Posterior acetabular wall fracture
This patient presented after a motor vehicle collision at a high speed with concern for pelvic trauma. Frontal radiographs of the pelvis demonstrated no apparent abnormality. The oblique radiograph shown here demonstrates an oblique fracture through the posterior wall of the acetabulum. The comminuted fracture is also defined on the second image which is an axial CT scan in bone windows. This fracture can occur with a dashboard injury where the knee hits the dashboard when the hip is flexed causing the femoral head to dislocate posteriorly and fracture the posterior wall of the acetabulum.