Unrecognized posterior dislocation of the hip associated with transverse and T-type fractures of the acetabulum.

Five patients who had displaced transverse or T-type fractures of the acetabulum and who were transferred 3-5 days after their injury with an unrecognized posterior dislocation of the hip are reported. On the anteroposterior pelvis radiograph, central displacement of the acetabular fragment dominated the radiographic appearance; however, superior displacement of the femoral head with superimposition on the intact acetabular roof was a consistent finding. The typical radiographic findings of adduction and internal rotation of the femur were not present. Oblique views of the pelvis, and/or a computed tomography scan made the diagnosis obvious. Appropriate initial radiographic evaluation is imperative in all patients with acetabular fractures. Failure to recognize the posterior hip dislocation in this group of patients may have led to an increased incidence of avascular necrosis of the femoral head, nerve palsy, and femoral head articular cartilage damage. We recommend either closed reduction with the patient under anesthesia followed by skeletal traction and delayed open reduction/internal fixation, or immediate open reduction/internal fixation if the reduction is not stable.