Association of knee and ankle osteoarthritis with physical performance

The direct measurement of the ability to perform physical tasks yields information about factors contributing to poor function and insights into strategies for preventing disability. Our goal was to evaluate the relationship of walking speed and balance tests with specific radiographic features of knee and ankle osteoarthritis (OA).

A timed eight foot walk and a standing balance test were performed by 138 participants of a longitudinal observational study of knee OA progression. Radiographic features of OA severity, joint space narrowing (JSN), a surrogate for cartilage loss and osteophyte (OST) formation, were assessed for the knee and ankle. The association of these performance measures with radiographic OA was evaluated using correlation analysis, adjusted for age, gender, body mass index (BMI), and number of comorbidities.

Knee and ankle JSN, but not OST, was negatively associated with specific performance tests: walking speed was associated with knee JSN (Spearman rho = -0.20, P = 0.02) and balance was associated with ankle (subtalar joint) JSN (Spearman rho = -0.22, P = 0.01). These relationships remained significant upon further control for knee and ankle pain.

Structural joint damage due to OA (JSN in contrast to OST) negatively impacted specific domains of physical performance. These results indicate that targeting specific joints for specific functional outcomes may be indicated, and suggest that prevention of cartilage damage in these joints is a sensible target for OA disease modification to prevent disability.