Delayed onset of quadriceps activity and altered knee joint kinematics during stair stepping in individuals with knee osteoarthritis

Abstract

Objective: To determine if the electromyographic onset of vastus lateralis and kinematic knee joint motion in individuals with knee osteoarthritis (OA) differs from that of asymptomatic persons, during the task of stair stepping. Design: Cross-sectional. Setting: University laboratory in Australia. Participants: Twenty-five participants with symptomatic knee OA and 33 asymptomatic controls. Interventions: Not applicable. Main Outcome Measures: Surface electromyography to determine the onset of vastus lateralis activity. Two-dimensional kinematic analysis of sagittal plane knee motion during stance phase of stair ascent and descent. Results: Participants with knee OA showed delayed onset of v..