Objectives Shift work-induced circadian rhythm disruption has been identified as a risk factor for specific diseases. Additionally, physically demanding work has been linked to osteoarthritis. This study investigated the independent associations of shift work and physical work with risk of large joint osteoarthritis. Design UK Biobank participants completed questionnaires detailing their employment status, including shift work, night shifts, heavy manual work and prolonged non-sedentary work. Responses were categorised into binary and categorical variables. Knee and hip osteoarthritis diagnoses were extracted from hospital records and osteoarthritis (any site) was self-reported. Logistic regression models, adjusted for age, sex, BMI, Townsend Deprivation Index and other work factors, were used to investigate the relationships between work characteristics and osteoarthritis outcomes. Results This study included 285,947 participants (mean age 52.7 years; males 48.0%). Shift work and night shifts were associated with knee osteoarthritis (fully adjusted OR: 1.12 [95% CI:1.07-1.17] and 1.12 [1.04-1.20], respectively), and self-reported osteoarthritis but there was little evidence of an association with hip osteoarthritis (1.01 [0.95-1.08] and 1.03 [0.93-1.14]). Heavy manual work and prolonged non-sedentary work were associated with increased risk of all osteoarthritis outcomes. Conclusions Shift work showed independent associations with knee osteoarthritis and self-reported osteoarthritis but not hip osteoarthritis, suggesting circadian rhythm dysfunction may play a role in knee osteoarthritis pathogenesis. Heavy manual work and prolonged non-sedentary work were associated with all outcomes, with stronger associations in knee osteoarthritis, possibly reflecting the knee's higher susceptibility to biomechanical stress. Further research is needed to explore workplace interventions for reducing these risks.

The authors have declared no competing interest.

AH and SS were self-funded undergraduate students. BGF is supported by an NIHR Academic Clinical Lectureship. RB and MJ were supported by a Wellcome Trust collaborative award (209233/Z/17/Z). QJM was supported by a Versus Arthritis Senior Fellowship Award 20875.

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