Three-dimensional-printed porous titanium scaffolds outperform biphasic calcium phosphate ceramics for load-bearing critical-sized bone defect repair

Repairing critical-sized, load-bearing bone defects remains a formidable clinical challenge, primarily due to the mechanical fragility of traditional bioceramics. This study systematically compared the bone regenerative efficacy of surface-microstructured three-dimensional (3D)-printed porous titanium (3D-SMPT) and reinforced biphasic calcium phosphate (RBCP) ceramics. In vitro evaluations demonstrated that a biomimetic coating effectively overcame titanium’s bioinertness, thereby endowing 3D-SMPT with excellent biocompatibility and osteoinductivity comparable to those of RBCP. In vivo cross-species assessments revealed significant biomechanical differences: in a low-load rabbit ulnar model, both scaffolds exhibited equivalent osteogenesis. However, in a true weight-bearing beagle femoral model, RBCP suffered severe structural collapse due to inherent brittleness. In stark contrast, leveraging its cortical bone-matched compressive strength (83.14 MPa, approximately 10-fold higher than that of RBCP at 7.68 MPa) and interconnected porosity, 3D-SMPT maintained long-term mechanical stability, effectively mitigating stress shielding to facilitate massive mature bone ingrowth and robust osseointegration. In conclusion, 3D-SMPT achieves a perfect integration of bioactivity and load-bearing stability, overcoming the inherent fragility of traditional ceramics and offering a highly promising clinical alternative for the repair of massive load-bearing bone defects.