Review Question - QID 9023

From the following options, a short working length of the construct is a known risk factor for femoral plate failure.

Implant failure is common in distal femur fractures stabilized with plate fixation. Contributors to failure include a short working length of the construct, plate-screw density more than 0.5 and short plate lengths. This will lead to failure as it causes increased strain on the plate over a short segment, and does not allow enough motion at the fracture site to form bone for healing by secondary intention.

Ricci et al. reviewed 355 cases of distal femur plate fixation. 64 patients (19%) required reoperation to promote union, including 30 that had a planned staged bone grafting. Risk factors for proximal implant failure included open fracture, smoking, increased body mass index, and shorter plate length.

Kregor et al. reviewed 119 patients with distal femoral plate fixation. They found that 93% fractures healed without acute bone grafting. Complications included 5 losses of proximal fixation, 2 nonunions, and 3 acute infections.

Illustration A is an AP of the distal femur demonstrating a comminuted distal femur fracture which has failed fixation with a laterally based distal femur locking plate. It has undergone varus collapse which is a common mechanism of failure for these injuries. Illustration B is a series of AP radiographs of the distal femur of the same patient that was revised to an intramedullary retrograde nail. Illustration C and D show the concepts of plate length, plate-to-screw density and the working length of the plate.

Incorrect Answers:
Answer 1: Early postoperative knee range of motion has not been associated with failure of this construct.
Answer 2: Early weight-bearing can put too much force across the plate, causing fatigue failure of the plate.
Answer 4: Bridge plate fixation would have been the proper technique to use in this situation.
Answer 5: Plate-screw density less than 0.5 would have been the proper technique to use in this situation. This would have helped to avoid this complication.