Role of Muscle Strength in Dynamic Balance for Subjects with Knee Osteoarthritis

People with knee osteoarthritis (OA) suffer from excessive varus torque on the knee joint, which induces pain and deformity. Subjects reveal difficulties in performing daily activities, such as walking and stair climbing. The kinematical outcomes of the centre of pressure (Col?) length, anterior-posterior and medial-lateral sway are greater in knee OA subjects than the age-matched normal group on performing a static task. However, effective control of balance rely not only accurate sensory input but also a timely response of strong muscles. Therefore, the purpose of this study is to investigate the role of muscle strength in dynamic balance for subjects with knee OA and to determine the influence of severity of knee pain on muscle strength. 10 subjects with symptomatic knee OA participated in this study. Dynamic balance measured the CoP excursion during directions of pitch and row by Steward platform. Isokinetic strength measured concentric contractions of lower extremities in sagittal and frontal plane. The VAS (Visual Analogue Scale and WOMAC (Western Ontario and McMaster University Osteoarthritis Index) were used to assess knee pain. The variables include traveling distance of CoP and intensity of muscles. The results showed ankle muscle strength plays an important role in maintaining dynamic balance in subjects with knee OA regardless of the severity of pain. Therefore, we recommend a strength training program of lower extremities for increasing stability.