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

• Published in: Scandinavian journal of surgery Vol. 102; no. 3; pp. 197 - 203
• Main Authors: Tiusanen, H., Mäkelä, K., Kiilunen, M., Sarantsin, P., Sipola, E., Pesola, M.
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01-09-2013
• Subjects: Alloys; Arthritis - surgery; Arthritis, Rheumatoid - surgery; Arthroplasty, Replacement, Hip - instrumentation; Biomarkers - urine; Chromium - urine; Cobalt - urine; Female; Follow-Up Studies; Hip Prosthesis; Humans; Ions - urine; Male; Metal-on-Metal Joint Prostheses; Metals, Heavy - urine; Middle Aged; Molybdenum - urine; Osteoarthritis, Hip - surgery; Polyethylene; Prospective Studies; Prosthesis Design; Treatment Outcome; wear; bearing surfaces; metal-on-metal; head size; Total hip arthroplasty; metal ion levels
• ISSN: 1457-4969; 1799-7267
• DOI: 10.1177/1457496913491874

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.