Long-term survival of hybrid total hip arthroplasty with the uncemented CLS cup, cemented Müller cobalt-chromium stem, and 28-mm Metasul™ bearings: Retrospective review of 115 hips after a minimum of 17.8 years.
Summary: This study tested the safety and efficacy of using a hybrid total hip arthroplasty with an uncemented CLS cup to treat patients with hip osteoarthritis.
Conclusion: The study found that the rate of survival to revision for any reason was 86.1% and specifically for aseptic loosening was 92.6%.
Background: Hard-on-hard bearings require a meticulous implantation technique but may be associated with lower wear rates in young active patients. Among them, metal-on-metal (MoM) bearings have been blamed for specific complications including adverse reactions to metal debris and metal hypersensitivity. These complications have been chiefly reported with large-head MoM implants (except when used for hip resurfacing). Most of the published data on small-head MoM implants were obtained using uncemented stems. To our knowledge, no information on outcomes beyond 15 years is available for small-head MoM implants with cemented cobalt-nickel-chromium (Co-Ni-Cr) stems, which might increase the risk of complications. The objective of this study was to collect long-term follow-up data on patients who underwent hybrid total hip arthroplasty (THA) with 28-mm MoM Metasul™ bearings in order to assess: (1) long-term survival (based on the revision rate), (2) and the occurrence of adverse reactions to metal debris documented during revision. Hypothesis: Survival of 28-mm Metasul™ bearings used with hybrid THA is acceptable. Patients and
Methods: A single-centre retrospective study was conducted in consecutive patients managed using 28-mm Metasul™ bearings in a press-fit cup, with a cemented Co-Ni-Cr stem. Follow-up was at least 17 years. The clinical and radiographic data were analysed. Mean age at surgery was 57.3±7.9 years (range, 29.6-75.3 years).
Results: The study included 115 hips with a mean follow-up of 20.3±0.8 years (range, 17.8-21.6 years). Survival to revision for any reason was 86.10% (95% CI, 79.8-92.4%) and survival to revision for aseptic loosening was 92.6% (95% CI, 87.7-97.6). Half the specimens obtained during revision showed a macrophage reaction and a non-specific inflammatory infiltrate. No patient experienced complications specifically related to the use of Metasul™ bearings with a cemented Co-Ni-Cr stem. Discussion: Long-term survival of 28-mm MoM Metasu™ bearings was close to that of metal-on-polyethylene bearings and lower than that of ceramic-on-ceramic or small-head MoM bearings in other studies. No complications specifically related to the use of small-head MoM bearings with a cemented Co-Ni-Cr stem were recorded. Level of evidence: IV, retrospective study.