Marmon Adam R, Milcarek Barry I, Snyder-Mackler Lynn
University of Delaware, Newark DE, USA.
Int J Sports Phys Ther. 2014 Apr;9(2):168-78.
PURPOSE/BACKGROUND: Deficits in functional abilities persist after total knee arthroplasty (TKA), while static measures of knee extensor strength (e.g. isometric contractions) are related to functional performance, little is known about the associations between functional ability and dynamic knee extensor strength (e.g. power). With the growing rate of these procedures, in a progressively younger and more active cohort, a better understanding of the functional importance of dynamic strength (muscle power) is needed. The purpose of this study was to examine the associations between functional performance and peak knee extensor power (isokinetic and isotonic measures) from patients after unilateral TKA.
Cross-sectional, controlled laboratory study, with correlation and regression analyses.
Institutional clinic and research laboratory.
Patients 6 months after TKA (N=24, 12 men and women), most of whom were mildly to very active. A normal control group without knee pain (CON; N=22, 10 men and 12 women) was also assessed for comparison.
Static and dynamic strength measures were assessed during normalized voluntary isometric contractions (NMVIC), isokinetic contractions at three velocities (60, 90, and 120 deg/s), and isotonic contractions against three body weight normalized resistances (20, 30 and 40% BW). Functional performance was assessed using the timed up-and-go (TUG), stair climbing test (SCT), and 6- minute walk (6MW). Analyses of the relationships between functional performance measures and peak knee extensor NMVIC and power were performed. Regression analyses predicting functional performance from power were also performed after controlling for NMVIC.
Peak power across isokinetic velocities, isotonic resistances, and NMVICs were correlated with the functional performance measures for the TKA group. Unlike the TKA group, functional performance was not significantly associated with peak power across all isokinetic velocities and isotonic resistances (e.g no significant associations between peak isotonic power and 6MW distance). In the TKA group, inclusion of the isotonic power against 30% BW, after controlling for NMVIC, improved the predictability of all three functional performance tests; TUG (p= 0.022), SCT (p=0.006), and 6MW (p=0.001).
Measurements of knee extensor power may be a useful tool for clinicians when assessing and setting milestones during rehabilitation.
Prospective cohort study, level II.
目的/背景：全膝关节置换术（TKA）后功能能力的缺陷仍然存在，虽然膝关节伸肌力量的静态测量（如等长收缩）与功能表现相关，但关于功能能力与动态膝关节伸肌力量（如功率）之间的关联却知之甚少。随着这些手术的发生率不断上升，且患者群体越来越年轻、活动量越来越大，因此需要更好地了解动态力量（肌肉功率）的功能重要性。本研究的目的是探讨单侧TKA术后患者的功能表现与膝关节伸肌峰值功率（等速和等张测量）之间的关联。
横断面、对照实验室研究，并进行相关性和回归分析。
机构诊所和研究实验室。
TKA术后6个月的患者（N = 24，男12例，女12例），其中大多数为轻度至非常活跃的患者。还评估了一个无膝关节疼痛的正常对照组（CON；N = 22，男10例，女12例）以作比较。
在标准化自愿等长收缩（NMVIC）、三种速度（60、90和120度/秒）的等速收缩以及三种体重标准化阻力（20%、30%和40%体重）的等张收缩过程中评估静态和动态力量指标。使用计时起立行走测试（TUG）、爬楼梯测试（SCT）和6分钟步行测试（6MW）评估功能表现。分析功能表现指标与膝关节伸肌峰值NMVIC和功率之间的关系。在控制NMVIC后，还进行了从功率预测功能表现的回归分析。
TKA组中，等速速度、等张阻力和NMVIC下的峰值功率与功能表现指标相关。与TKA组不同，在所有等速速度和等张阻力下，功能表现与峰值功率均无显著关联（例如，等张峰值功率与6MW距离之间无显著关联）。在TKA组中，在控制NMVIC后，纳入30%体重的等张功率可提高所有三项功能表现测试（TUG，p = 0.022；SCT，p = 0.006；6MW，p = 0.001）的预测能力。
膝关节伸肌功率测量可能是临床医生在康复评估和设定里程碑时的有用工具。
前瞻性队列研究，二级。
