Association of different pain patterns with physical function in participants with knee osteoarthritis: data from the osteoarthritis initiative.

BACKGROUND

Pain is a multidimensional experience and a key symptoms of knee osteoarthritis (KOA). However, it remains unknown whether there is a specific pain pattern that is more strongly associated with physical function compared to other pain patterns among individuals with KOA. This study aimed to compare the correlations between different pain patterns and physical function, and identify the most related pain pattern with physical function in KOA.

METHODS

412 participants with radiological KOA were included from the Osteoarthritis Initiative (OAI). Pain severity and four pain patterns were assessed, including 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), 20-Meter Walking Test (20-MWT) and Repeated Chair Stand test (RCS).

RESULTS

Among pain severity and all pain patterns, the weight-bearing pain pattern had the strongest correlation with WOMAC-PF, and showed significant correlations with both WOMAC-PF and KOOS-FSR at baseline, year-2 follow up, and 2-year change (p < 0.001). All pain patterns and pain severity showed weakly significant correlation with 20-MWT and RCS.

CONCLUSIONS

Weight-bearing pain pattern was most closely associated with self-reported physical function. Therapeutic targets related to weight-bearing pain should be preferred when administering analgesic therapies to improve physical function in KOA.