A fracture is a structural break and disruption in a bone of any size or shape. A fracture occurs when force is applied to a bone in an amount greater than it can support. The amount of force required to cause a fracture depends on the composition and strength of the bone. The force may be a direct force, as from a blow (direct trauma) or a motor vehicle accident, a twisting force, or repeated pounding on the same bone. Repeated impact and loading on an area of bone (e.g., prolonged marching, running) can cause a break referred to as a stress fracture. Fractures also can occur because of diseases that affect the strength of the bone (e.g., osteopenia, osteoporosis, bone tumors) or the protective structures around it (pathological fractures).
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Fractures vary with the number of bone fragments affected and their position. All fractures are described in terms of five categories: location of the bone in the body (anatomic location), direction of the fracture lines (i.e., transverse, oblique, spiral, comminuted, impacted), the relation of the bone pieces to each other (alignment and apposition), the stability of the fracture, and the amount of soft tissue damage around the fracture (i.e., simple or closed, compound or open, complicated or uncomplicated). An open or compound fracture is one where the fractured bone end pierces the skin; a greenstick fracture is one where the fracture is only on one side of the bone but the other side of the bone is caused to bend; a comminuted fracture is one where the bone has broken into three or more fragments ("Fractures"). Muscles attached to the bones involved often pull the fracture fragments out of position, especially if the muscles spasm. This can change the status of a fracture from one where the fragments have not shifted out of position (nondisplaced) to one where they have become displaced.
Risk: Individuals of advanced age, individuals exposed to falls and/or objects falling on them, those who experience a motor vehicle accident, as well as individuals involved in high-risk activities performed with high-impact or at high-velocity are at increased risk for fractures.
Individuals who participate in sports activities that involve running, jumping, and sprinting have a higher risk for stress fractures, since the force of each running step is at least three times that of the individual's body weight (DeLee). Individuals with a genetic predisposition to rigid, high-arched feet (pes cavus), those with a leg length discrepancy that imparts greater stresses to the longer leg, those with a hallux valgus deformity or a longer second ray (Morton's foot), and those with pronounced hip external rotation are also at increased risk for a lower extremity stress fracture (DeLee).
Individuals with inflammatory bowel disease have a 40% greater incidence of fracture than the general population (Berstein 759).
Older individuals with a heightened risk of fracture include those with history of prior fracture or a fall within the previous 12 months and those with low bone mineral density, quadriceps weakness, or postural instability. Women with osteoporosis are 1.6 times more likely to sustain a fracture than men with osteoporosis, although 50% of all fractures occur in individuals without osteoporosis (Nguyen).