Occupational biomechanical risk factors for hip and knee arthroplasty incidence: a register-based cohort study in male construction workers

OBJECTIVE: To evaluate the association between exposure to occupational biomechanical factors and the incidence of surgically treated osteoarthritis (OA) treated with arthroplasty in the hip and knee among male construction workers. DESIGN: Longitudinal register-based cohort study. PARTICIPANTS AND SETTING: Male construction workers (n=291 062) who participated in a national Swedish occupational health examination programme between 1971 and 1993, delivered through multiple primary-level nationwide occupational health centres. PRIMARY AND SECONDARY OUTCOME MEASURES: Hip and knee arthroplasties performed due to OA from 1987 to 2019 were identified through linkage with the Swedish National Patient Register. Data on age, smoking habits, body mass index, job title and self-reported biomechanical exposures were collected during the health examinations. Occupational biomechanical workload was assessed using eight factors from a job-exposure matrix. Poisson regression was applied to estimate adjusted incidence rate ratios (IRRs) associated with each type of occupational biomechanical exposure. RESULTS: The study included 10 336 cases of hip arthroplasties and 8926 cases of knee arthroplasties. All studied biomechanical risk factors were associated with an increased risk of knee OA requiring arthroplasty, especially for individuals exposed to static work in non-neutral lumbar postures (IRR 1.38, 95% CI 1.16 to 1.65) and those with a high frequency of kneeling (IRR 1.27, 95% CI 1.12 to 1.45). In contrast, only a few biomechanical factors were associated with an increased risk of hip OA requiring arthroplasty. Similar results were observed when alternative exposure measures, such as occupational group and self-reported exposure assessments, were employed. CONCLUSIONS: Occupational workload was associated with an increased risk of knee arthroplasty due to OA, whereas the association for hip arthroplasty remains unclear.