Imaging of traumatic injuries to the hip.

Traumatic injuries of the hip are an increasingly common cause of morbidity and mortality. These injuries can be grouped into fairly discrete patterns including femoral head fractures and hip dislocations, femoral neck fractures, greater trochanteric fractures, intertrochanteric fractures, subtrochanteric fractures, and soft tissue injuries. For each of these entities, specific features provide helpful diagnostic, prognostic, and therapeutic information. Femoral head fractures and hip dislocations commonly occur in combination. Fractures of the femoral head confer an increased risk of avascular necrosis of the femoral head. Rare variations of hip dislocations exist including an irreducible posterior dislocation and multiple varieties of anterior dislocation. Femoral neck fractures, which can occur in younger individuals during high-energy trauma and occur with far greater frequency in older osteoporotic individuals with low-energy trauma, are commonly encountered radiographically but can also be radiographically occult. Similarly, greater trochanter fractures have a high frequency of radiographically occult distal extension. As is the case with many other femur fracture types, intertrochanteric and subtrochanteric fractures are less stable and more prone to developing nonunion the more comminuted and extensive they are. All of these injury patterns are frequently encountered in the emergency setting. The ability to distinguish between different types of injury and the knowledge of key discriminating and prognostic features are a must for the interpreting radiologist.