术本身并没有改变 TKA 患者的 APA。需要进一步研究 TKA 患者与对照组相比，EMG 幅度差异的潜在原因，如神经激活受损或减少受累膝关节压力的努力。
