Effects of Weight Change on Knee and Hip Radiographic Measurements and Pain Over Four Years: Data From the Osteoarthritis Initiative

Objective To assess the effects of weight loss and weight gain on hip and knee radiographic changes, pain, and joint replacement over 4 years. Methods Participants (n = 2,752) from the Osteoarthritis Initiative were classified as those with weight gain (more than 5% gain), weight loss (more than –5% loss), or as controls (–3% to 3% change) over 4 years. Generalized estimating equations (adjusted for age, sex, and body mass index) were used to assess the relationship between the weight‐change group and 4‐year changes in knee radiographic osteoarthritis (OA) (Kellgren/Lawrence [K/L] grade), hip OA (Croft summary grade), joint space narrowing (JSN), and joint pain. Results For radiographic knee OA, weight loss was associated with significantly lower odds of K/L grade worsening over 4 years (odds ratio [OR] 0.69 [95% confidence interval (95% CI) 0.53–0.91], P  = 0.009), and weight gain was significantly associated with higher odds of medial knee JSN (OR 1.29 [95% CI 1.01–1.64], P  = 0.038) compared to controls. For knee pain, weight loss was significantly associated with knee pain resolution over 4 years (OR 1.40 [95% CI 1.06–1.86], P  = 0.019) while weight gain was associated with knee pain development (OR 1.34 [95% CI 1.08–1.67], P  = 0.009) compared to controls. For all hip outcomes, no significant associations ( P  > 0.05) were found with weight‐change groups. The associations between the weight‐change group and total hip or total knee replacement were not significant ( P  > 0.05). Conclusion This large, longitudinal study (n = 2,752 with 4‐year follow‐up) suggests that weight loss may protect against, and weight gain may exacerbate, radiographic and symptomatic knee OA, while weight change (at a 5% threshold) does not have significant effects on hip OA.