Distribution of Fracture Sites in Postmenopausal Overweight and Obese Women: The FRISBEE Study

The association between obesity and fracture sites in postmenopausal women has been little studied. We examined the most common types of fractures in obese and overweight postmenopausal women compared to subjects with a normal BMI in the FRISBEE study, a cohort of postmenopausal women followed since 9.1 (7.2-10.6) years. Chi-squared tests and logistic regressions were used to compare the percentages of fracture sites in overweight/obese subjects to subjects with a normal BMI. Their mean (± SD) age was 76.7 ± 6.9 years and their mean BMI was 26.4 ± 4.4. Seven hundred seventy-seven subjects suffered at least one validated fragility fracture with a total of 964 fractures in the whole cohort. Subjects with a BMI higher than 25 had significantly more ankle fractures and less pelvic fractures than subjects with a normal BMI (OR 1.63, 95% CI 1.02-2.56, P = 0.04 and OR 0.55, 95% CI 0.34-0.89, P = 0.01, respectively). There were no significant differences between overweight and obese subjects. Among those older than 75, there were significantly fewer pelvic fractures in overweight/obese subjects (OR 0.49, 95% CI 0.27-0.87, P = 0.01), but before 75, ankle fractures were significantly more frequent in overweight/obese subjects than in subjects with a normal BMI (OR 1.89, 95% CI 1.01-3.57, P = 0.04). In conclusion, the proportion of ankle and pelvic fractures in obese and overweight subjects differs from that in subjects with a normal BMI, but these differences are age dependent. Fracture prevention strategies should take into account the differential effects of excess weight according to age and the site of fracture.