Associations of radiological osteoarthritis of the hip and knee with locomotor disability in the Rotterdam Study

OBJECTIVE: To assess the contribution of radiological osteoarthritis of the hips and knees to disabilities in the activities of daily living related to lower limb function. METHODS: During a home interview 1156 men and 1739 women, randomly chosen from the source population of all independently living residents aged 55 years and over living in a district of Rotterdam (the Rotterdam Study) were asked about locomotor disability by six questions of the Health Assessment Questionnaire (HAQ) and about pain in the hips and knees in the past month. Radiographs of hips and knees were scored according to the Kellgren grading system for osteoarthritis. RESULTS: The prevalence of locomotor disability, defined as at least some difficulty with three or more out of six lower limb functions, was 20.2% for men and 31.9% for women; hip pain was present in 8.3% of the men and 16.6% of the women; knee pain in 12.6% of the men and 22.3% of the women. The prevalence of radiological osteoarthritis grade 2+ of the hip was 14.1% for men and 15.9% for women, and of the knee 16.3% and 29.1% respectively. The odds ratio (OR) (95% confidence intervals) of hip radiological osteoarthritis for locomotor disability adjusted for age and all other variables was for men: 1.4 (0.9, 2.1) and for women: 2.2 (1.6, 2.9). The ORs of knee radiological osteoarthritis adjusted for age and all other variables were 1.1 (0.9, 2.1) and 1.4 (1.1, 1.8) respectively. Severe radiological osteoarthritis (grade 3+) was stronger associated. The ORs of pain in the hips or knees and morning stiffness were much higher (between 2.7 and 5.5 for men and between 2.1 and 5.1 for women). CONCLUSIONS: Radiological osteoarthritis of the hip and knee are only weak independent predictors of locomotor disability in women, and not at all independently associated with locomotor disability in men. Age, pain of the hips and knees, and morning stiffness seem to be the most important independent determinants of locomotor disability.