Characterization of De Novo Bone Microarchitectural Maturation During Osseointegration of Polyetheretherketone Implants Interface

ABSTRACT Polyetheretherketone (PEEK) has emerged as a promising orthopedic implant material due to its mechanical properties and biocompatibility, yet successful clinical outcomes depend critically on achieving robust osseointegration. However, the fundamental mechanisms governing microstructural evolution of de novo bone during PEEK osseointegration and the characteristic features of the bone‐implant interface microarchitecture remain poorly understood. We employed a standardized rat femoral defect model with multi‐scale analytical modalities to examine the osseointegration process of PEEK implants at 4 and 8 weeks post‐implantation, utilizing ultrastructural examination techniques to assess bone formation, cellular phenotypes, and mineralization patterns. Our investigation revealed a distinctive biphasic pattern of bone formation characterized by the initial formation of disorganized woven bone with stochastic collagen orientation at 4 weeks, followed by architectural metamorphosis toward a highly orchestrated lamellar configuration with parallel fibrillar arrays at 8 weeks, with cellular constituents transitioning from metabolically active osteoblasts with elaborate intercellular networks to quiescent, mechanosensitive phenotypes, while mineralization progressed from amorphous aggregates to directionally aligned forms during the observation period. These findings demonstrate that PEEK osseointegration follows a time‐dependent microstructural evolution pattern characterized by the progressive organization of both cellular and extracellular matrix components, providing critical mechanistic insights into PEEK osseointegration processes and establishing a framework for developing biomimetic modification strategies.