A Gait-Dependent Model of Wear from Retrieved Polyethylene Components of Total Knee Replacements

Recent advancements in design and materials of total knee replacements have improved one the most common and successful orthopedic surgeries. However, increasing demand, changing demographics and expanded expectations of outcomes challenge the future success of primary total knee replacements. Although wear of the ultrahigh molecular weight polyethylene component is one of the main factors limiting the lifespan of these implants, the exact relationship between patient mechanics and implant wear on the articular bearing surface is not fully understood. Analysis of components retrieved from revision surgery can provide significant insights to in vivo wear, but most retrieval analysis techniques rely on semi-quantitative methods. Using a novel method to quantify wear on a unique cohort of retrieved inserts for which patient gait testing was available, we can understand the effects of patient-specific gait pattern on wear. In the first study, I develop and validate a novel method of measuring wear on the articular surface of retrieved total knee replacement inserts. In the second study, I apply that method to a clinically relevant population of retrieved components, baselining volumetric wear in relation to traditional methods of established wear. In the third study, I demonstrate the individuality of patient kinematics through retrieval analysis of bilaterally retrieved total knee replacements. In the final study, I conduct a retrospective longitudinal study in which I compare volume loss on retrieved components to archived gait analysis testing from those same individuals using a simplified model of wear. The results of these studies demonstrate the importance of patient-specific gait patterns in understanding the wear of total knee replacements, which has implications for pre-clinical testing and the future of individualized medicine in orthopedics.