Occupational risk in knee osteoarthritis: a systematic review and meta-analysis of observational studies

Purpose: prevalence of knee osteoarthritis has been associated with work-related repetitive joint movements and excess knee load, but little is known of the relationship between specific job titles and risk of knee osteoarthritis; especially light to moderate physically demanding occupations. This review aims to assess the association between occupational exposures and knee osteoarthritis (OA).Methods: we systematically searched for observational studies that compared occupational exposures in relation to primary knee OA and total knee replacement (TKR). Occupational exposures included job titles, job categories and occupational activities such as lifting, kneeling etc. MEDLINE, EMBASE, CINAHL and Web of Science were searched for relevant literature from inception to Oct 1st, 2019. Odds ratios (OR) and 95% confidence intervals (CI) were retrieved/calculated for meta-analysis using random-effects models.Results: a total of 80 eligible studies were identified including 25 case-control (N = 20,505), 36 cross-sectional (N = 139,463) and 19 cohort studies (N = 16,824,492). Synthesis of 71 studies yielded an increased risk of knee OA (OR: 1.52; 95%CI: 1.37, 1.69), which combined different physically demanding jobs and occupational activities, compared to sedentary occupations and/or low exposure groups (Figure 1). The risk of knee OA was greater in males, industry-based studies and studies assessing lifetime occupational exposures. Specific job titles that were associated with an increased risk of knee OA included agriculture workers, construction workers, metal workers, floor layers, carpenters, craftsmen, service workers, cleaners and houseworkers. Occupational lifting, kneeling, climbing, squatting and standing were all associated with a higher risk of knee OA.Conclusions: an increased risk of knee OA was found in heavy physical demanding occupations and occupational activities supported by moderate-quality evidence. Specific job titles were mainly in agriculture and construction sectors which involve heavy lifting, frequent climbing, prolonged kneeling, squatting and standing