Abstract
Ceramic-ceramic articulations have been in used in total hip arthroplasty (THA) since 1970. Although the problems of wear were well recognised in the early days of hip replacement, early ceramic-ceramic implants were plagued by poor design, fixation problems and component fractures. Early designs were often uncemented with no biological coating to augment fixation. Loosening of one side of the joint or the other was common-place.
Improvements in ceramic manufacturing were made and included improved purity, hot isostatic pressing and proof testing. The grain size, an indicator of toughness had dropped from 4.5 um in the 1970’s to 1.8 um in the 1990’s. Ceramic ball heads were approved in both alumina and zirconia in the late 1980’s for use on polyethylene. The hardness and toughness of ceramic pieces had now reached a new level of reliability, worthy of routine use in total hip replacements. Taper technology was also enhanced, resulting in proper load transfer to the ceramic parts. Fracture rates are estimated at 4/100 000. Stem fractures occur at a rate of 35 times higher.
Wear studies label ceramic-ceramic bearings among the lowest in debris generation, up to 200 times less than metal on conventional polyethylene. Modern alumina-alumina ceramic THAs were developed and clinical trials began under the auspices of several FDA Investigational Device Exemptions (IDE). Two have been completed and await full approval from the FDA. With a much better understanding of the aspects of design coupled with successful fixation, both cemented and uncemented, ceramic components can be coupled with these implants with the potential for optimal survivorship. America, brace yourself for the next generation of THA that is truly new and improved.
The abstracts were prepared by Mrs Dorothy L. Granchi, Course Coordinator. Correspondence should be addressed to her at PMB 295, 8000 Plaza Boulevard, Mentor, Ohio 44060, USA.
