Plasma immersion ion‐implanted 3D‐printed PEEK bone implants: In vivo sheep study shows strong osseointegration

Adhesion of regenerating bone tissue to orthopaedic implants is critical to their long-term success. Titanium has excess rigidity, interferes with imaging, and complicates radiation treatment. Poly(ether-ether-ketone) (PEEK) is a preferred material, but is limited by biological inertness. We show that plasma immersion ion implantation (PIII) imparts osteoadhesion on 3D printed PEEK using in vitro pull-off tests and in vivo torque tests in a sheep scapula model. PIII-PEEK prints incubated with bone cells in vitro show 9-14 times higher pull-off strength, compared to untreated implants. Treated implants in vivo require seven times higher torque for release from the sheep scapula. We propose PIII-PEEK as a scaffold material with tensile properties analogous to collagen, the fibrillar component of bone, to produce fracture-tough fully integrating scaffolds.