Physical activity, alignment and knee osteoarthritis: data from MOST and the OAI

Area of Science:

• Orthopedics and Sports Medicine
• Rheumatology
• Epidemiology

Background:

• Knee osteoarthritis (OA) is a prevalent degenerative joint disease.
• The role of physical activity in the development of knee OA, particularly in individuals without prior injury and considering knee alignment, remains an area of investigation.

Purpose of the Study:

• To investigate the association between high levels of physical activity and the incidence of knee OA.
• To examine whether knee alignment modifies the effect of physical activity on knee OA development.

Main Methods:

• Combined data from the Multicenter Osteoarthritis (MOST) and Osteoarthritis Initiative (OAI) studies.
• Included participants without radiographic knee OA and major knee injury, assessed via long limb and knee radiographs.
• Physical activity was measured using the Physical Activity Survey for the Elderly (PASE), with the highest quartile defined as 'active'. Incident outcomes included symptomatic tibiofemoral OA and joint space narrowing over 30-48 months.
• Logistic regression analysis adjusted for covariates, with stratification by knee alignment.

Main Results:

• The study analyzed 2,073 subjects (3,542 knees) with a mean age of 61 years.
• High physical activity (top PASE quartile) showed no significant reduction in the risk of developing symptomatic tibiofemoral OA (OR 0.6, 95% CI 0.3-1.3) or joint space narrowing (OR 0.9, 95% CI 0.5-1.5).
• These findings were consistent across different knee alignment statuses.

Conclusions:

• Engaging in high levels of physical activity, as defined by the highest PASE quartile, did not demonstrate a protective effect against the development of knee OA in this cohort.
• Knee alignment did not appear to influence the relationship between physical activity and OA incidence.