Similar Wear in Total Hip Arthroplasties with Metallic or Zirconia Femoral Heads

Abstract

Ceramic femoral heads have been used in an attempt at reducing polyethylene wear of total hip arthroplasties. Clinical results with zirconia femoral heads have been mixed. This study was undertaken to compare the polyethylene wear and incidence of periprosthetic osteolysis in total hip replacements performed using a 28-mm zirconia versus a 28-mm cobalt chromium femoral head. Thirty-five hips with a 28-mm cobalt chromium head and 68 hips with a 28-mm zirconia head were evaluated after a minimum follow-up of 2 years (average, 4.0 years; range, 2.0 to 9.1 years). A monoblock acetabular component was used in all patients. Polyethylene wear was measured in serial radiographs from 58 of the hips utilizing a computerassisted vector wear technique. Periacetabular osteolysis developed in three patients (two with a zirconia head and one with a cobalt chromium head). The total wear and the annual wear rate were 0.48 mm and 0.11 mm/year for the cobalt chromium heads and 0.53 mm and 0.14 mm/year for the zirconia heads, respectively. We found no benefit with respect to the rate of polyethylene wear or incidence of osteolysis with the use of zirconia femoral heads.

Clinical Comparison of Polyethylene Wear with Zirconia or Cobalt-Chromium Femoral Heads

“…For the Zr-on-PE bearing, this mechanism is well established as a partial tetragonal to monoclinic phase transformation resulting from in vivo physiologic mechanical and hydrothermal stresses [19,21], which increase Zr surface roughening and grain pullout and provide the potential for accelerated PE wear. This theory explains why Zr-on-PE in our study and other studies [7,17,23] has a similar wear performance as CoCr-on-PE at midterm followup. Also, the continuous deterioration of Zr in vivo [21] explains the report of progressive wear with Zron-PE bearing couples from midterm to a minimum of 10 years' followup as described by Hernigou and Bahrami [17], and reduced survival of Zr-on-PE bearing couples (63%) at midterm (5.8 years') followup compared with an historical control group of identical implants with a 93% 9-year survival described by Allain et al [1].…”

In vivo and in vitro outcomes of alumina, zirconia and their composited ceramic-on-ceramic hip joints

“…46) In an in vivo study, Clark et al had found that Alumina liners wore at steady-state phase of 0.004 mm 3 per million cycles; 5000 times less wear rate compared to metal-on-polyethylene bearing couple. 49) This results were comparable after Cohn et al 50) run in vitro experiment. They found that Alumina CoC bearings produce 0.2 billion wear particles/year, which was 3000 times (0.6 trillion wear particles/ year) lesser wear rate than metal-on-polyethylene bearings, and the wear debris of the ceramics were small.…”

“…Laboratory wear studies of zirconia-on-zirconia articulation have been uneven. Recently, in a study to compare the polyethylene wear and prevalence of periprosthetic osteolysis in THRs performed using a 28-mm Zirconia against a 28-mm Cobalt Chromium femoral ball head, Cohn et al 50) found that the wear rate were 0.11 mm/ year for the cobalt chromium and 0.14 mm/year in Zirconia femoral ball heads. They concluded that there was no different in wear rates in THRs between the metal and zirconia femoral ball heads which contradict the purpose of the ceramic itself.…”

In vivo wear performance of highly cross-linked polyethylene vs. yttria stabilized zirconia and alumina stabilized zirconia at a mean seven-year follow-up

“…However, with Y-TZP, the potential exists for late phase transformation and aging, resulting in grain pullout, surface cracking, and increasing surface roughness [8]. In one study of 52 retrieved Y-TZP heads, the monoclinic content within the bearing surface averaged 40% compared with 3% in nonimplanted heads [8,9]. The tetragonal to monoclinic phase transformation of zirconia can be suppressed by the addition of a small amount of aluminum oxide (Al 2 O 3 ).…”