A biomechanical investigation of a novel intramedullary nail used to salvage failed internal fixations in intertrochanteric fractures

Purpose The ideal approach for revision surgery following femoral head salvage treatments for an intertrochanteric fracture is still up for debate. A novel variety of proximal femoral bionic intramedullary nail (PFBN) has been created in clinical practice. We aimed to compare the biomechanical results of the novel implant to conventional intramedullary and extramedullary fixation in the treatment of intertrochanteric fracture following primary internal fixation failure.Methods Using finite element analysis, we created a three-dimensional model of the intertrochanteric fracture's helical blade cut-out for this investigation. The PFBN 1 group, the PFBN 2 group, the PFNA group, and the DHS group were our four test groups. For each fracture group, the von Mises stress and displacements of the femur and internal fixation components were measured under 2100 N axial loads.Results The values for the femoral displacement in the PFBN1 group, PFBN2 group, PFNA group, and DHS group were 6.802 mm, 6.716 mm, 8.080 mm, and 8.679 mm, respectively. The internal implant displacement values were 6.201 mm, 6.138 mm, 7.396 mm, and 8.075 mm in the PFBN1 group, PFBN2 group, PFNA group, and DHS group, respectively. The maximum von Mises Stress in the femoral was 187.2 MPa, 85.18 MPa, 106.6 MPa, and 386.2 MPa in the PFBN1 groups, PFBN2 groups, PFNA groups, and DHS groups, respectively. In the PFBN1 groups, PFBN2 groups, PFNA groups, and DHS groups, the maximum von Mises Stress in internal fixation was 586.7 MPa, 559.8 MPa, 370.7 MPa, and 928.4.8 MPa, respectively.Conclusion Our biomechanical research demonstrates that intramedullary fixation is more stable than extramedullary fixation when salvaging failed internal fixations in intertrochanteric fracture. Compared with PFNA and DHS, PFBN showed better biomechanical stability in the treatment of patients with revised intertrochanteric fractures. In light of this, we advocate PFBN fixation as the method of choice for intertrochanteric fracture revision. This result still has to be confirmed in more clinical research.