Isoelastic Polyaryletheretherketone Implants for Total Joint Replacement

Abstract

PEEK biomaterials in orthopedics are currently in a period of consideration and conservative adoption. The traditional metal, ceramic, and polymer implants currently used for total hip and knee replacement are perceived by many surgeons and patients as reasonably successful, with survival rates in the elderly population exceeding 90% at 10 years. The clinical needs for the orthopedic community, therefore, have been focused on extending the longevity of existing implants for the elderly patient population, as well as on expanding the clinical success of total joint replacements to younger and more active patients. In orthopedics, novel implant technologies need to demonstrate sustained, long-term improved performance relative to historical alternatives. Animal studies and clinical data have been accumulated to demonstrate the viability of composite stems incorporating PEEK biomaterials as an alternative to monolithic metal alloys in hip stems. Other novel designs of PEEK implants are still in the early stages of clinical evaluation. PEEK and CFR-PEEK composites are now established as sufficiently versatile and durable for isoelastic orthopedic implants. The design ideal of isoelastic femoral stems shows clinical evidence of reasonably sustained fixation and reduced stress shielding when compared with traditional metallic stems. Of the variety of polymers that have been evaluated for composite hip stems over the past 40 years, only PEEK has demonstrated the requisite combination of mechanical properties, biocompatibility, manufacturability, and consistent availability throughout this time period.