Occupational workload has been associated with an increased risk of osteoarthritis. The objective was to further examine the association between workload and occurrence of osteoarthritis and in particular to study whether heavy workload has similar importance as a causative factor for osteoarthritis of the hip and knee.
In a cohort study, the authors investigated the incidence of surgically treated osteoarthritis in the hip and knee among men employed in the Swedish construction industry (n = 204 741). Incident cases were found by linkage with the Swedish hospital discharge register between 1987 and 1998. Incidence rates adjusted for age and BMI were compared between different occupational groups.
The incidence rates for osteoarthritis in hip and knee were positively correlated (r = 0.62; p = 0.01). There was a significantly increased risk of surgically treated osteoarthritis in the knee among floor layers, asphalt workers, sheet-metal workers, rock workers, plumbers, brick layers, wood workers and concrete workers. Even if there was a trend towards increased relative risks for osteoarthritis in the hip in floor layers, asphalt workers, wood workers and concrete workers they were not statistically significant. The relative risk for surgically treated osteoarthritis of the knee was 4.7 (95% CI 1.8 to 12.3) among floor layers, indicating an attributable fraction for work factors of 79%.
This study shows that some work-related factors seem to be risk factors for osteoarthritis both in the knee and hip. However, the risk factors seem to be of greater importance for osteoarthritis in the knee compared with the hip. This study indicates that at least 50% of the cases of severe osteoarthritis of the knee can be prevented through decreasing occupational risk factors in some occupational groups.