Structural design and multiphase biomechanical evaluation of a topology-optimized metal 3D-printed dual-compression plate for patellar fractures

Patellar fractures, especially transverse and comminuted types, often present mechanical challenges that exceed the capabilities of conventional fixation constructs. This study developed a topology-optimized metal 3D-printed dual-compression patellar plate designed to improve fragment stability while maintaining appropriate intraoperative rigidity. The plate design was first refined by original anatomically assembled thin bone plate (AATBP) through finite element (FE) analysis and topology optimization to preserve primary load-bearing paths and reduce excessive stiffness. The optimized structure was subsequently fabricated using selective laser melting (Ti-6Al-4V) and mechanically evaluated in accordance with ASTM F382 standards. Static four-point bending tests demonstrated a proof load (P) of 257.31 ± 5.40 N and structural bending stiffness (EIe) of 1.10 ± 0.01 N·m². Fatigue testing showed runout at 15%P, while failure occurred at higher load levels (25%P and 30%P), revealing two distinct modes: plate fracture at topology-optimized transition zones and locking-screw shear failure. Static tensile testing revealed that dual-compression fixation significantly (p