Osteoarthritis of the knee is associated with vertebral and nonvertebral fractures in the elderly: the Rotterdam Study

OBJECTIVE: To study the association between prevalent radiographic osteoarthritis (ROA) of the knee and incident vertebral and nonvertebral fractures. METHODS: A sample of 2,773 subjects was drawn from the Rotterdam Study, a prospective population-based cohort study of the elderly. Status on knee ROA was assessed at baseline using the Kellgren score. Incident nonvertebral fractures were scored for all subjects, and for 1,466 subjects additional data on incident vertebral fractures were available. RESULTS: Although people with ROA had a higher bone mineral density (BMD), their incident fracture risk was increased as compared with those without ROA. After adjustment for potential confounding factors, including parameters of postural stability, the relative risks for incident vertebral and nonvertebral fractures in the presence of knee ROA were 2.0 (95% confidence interval [95% CI] 1.1-3.4) and 1.5 (95% CI 1.1-2.0), respectively. CONCLUSIONS: Knee ROA is associated with an increased risk of incident vertebral and nonvertebral fractures, independent of BMD and parameters of postural stability.