Finite Element Analysis of Lateral Plate, Intramedullary Nail, and Nail-Plate Combination Techniques in Osteoporotic Distal Femur Fractures

Introduction Osteoporotic distal femur fractures are known for their high mechanical complication rates. In our study, using finite element analysis in the osteoporotic distal femur fracture model; under two different loads; It was aimed to investigate the fracture reduction displacement amount and directions, the amount of stress on the implant and implant fatigue analysis of lateral plate, intramedullary nail and nail plate combination fixation models. Method: The 3D femur model was drawn by us with the Materialize Mimics Medical 21.0® (Materialise, Leuven, Belgium) program. 3D drawings of intramedullary nails, lateral plates and implant screws were made by us with the Dassault Systèmes Solidworks 2021 SP4.1® program. Three different groups were created by combining the planned fracture model, modeled lateral plate, intramedullary nail and nail plate combination methods. Then, the deformation amounts, stress analyzes and fatigue analysis of the models were examined under 2 different loading conditions. Total deformation; defined as the sum of displacement amounts experienced by a model under loading. Stress on implants was examined, and breaking in the implant under cyclic loading was defined as failure. Results: In the compression analysis, the total deformation amount of the nail model was max: 101.1 mm; lateral plate max:110.4 mm; the maximum in nail and plate combination was 50.3 mm. After loading, the maximum stress on the implants was 1132 MPa in the nail fixation model, 1278 MPa in the lateral plate model, 671 MPa in the nail system and 595 MPa in the plate system in the nail-plate combination model. In the fatigue analysis, failure was observed after 7725 cycles in the model created with the nail, while failure was observed after 2473 cycles in the lateral plate and 1023200 cycles in the nail-plate combination. Discussion: Nail-plate combinations seem promising in terms of mechanical complications in osteoporotic fractures of the distal femur. Finite element analysis is a widely accepted tool that is increasingly used in many industries. Among the tested models, the nail-plate combination showed higher cyclic strength and less displacement in fracture fragments under loading compared to the nail-only or plate-only model, which seems to support other clinical studies. Conclusion: The nail-plate combination for osteoporotic fractures of the distal femur may reduce mechanical complications through longer cycle strength, reduced stress on the implant, and less movement between fracture fragments. Randomized controlled clinical studies will better evaluate these hypotheses.