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A comparative assessment of small-head metal-on-metal and ceramic-on-polyethylene total hip replacement
A Lübbeke1, A Gonzalez1, G Garavaglia1
1Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, Geneva, CH-1211, Switzerland.
Abstract:
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.
Insights
Small-head metal-on-metal (MoM) hip replacements showed similar outcomes to ceramic-on-polyethylene (CoP) for up to ten years. After ten years, MoM implants had a higher revision rate, with concerns about adverse tissue reactions.
Area of Science:
- Orthopedic surgery
- Biomaterials science
- Clinical outcomes research
Background:
- Large-head metal-on-metal (MoM) total hip replacements (THR) have raised safety concerns.
- Comparative long-term data for small-head MoM THR versus other bearing surfaces are limited.
Purpose of the Study:
- To compare complication incidence, including infection, dislocation, revision, and adverse local tissue reactions.
- To evaluate radiological and clinical outcomes between small-head (28 mm) MoM and ceramic-on-polyethylene (CoP) THR up to 12 years post-operatively.
Main Methods:
- Prospective cohort study of 3341 THRs in 2714 patients (mean age 69.1 years).
- Follow-up averaged 115 months, comparing 883 MoM bearings with 2458 CoP bearings.
- Incidence rates and revision risks were analyzed, focusing on outcomes after ten years.
Main Results:
- No significant differences in infection, dislocation, mortality, osteolysis, or clinical outcomes were observed up to ten years.
- A significantly higher all-cause revision rate was found for MoM THRs after ten years (adjusted hazard ratio 9.4).
- Ten of 26 MoM revisions showed adverse local tissue reactions, indicating a potential concern for metal debris response.
Conclusions:
- Small-head MoM and CoP THR implants demonstrated comparable results for the first decade.
- Beyond ten years, MoM THRs exhibited an increased risk of all-cause revision.
- Adverse local tissue reactions associated with metal debris in MoM THRs warrant further investigation and clinical concern.
