“…These include two cohort studies, 21,33 five case-control studies, 11,13,37,40,44 and five cross-sectional studies. 17,18,23,28,42 Nine studies reported a positive relationship between knee OA and occupation (OR ¼ 1.4-4.7), 11,13,17,21,23,37,40,44 but only three scored high on methodological quality. 13,37,40 Many studies in this subgroup are older and have procedural flaws, such as failing to control for relevant covariates 17,21 or low participation rates.…”