[Risk of hip fractures in the elderly: biomechanical aspects of the falling process]

Age-related fractures are considered to be primarily the consequence of bone loss and increased bone fragility. In line with this dominant view on fracture etiology, prevention studies have primarily focused on pharmacologic interventions to increase bone density of the femoral neck. However, osteoporotic fracture occurrence is not entirely accounted for by bone strength but also related to the incidence and impact of falls. Recent data have provided evidence that an intensive multifactorial intervention strategy can be used to decrease the incidence of falls, but it remains to be determined whether fall prevention can be used successfully to prevent fall-related injuries or hip fracture. In fact, while more than 90% of hip fractures involve falls, hip fracture occurs in only about 1% of falls, suggesting that falls that cause hip fracture may differ qualitatively from other falls. These differences relate to the biomechanical aspects of falls, i.e., the energy that is ultimately transmitted to the proximal femur. Fall severity, rather than fall initiation, may therefore have to be the primary subject of future research.