Are Modern Bearings Changing the Reasons for Revision in Total Hip Arthroplasty?

During the last decades modern technology dramatically changed in total hip replacement (THR). After the promising results for low-friction arthroplasty developed by Sir John Charnley, wear and loosening were found at a long-term particularly in young patients. Uncemented fixation did not solve the problem of wear and osteolysis around THR, so researchers focused their research on bearing surfaces. Firstly, ceramic-on-ceramic couple was introduced due to their excellent characteristics in terms of tribology, wettability and biocompatibility. Last generation ceramics, both pure alumina and alumina matrix composite, improved strength and versatility. Nowadays, most surgeons use ceramic heads worldwide as first option in THR. More than 1,000 ceramic-on-ceramic THR have been implanted at our institution during the last 25 years showing encouraging results. Secondly, laboratory assays demonstrated that highly cross-linked polyethylene (HXLPE) liners decreased wear comparing to conventional polyethylene. After randomised controlled trials confirmed extremely early low-wear rates, HXLPE replaced old polyethylene worldwide due to their excellent clinical results at a medium- and long-term. We confirmed this excellent performance in a comparative study at a minimum follow-up of 20 years. Although modern bearing surfaces seem to solve the problem of wear and osteolysis at a long-term, there are other concerns in THR. Large femoral heads may result in problems of corrosion of the femoral neck, HXLPE and ceramic ruptures can occur, and modular components may result in adverse reactions. At our institution, surgeons did not use a modular stem or femoral heads larger than 36 mm. Clinical studies are essential to confirm the evolution of modern THR. Lastly, periprosthetic infection, dislocation and periprosthetic fractures are gaining importance as reasons for revision in THR.