Normalized Knee-Extension Strength or Leg-Press Power After Fast-Track Total Knee Arthroplasty: Which Measure Is Most Closely Associated With Performance-Based and Self-Reported Function?

• Published in: Archives of physical medicine and rehabilitation Vol. 94; no. 2; pp. 384 - 390
• Main Authors: Aalund, Peter K., PT, Larsen, Kristian, PhD, Hansen, Torben B., PhD, Bandholm, Thomas, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2013
• Subjects: Aged; Arthritis; Arthroplasty, replacement; Arthroplasty, Replacement, Knee; Cross-Sectional Studies; Exercise Test; Female; Follow-Up Studies; Humans; Knee Joint - physiopathology; Leg; Male; Muscle strength; Muscle Strength - physiology; Muscle Strength Dynamometer; Outcome assessment (health care); Outcome Assessment (Health Care) - methods; Pain Measurement; Physical Medicine and Rehabilitation; Postoperative Period; Rehabilitation; Self Report; Surveys and Questionnaires; total knee arthroplasty; Muscle strength; Arthroplasty, replacement; WOMAC; Western Ontario and McMaster Universities Osteoarthritis Index; VAS; Arthritis; Rehabilitation; TKA; visual analog scale; Outcome assessment (health care); Leg
• ISSN: 0003-9993; 1532-821X
• DOI: 10.1016/j.apmr.2012.09.031

Abstract Objective To investigate which of the 2 muscle-impairment measures for the operated leg, normalized knee extension strength or leg press power, was most closely associated with performance-based and self-reported measures of function shortly after total knee arthroplasty (TKA). Design Cross-sectional, exploratory study. Setting Laboratory at a regional hospital. Participants Individuals (N=39) with an average age ± SD of 65.5±10.3 years, who all had unilateral TKA 28 days prior. Interventions None. Main Outcome Measures The patients performed maximal isometric knee extensions and dynamic leg presses to determine their body-mass normalized knee extension strength and leg press power, respectively. The 10-meter fast speed walking- and 30-second chair stand tests were used to determine performance-based function, while the Western Ontario and McMaster Universities Osteoarthritis Index and Oxford Knee Scores were used to determine self-reported function. Results Normalized leg press power was more closely associated with both performance-based ( r =.82, P <.001) and self-reported ( r =.48, P =.002) measures of function compared with normalized knee extension strength ( r =.51, P =.001 and r =.39, P =.015, respectively). Conclusions Normalized leg press power was more closely associated with both performance-based and self-reported function early after TKA than normalized knee extension strength. It may be explained by the fact that performance-based measures of function are typically closed kinetic chain tasks, such as walking or rising from a chair, and self-reported measures of function typically include questions that address perceived difficulty with performing these same tasks.