Exploration of mechanical properties and osseointegration capacity of porous PEEK composites containing strontium and alendronate under 3D printing: an emerging bone implant

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The aim of this study was to evaluate the biomechanical and osseointegrative properties of 3D printed porous PEEK materials loaded with strontium (Sr) and alendronate (ALN), which prepared porous cylindrical material by a fused deposition molding process, coated with Sr and ALN by hydrothermal reaction and dopamine assistance. According to the different coating materials, it could be divided into the PEEK group, PEEK-ALN group, PEEK-Sr group and PEEK-ALN-Sr group. After completing the mechanical analyses, the materials were implanted into the femoral condyles of New Zealand rabbits and the osteogenic capacity of the bracket materials was assessed by Micro-CT scanning, histology and fluorescence staining. The results showed that ALN and Sr were successfully loaded onto the surface of the material, and the elastic modulus and porosity of the material were not changed significantly after loading. The Micro-CT revealed that the PEEK-ALN-Sr group exhibited differences in bone volume/total Volume (BV/TV), trabecular spacing (TB.Sp),trabecular thickness (TB.Th)and trabeculae number (TB.N) in comparison to the PEEK group and PEEK-ALN group. And more new bone tissues could be observed in the PEEK-ALN-Sr group under 3D reconstruction of the bone proliferation model, toluidine blue and fluorescence staining. Thus, we can conclude that the 3D printed porous PEEK material has stable pore size and porosity, which has an ideal structure for bone growth. The PEEK- ALN-Sr composite material can be used as an emerging bone implant due to its excellent elastic modulus and osseointegration ability and provides a clinically viable treatment for patients with bone defects.