Risk factors for stress fractures

Preventing stress fractures requires knowledge of the risk factors that pre dispose to this injury. The aetiology of stress fractures is multifactorial , but methodological limitations and expediency often lead to research stud y designs that evaluate individual risk factors. intrinsic risk factors inc lude mechanical factors such as bone density, skeletal alignment and body s ize and composition, physiological factors such as bone turnover rate, flex ibility, and muscular strength and endurance, as well as hormonal and nutri tional factors. Extrinsic risk factors include mechanical factors such as s urface, footwear and external loading as well as physical training paramete rs. Psychological traits may also play a role in increasing stress fracture risk. Equally important to these types of analyses of individual risk fact ors is the integration of information to produce a composite picture of ris k. The purpose of this paper is to critically appraise the existing literature by evaluating study design and quality, in order to provide a current syno psis of the known scientific information related to stress fracture risk fa ctors. The literature is not fully complete with well conducted studies on this topic, but a great deal of information has accumulated over the past 2 0 years. Although stress fractures result from repeated loading, the exact contribution of training factors (volume, intensity, surface) has not been clearly established, From what we do know, menstrual disturbances, caloric restriction, lower bone density, muscle weakness and leg length differences are risk factors for stress fracture. Other time-honoured risk factors suc h as lower extremity alignment have not been shown to be causative even tho ugh anecdotal evidence indicates they are likely to play an important role in stress fracture pathogenesis.