Search

Although knee inflammation is thought to adversely affect joint function in patients with knee osteoarthritis (OA), the effects of reducing knee inflammation on gait biomechanics and strength are unknown. Our objectives were to compare ultrasound (US) measures of knee inflammation, gait biomechanics, knee extension and flexion strength, and pain before and after knee aspiration and glucocorticoid injection, and to explore associations among changes. Forty‐nine patients (69 knees) with symptomatic knee OA and synovitis were tested before and 3–4 weeks after US‐guided knee aspiration and glucocorticoid injection. At each visit, participants completed US assessments for inflammatory features of knee OA, 3D gait analysis, isokinetic knee extension and flexion strength tests, and Knee Osteoarthritis Outcome Score (KOOS) pain subscales. Linear and polynomial mixed‐effects regression models were used to investigate changes and their associations. Changes were observed for the synovitis score (unstandardized β [post‐injection minus pre‐injection] –0.55/9 [95% confidence interval (95% CI) –0.97, –0.12]), effusion depth (–1.05 mm [95% CI –1.07, –0.39]), KOOS pain (unstandardized β 5.91/100 [95% CI 1.86, 9.97]), peak external knee flexion and extension moments (KFM; 3.33 Nm [95% CI 0.45, 6.22]), KEM (–2.99 Nm [95% CI –5.93, –0.05]), and knee extension strength (4.70 Nm [95% CI 0.39, 9.00]) and flexion strength (3.91 Nm [95% CI 1.50, 6.81]). The external KFM increased during 13–38% and 76–89% of stance post‐injection. When controlled for time, greater synovitis was associated with lower knee extension strength, while lower pain was associated with increased knee extension and flexion strength. In patients with knee OA and synovitis, reduced inflammation and pain after aspiration and glucocorticoid injection are associated with changes in knee gait biomechanics and strength.

ObjectiveTo examine the association between ultrasound (US)-detected knee inflammation and intermittent and constant pain experiences in patients with knee osteoarthritis (OA).MethodsParticipants with radiographically early-stage (Kellgren-Lawrence arthritis grading scale [KL] ≤ 2) and late-stage (KL ≥ 3) disease and frequent symptoms underwent musculoskeletal US measures of inflammation using the Outcome Measures in Rheumatology (OMERACT) knee US scoring system. Pain experiences were captured using the Measure of Intermittent and Constant Osteoarthritis Pain (ICOAP) tool. We assessed the association between US-synovitis and ICOAP pain experiences using a series of linear, logistic, or multinomial logistic regression models (as appropriate for each variable), while adjusting for age, sex, BMI, and radiographic stage. Secondary analyses were performed similarly by radiographic stage.ResultsPain and synovitis measures from 248 patients (453 knees) were included. Worse synovitis was associated with higher ICOAP constant pain scores (β 8.05, 95% CI 0.67–15.43), but not intermittent pain scores. Moderate-to-severe synovitis was associated with a 4.73-fold increased relative risk (95% CI 1.06–17.00) of a constant pain pattern. In secondary analyses, moderate-to-severe synovitis in early radiographic OA was associated with 2.70-higher odds (95% CI 1.04–7.02) of any constant pain, 3.28-higher odds (95% CI 1.43–7.52) of any intermittent pain, and with higher intermittent (β 10.47, 95% CI 1.03–19.91) and constant (β 12.62, 95% CI 3.02–22.23) pain scores. No associations were identified for synovitis in those with late radiographic OA.ConclusionIn patients with knee OA, moderate-to-severe synovitis is most strongly associated with constant pain. Inflammation may play context-specific roles across pain experiences, especially in earlier radiographic stages of knee OA.