Finite Element Analysis of Conventional Fixation and 3D-Printed Scaffold Integration for Treating Large Osseous Femoral Defects.

This study investigated the biomechanical efficacy of conventional and 3D-printed scaffold-augmented fixation methods for a large 6 cm osseous femoral defect. Finite element analyses were conducted to compare four conventional techniques: single plate, intramedullary nail, combined plate and nail, and double plate. These were then evaluated with the addition of three porous Ti-6Al-4V scaffold designs (Weaire-Phelan, Diamond, and Voronoi) with 70% porosity. Models were subjected to peak physiological loading from gait, simulating a 106 kg patient. Performance was assessed based on implant stress and the volume fraction of the fracture callus experiencing osteogenic strains (0.005%-2.5%). Results showed that conventional single-implant methods were mechanically insufficient; the single plate failed at 20% of the physiological load and the nail at 90%. These methods also produced suboptimal osteogenic environments, with an osteogenic volume fraction < 16%. In contrast, combined conventional methods (plate and nail, double plate) withstood 100% of the load with significantly lower stresses and promoted highly osteogenic environments, with an osteogenic volume fraction > 95%. The integration of 3D-printed scaffolds transformed the single-implant constructs, enabling them to withstand 100% physiological load and increasing their osteogenic volume fraction to over 90%. Scaffolds also substantially reduced stress on the primary implants in all configurations. The plate and nail fixation augmented with a scaffold emerged as the most robust strategy, reducing conventional implant stresses to approximately 140 MPa while maintaining an exceptional osteogenic volume fraction > 99%. These findings highlight the quantitative potential of 3D-printed scaffolds to improve treatment outcomes for large bone defects.