Histological Investigation of Polyethylene Particles in Total Hip Replacement: Ceramic versus Metal Heads

Pseudocapsules and interface membranes around hip prostheses with ceramicand metal polyethylene combinations from 128 revision cases and 40 autopsy cases were histomorphologically analysed, including a semiquantitative grading of the wear particles and histological changes. The amount of wear particles increased with increasing implant duration.

Comparing the revision cases with metal-on-polyethylene combinations and ceramic-on polyethylene combinations 4 to 8 years in situ, more than twice as many polyethylene wear particles were produced from prostheses with metallic heads. In the autopsy cases with stable prostheses 3 times more polyethylene wear was found. The synovial layer was found to be thicker in the metal-polyethylene couplings, the villous transformation of the synovial surface and the scar-like fibrosis of the pseudocapsules appeared to be more pronounced too. Differences between the different types of prostheses with metal-polyethylene combinations were not apparent with the exception of the bipolar prostheses, which showed markedly increased polyethylene wear.