Prevention of hip fractures: risk factor modification.

Factors that influence the risk of hip fracture have been identified, many of which can be eliminated or modified. Even those risk factors that cannot be modified are important for identifying at-risk patients, who may benefit most from therapies that after other risk factors. Bone mineral density (BMD) is the major measurable determinant of the risk of fragility fractures. However, recent prospective studies have identified factors that influence the risk of having a hip fracture independently of the risk associated with low BMD. Skeletal factors other than BMD that may increase the risk of hip fracture in women include hip geometry and height (tallness). Other factors, some of which are potentially modifiable, operate through effects on the risk of trauma, including decreased visual acuity, neuromuscular impairment, cognitive impairment, residence in a nursing home, poor general physical health, and use of medications that diminish alertness. Fall mechanics also play an important role in the etiology of hip fractures. Falls to the side, particularly those with impact on the hip or side of the leg, more often result in hip fractures than do other falls. Protection of the hip with external padding offers great promise in the prevention of hip fracture in patients with very low bone mass or with conditions that make falls almost inevitable. Increases in hip fracture rates in developing countries suggest a possible relationship with declining physical activity (particularly load-bearing activity). Although the role of exercise in the prevention of osteoporosis and hip fracture has not yet been proven, there is evidence of independent protective effects of both past physical activity and moderate levels of recent physical activity on the risk of hip fracture. Low body weight secondary to poor appetite or poor health (as opposed to intentional weight loss) has been associated with increased hip fracture risk, and nutritional deficiencies may also play a role in hip fracture pathogenesis. These are potentially modifiable. Future studies should be aimed at confirming the hip fracture risk factors identified, ascertaining their independence from other factors, assessing their prevalence, and determining the outcomes and costs involved in interventions to modify them.