Bone mineral density and association of osteoarthritis with fracture risk.

OBJECTIVE: High body mass index (BMI) is associated with increased risk of osteoarthritis (OA) and reduced risk of fragility fracture. However, the relationship between fragility fracture and OA remained unclear. This study sought to investigate the effect of bone mineral density (BMD) in the OA-fracture relationship.

METHODS: Data from 2412 women and 1452 men aged >45 years in the Dubbo Osteoporosis Epidemiology Study (DOES) were analyzed. Individuals have been followed for up to 22 years (median: 7.5 years; range: 0.1-22 years). Femoral neck BMD (FNBMD) and lumbar spine BMD (LSBMD) was measured by dual energy X-ray absorptiometry (DXA) (GE LUNAR, Madison, WI). The presence of OA was ascertained at baseline by self-reported diagnosis. The incidence of low-trauma fracture was ascertained from X-ray reports.

RESULTS: Overall, 29% of women and 26% of men had reported a diagnosis of OA. Fracture risk was significantly higher in women with OA than those without OA (Hazard ratio (HR) = 1.50; 95% confidence interval (CI), 1.28-1.76). However, the association was mainly observed in women with osteopenic BMD (HR = 1.74; 95% CI, 1.38-2.17) and normal-BMD (HR = 1.50; 95% CI, 1.06-2.13) and not in those with osteoporosis. Further analysis revealed that osteopenic women with OA had significant increase in risk of vertebral (HR = 1.85; 95% CI, 1.24-2.75) and limb fracture (HR = 2.49; 95% CI, 1.77-3.48), but not in hip fracture. In men, no comparable relationship was found before and after adjustment for covariates.

CONCLUSION: Women with OA have an increased risk of fragility fracture, and the risk was mainly observed in non-osteoporotic group.