Repetitive knee bending and synovitis in people at risk and with knee osteoarthritis: Data from the FNIH Osteoarthritis Biomarkers Consortium.

OBJECTIVE: To investigate associations between engagement in knee bending (stair climbing, kneeling, squatting, heavy lifting, getting in/out of a squatting position) and synovitis prevalence on non-contrast magnetic resonance imaging (MRI) in people at risk and with knee osteoarthritis (OA).

METHODS: We included baseline data from 594 participants (age: 61.5 ± 8.9 years; 61% Kellgren-Lawrence grade ≥2; 59% female; body mass index: 30.7 ± 4.8 kg/m2 ) of the Osteoarthritis Biomarker Consortium Foundation for the National Institutes of Health project. Knee bending activities were queried by standard questionnaire and severity of Hoffa-synovitis and effusion-synovitis (surrogate outcomes of synovitis) graded utilizing the MRI OsteoArthritis Knee Scoring system. Logistic regression was used, unadjusted and adjusted for metabolic syndrome, physical activity level and sex. A grade ≥1 defined synovitis prevalence, with a grade ≥2 cut-off implemented in sensitivity analyses.

RESULTS: The prevalence of grade ≥1 Hoffa-synovitis and effusion-synovitis equaled 59% (n=353) and 62% (n=366), respectively. Adjusted for confounders, kneeling for ≥30 minutes during a single day was associated with grade ≥1 Hoffa-synovitis prevalence (odds ratio (OR) (95% confidence interval (CI)): 1.65 (1.11, 2.47)). Participants engaging in this activity one day or less per week had greater odds for prevalent Hoffa-synovitis, than those who did not perform the activity (OR (95% CI):1.88 (1.11, 3.18)). No other significant associations were found. Sensitivity analyses yielded similar findings.

CONCLUSIONS: In this selected sample with a preponderance of grade ≥1 Hoffa- and/or effusion-synovitis on non-contrast MRI, only prolonged kneeling associated with Hoffa-synovitis prevalence. Replication in other samples is warranted. This article is protected by copyright. All rights reserved.