How to cite this article: Al-Hajjar M, Fisher J, Williams S, Tipper JL, Jennings LM. 2013. Effect of femoral head size on the wear of metal on metal bearings in total hip replacements under adverse edge-loading conditions. J Biomed Mater Res Part B 2013:101B:213–222.
Effect of femoral head size on the wear of metal on metal bearings in total hip replacements under adverse edge-loading conditions†
Version of Record online: 20 DEC 2012
Copyright © 2012 Wiley Periodicals, Inc.
Journal of Biomedical Materials Research Part B: Applied Biomaterials
Volume 101B, Issue 2, pages 213–222, February 2013
How to Cite
Al-Hajjar, M., Fisher, J., Williams, S., Tipper, J. L. and Jennings, L. M. (2013), Effect of femoral head size on the wear of metal on metal bearings in total hip replacements under adverse edge-loading conditions. J. Biomed. Mater. Res., 101B: 213–222. doi: 10.1002/jbm.b.32824
- Issue online: 8 JAN 2013
- Version of Record online: 20 DEC 2012
- Manuscript Accepted: 5 AUG 2012
- Manuscript Revised: 24 JUN 2012
- Manuscript Received: 29 FEB 2012
- Orthopaedic Research UK (ORUK), the National Institute of Health Research (NIHR), Leeds Musculoskeletal Biomedical Research Unit (LMBRU), NIHR LMBRU, WELMEC Wellcome Trust, Technology Strategy Board, EPSRC, BBSRC
- EPSRC. Grant Number: WT088908/z/09/z
- edge loading;
- hip replacement;
- inclination angle
Metal-on-metal (MoM) bearings have shown low-wear rates under standard hip simulator conditions; however, retrieval studies have shown large variations in wear rates and mechanisms. High-wear in vivo has caused catastrophic complications and has been associated with steep cup-inclination angle (rotational malpositioning). However, increasing the cup-inclination angle in vitro has not replicated the increases in wear to the same extent as those observed in retrievals. Clinically relevant wear rates, patterns, and particles were observed in vitro for ceramic-on-ceramic bearings when microseparation (translational malpositioning) conditions were introduced into the gait cycle. In the present study, 28 and 36-mm MoM bearings were investigated under adverse conditions. Increasing the cup angle from 45° to 65° resulted in a significant increase in the wear rate of the 28 mm bearings. However, for the 36 mm bearings, head-rim contact did not occur under the steep cup-angle condition, and the wear rate did not increase. The introduction of microseparation to the gait cycle significantly increased the wear rate of the MoM bearings. Cup angle and head size did not influence the wear rate under microseparation conditions. This study indicated that high-in vivo wear rates were associated with edge loading due to rotational malpositioning such as high-cup-inclination angle and translational malpositioning that could occur due to several surgical factors. Translational malpositioning had a more dominant effect on the wear rate. Preclinical simulation testing should be undertaken with translational and rotational malpositioning conditions as well as standard walking cycle conditions defined by the ISO standard. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.