Risk factors for fractures in normally active children and adolescents.

Although many children sustain at least one fracture during growth, the majority do not, suggesting it is not the norm for healthy children to break their bones. Most childhood fractures occur during play and sport and result from mild or moderate, rather than severe trauma. The majority of fractures (86.4%) are treated solely in outpatient clinics. Furthermore, there is evidence that 66% of all fractures during growth occur in children and adolescents who fracture on more than one occasion, suggesting certain children may be predisposed to fracture. These individuals frequently fracture first at a young age (<5 years), and any previous history of fracture increases the risk of further fractures 2- to 3-fold. While rates of fracture vary considerably with age, sex and maturation, they peak in early puberty when rates of bone turnover are high but bone mineral accrual lags behind gains in height and weight. Fractures are also common in children with endocrine dysfunction, chronic illnesses or genetic disorders that affect bone metabolism and muscle mass, and/or require the use of medications that influence bone metabolism. A number of risk factors have been identified which may predispose children and adolescents to fracture. For instance, bone mineral content, bone size and bone accrual are all lower in apparently healthy children and adolescents with fractures, and low bone mineral density is a predictor of new fracture. There is also evidence that genetic factors, poor nutrition (including an inadequate intake of dietary calcium, milk avoidance and excessive consumption of carbonated beverages), lack of weight-bearing physical activity, obesity and high exposure to trauma may influence fracture risks in the general pediatric population.