Application of Polyetheretherketone in the Orthopedic Implants

Polyetheretherketone (PEEK) has been demonstrated to have superior mechanical properties, wear resistance, chemical resistance, and good biocompatibility. Moreover, its elastic modulus is comparable to human bone, and PEEK has excellent radiolucency, is easy to be processed and can be repeatedlysterilized. These outstanding features make PEEK a promising bone-implant material. PEEK now is one of potential candidates for replacing the conventional implant materials including stainless steel, titanium alloys, ultra high molecular weight polyethylene and even biodegradable materials in orthopedic implant applications. However, the bioinertness of PEEK limit its clinical application. To obtain good bone-implant interfaces, quite a number of techniques have been developed to enable PEEK and PEEK-based composites from bio-inert to bioactive. Initially, the bioactive ceramics (such as hydroxyapatite, beta-tricalcium phosphate, amorphous magnesium phosphate and calcium silicate) were added into the PEEK matrix through mechanical blending methods. These fillers have been found to significantly improve the bioactivity of PEEK composites at the expense of tensile strength. At present, many efforts have been done in fabrication of ternary composite, which is simultaneously incorporating bioactive ceramics and reinforced fiber into PEEK. The PEEK-based ternary composites enhanced both biomechanical properties and bioactivity of PEEK-based composites. Moreover, introducing porosity into PEEK manufactures porous PEEK, which provides available porosity for bone ingrowth. In this paper, the changes of the biomechanical properties and bioactivity of porous-PEEK, PEEK binary composites and PEEK ternary composites are summarized. The potential clinical applications are also reviewed according to the biomechanics and bioactivity of these PEEK-based composites. It is expected that this paper should provide a theoretical basis for fabricating PEEK-based orthopedic implants with biomechanics similar to human bone, good biocompatibility and biological safety and promote the application of PEEK and PEEK-based composites in orthopedic implants.