Biomechanical study on different lengths of PFNA fixation for unstable intertrochanteric femoral fractures

OBJECTIVE: The aim of our study was to compare the biomechanical stability of the Proximal Femoral Nail Antirotation (PFNA) (with 200 mm, 240 mm and 280 mm-long main nails) for the management of unstable intertrochanteric femoral fractures. METHODS: Tronzo-Evans Type IV and V fractures were built by applying a three-dimensional finite element model. Further, PFNA-II with 200 mm, 240 mm and 280 mm-long main nails were applied for fixation. The above model is the creation of 3 researchers designed in order to obtain average values of numerical stress. Von Mises stress distribution and medial & lateral stress peak of the femur and PFNA were compared. RESULTS: 240 mm and 280 mm PFNA medial stress peak was reduced significantly in comparison to 200 mm PFNA (p<0.05). However, there was no difference between 240 mm and 280 mm PFN. Also, no statistical difference was observed with any of 3 lengths in both medial & lateral stress peak for Evans Type IV and V PFNA. CONCLUSION: 240 mm and 280 mm PFNA could reduce femur fixation medial stress peak. Further, they were more efficient in comparison to the 200 mm PFNA, and their biomechanical stability was similar to that of the 280 mm nail.