Chemical Alterations of Periprosthetic Tissue and Joint Replacements: A Vibrational Spectroscopy Study

Metal and polyethylene debris generated from total hip and knee arthroplasty components can cause chronic inflammation and other adverse tissue responses that lead to premature implant failure. It adds immense burden to both patients and the healthcare system. Much effort has been made to understand the reasons of premature failure by studying human tissue pathological responses, performing preclinical in vitro and animal experiments, as well as improving the implant design and materials as well as surgical techniques. Yet, there is still a knowledge gap on interaction between debris and periprosthetic environment. The implant debris can be both solid and soluble, metallic, polymeric, as well as ceramic. It can be derived from primary articulating surface as well as secondary modular interfaces. Beyond a certain debris threshold, foreign body reactions will be elicited and subsequently an inflammation cascade will be triggered. Currently, tissue-level evaluation still heavily relies on conventional histology/immunohistochemistry examination, which is labor-intensive, slow, and may be subjected to observer’s bias. This dissertation proposes a new paradigm using FTIR imaging (FTIRI) to perform enhanced spectral histopathological assessment on retrieved tissue samples. It is a label-free, high-fidelity and high-throughput approach that can provide extensive biochemical information of underlying pathophysiological conditions. The presented research characterized the chemistry of debris from periprosthetic capsular tissues, as well as their associated biochemical alterations. Through incorporation with other spectro-imaging modalities, extensive information such as particle composition, speciation, and oxidation status have been generated. It facilitated the understanding of questions like the formation mechanism of characteristic CrPO4 debris associated with implant corrosion and the implication of potential delayed osteolysis due to the accumulation of ultrafine polyethylene debris. Besides the characterization of implant debris and associated chemical alterations of the periprosthetic tissue, the use of FTIRI in concert with Raman spectroscopy also enables the analysis of in vivo generated oxidation profile of polyethylene bearing surfaces from total joint replacements and how in vivo chemical changes are enable by the absorbance of various species from the periprosthetic environment. This new approach is important because it enables a better understanding of the long-term evolution of mechanical and tribological properties of these implants.