The weight-bearing pain is closest associated with physical function among different pain patterns: Data from the Osteoarthritis Initiative

Abstract

Abstract Objective To compare the correlations between different pain patterns and physical function, and identify the most related pain pattern with physical function in knee OA. Methods 736 participants with radiological knee OA were included from the Osteoarthritis Initiative (OAI). Five pain patterns were assessed, including pain severity, intermittent, constant, weight-bearing, and non-weight-bearing pain patterns. Physical function was evaluated by the Western Ontario and McMaster Universities Arthritis Index physical function subscale (WOMAC-PF), Knee Injury and Osteoarthritis Outcome Score Function in Sport and Recreation (KOOS-FSR) and 20-Meter Walking Test (20-MWT). Linear regression analysis were used to exam the associations between pain patterns and physical function, and heat map was plotted to visualize the standardized β coefficients. Results Among all pain patterns, the weight-bearing pain pattern had the strongest correlation with WOMAC-PF and KOOS-FSR at baseline (β = 0.451, p < 0.001; β = -0.354, p < 0.001), year-2 follow up (β = 0.345, p < 0.001; β = -0.279, p < 0.001) and 2-year change (β = 0.430, p < 0.001; β = -0.279, p < 0.001). Except for weight-bearing pain pattern at year-2 follow up (β = 0.079, p = 0.049), pain in other linear models showed no significant correlation with 20-MWT, and weight-bearing pain was always closest to the statistical threshold value (p < 0.05). Conclusions Weight-bearing pain pattern was most closely associated with physical function. Therapeutic targets related to weight-bearing pain should be preferred when administering analgesic therapies to improve physical function in knee OA.