Results of polyaxial locked-plate fixation of periarticular fractures of the knee

Background: Locked-plate fracture-fixation techniques and designs continue to evolve. Polyaxial locking plates that allow screw angulation and end-point locking have become available; however, there are no clinical data documenting their strength and efficacy, to our knowledge. The purpose of this study was to evaluate the clinical performance of a variable-axis locking plate in a multicenter series of periarticular fractures about the knee. Methods: Between 2003 and 2005, fifty-four patients with a total of fifty-six fractures were treated with a polyaxial locked-plate fixation system (DePuy, Warsaw, Indiana). There were twenty male patients and thirty-four female patients with a mean age of fifty-seven years. There were twenty-five distal femoral fractures and thirty-one proximal tibial fractures. Twelve of the fractures were open. Clinical and radiographic data, including changes in alignment, hardware breakage, or other mechanical complications of the device, were retrospectively reviewed. Function was assessed with use of the Knee Society scores. One patient with a bilateral fracture died less than three months postoperatively, and two patients were lost to follow-up prior to union. Fifty-two fractures in fifty-one patients were followed to union or for a minimum of six months; the mean duration of follow-up was nine months (range, six to twenty-five months). Results: Forty-nine (94%) of the fifty-two fractures united. There were no mechanical complications. Most importantly, there was no evidence of varus collapse as a result of polyaxial screw failure. There were three deep infections and one aseptic nonunion. No plate fractured, and no screw cut out. Conclusions: The variable-axis locking plates performed well, with a high rate of fracture union and no evidence of varus collapse due to failure of the polyaxial screw fixation, in a series of complex fractures about the knee. Complication rates were similar to those for historical controls treated with fixed-trajectory locking plates. Polyaxial locking plates offer more fixation versatility without an apparent increase in mechanical complications or loss of reduction. Level of Evidence: Therapeutic Level IV.