Intramedullary bone pedestal formation contributing to femoral shaft fracture nonunion: A case report and review of the literature.

backgroundFemoral shaft fracture is a commonly encountered orthopedic injury that can be treated operatively with a low overall delayed/nonunion rate. In the case of delayed union after antegrade or retrograde intramedullary nail fixation, fracture dynamization is often attempted first. Nonunion after dynamization has been shown to occur due to infection and other aseptic etiologies. We present a unique case of diaphyseal femoral shaft fracture nonunion after dynamization due to intramedullary cortical bone pedestal formation at the distal tip of the nail. CASE SUMMARY: A 37-year-old male experienced a high-energy trauma to his left thigh after coming down hard during a motocross jump. Evaluation was consistent with an isolated, closed, left mid-shaft femur fracture. He was initially managed with reamed antegrade intramedullary nail fixation but had continued thigh pain. Radiographs at four months demonstrated no evidence of fracture union and failure of the distal locking screw, and dynamization by distal locking screw removal was performed. The patient continued to have pain eight months after the initial procedure and 4 mo after dynamization with serial radiographs continuing to demonstrate no evidence of fracture healing. The decision was made to proceed with exchange nailing for aseptic fracture nonunion. During the exchange procedure, an obstruction was encountered at the distal tip of the failed nail and was confirmed on magnified fluoroscopy to be a pedestal of cortical bone in the canal. The obstruction required further distal reaming. A longer and larger diameter exchange nail was placed without difficulty and without a distal locking screw to allow for dynamization at the fracture site. Post-operative radiographs showed proper fracture and hardware alignment. There was subsequently radiographic evidence of callus formation at one year with subsequent fracture consolidation and resolution of thigh pain at eighteen months.

conclusionThe risk of fracture nonunion caused by intramedullary bone pedestal formation can be mitigated with the use of maximum length and diameter nails and close follow up.