The Effect Of Different Bearing Surfaces On Metal Ion Levels In Urine Following 28 Mm Metal-On-Metal And 28 Mm Metal-On-Polyethylene Total Hip Arthroplasty

Abstract

Background and Aims: Recent advancements in manufacturing technology have enabled more precise tolerances and surface finishes using metal-on-metal bearing surfaces in total hip arthroplasty. The aim of this study was to compare the level of metal ions in urine after implantation of a 28-mm metal-on-metal bearing manufactured from high-carbon wrought alloy and a 28-mm metal-on-polyethylene bearing.Material and Methods: A total of 92 total hip arthroplasty patients were prospectively randomized into two groups: those receiving metal-on-metal bearings and those receiving metal-on-polyethylene bearings. Chromium, cobalt, and molybdenum ion levels in urine were measured preoperatively and at 1 year and 2 years postoperatively.Results: In the metal-on-polyethylene group, there was a slight increase in mean chromium and cobalt concentrations at 2-year follow-up compared to the preoperative level (p = 0.02 for both chromium and cobalt). In the metal-on-metal group, there was a 15-fold increase in chromium and a 26-fold increase in cobalt at 2-year follow-up compared to the preoperative level (p < 0.001 for both chromium and cobalt). However, the quantity of chromium and cobalt in urine from the metal-on-metal group was not higher at 2-year follow-up than at 1-year follow-up (p = 0.5 and p = 0.6, respectively).Conclusions: The 28-mm metal-on-metal bearings yield chromium and cobalt concentrations in urine that can be higher than those recommended for occupational exposure. However, our results also indicate that a steady state in wear and ion production using metal-on-metal total hip arthroplasty can occur.

Differences in concentration of metal debris in blood, serum, and plasma samples of patients with metal-on-metal hip resurfacing arthroplasty

“…The earlier argument is supported by the presence of higher urinary cobalt than chromium in urine of patients with metal on metal hips. 11 Moreover, renal excretion capacity of cobalt has been shown to increase more than threefolds after metal-on-metal hip arthroplasty. 12 Another explanation could be removal of chromium by its binding to clotted blood, which is required for preparation of serum.…”

Wear prediction on silicon nitride bearing couple in human hip prosthesis using finite element concepts

“…The metal ion Cr released from the patient's body showed increase in concentration prior to post-operative conditions. 1 This promotes the development of new materials for hip joint replacements that are highly bio-compatible and bio-degradable. Silicon nitride (Si 3 N 4 ) has wear rate which is closer to that of Al 2 O 3 bearing couple.…”