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Applied Bionics and Biomechanics
Volume 4 (2007), Issue 2, Pages 83-88
http://dx.doi.org/10.1080/11762320701523679
Brief Communication

Simple Mathematical and Computational Wear Model for Ultra-High-Molecular-Weight Polyethylene Total Hip Replacements

K. H. S. Chan,1 T. Pearce,2 R. W. Blake,1 L. Chow,1 S. Wu,1 F. Wong,1 and J. Li1

1Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
2Committee on Evolutionary Biology, University of Chicago, Chicago, IL 60637, USA

Copyright © 2007 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ultra-high-molecular-weight polyethylene is an important constituent of hip implants. Surgical revisions are required because of implant loosening and osteolysis (destruction or resorption of bone tissue). We develop a mathematical and a computational model to determine implant life (defined as the time when 20% of the implants operating at a given wear rate is revised) based on wear rates and apply them to the data of Sochart (Clin Orthop Relat Res, 363:135–50, 1999). No significant difference was found between mathematical and computational model predictions (14.8 and 14.7 years, respectively) from the actual value of 15.0 ± 3.9 years (X¯ ± 2SE; P > 0.05). We find that an increase in cross-linking does not decrease implant life greatly. However, a large decrease in implant life occurs with an increase in surface roughness, cycles per year and body weight or a decrease in contact stress and femoral head radius.