The Effect of Prophylactic Femoral Neck Fixation in a Synthetic Osteoporosis Bone Model

Introduction: Intramedullary nailing is a popular treatment option for elderly patients with femoral shaft fractures. Recently, prophylactic neck fixation has been increasingly used to prevent proximal femoral fractures during intramedullary nailing. Osteoporosis is a risk factor for late hip fractures. Therefore, this study aims to investigate the biomechanical strength of prophylactic neck fixation for osteoporotic femoral fractures.Methods: An osteoporotic femur model was created to simulate the union of femoral shaft fractures with intramedullary nailing. Two study groups comprising six specimens were created for intramedullary nailing with two standard proximal locking screws (SN group) and intramedullary nailing with two reconstruction proximal locking screws (RN group). Axial loading was conducted to measure the stiffness, load to failure, and failure modes.Results: There were no statistically significant differences in stiffness between the two groups. However, the load to failure in the RN group was significantly higher than that in the SN group (p < 0.05). In the failure mode, femoral neck fractures occurred in all specimens in the SN group. Five constructs in the RN group showed a subtrochanteric fracture without femoral neck fractures. However, one construct was observed in both the subtrochanteric and femoral neck fractures.Conclusion: In the osteoporotic femoral model with intramedullary nail fixation, reconstruction screw fixation significantly increased load to failure and prevented femoral neck fractures under the axial compression test. Therefore, prophylactic neck fixation can be considered an alternative biomechanical solution for preventing proximal femoral fractures when performing intramedullary nail fixation in an osteoporotic femoral fracture.