Retrieval analysis of contemporary antioxidant polyethylene: multiple material and design changes may decrease implant performance
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With the introduction of the Attune Knee System (DePuy) in March 2013, a new polyethylene formulation incorporating anti-oxidants was used. Although several in vitro studies have demonstrated the positive effects of antioxidants on UHMWPE, no retrieval study has looked at polyethylene damage of this system yet. It was the aim of this study to investigate the in vivo performance of this new design, by comparing it with its predecessors in retrieval analysis.
24 PFC (18 fixed bearing and 6 rotating platform designs) and 17 Attune (8 fixed bearing and 9 rotating platform designs) implants were retrieved. For retrieval analysis, a macroscopic analysis of polyethylene components, using a peer-reviewed damage grading method was used. Medio-lateral polyethylene thickness difference was measured with a peer-reviewed micro-CT based method. The roughness of metal components was measured. All findings were compared between the two designs.
Attune tibial inserts with fixed bearings showed significantly higher hood scores on the backside surface when compared with their PFC counterparts (p = 0.01), no other significant differences were found in the polyethylene damage of all the other surfaces analysed, in the surface roughness of metal components and in medio-lateral linear deformations.
A significant difference between PFC and Attune fixed bearing designs was found in terms of backside surface damage: multiple changes in material and design features could lead to a potential decrease of implant performance. Results from the present study may help to understand how the new Attune Knee System performs in vivo, impacting over 600,000 patients.
KeywordsTotal knee arthroplasty Polyethylene Retrieval analysis Polyethylene surface damage Polyethylene linear deformation
There is no direct funding for this study.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All investigations were conducted in conformity with ethical principles of research and that institutional approval of the human protocol for this investigation was obtained.
Informed consent for participation in the study was obtained.
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