Biomechanical aspects of occupation and osteoarthritis of the hip: a case-control study.

OBJECTIVE

Our study was designed to examine the association between biomechanical aspects of occupation and hip osteoarthritis (OA).

METHODS

Ninety-nine cases of primary hip OA and 233 controls were recruited from the outpatient clinics of a Department of Veterans Affairs Hospital. Subjects were mailed a questionnaire which asked about lifetime participation in various occupational and recreational activities, body mass, medical conditions and demographic information. Occupational work load was defined based on the joint compression forces produced by an occupational activity. Activities which produced joint compression forces at least twice body weight were considered heavy. Activities which produced joint compression forces less than body weight were considered light. All others were considered intermediate. Based on responses to the questionnaire, subjects were classified as exposed to heavy, intermediate or light work.

RESULTS

Using light work as the reference category, subjects in the intermediate work category had 2.0 times and those in the heavy work category had 2.4 times the odds of having hip OA. Logistic regression was used to control for possible confounding. After adjusting for cancer, football and obesity at age 40, subjects who performed heavy work for at least 15 years had 2.4 times the odds of having hip OA compared to subjects who had performed light work. A test for trend in the odds of hip OA with increasing levels of exposure to heavy work was significant.

CONCLUSION

The biomechanical aspects of occupation may contribute to the risk of hip OA.