股骨頸骨折 (femoral neck fracture) 所造成的併發症中，下列何者最為罕見？
腳長不等 (leg length discrepancy)
骨折不癒合 (nonunion)
坐骨神經 (sciatic nerve) 損傷
股骨頭之缺血性壞死 (avascular necrosis of femoral head)
