Treatment of periprosthetic femur fractures with the non-contact bridging plate : a new angular stable implant

OBJECTIVES: We report the application of a new fixed angle plate (NCB DF, Zimmer inc. USA, Warsaw, IN) in the treatment of periprosthetic femur fractures. The NCB DF combines conventional plating technique with polyaxial screw placement and angular stability. DESIGN: Prospective cohort study. SETTING: A single level-1 trauma center. PATIENTS: From May 2003 to December 2005, a total of 24 patients with periprosthetic femur fractures were treated. The NCB DF femur plate was used in all cases. The average follow-up period was 12 months (3-31 months). Twelve patients had a periprosthetic fracture after total knee replacement (TKA) and 12 patients after total hip replacement (THA). The mean period from primary joint replacement to periprosthetic fracture was 8.2 years for the THA group and 7.2 years for the TKA group. INTERVENTION: A combined conventional/locking surgical technique was performed in all the cases. MAIN OUTCOME MEASURES: Union, non-union, mal-union, duration of surgery, range of motion, postoperative mobility, subjective patient satisfaction and complications. RESULTS: The union rate was 90%, the mal-union rate 5% and the re-operation rate 15%. Postoperative mobility reached the preoperative level in all but for two patients. Three complications occurred relating to the implant or the procedure: one fatigue failure of the plate (non-union), one screw breakage, and one wound infection. CONCLUSIONS: The NCB DF combines conventional plating technique with polyaxial screw placement and angular stability. This combination technique shows promising results regarding union and mal-union rates in periprosthetic fractures in elderly and osteoporotic patients.