Traumatic anterior dislocation of the hip: spectrum of plain film and CT findings.

Traumatic anterior dislocation of the hip represents 11% of all hip dislocations and is classified into superior and inferior types [1]. Whereas inferior anterior hip dislocation is easily recognized on an anteroposterior radiograph of the pelvis, the radiographic appearance of superior anterior hip dislocation is less straightforward, often leading to an initial misdiagnosis of posterior hip dislocation. Misdiagnosis of the direction (anterior versus posterior) of a hip dislocation can result in failed closed reduction or an improper surgical approach to open reduction. In addition, recognition of associated impaction fractures is important, as patients with this finding have a greater tendency to develop traumatic arthritis [2, 3]. This pictorial essay, which is based on our experience with 20 cases of anterior hip dislocation, including five of the rare superior type, illustrates the spectrum of radiographic findings and distinguishing features associated with anterior hip dislocation.