A review on plasma sprayed titanium and hydroxyapatite coatings on polyetheretherketone implants

Polyetheretherketone (PEEK) is a biocompatible polymer with good mechanical strength, thermal and chemical stability and is suitable for magnetic resonance and X-ray imaging. Moreover, density and elasticity of PEEK is closer to bones compared to metals. Nevertheless, the hydrophobicity of the PEEK surface causes a soft tissue formation at the bone/implant interface that prevents direct bone apposition. Although numerous methods have been developed for improving PEEK's bioactivity, the most widely used and accepted method have been coating the surface with a thin layer of osseointegrative material by thermal spraying. Most widely used coating materials in the manufacture of orthopaedic implants have been hydroxyapatite (HAp) and titanium. Thus, this review focuses on the recent progress on HAp and Ti coatings deposited by plasma spraying methods on PEEK implants.