Stress and insufficiency fractures.

Stress fractures of the axial and appendicular skeleton typically present as localized pain that develops without a history of specific acute injury. The differential diagnosis includes primary or metastatic neoplasms, infections, musculoskeletal soft tissue injuries, nerve compression syndromes and joint diseases. Plain radiographs may demonstrate changes consistent with fracture, including a fracture line or fracture callus. In many cases, however, initial radiographs are normal or nondiagnostic. This occurs most frequently in three situations: (1) when radiographs are obtained soon after the onset of symptoms, before the appearance of a fracture line or new bone formation; (2) in patients with osteopenia, in whom detection of a fracture line and new bone formation is difficult, and (3) when the fracture involves areas of the skeleton that are difficult to study with plain films (including the spine and pelvis). When the plain films are normal, other tests such as bone scans, computed tomography or magnetic resonance imaging usually demonstrate the fracture.