Background: The mechanical properties of alumina ceramic, now in its
third generation, have been markedly improved through the evolution of design
features and manufacturing processes and the introduction of proof-testing.
Nonetheless, because of the lack of ductility of alumina ceramic, there is
concern regarding the risk of fracture during insertion or in vivo use. The
purpose of the present study was to present a multicenter review of primary
total hip arthroplasties performed with use of a polyethylene-ceramic
composite liner combined with a ceramic femoral head, with particular
attention to failure of the ceramic bearing.
Methods: We evaluated 357 primary total hip arthroplasties that had
been performed in 319 patients with use of a contemporary alumina-on-alumina
bearing design incorporating a polyethylene-ceramic composite liner within a
titanium-alloy shell coupled with a 28-mm-diameter ceramic femoral head. The
procedures were performed at four participating centers from 1998 to 2001.
Ceramic failure without trauma occurred in six hips (1.7%). All of these hips
were revised, and the retrieved alumina implants were examined by means of
visual inspection and scanning electron microscopy equipped with
energy-dispersive x-ray spectrometry.
Results: Two femoral heads fractured during the first postoperative
year, and four alumina liners fractured after an average of 36.8 months in
vivo. All four of the explanted alumina liners revealed evidence of rim
contact with the metal neck of the femoral component. Composition analysis
confirmed that surface-stain materials were titanium particles transferred
from the femoral component.
Conclusions: Despite the theoretical improvement in the fracture
toughness of a polyethylene-alumina composite liner, a relatively high rate of
catastrophic ceramic bearing surface failure was still observed at the time of
short-term follow-up. This finding prompted us to discontinue the use of this
type of alumina bearing design.
Level of Evidence: Therapeutic Level IV. See Instructions
to Authors for a complete description of levels of evidence.