We prospectively assessed the efficacy of a ceramic-on-metal (CoM) hip bearing with uncemented acetabular and femoral components in which cobalt–chrome acetabular liners and alumina ceramic heads were used.
The cohort comprised 94 total hip replacements (THRs) in 83 patients (38 women and 45 men) with a mean age of 58 years (42 to 70). Minimum follow-up was two years. All patients had pre- and post-operative assessment using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), Oxford hip score and Short-Form 12 scores. All showed a statistically significant improvement from three months post-operatively onwards (all p < 0.001).
After two years whole blood metal ion levels were measured and chromosomal analysis was performed. The levels of all metal ions were elevated except vanadium. Levels of chromium, cobalt, molybdenum and titanium were significantly higher in patients who underwent bilateral THR compared with those undergoing unilateral THR (p < 0.001). Chromosomal analysis demonstrated both structural and aneuploidy mutations. There were significantly more breaks and losses than in the normal population (p < 0.001). There was no significant difference in chromosomal aberration between those undergoing unilateral and bilateral procedures (all analyses p ≥ 0.62).
The use of a CoM THR is effective clinically in the short-term, with no concerns, but the significance of high metal ion levels and chromosomal aberrations in the long-term remains unclear.
Cite this article: Bone Joint J 2013;95-B:1040–44.
The authors would like to thank Dr M. Morris (Senior Lecturer in Physiology, The University of Chester) for data analysis and statistical advice; Mr B. Sampson (Director, Supraregional Trace Element Laboratory, Imperial College Healthcare NHS Trust) for whole blood metal ion analysis; and Dr D. Ladon (Senior Research Cytogeneticist, The Rayne Institute, King’s College London), for the 24-colour FISH analysis.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
This article was primary edited by D. Rowley and first-proof edited by J. Scott.
- Received January 11, 2013.
- Accepted April 15, 2013.
- ©2013 The British Editorial Society of Bone & Joint Surgery