Association between occupation and knee and hip replacement due to osteoarthritis: a case-control study

INTRODUCTION: The objective of this study was to examine the association between occupation and osteoarthritis (OA) leading to total knee (TKR) or hip (THR) joint replacement. METHODS: The following is the case-control study design. All patients still living in Iceland who had had a TKR or THR due to OA as of the end of 2002 were invited to participate. First degree relatives of participating patients served as controls. N = 1,408 cases (832 women) and n = 1,082 controls (592 women), 60 years or older and who had adequately answered a questionnaire were analyzed. Occupations were classified according to international standards. Inheritance of occupations was calculated by using the Icelandic Genealogy Database. RESULTS: The age adjusted odds ratio (OR) for male farmers getting a TKR due to OA was 5.1 (95% confidence interval (CI) 2.1 to 12.4) and for a male farmer getting a THR due to OA the OR was 3.6 (95% CI 2.1 to 6.2). The OR for a fisherman getting a TKR was 3.3 (95% CI 1.3 to 8.4). No other occupations showed increased risk for men. For women there was no increased risk for any occupation. Farming and fishing were also the occupations that showed the greatest degree of inheritance. CONCLUSIONS: These results support an association in males between occupations with heavy physical load and both TKR and THR for OA.