Unrecognized foreign body in the hip joint.

A 40-year-old woman involved in a motor vehicle accident sustained a left acetabular fracture and a dislocated left hip with a large ipsilateral traumatic hip wound. Multiple plain radiographic films of the pelvis and a pelvic computed tomographic scan were obtained. None of these images showed a 25 x 20 x 12-mm piece of the gearshift that was found in the hip joint at the time of the surgery. Hence, we present this case highlighting an unusual phenomenon in which a large foreign body was not recognized on preoperative radiographic studies.