Late complication of Acetabular fracture: (A) Avascular necrosis of lilac crest, (B) Avascular necrosis of head of femur, (C) Fixed deformity of the hip joint, (D) Secondary osteoarthritis of hip joint
Answer is B. Avascular necrosis - osteonecrosis of the femoral head may occur even if the hip is not fully dislocated. 
The condition is probably overdiagnosed because of an erroneous interpretation of x-ray appearance following impacted marginal fractures of the acetabulum.
Other complications : *iliofemoral venous thrombosis *sciatic nerve injury *heterotopic bone formation *loss of joint movement & secondary osteoarthritis