A design framework for additively manufactured Ti-6Al-4V cervical corpectomy cage combining standardized topology-optimized core and customized lattice interfaces

Additive manufacturing (AM) enables the integration of topology-optimized load-bearing architectures with lattice-based contact surfaces, offering new opportunities to tailor the mechanical performance of metallic spinal implants. In this study, a Ti-6Al-4V AM cervical corpectomy fusion (PCCF) cage with a weighted topology-optimized core and customized lattice contact surfaces was developed. Finite element analysis and topology optimization under triaxial physiological loading conditions were employed to define the optimal material distribution, resulting in a load-bearing outer shell with a lightweight, hollow interior suitable for bone grafting. The superior and inferior contact surfaces were reconstructed from patient CT data and integrated with a bionic lattice to promote osseointegration. Experimental validation was performed using static compression, fatigue, and subsidence tests in accordance with ASTM F2077-22 and ASTM F2267-22, benchmarked against ISO 23089-2. The PCCF cage exhibited an axial stiffness of 7397.93 ± 142.62 N/mm and a yield load of 8250.79 ± 281.92 N, exceeding ISO reference values, and withstood 5,000,000 cycles of axial (1582 N) and torsional (1.0 N·m) loading without structural failure. Subsidence testing yielded a stiffness (Kp) of 476.06 ± 52.97 N/mm, approximately 1.85 times higher than the ISO benchmark, indicating improved load distribution at the bone–implant interface. In vitro cell viability testing further showed higher metabolic activity on the lattice surface than on a solid surface. The proposed design framework was demonstrated using a customized C3–C6 PCCF cage as a representative case study, highlighting the potential of AM as a design-enabling approach for mechanically robust and subsidence-resistant spinal implants.