Surface modification of polyetheretherketone for boosted osseointegration: A review

The field of orthopaedic implants has experienced rapid growth in recent decades, evolving from a few obscure examples to become one of the most vibrant domains within regenerative medicine. Polyetheretherketone (PEEK) stands out as a formidable competitor in this field due to its exceptional biocompatibility and appropriate mechanical strength. However, the clinical application of PEEK is limited by its inherent biological inertness. Therefore, numerous studies have focused on overcoming the bio-inert issue of PEEK using surface activation techniques. It is necessary to delve into the intricate effects of these modifications and their corresponding methods. In this review, we provide a comprehensive summary of contemporary research on surface modification for enhancing osseointegration of PEEK implants, categorising them into four parts based on their modification methods and techniques used: (1) physical treatment, (2) wet chemical methods, (3) combination of physical and chemical treatments, and (4) bioactive coating. Finally, we outline the challenges and unmet needs that must be addressed by future designs of PEEK surfaces. Overall, altering the surface morphology and/or surface group of PEEK to obtain a rough, porous, hydrophilic, and bioactive surface, or incorporating bioactive agents/coatings with bone-forming abilities onto the surface of PEEK has shown great potential for promoting osseointegration, which can serve as a solid foundation for subsequent clinical translation.