Summary
This study aimed to investigate the relationship between ultrasound (US)–detected knee inflammation and different pain experiences in patients with knee osteoarthritis (OA). Participants with early-stage (Kellgren-Lawrence arthritis grading scale [KL] ≤ 2) and late-stage (KL ≥ 3) knee OA underwent musculoskeletal US assessments using the Outcome Measures in Rheumatology (OMERACT) knee US scoring system.
Pain experiences were measured using the Measure of Intermittent and Constant Osteoarthritis Pain (ICOAP) tool. The analysis, adjusting for various factors, revealed that worse synovitis was associated with higher ICOAP constant pain scores but not intermittent pain scores. Moderate-to-severe synovitis increased the relative risk of a constant pain pattern.
In secondary analyses, moderate-to-severe synovitis in early-stage OA was associated with higher odds of any constant pain, any intermittent pain, and higher intermittent and constant pain scores. However, no such associations were identified for synovitis in late-stage OA. The study concludes that in knee OA patients, moderate-to-severe synovitis is strongly linked to constant pain, suggesting inflammation may have context-specific roles across different pain experiences, particularly in the earlier stages of knee OA.
