Characterization of Potential Wear Sources in Knee Arthroplasty Prostheses After In Vivo Function

Total joint arthroplasty (TJA) is a common procedure generally performed in patients with osteoarthritis. While TJA continues to be a successful treatment for degenerative joint disease, there are many studies that demonstrate wear and its sequelae as the major limitation of joint replacement longevity. Previous studies have shown that wear debris originates from four main locations: articulating surfaces, modular component surfaces, surfaces of fixation, and adjuvant fixation devices. Each of these possible wear sources can initiate the cascade of failure associated with wear-induced osteolysis and lead to subsequent revision surgery. The objective of this thesis is to characterize the in vivo performance of knee prostheses by quantitatively assessing performance at different potential wear-inducing interactions, including bearing surfaces and modular articular surfaces. The objective will be accomplished through three studies that will aim to investigate different wear modes. The purpose of Study 1 is to explore the relationships between femoral component surface roughness, polyethylene insert damage and in vivo duration through the evaluation of metal-polymer UKA bearing couples that were retrieved after 1 to 19 years of in vivo service. This study characterizes the distribution of damage on matched metal-polymer bearing couples of retrieved UKA and quantifies ranges of surface roughness corresponding to the different damage modes visually identified on both bearing surfaces. The purpose of Study 2 is to characterize the damage of retrieved knee replacement bearing couples that have experienced complete polyethylene wear-through, while considering the material properties of common alloys used to fabricate femoral components and tibial baseplates, including cobalt-chrome alloy, titanium alloy, and oxidized zirconium alloy. The purpose of Study 3 is to evaluate the clinical outcomes of 84 patients implanted with primary TKA prostheses of a single design that utilizes a Morse taper feature for attaching a modular tibial stem. The results from this thesis provide clinically relevant data for understanding the performance of knee prosthesis designs under physiologic conditions. Additionally, this thesis provides relevant surface roughness values for prostheses with in vivo function for assessing the predictive capabilities of in vitro simulation and analytical models