Characterizing the Wear Particles of Intervertebral Disc Prosthesis and their Biological Response

Abstract

Prosthetic debris is the leading factor causing prosthetic loosening and requiring revision surgery. Wear debris is formed over time with any prosthesis. Factors determining disc arthroplasty survivability are similar to those for joint replacement technology, and include prosthetic wear, formation of wear debris, and tissue reaction to the wear debris. All wear debris causes a foreign-body reaction that induces an inflammatory response, which results in progressive local bone loss (osteolysis) and possible prosthetic loosening and failure. In this paper are described the nature of particle shape and surface texture, as detected on the particle profile. Detailed surface characteristics of the particles produced during fretting may well be significant in determining their biological effects. Careful processing and analysis of the digitised image enabled both the sizes of microprojections and their relative numbers to be determined. Such processing of images of a large number of particles generated a considerable amount of data. AutoCAD and MathCAD were used to establish categories the data and to compare the nature of fretting particles generated by UHMWPE and, cobalt-chromium-molybdenum. Although showing a tendency towards a spherical form, all two materials produced different results, with UHMWPE showing the greatest diversity of textures and sizes.