Balance Control and Knee Osteoarthritis Severity

OBJECTIVE: To investigate balance control according to the severity of knee osteoarthritis (OA) using clinical tests and Tetra-ataxiometric posturography (Tetrax®). METHOD: A total 80 patients with primary knee OA classified according to American College of Rheumatology criteria, and 40 age-matched controls were enrolled in this study. Of those with OA, 39 patients had mild OA (Kellgren-Lawrence [KL] grade 1, 2) and the other 41 had moderate to severe OA (KL grade 3, 4). The postural control capabilities of the subjects were assessed using the timed up and go test (TUG), Berg balance scale (BBS), and Tetrax®, which utilizes two paired force plates to measure vertical pressure fluctuations over both heels and forefeet. The subjects were checked for their stability index (ST), Fourier index, weight distribution index (WDI), and synchronization index (SI) in eight positions using Tetrax®. RESULTS: Patients with moderate to severe OA exhibited significantly higher stability indices in all positions than patients with mild OA. The Fourier index was also higher in patients with moderate to severe OA than in patients with mild OA. However, the weight distribution index and synchronization of both heels and forefeet were not significantly different in the three groups. CONCLUSION: These findings suggest that patients with moderate to severe OA have more deficits in balance control than those with mild disease. Therefore, evaluation of balance control and education aimed at preventing falls would be useful to patients with knee OA.