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Arthritis Care Res (Hoboken). 2018 Sep 17. doi: 10.1002/acr.23760. [Epub ahead of print]

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

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Dept of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.
Dept of Rheumatology, Ghent University Hospital, Ghent, Belgium.
Dept of Internal Medicine, Ghent University, Ghent, Belgium.
Dept of Podiatry, Artevelde University College, Ghent, Belgium.



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).


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.


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.


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.

[Available on 2020-03-17]

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