Dual reinforcement of PEKK composites with hydroxyapatite and silicon nitride nanowires for enhanced mechanical, tribological, antibacterial, and osteogenic performance

Polyetherketoneketone (PEKK) has attracted interest for load-bearing orthopedic implants due to its favorable elastic modulus and radiolucency; however, its biological inertness and weak interfacial bonding limit its clinical application. Here, we developed a dual-reinforced PEKK composite by incorporating hydroxyapatite (HA) particles and silicon nitride (SN) nanowires to improve its mechanical, tribological, antibacterial, and osteogenic properties. The ternary PEKK/HA/SN composite (PSH) exhibited tensile, compressive, and flexural strengths of 112.23, 241.36, and 201.48 MPa, increased from 23.04, 92.34, and 60.23 MPa for pure PEKK, respectively. Under dry sliding conditions, PSH showed a friction coefficient of 0.34 and a wear rate of 0.69 × 10$^{−5}$ mm$^3$/N·m, corresponding to reductions of 30.6% and 24.2% compared to PEKK, respectively. In bovine serum, the friction coefficient and wear rate further decreased to 0.23 and 0.63 × 10$^{−5}$ mm$^3$/N·m, with reductions of 45.2% and 25.9%, respectively. Furthermore, PSH exhibited antibacterial activity, with inhibition rates of 66.81% against E. coli and 75.25% against S. aureus, and reduced S. ... mehraureus biofilm biomass to 48.77 ± 6.51% of pristine PEKK. Biological assays showed improved osteoblast proliferation, osteogenic differentiation, and peri-implant bone formation in vivo. These findings suggest that the combined incorporation of HA and SN nanowires may provide a feasible strategy for improving the mechanical strength, tribological stability, antibacterial activity, and osteogenic performance of PEKK-based composites.