Tribological and material analyses of retrieved alumina and zirconia ceramic heads correlated with polyethylene wear after total hip replacement

Abstract

It has been suggested that the wear of ultra-high molecular weight polyethylene (UHMWPE) in total hip replacement is substantially reduced when the femoral head is ceramic rather than metal. However, studies of alumina and zirconia ceramic femoral heads on the penetration of an UHMWPE liner in vivo have given conflicting results. The purpose of this study was to examine the surface characteristics of 30 alumina and 24 zirconia ceramic femoral heads and to identify any phase transformation in the zirconia heads. We also studied the penetration rate of alumina and zirconia heads into contemporary UHMWPE liners. The alumina heads had been implanted for a mean of 11.3 years (8.1 to 16.2) and zirconia heads for a mean of 9.8 years (7.5 to 15). The mean surface roughness values of the explanted alumina heads (Ra 40.12 nm and Rpm 578.34 nm) were similar to those for the explanted zirconia heads (Ra 36.21 nm and Rpm 607.34 nm). The mean value of the monoclinic phase of two control zirconia heads was 1% (0.8% to 1.5%) and 1.2% (0.9% to 1.3%), respectively. The mean value of the monoclinic phase of 24 explanted zirconia heads was 7.3% (1% to 26%). In the alumina group, the mean linear penetration rate of the UMWPE liner was 0.10 mm/yr (0.09 to 0.12) in hips with low Ra and Rpm values (13.22 nm and 85.91 nm, respectively). The mean linear penetration rate of the UHMWPE liner was 0.13 mm/yr (0.07 to 0.23) in hips with high Ra and Rpm values (198.72 nm and 1329 nm, respectively). This difference was significant (p = 0.041). In the zirconia head group, the mean linear penetration rate of the UHMWPE liner was 0.09 mm/yr (0.07 to 0.14) in hips with low Ra and Rpm values (12.78 nm and 92.99 nm, respectively). The mean linear penetration rate of the UHMWPE liner was 0.12 mm/yr (0.08 to 0.22) in hips with high Ra and Rpm values (199.21 nm and 1381 nm, respectively). This difference was significant (p = 0.039). The explanted zirconia heads which had a minimal phase transformation had similar surface roughness and a similar penetration rate of UHMWPE liner as the explanted alumina head.

Cementless total hip arthroplasty with ceramic-on-ceramic bearing in patients younger than 45 years with femoral-head osteonecrosis

“…Black discoloration, such as that observed on the alumina ceramic liner and head in two patients in this series, is not an uncommon finding [14,16]. Such a dark metallic stain has been previously reported as the result of There in no radiolucent line or osteolysis around the acetabular or femoral components.…”

“…Grade 3 bone loss is observed in the calcar region of both hips. b CT scanning of both hips taken 10 years after surgery reveals no evidence of osteolysis around the acetabular or femoral components metal transfer from the edge of the acetabular shell [14,16]. The transfer occurs even after relatively minor contact, and its severity is related to increased bearing-surface roughness [14,16].…”

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

“…Vigorous use of a THA may increase the risk of frictional heating and mechanical stress in the articulation [24] and lead to increased wear. 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.…”

“…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 comparison, we had no revisions at midterm.…”

Polyethylene wear analysis

“…It still unclear why some Zr heads phase transform whereas others do not (129), and the performance of individual Zr heads is impossible to predict. The strong crystalline structure of Zr also accounts for its brittleness and low fracture toughness.…”