Large-head metal-on-metal (MoM) total hip replacements (THR) have given rise to concern. Comparative studies of small-head MoM THRs over a longer follow-up period are lacking. Our objective was to compare the incidence of complications such as infection, dislocation, revision, adverse local tissue reactions, mortality and radiological and clinical outcomes in small-head (28 mm) MoM and ceramic-on-polyethylene (CoP) THRs up to 12 years post-operatively.
A prospective cohort study included 3341 THRs in 2714 patients. The mean age was 69.1 years (range 24 to 98) and 1848 (55.3%) were performed in women, with a mean follow-up of 115 months (18 to 201). There were 883 MoM and 2458 CoP bearings. Crude incidence rates (cases/1000 person-years) were: infection 1.3 vs 0.8; dislocation 3.3 vs 3.1 and all-cause revision 4.3 vs 2.2, respectively. There was a significantly higher revision rate after ten years (adjusted hazard ratio 9.4; 95% CI 2.6 to 33.6) in the MoM group, and ten of 26 patients presented with an adverse local tissue reaction at revision. No differences in mortality, osteolysis or clinical outcome were seen.
In conclusion, we found similar results for small-head MoM and CoP bearings up to ten years post-operatively, but after ten years MoM THRs had a higher risk of all-cause revision. Furthermore, the presence of an adverse response to metal debris seen in the small-head MOM group at revision is a cause for concern.
Cite this article: Bone Joint J 2014; 96-B:868–75.
- Total hip replacement
- 28 mm head
- Adverse local tissure reaction
Institutional financial support was received from the “Fondation pour la recherche ostéo-articulaire”. The authors thank Professor T. Perneger for valuable statistical advice, F. Renevey, C. Bandi and L. Blatter-Sellak for data entry and the organisation of the follow-up, Dr P. Christofilopoulos for surgical advice and C. Barea for data management, as well as the orthopaedic surgeons who have contributed to our registry since 1996.
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 G. Scott and first proof edited by A. Ross.
- Received May 6, 2013.
- Accepted March 18, 2014.
- ©2014 The British Editorial Society of Bone & Joint Surgery