Tuesday, October 1, 2013

The influence of stem design on critical squeaking friction with ceramic bearings.


J Orthop Res. 2013 Oct;31(10):1627-32. doi: 10.1002/jor.22413. Epub 2013 Jun 27.
The influence of stem design on critical squeaking friction with ceramic bearings.
Fan NMorlock MMBishop NEHuber GHoffmann NCiavarella MChen GXHothan AWitt F.
Source
Tribology Research Institute, Southwest Jiaotong University, Chengdu, 610031, China; Biomechanics Section, TUHH Hamburg University of Technology, Hamburg, 21073, Germany.

Abstract
Ceramic-on-ceramic hip joints have been reported to squeak, a phenomenon that may occur in compromised lubrication conditions. One factor related to the incidence of in vivo squeaking is the stem design. However, it has not yet been possible to relate stem design to squeaking in deteriorating lubrication conditions. The purpose of this study was to determine critical friction factors for different stem designs. A hip simulator was used to measure the friction factor of a ceramic bearing with different stem designs and gradually deteriorating lubrication represented by evaporation of a volatile fluid lubricant. The critical squeaking friction factor was measured at the onset of squeaking for each stem. Critical friction was higher for the long cobalt chrome (0.32 ± 0.02) and short titanium stems (0.39 ± 0.02) in comparison with a long titanium stem (0.29 ± 0.02). The onset of squeaking occurred at a friction factor lower than that measured for dry conditions, in which squeaking is usually investigated experimentally. The results suggest that shorter or heavier stems might limit the possibility of squeaking as lubrication deteriorates. The method developed can be used to investigate the influence of design parameters on squeaking probability. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1627-1632, 2013.
Copyright © 2013 Orthopaedic Research Society.

No comments:

Post a Comment