Optimizing implant lattice design for large distal femur defects: Stimulating interface bone growth to enhance osseointegration

Large bone defects in the distal femur present a significant challenge due to the lack of inherent self-healing capabilities. Traditional approaches, such as utilizing polymethyl methacrylate (PMMA) in conjunction with a plate for distal femur reconstruction, have shown unsatisfactory osseointegration outcome, which leads to complications. To address this challenge, this study focuses on developing a lattice-structured implant for reconstructing distal femoral bone defects. The lattice geometry is based on the cuboctahedron lattice, with its design optimized through the adjustment of pillar diameter and arrangement angle. The lattice structure is designed to stimulate the surrounding bone, ultimately enhancing osseointegration in distal femur reconstruction. Finite element analysis revealed that for promoting bone ingrowth toward the implant, setting the optimal lattice structure parameters, i.e., a 45° arrangement angle and a 0.8 mm pillar diameter, is required. Fabricated using state-of-the-art metal three-dimensional printing, the implant underwent rigorous validation through biomechanical testing, in vitro biological assays, and animal experiments. The comprehensive results affirmed the bioactivity of the lattice-structured implant, underscoring its capability to improve osseointegration in distal femoral defect reconstruction.