Surface Damage Evaluation and Computational Modelling of Clinically Failed Knee Liners

<p> <dl id="x-x-citationFields"> <dd> Five retrieved <strong> knee </strong> <strong> liners </strong> made of cross-linked, ultra-high molecular weight polyethylene were investigated. Each <strong> liner </strong> was examined by five investigators and in vivo <strong> damage </strong> was evaluated using four methods (Wasielewski, Brandt, Lombardi, and Hood). Both optical and confocal microscopy techniques were used to quantify <strong> damage </strong> modes. Oxidation index, crystallinity and hardness parameters were calculated for material characterization. Gait profiles of two subjects (one male and one female) for three different activities were considered in finite element analysis (FEA) simulations. The main hypotheses of this study were that 1) the wear tracks on the <strong> liners </strong> may be represented by maximum von Mises stress areas, 2) a single composite index may be used to represent 10 different <strong> damage </strong> modes. Significant reduction in tensile strength was observed with an average value of 27.7 MPa at 50KGy due to oxidation in all the <strong> liners </strong> . Correlations were made between FEA results and <strong> surface </strong> <strong> evaluation </strong> results. Gait analysis of the <strong> liners </strong> showed males typically have a higher stress level in vivo than females, leading to increased wear. Attempts were made to relate the <strong> damage </strong> patterns on the <strong> liners </strong> with the stress development and the <strong> damage </strong> <strong> evaluation </strong> methods and our <strong> computational </strong> simulation validates the methods that we used. Higher stress areas were compared against the <strong> surface </strong> <strong> evaluation </strong> results, showing those regions experiencing the high stress also had a high <strong> damage </strong> index. Even though the <strong> liners </strong> were mechanically intact, they <strong> failed </strong> <strong> clinically </strong> and more likely due to abrasive wear (due to third-body wear particles). [ABSTRACT FROM AUTHOR] </dd> <dt> </dt> <dd> Copyright of Computer Methods in Biomechanics &amp; Biomedical Engineering: Imaging &amp; Visualisation is the property of Taylor &amp; Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) </dd> </dl></p>