Unreinforced polyetheretherketone (PEEK) femoral stem: geometry refinement supported by prototype manufacturing and fatigue testing

Polyetheretherketone (PEEK) is a promising alternative to metallic biomaterials, but its mechanical performance without reinforcement remains uncertain. This study evaluated whether geometric optimization alone enables unreinforced PEEK femoral stems to satisfy ISO 7206-4:2020 mechanical requirements. Ten designs were developed and assessed using finite element analysis and a standardized runout fatigue test. Two designs met simulation criteria and completed up to 1×107 fatigue cycles experimentally without failure, plastic deformation, or thermal instability. One also showed superior anatomical compatibility. These findings suggest mechanical feasibility of pure PEEK femoral stems without reinforcement and provide preliminary evidence of survival under an ISO-based loading protocol.