The incidence of periprosthetic fractures of distal femur (PPDFFx) after primary total knee arthroplasties is described around 0.3% and 2.5% and it is increasing as the number of patients with total knee arthroplasty continues to arise. surgical options treatments for PPDFFx include fixation in the form of eather Open reduction and internal fixation (ORIF), or retrograde intramedullary nailing (RIMN), or conventional (non locked) plating, or locked plating such as the Less Invasive Stabilization System (LISS), or dynamic condylar screws. In recent years, however, the use of megaprostheses has been increasing. Patients with periprosthetic fractures of distal femur after primary total knee arthroplasties treated with ORIF or with the use of Distal femur replacement (DFR) were retrospectively analyzed in this to evaluate differences in intra-operative blood loss, need of blood trasfusion, weight bearing, range of motion, rate of complications, rate of revision surgery and functional outcome according Oxford Knee Score between two groups. Treatment of Periprosthetic distal femur fracture remains controversial. While ORIF seems to guarantee less percentage of complications and reoperation rate, those treated with megaprosthesis seem to gain better range of motion in a very short post-operative time. In the future it will be necessary to investigate with greater numbers possible advantages and disadvantages of the various treatments in periprosthetic distal femur fractures.