LOW-VOLTAGE SCANNING ELECTRON-MICROSCOPIC IMAGING OF ULTRAHIGH-MOLECULAR-WEIGHT POLYETHYLENE

Submicron ultrahigh-molecular-weight polyethylene (UHMWPE) wear partic les from total joint prostheses may contribute to implant failure thro ugh particle-mediated aseptic loosening. The purpose of this study was to examine the microstructure of virgin UHMWPE powder to determine it s morphology for future comparison with wear debris. A new method of l ow-voltage scanning electron microscopy (LVSEM) in an oil-free vacuum was applied, which produced high-resolution images of UHMWPE micromorp hology, while minimizing specimen damage and obviating the need for im age processing. GUR 415 UHMWPE virgin powder particles were examined b y using routine high-voltage SEM, LVSEM, and image analyses. LVSEM sho wed that UHMWPE particles were composed of submicron-size spherical su bparticles connected by numerous nanometer-size fibrils. These spheric al subparticles had a highly textured surface morphology seen only by LVSEM. Fracture of the nanometer-size fibrils was observed. Routine hi gh-voltage SEM obfuscates the intricate and delicate UHMWPE micromorph ology as well as the damage done by the accompanying high-voltage elec trons. This study suggests that the micromorphology of wear particles previously studied with routine high-voltage SEM was overlooked or dam aged, justifies the need for LVSEM in future studies, and raises the q uestion of what is the true morphology of polyethylene wear debris ret rieved from human tissues. (C) 1995 John Wiley & Sons, Inc.