National Registry Data Analysis on a Unique Highly-Crosslinked Polyethylene for Total Hip Arthroplasty

We 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. Furthermore, we respectfully disagree with the assertion that "registry data are an effective means to establish safety and efficacy of prosthetic products." While we acknowledge their utility, we firmly believe that such data, while valuable, are not sufficient for unequivocal establishment. Rather, they serve as a valuable tool in identifying potential anomalies and hazards, particularly after extended periods of widespread device usage. Indeed, as the author points out, revision may occur for non–device-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. In addition, whether a revision surgery actually takes place or not depends on a variety of reasons including patient's general health, surgeon's desire to undertake revision surgery, and/or patient's symptoms being bad enough to warrant a major intervention. Indeed, one often sees huge variations in the revision rates of the same implant across different registries as well as across different time points, thereby confirming the complex interplay between patient, surgeon, indication, and implant which all together decide the need (and actual undertaking) of a revision procedure. When investigating materials used in the production of various devices, discerning between failures attributable to surgical error, patient characteristics, design or interface problems, and those resulting from the material itself can be challenging. Hence, the appropriate approach involves analyzing different devices in distinct datasets to identify common patterns. The author of the letter to the editor adopted a methodology contrary to sound scientific practice by scrutinizing one specific device combination in a singular dataset (AMIStem H/Versafit Trio/ XLPE with metal heads). This approach is irrelevant to the paper's focus. A cursory examination would reveal that in the Australian registry, encompassing a more extended timeframe and a larger population, the mentioned devices exhibit exceedingly robust representation with overall revision rates aligning, if not being lower than, the benchmark. Consequently, professionals conducting analyses based on SIRIS data and the Swiss national authority Swissmedic have scrutinized and investigated the specific configuration highlighted by the author of the letter. Their unanimous conclusion is that there is no indication of a potentially dangerous anomaly. At present, no standard exists for defining highly crosslinked polyethylene. Therefore, users rightfully inquire about the distinctions between proprietary materials and seek extensive, long-term performance data for each product. This study, grounded in unaltered registry data, was undertaken with the intention of contributing valuable insights to the scientific community. Conversely, the motivations behind the letter to the editor appear to stem from personal interests or potential influences from uninformed or biased individuals. Thank you for allowing us to clarify these important points. E.P. and D.B. are paid employees for Medacta International. H.P. is a paid consultant for Zimmer Biomet, Allay Therapeutics, Medacta International, Paradigm Pharma, Smith and Nephew, MAT Ortho, Teleflex, and Invibio. D.B. has stock or stock options in Medacta International. H.P. receives research support as a principal investigator from Zimmer Biomet, Depuy Synthes, and Invibio. H.P. is an Editor of Journal of Arthroscopy and Joint Surgery. For full disclosure statements refer to https://doi.org/10.1016/j.artd.2024.101345. Elda Paoli: Writing – review & editing. Dario Bergadano: Conceptualization, Data curation, Formal analysis, Writing – original draft, Writing – review & editing. Shuya Sheng: Writing – review & editing. Hemant Pandit: Writing – review & editing. Download .pdf (.57 MB) Help with pdf files Conflict of Interest Statement for All Authors