Endocrine Abstracts

Until recently obesity was believed to be protective against fractures as a result of higher bone mass and the protective effect of subcutaneous fat during falls. However, recent studies indicate that fractures in obese postmenopausal women and older men make a substantial contribution to the overall fracture burden in these populations. The effect of obesity on fracture risk is site-dependent, with protection against hip and wrist fractures but increased risk of ankle and lower leg fractures.

The pathophysiology of bone fragility in obese individuals has not been clearly established. Adipose tissue can produce adipokines and cytokines, many of which have adverse effects on bone. Increased intramuscular adipose tissue is likely to contribute to reduced muscle strength, reducing bone mass and increasing the risk of falls. Other potential pathogenetic factors include vitamin D insufficiency, secondary hyperparathyroidism and hypogonadism.

The evidence for efficacy of anti-osteoporosis medication in the obese is weak, since pivotal clinical trials have included relatively few obese individuals. There is some evidence that anti-resorptive medications may not be effective in reducing non-vertebral fractures in obese postmenopausal women. Further studies are needed to enable the development of effective strategies to reduce the growing fracture burden in the obese population.