A Preclinical Approach to 3D-Printed Osseointegration Prosthesis: Improving Functional Outcomes and Reducing Complications in Residual Limb Reconstruction.

This study presented a novel additively manufactured osseointegration prosthesis (OIP) for patients with amputation residual limb functional reconstruction, elaborating its design concept, conducting finite element mechanical analysis, and evaluating efficacy via animal models to provide a clinical theoretical basis. Our designed OIP system were categorized into four types: Type I (solely intramedullary press-fit fixation) and Type II (combined intramedullary press-fit-extramedullary sleeve fixation); Type a (no auxiliary anti-rotation screws) and Type b (with such screws). The cloverleaf sleeve's inner wall and intramedullary stem surface featured 3D-printed metal porous structures. Finite element models were established using adult femoral CT data to simulate stress/displacement under 15,000/20,000 N*mm torque and 600/900 N vertical stress. A mid-femoral amputation model was constructed in Small-tailed Han sheep (n = 3), with Type IIa OIP press fitted after intramedullary cavity reaming and cortical decortication, evaluating functional reconstruction, biocompatibility, and osseointegration. Finite element analysis yielded stress peaks, maximum displacement, and distribution contour plots. Results showed cloverleaf sleeve-equipped prostheses had lower stress peaks under high vertical stress, more dispersed stress distribution, and superior displacement resistance. Animal model data demonstrated stable fixation, no obvious infection, and favorable prosthesis-femur osseointegration. This newly designed OIP possesses good biocompatibility and osseointegration capacity and the extramedullary cloverleaf sleeve enhances mechanical properties, laying a theoretical foundation for future clinical application.