The effect of additional reduction screw fixation for basicervical femoral neck fracture: a finite element analysis

PURPOSE: Using a finite element (FE) model, we aimed to validate the efficacy of our new additional reduction screw technique to basicervical femoral neck fractures. METHODS: To investigate the biomechanical effects of an additional screw in an FE model of a femoral fracture, we recorded von Mises stress distributions. The fracture was simulated along the trochanteric line, with the additional screw positioned as inferior to the femoral neck as possible without invading the cortical bone. We compared models with and without the additional reduction screw to assess differences in external stress resistance. RESULTS: In the model without the additional screw, stress was distributed along the inferior neck of the fractured femoral head fragment. With the additional screw, stress in this region decreased, leading to better stress redistribution and improved structural integrity. The peak implant stress - particularly at junctions - was lower with the additional screw. Fracture fragment displacement around the femoral head centre was 61.9 mm without the additional screw and 9.5 mm with it. CONCLUSIONS: In basicervical fractures, additional reduction screw fixation enhanced stress distribution across the bone at the fracture site - especially on the anteromedial cortex - reduced implant stress, and minimised fracture fragment movement during cephalomedullary nailing.