McGinnis Kevin, Snyder-Mackler Lynn, Flowers Portia, Zeni Joseph
University of Delaware, Newark, DE 19717, USA.
Clin Biomech (Bristol). 2013 Feb;28(2):205-10. doi: 10.1016/j.clinbiomech.2012.11.008. Epub 2012 Dec 5.
Although total knee arthroplasty reduces pain and improves function, patients continue to walk with asymmetrical movement patterns, that may affect muscle activation and joint loading patterns. The purpose of this study was to evaluate the specific biomechanical abnormalities that persist after total knee arthroplasty and examine the neuromuscular mechanisms that may contribute to these asymmetries.
Dynamic joint stiffness at the hip, knee and ankle, as well as co-contraction at the knee and ankle, were compared between the operated and non-operated limbs of 32 subjects who underwent total knee arthroplasty and 21 subjects without lower extremity impairment.
Subjects after total knee arthroplasty demonstrated higher dynamic joint stiffness in the operated knee compared to the non-operated knee (0.056 (0.023) Nm/kg/m/deg vs. 0.043 (0.016) Nm/kg/m/deg, P=0.003) and the knees from a control group without lower extremity pathology (controls: 0.042 (0.015) Nm/kg/m/deg, P=0.017). No differences were found between limbs or groups for dynamic joint stiffness at the hip or ankle. There was no relationship between dynamic joint stiffness at the knee and ankle and the amount of co-contraction between antagonistic muscles at those joints.
Patients after total knee arthroplasty walk with less knee joint excursion and greater knee stiffness, although no differences were found between groups for stiffness at the hip or ankle. Mechanisms other than co-contraction are likely the underlying cause of the altered knee mechanics. These findings are clinically relevant because the goal should be to create interventions to reduce these abnormalities and increase function.
尽管全膝关节置换术可减轻疼痛并改善功能，但患者仍以不对称的运动模式行走，这可能会影响肌肉激活和关节负荷模式。本研究的目的是评估全膝关节置换术后持续存在的特定生物力学异常，并研究可能导致这些不对称的神经肌肉机制。
比较了32例行全膝关节置换术的受试者和21例无下肢损伤的受试者手术侧与非手术侧髋、膝和踝关节的动态关节刚度，以及膝和踝关节的协同收缩情况。
全膝关节置换术后的受试者手术侧膝关节的动态关节刚度高于非手术侧膝关节（0.056（0.023）Nm/kg/m/度对0.043（0.016）Nm/kg/m/度，P = 0.003），也高于无下肢病变的对照组膝关节（对照组：0.042（0.015）Nm/kg/m/度，P = 0.017）。髋或踝关节的动态关节刚度在各肢体或组间未发现差异。膝关节和踝关节的动态关节刚度与这些关节拮抗肌之间的协同收缩量之间没有关系。
全膝关节置换术后的患者行走时膝关节活动度较小且膝关节刚度较大，尽管髋或踝关节的刚度在各组间未发现差异。协同收缩以外的机制可能是膝关节力学改变的根本原因。这些发现具有临床相关性，因为目标应该是制定干预措施以减少这些异常并提高功能。
