Abstract
Introduction: There is increasing interest in the use of ceramic on ceramic bearings for hip replacement, due to recognition of their extremely low wear and biocompatibility of the wear debris [1].
The aim of this study was to investigate the influence of cup inclination angle and head position on the wear of ceramic-on-ceramic total hip replacements.
Methods: The wear of Biolox Delta alumina matrix composite ceramic (CeramTec AG, Germany) was investigated using the six station Leeds II Physiological Anatomical hip joint simulator, using 25% bovine serum as a lubricant. Three ceramic-on-ceramic bearings were mounted with the cup providing a clinical angle of 55o (representing the standard condition) and three were mounted to provide a clinical angle of 65o (representing the steep cup angle condition). Simulator studies were carried out under standard gait conditions for 2 million cycles, and under micro-separation conditions for a further 3 million cycles. Micro-separation and dynamic lateralisation of the position of the head replicate head/cup rim contact at heel strike and simulate stripe wear on a ceramic femoral head as found on ceramic-on-ceramic retrievals [2]. Volumetric wear was determined gravimetrically and statistical analysis was performed using One Way ANOVA.
Results: There was no difference in the wear rates under standard gait conditions for the standard and steep cup angles, with a wear rate of 0.05 mm3/million cycles. Under micro-separation conditions the wear rates increased significantly to 0.13 and 0.11 mm3/million cycles for the standard and steep cup angles respectively. However, there was no significant difference between the standard and steep cup angle groups.
Discussion: Micro-separation and dynamic lateralisation of the position of the head during gait simulation significantly increased wear. However, the inclination of the cup in ceramic-on-ceramic THRs did not have a significant effect on the wear under either standard gait or micro-separation conditions.
Correspondence should be addressed to BHS c/o BOA, at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London, WC2A 3PE, England.
References
1 Heisel et al. JBJS, 85-A (7), 1366, 2003. Google Scholar
2 Nevelos et al. J Athroplasty, 15, 793, 2000. Google Scholar
