Metal-on-metal hip resurfacings and the year 2019

Hellman et al. addressed the proposed advantages of metal-on-metal (MoM) hip resurfacings (HR) over tradition total hip replacements (THR) in their recent systematic review. There has been relative paucity in the literature regarding positive studies in MoM HRs. Some single surgeon and single center studies have been published, but in general, the study by Hellman is first of its kind in few years.

Hellman et al. pooled level I-III studies comparing HRs and traditional THRs. They concluded that HR ”offers some potential advantages over THA, including improved return to high level activities and sport, restoration of native hip biomechanics, and decreased proximal femoral stress shielding”.

None of the proposed advantages are new; they have been stated many times in the vast bulk of literature before. Two latter are the main fundamental and theoretical advantages of large diameter HRs outlined early in the history of second generation MoM HRs. Hellman et al. looked at 27 studies of which the latest was published in 2015 so this study does not include any new evidence. Hence it is interesting that this study was published when HRs have been largely abandoned due the massive ”MoM epidemic”.

From time to time, one can hear inquiries what is the status of HRs. It is a clear fact that MoM hips represent of case of ”never again” example how to implement new medical devices. It is, however, also clear the statement ”throw the baby out with the bathwater ” applies to case with HRs.

Birmingham Hip Resurfacing was the very first HR introduced in the late ´90s. The main reason for the MoM catastrophe is the other devices developed and introduced after BHR. Cumulative revision rate (CRR) at 14 years for BHR in the National Joint Registry of England and Wales (NJR) is 11.02% (95% CI: 10.40 – 11.68). The similar rate in the Australian Registry (AOANJRR) at 15 years is 10.0% (95% CI: 9.3 – 10.7). A reasonable comparison group would be male patients aged 55-64 years. CRR at 14 years in this group in the NJR is 9.03% (95% CI: 8.54 – 9.54). CRR at 15 years in the similar group with primary diagnosis of OA in the AOANJRR is 8.6% (95% CI: 8.3 – 8.9). It is important to note that both estimates for BHR includes female patients in whom the prevalence of ARMD is very high and therefore the survival in male patients is superior to the estimates reported in the registries as a whole.

Annual number of HRs performed in the UK are as follows: 2013, 913 hips; 2014, 901 hips; 2015, 801 hips; 2016, 801 hips; 2017, 666 hips.

So what is the status of HR in the year 2019? Tennis elite Andy Murray had his hip operated on with BHR this year. Use of HR remains marginal and registry data show fairly good survival in longer term. It is interesting to see whether in following years there will be a surge of studies advocating the use of HRs in male patients with suitable anatomy. The main question will remain as follows: does the proposed advantages of HR outweigh the risk of ARMD?

An editorial accompanying the one previous study also by Hellman et al. states fairly well: “[…] patients who truly fit the inclusion criteria are extremely rare, the possible benefits to these patients of SRA compared with total hip arthroplasty are slight (if at all present), and the possible risks of the metal-on-metal articulation remain a concern“.

References

Hellman MD, Ford MC, Barrack RL. Is there evidence to support an indication for surface replacement arthroplasty? Bone Joint J. 2019 Jan;101-B(1_Supple_A):32-40.

AOANJRR Annual Report 2018: https://aoanjrr.sahmri.com/documents/10180/576950/Hip%2C%20Knee%20%26%20Shoulder%20Arthroplasty

NRJ 15th Annual Report 2018: http://www.njrreports.org.uk/Portals/0/PDFdownloads/NJR%2015th%20Annual%20Report%202018.pdf

NRJ 15th Annual Report 2018: Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2017

NRJ 14th Annual Report 2017: Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2016

NRJ 13th Annual Report 2016: Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2015

NRJ 12th Annual Report 2015: Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2014

NRJ 11th Annual Report 2014: Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2013

Giori NJ. Is There a Role for Surface Replacement Arthroplasty in Today’s Orthopaedic Practice?: Commentary on an article by Marcus C. Ford, MD, et al.: “Five to Ten-Year Results of the Birmingham Hip Resurfacing Implant in the U.S. A Single Institution’s Experience”. J Bone Joint Surg Am. 2018 Nov 7;100(21):e142



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