RADIOLOGIC PREDICTIVE FACTORS FOR CUT OUT FAILURE OF PROXIMAL FEMORAL NAIL ANTI-ROTATION IN TREATMENT OF INTERTROCHANTERIC FRACTURES

Abstract

Background: Proximal femoral fractures are the most common type of fracture among elderly patients. Moreover, half of the fractures are unstable types (AO31A2-A3). The aim of surgical treatments of these fractures is to achieve stable fracture fixation allowing early weight-bearing and returning to pre-fracture functional status. Even though the Tip Apex Distance (TAD) less than 25mm has been used to identify the appropriate position of the lag screw, little data has demonstrated the optimized TAD using a helical blade.Objectives: The study aimed to identify radiologic factors influencing fixation failure using a  newly designed Proximal Femoral Nail Anti-rotation (PFNA)Methods: A total o 400 cases of low energy intertrochanteric fractures undergoing PFNA fixation were reviewed. Of these, 10 cases of fixation failure were further investigated determining the exact cause. Of 390 patients with successful outcomes treated using PFNA fixation, 20 cases were randomized as a control group. A comparative study was conducted between those with fixation failure group and control group.Results: The displacement in lateral view and sum of displacement between AP and lateral view of radiographs were noted to have significant differences between the group (p=0.002 and 0.015). No significant differences were found between the groups in terms of Neck Shaft Angle (NSA) and Tip Apex Distance (TAD) including migration of the PFNA blade in the Cleveland zone. Additionally, the cutoff point was determined as less than 0.91 using the sum of the distance of displacement of AP with specificity of 95% and sensitivity of 80%. Moreover, the lateral view of the radiographs was less than 1.42 with specificity of 80% and sensitivity of 80%.Conclusion: This study demonstrated that the displacement in lateral hip view and sum of the displacement in both AP and lateral hip view were alternative parameters measured to decrease failure rate in PFNA. These parameters may be useful as an alternative to decrease the mechanical failure of PFNA fixation.