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

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.

Aseptic lymphocyte-dominated vasculitis-associated lesions are related to changes in metal ion handling in the joint capsules of metal-on-metal hip arthroplasties

Objectives

We have encountered patients who developed large joint fluid collections with massive elevations in chromium (Cr) and cobalt (Co) concentrations following metal-on-metal (MoM) hip arthroplasties. In some cases, retrieval analysis determined that these ion concentrations could not be explained simply by the wear rates of the components. We hypothesized that these effects may be associated with aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL).

Patients and Methods

We examined the influence of the ALVAL grade on synovial fluid Co and Cr concentrations following adjustment for patient and device variables, including volumetric wear rates. Initially restricting the analysis to include only patients with one MoM hip resurfacing device, we performed multiple regression analyses of prospectively collected data. We then repeated the same statistical approach using results from a larger cohort with different MoM designs, including total hip arthroplasties.

Results

In the resurfacing cohort (n = 76), the statistical modelling indicated that the presence of severe ALVAL and a large fluid collection were associated with greater joint fluid Co concentrations after adjustment for volumetric wear rates (p = 0.005). These findings were replicated in the mixed implant group (n = 178), where the presence of severe ALVAL and a large fluid collection were significantly associated with greater fluid Co concentrations (p < 0.001).

Conclusion

The development of severe ALVAL is associated with elevations in metal ion concentrations far beyond those expected from the volumetric loss from the prosthetic surfaces. This finding may aid the understanding of the sequence of events leading to soft-tissue reactions following MoM hip arthroplasties.

Cite this article: D. J. Langton, R. P. Sidaginamale, T. J. Joyce, J. G. Bowsher, J. P. Holland, D. Deehan, A. V. F. Nargol, S. Natu. Aseptic lymphocyte-dominated vasculitis-associated lesions are related to changes in metal ion handling in the joint capsules of metal-on-metal hip arthroplasties. Bone Joint Res 2018;7:388–396. DOI: 10.1302/2046-3758.76.BJR-2018-0037.