Knee Extensor and Flexor Muscle Power Explains Stair Ascension Time in Patients With Unilateral Late-Stage Knee Osteoarthritis: A Cross-Sectional Study

Abstract Objectives To determine the extent of asymmetrical deficits in knee extensor and flexor muscles, and to examine whether asymmetrical muscle deficits are associated with mobility limitations in persons with late-stage knee osteoarthritis (OA). Design Cross-sectional. Setting Research laboratory. Participants A clinical sample (N=56; age range, 50–75y) of eligible persons with late-stage knee OA awaiting knee replacement. Interventions Not applicable. Main Outcome Measures Knee extensor and flexor power and torque assessed isokinetically; thigh muscle cross-sectional area (CSA) assessed by computed tomography; mobility limitation assessed by walking speed and stair ascension time; and pain assessed with the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire. Results The asymmetrical deficits in knee extensor and flexor power and torque were between 18% and 29% ( P