Biomechanical Behavior of Dynamic vs. Static Distal Locking Intramedullary Nails in Subtrochanteric Femur Fractures

Objective: Hip fractures are one of the most frequent fractures presenting to the emergency department and orthopedic trauma teams. The aim of this study was to determine the best indication and therapeutic technique for subtrochanteric fractures and unifying criteria when choosing the most suitable type of nail. Materials and methods: To analyze the influence of the material and the type of distal locking of intramedullary nails (static or dynamic), a femur model with a fracture in the subtrochanteric region stabilized with a long Gamma intramedullary nail was applied using finite element method (FEM) simulation. Results: The mechanical study shows that titanium nails allow for greater micromobility at the fracture site, which could act as a stimulus for the formation of callus and consolidation of the fracture. In the mechanical study, the type of distal locking mainly affects mobility at the fracture site and stress in the cortical bone around the distal screws, without in any case exceeding values that may compromise the viability of the assembly or that may result in detrimental effects (in terms of mobility at the fracture site) for the consolidation process. Conclusion: Subtrochanteric fractures treated with titanium nail and static distal locking is safe and does not hinder consolidation.