Submicron ultrahigh-molecular-weight polyethylene (UHMWPE) wear particles from total joint prostheses may contribute to implant failure through particle-mediated aseptic loosening. The purpose of this study was to examine the microstructure of virgin UHMWPE powder to determine its morphology for future comparison with wear debris. A new method of low-voltage scanning electron microscopy (LVSEM) in an oil-free vacuum was applied, which produced high-resolution images of UHMWPE micromorphology, while minimizing specimen damage and obviating the need for image processing. GUR 415 UHMWPE virgin powder particles were examined by using routine high-voltage SEM, LVSEM, and image analyses. LVSEM showed that UHMWPE particles were composed of submicron-size spherical subparticles connected by numerous nanometer-size fibrils. These spherical subparticles had a highly textured surface morphology seen only by LVSEM. Fracture of the nanometer-size fibrils was observed. Routine high-voltage SEM obfuscates the intricate and delicate UHMWPE micromorphology as well as the damage done by the accompanying high-voltage electrons. This study suggests that the micromorphology of wear particles previously studied with routine high-voltage SEM was overlooked or damaged, justifies the need for LVSEM in future studies, and raises the question of what is the true morphology of polyethylene wear debris retrieved from human tissues.
Morphological similarities between virgin ultra-high-molecular-weight polyethylene (UHMWPE) powder and debris retrieved from failed UHMWPE total joint implants motivated this study's objective: to establish the internal microstructural features of consolidated UHMWPE. Cylindrical specimens were cored from a gamma-irradiation-sterilized tibial component (extruded from GUR 415 resin), and then these specimens were freeze-fractured at high strain rates. Low-voltage scanning electron microscopy was used to examine these surfaces. Two types of areas were observed. The first were uniform, homogeneous, and continuous with microridge structures (45-70 nm wide) and hillocks (0.1-0.3 microns in diameter). The second was nonhomogeneous and discontinuous with febrils (10-200 nm long), microridges, fenestra as small as 20 nm, and large crater-like structures (6-12 microns in diameter). Many of the submicronsized structures observed were similar to the structures observed in virgin powder, as well as those observed by others from wear debris retrieval studies. These data support the hypotheses that wear debris originates, in part, from structures originally present in the powder resin, and that these structures retain their identity throughout consolidation, machining, and in vivo wear, and are released into periprosthetic tissues as wear debris.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.