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

OBJECTIVES: To assess the association between occupational exposures and knee osteoarthritis (OA). METHODS: We systematically searched for observational studies that examined the relationship between occupational exposures and, knee OA and total knee replacement (TKR). Four databases were searched until Oct 1st , 2019. Two reviewers independently assessed study quality using the Newcastle-Ottawa Scale and evidence quality using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Subgroup meta-analyses were conducted for important study characteristics and each type of occupational exposure. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for meta-analysis using random-effects models. RESULTS: Eighty eligible studies were identified including 25 case-control (total study participants: N=20,505), 36 cross-sectional (N=139,463) and 19 cohort studies (N=16,824,492). Synthesis of 71 studies suggested increased odds 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. Odds of knee OA were greater in males, industry-based studies and studies assessing lifetime occupational exposures. There were 9 specific job titles that were associated with knee OA, including farmers, builders, metal workers and floor layers. Occupational lifting, kneeling, climbing, squatting and standing were all associated with a higher odds of knee OA compared to sedentary workers, respectively. CONCLUSIONS: Heavy physically demanding occupations and occupational activities were associated with increased odds of knee OA; as supported by moderate-quality evidence. Specifically, agricultural and construction sectors which typically involve heavy lifting, frequent climbing, prolonged kneeling, squatting and standing carried increased odds of knee OA.