In 2017, me and colleagues published both a literature and registry based analysis of use of metal-on-metal hip replacements. This study, titled Lack of evidence—the anti-stepwise introduction of metal-on-metal hip replacements, was a hypothesis-driven study since at that time it seemed that the use of ASR hip replacements was not that evidence based but mainly promoted by marketing and simulator based studies.
We compared the number of implanted hips reported in the registries to the number of hips included in the studies published in the peer-reviewed literature. Here are the main results:
The chose Birmingham Hip Resurfacing implant also in the analyses since it was the most used when ASR hip replacements were introduced. BHR also had the best track-record and early results. Based on the graph above we concluded:
To conclude, the introduction of the ASR hip replacement violated the fundamental principles of adoption by an almost complete lack of studies in the peer-reviewed literature following its introduction. The results obtained with hip simulators, the claims of similarity to or equivalence with other implants and theoretical advantages failed catastrophically to substitute for the most fundamental foundation of any innovation: the evidence in the literature.
Regarding BHR we wrote:
With the BHR there was a sufficient number of studies that included adequate numbers of patients to provide evidence of its use following the years of introduction, at least in male patients. To sum up, in the case of BHR we postulate that there was causality between the registry and literature data meaning that the numbers reported in the registry predicted the numbers reported in the literature.
It was great to read an “Evidence in focus” or “Publication summary” published just this month by the manufacturer of the BHR implant. It is a great looking one page report:
An unknown scientific writer made the following conclusion from our study:
BHR was introduced gradually thorough preclinical and clinical testing, in line with the step-wise, evidence-based introduction of orthpaedic implants proposed by the IDEAL Collaboration. The introduction of ASR and ASR XL was rapid, with regulatory approval based on preclinical proof of similarity studies, and did not follow the recommended step-wise introduction
It may be true, but based on our study that is quite far reaching conclusion. We did not show that introduction of BHR followed the IDEAL guidelines. We merely said that number of hips implanted was somewhat associated with the number of hips included in published studies so there was some evidence to support the increasing use of BHR. What really can be said from our study, however, is that there was no evidence to support the widespread use of ASR implant.
But it is a summary written by the manufacturer. And hey, there is no such thing as bad publicity!