Letter to the Editor regarding National Registry Data Analysis on a Unique Highly-Crosslinked Polyethylene for Total Hip Arthroplasty

I read with interest the above-mentioned publication by Paoli et al. [[1]Paoli E. Bergadano D. Sheng S. Pandit H. National registry data analysis on a unique highly-cross-linked polyethylene for total hip arthroplasty.Arthroplast Today. 2023; 24101267Abstract Full Text Full Text PDF Scopus (0) Google Scholar] investigating the long-term safety of the HIGHCROSS highly cross-linked polyethylene (XLPE) liners (Medacta International SA, Castel San Pietro, Switzerland) in total hip arthroplasty with Versafit cups in combination with AMIStem-H and Quadra-H stems. Whereas the authors concluded on results comparable to other XLPE liners, total hip arthroplasty of these brands have been listed as outliers with increased revision rates various times in the annual report 2023 of the Swiss National Joint Registry (SIRIS) [[2]Swiss National Hip, Knee Joint RegistryReport December 2023 – annual report of the SIRIS registry hip & knee.https://www.swiss-medtech.ch/sites/default/files/2023-11/231117_SIRIS-Report-2023_Final_online.pdfDate accessed: March 13, 2024Google Scholar], which had been published the same month. This seems contradictory. I agree completely that National Joint Registries provide a unique opportunity to analyze large datasets and, therefore, are an effective means of establishing the safety and efficacy of prosthetic products. Data extracted from industry reports from the Australian Orthopaedic Association National Joint Replacement Registry and SIRIS was used, not original data, to compare cumulative revision rates according to the Kaplan-Meier method of the HIGHCROSS polyethylene liners with other highly XLPE liners. The arthroplasty registries should rule regarding the reliability of the methods. However, the authors focused exclusively on revisions attributed explicitly to wear and/or osteolysis. The inclusion of cases thus dropped down to around 1% of the overall number of revisions with HIGHGROSS liners: in case of the AMIStem-H from the reported 677 revisions (3.9%, mean 4.3 years) to only 7 cases (0.04%), and for the Quadra-H from 318 revisions (3.6%, mean 3.8 years) to only 3 cases (0.03%), respectively. Whatever reasons the authors may have to exclude about 99% of the revisions with HIGHCROSS liners, this violates the recommendations of the International Prosthesis Benchmarking Working Group, indicating that all-cause revision is the principal outcome measure of choice for both early and late benchmarking, considering limitations of data input and registration in registries [[3]International Prosthesis Benchmarking Working Group Guidance DocumentHip and knee arthroplasty devices. Mai.2018https://drive.google.com/file/d/0BwKvdROo5Eg-MjZYc2VHQUZGYzNJMlRaenZEVUN3cTdMYlBj/view?pli=1&resourcekey=0-OtTMX1RmF7E-HAZgxXiNZgDate accessed: March 13, 2024Google Scholar]. Under this light, it seems ambiguous to conclude that the large number of patients confirms the safety and efficacy of HIGHCROSS liners, and the results cannot be considered as a true representation of real-world data. Benchmarking prosthetic components reassures patients, surgeons, hospitals, and governments that all components have been assessed independently as having an acceptable and proven quality of performance and longevity. Revision is an unambiguous endpoint that indicates an unsatisfactory outcome for both the surgeon and the patient. All-cause revision rather than specific reasons for revision is most relevant as a public health outcome. Revision may occur for nondevice-related reasons, making it difficult to determine exactly the impact of specific brands on the different reasons for revision. Reporting in arthroplasty registries may be incomplete [[3]International Prosthesis Benchmarking Working Group Guidance DocumentHip and knee arthroplasty devices. Mai.2018https://drive.google.com/file/d/0BwKvdROo5Eg-MjZYc2VHQUZGYzNJMlRaenZEVUN3cTdMYlBj/view?pli=1&resourcekey=0-OtTMX1RmF7E-HAZgxXiNZgDate accessed: March 13, 2024Google Scholar]. However, taking into consideration all reported causes of revision makes it unlikely to systematically advantage or disadvantage one device over another. Comparing the results and conclusions of the present study with the latest annual report of SIRIS, important discrepancies can be seen [2, pages 64-66]:1.The Kaplan-Meier curves (Fig. 1 - Fig. 3.5d of SIRIS) for the different bearing combinations for AMIStem-H/Versafitcup trio/ccl. compared to the average of the group indicate that the combination with metal-on-highly cross-linked polyethylene has an excessively high revision rate that reaches outlier status after 9 years [[2]Swiss National Hip, Knee Joint RegistryReport December 2023 – annual report of the SIRIS registry hip & knee.https://www.swiss-medtech.ch/sites/default/files/2023-11/231117_SIRIS-Report-2023_Final_online.pdfDate accessed: March 13, 2024Google Scholar].2.AMIStem-H and Quadra-H uncemented stems combined with Versafitcup Trio/ccl. both have a 10-year revision rate of 6.8% (95% confidence interval 6.2-7.6 and 5.8-8.0, respectively). All other uncemented combinations show a 10-year revision of 4.9% (95% confidence interval 4.5-5.3). Looking at such unbiased data, it would be indicated to perform a more accurate analysis of failure to elucidate the reasons for the outlier status of Versafit cups with AMIStem-H and Quadra-H combinations, particularly for the metal-on-highly cross-linked polyethylene bearing. Whether these bearing components alone are responsible for such a bad performance is debatable, looking at the fact that the same prosthetic components utilized with ceramic-on-ceramic or ceramic-on-highly cross-linked polyethylene bearings behave much better but are still worse than other combinations. In conclusion, the present study not only fails to add relevant information to the literature but also may even mislead any reader. Considering the industry reports used for data extraction one must have included information regarding the upcoming reporting of the outlier status in the annual report [[2]Swiss National Hip, Knee Joint RegistryReport December 2023 – annual report of the SIRIS registry hip & knee.https://www.swiss-medtech.ch/sites/default/files/2023-11/231117_SIRIS-Report-2023_Final_online.pdfDate accessed: March 13, 2024Google Scholar], it makes me wonder why this publication was made at all. The authors declare there are no conflicts of interest. For full disclosure statements refer to https://doi.org/10.1016/j.artd.2024.101346. Emanuel Gautier: Writing – original draft, Writing – review & editing. Download .docx (.41 MB) Help with docx files Conflict of Interest Statement for Gautier National Registry Data Analysis on a Unique Highly-Crosslinked Polyethylene for Total Hip ArthroplastyArthroplasty TodayPreviewWe appreciate the opportunity to address the concerns raised in the recent letter to the editor regarding our paper. It is crucial to clarify that our research relies exclusively on original registry reports, untouched by any post-processing interventions from the authors. Therefore, the assertion made in the aforementioned letter that we utilized “not original data” is unequivocally incorrect. Full-Text PDF Open Access