Implant brand portfolios, the potential for camouflage of data, and the role of the Orthopaedic Data Evaluation Panel in total knee arthroplasty

Aims Knee arthroplasty surgery is a highly effective treatment for arthritis and disorders of the knee. There are a wide variety of implant brands and types of knee arthroplasty available to surgeons. As a result of a number of highly publicized failures, arthroplasty surgery is highly regulated in the UK and many other countries through national registries, introduced to monitor implant performance, surgeons, and hospitals. With time, the options available within many brand portfolios have grown, with alternative tibial or femoral components, tibial insert materials, or shapes and patella resurfacings. In this study we have investigated the effect of the expansion of implant brand portfolios and where there may be a lack of transparency around a brand name. We also aimed to establish the potential numbers of compatible implant construct combinations. Methods Hypothetical implant brand portfolios were proposed, and the number of compatible implant construct combinations was calculated. Results A simple knee portfolio with cemented cruciate-retaining (CR) and posterior-stabilized (PS) components, with and without a patella, has four combinations. If there are two options available for each component, the numbers double for each option, resulting in 32 combinations. The effect of adding a third option multiplies the number by 1.3. Introducing compatible uncemented options, with the effect of hybrids, multiplies the number by 4. An implant portfolio with two femoral components (both in CR and PS), with two insert options and a patella, all in cemented and uncemented versions leads to 192 possible compatible implant construct combinations. There are implant brands available to surgeons with many more than two options. Conclusion This study demonstrates that the addition of multiple variants within a knee brand portfolio leads to a large number (many hundreds) of compatible implant construct combinations. Revision rates of implant combinations are not currently reviewed at this level of granularity, leading to the risk of camouflage of true outcomes. Cite this article: Bone Joint J 2021;103-B(10):1555–1560.

11 Understanding the Clinical Performance of Ceramic Coated Femoral Components in Knee Arthroplasty Surgery

Aim In vitro knee simulation has demonstrated favourable wear properties and decreased metal ion release of ceramic coated metal femoral components in total knee arthroplasty surgery. Femoral implants coated with ceramic have been used in patients, however the subsequent clinical performance and time-to-revision of these implants is largely unknown. The scope of this study was to review the current available clinical literature, focusing on retrieval studies of Ceramic-Coated TKAs. Method Literature review of PubMed and MEDLINE. All studies included demonstrated clinical evaluation of implant performance, either in vivo or at revision. Results 9 studies were identified and included for analysis in this study. Retrieval analysis has illustrated microscopic defects in coatings of revised implants, with associated abrasion and 3rd body wear of the polyethylene component. Evidence suggests that coating femoral components with ceramic can prevent effective cement bonding, leading to aseptic loosening and thus earlier implant failure. Despite these problems, high volume centres have been able to demonstrate comparable results when compared with traditional bearing surface combinations. The mechanism behind metal ion hypersensitivity is currently poorly understood; however, the use of ceramic coated knee replacements is demonstrating a reduction in metal ion release. Conclusions Whilst conferring favourable clinical properties in certain instances, the lack of surgical, implant and patient data surrounding the use of this coated implants remains concerning. The literature base remains limited, and meaningful clinical conclusions cannot be drawn. Recommendations include performing robust clinical trials in order to delineate the clinical efficacy of ceramic coatings in knee arthroplasty.