Contamination of surfaces for osseointegration of cementless total hip implants by small aluminium oxide particles: analysis of established implants by use of a new technique.

Background: The failure of total hip replacements because of wear, particle-induced osteolysis, and aseptic loosening has focussed interest on factors potentially affecting the rate of wear. In this context the effect of particle release from the bone-implant interface of cementless implants is poorly understood. The surface structure for bony ongrowth of many cementless implants is created by grit-blasting. Remnants from this process (Al2O3 particles) on these surfaces have been reported; these remnants have the potential to cause third-body wear.

Methods: We report a novel technique for isolation and quantification of alumina particle contamination. Stems from different manufacturers were electrochemically activated and etched to isolate the alumina residues. After filtration the particles were characterised by scanning electron microscopy and energy-dispersive X-ray analysis.

Results: Many Al2O3 particles were found on all the implants tested. A mean of 426,814 particles per mm(2) was measured. Particle size distribution ranged from 0.125 to 66.304 μm with a peak in the range 0.25-1 μm.

Conclusions: Our main finding was a large amount of small Al2O3 particles on all blasted surfaces. On the basis of our results these alumina particle remnants cannot be excluded as a factor causing increased third-body wear.