Periprosthetic Supracondylar Femoral Fractures Above a Total Knee Replacement: An Updated Compatibility and Technique Guide for Fixation With a Retrograde Intramedullary Nail

Background: Multiple studies have described retrograde nailing as a treatment of periprosthetic supracondylar femoral fractures (OTA/ AO type 33A-C) above total knee replacements (TKRs). It is often difficult to discern which TKRs will be compatible with intramedullary nailing because the femoral component design and intercondylar distance is highly variable among total knee designs. The goal of our study is 3-fold: (1) Review and update previous work of intercondylar distances of all currently available prostheses in the United States. (2) Review retrograde nails currently on the market and associated driving end to nail shaft diameter mismatch and opening reamer sizing. (3) Review technical tricks for executing a retrograde femoral nail for the treatment of periprosthetic supracondylar femur fractures. Methods: Data for the intercondylar distance of the femoral components, diameter of retrograde nails and reamers, and notch compatibility were gathered. Results: The results were compiled and recorded. A "technical tricks" section was included that highlights reduction and fixation techniques. Conclusions: This update further empowers surgeons to use all the tools available when treating periprosthetic femur fractures and allows efficient identification of the compatibility of different TKR designs with various intramedullary nails.