REVIEW OF 97 ANATOMIC CEMENTED TOTAL HIP ARTHROPLASTIES WITH A ZIRCONIA-POLYETHYLENE BEARING

Abstract

Purpose of the study: The introduction of ceramic bearings in the 1970s raised several issues, including the definition of what should be considered as a ceramic. The simplest definition would appear to refer to the periodic table: a ceramic is composed of a non-metal ion, generally with oxygen as the covalent ion. Alumina is the most commonly used bearing, and is generally considered the most reliable despite certain worrisome reports. Zirconium is also a very promising ceramic as was shown by a review of our firs 97 cases at ten years follow-up.

Material and methods: All patients were reviewed by the same investigator who was not one of the operating surgeons. The patients were classified by group according to their BLMI correlated by the Tanner curve, associated with the Charnley index and the Devane classification

Results: There were no septic complications. There was one dislocation and one head fracture. For the other patients, no revision was required nor planned. Preoper-ative Postel-Merle-d’Aubigné (PMA) score was 8.8 pre-operatively and 17.3 postoperatively. Radiographically, the Barrack, Guen, DeLee and Charnley and Brooker classifications for filling, lucent lines and periprosthetic calcifications were assessed on digitalized films with 115% magnification. Wear was measured on 250% magnification weight-bearing images two or three times more accurate than the classical Charnley Cupic, Liver-more or Ebra methods. This study found that 72% of the prostheses were free of femoral lucent lines, that 82% had no acetabular lucent line, and that wear was 0.114 mm/yr with an accuracy two or three times better than classical non-weight-bearing methods. There were no revisions for loosening and none were planned.

Discussion: These good results should be considered with caution because of the presence of one head fracture. In the event of a head fracture, use of these ceramic bearings almost always requires the use of another ceramic bearing, raising many technical, ethical, and legal problems which do not all have an adequate solution.