Date Approved

6-14-2023

Embargo Period

6-15-2023

Document Type

Thesis

Degree Name

Master of Science in Biomedical Engineering

Department

Biomedical Engineering

College

Henry M. Rowan College of Engineering

Advisor

Erik Brewer, Ph.D.

Committee Member 1

Anthony Lowman, Ph.D.

Committee Member 2

Joseph F. Stanzione, III, Ph.D.

Keywords

Degradation, FTIR, Hydrolysis, Polymer, TGA, Thermal Oxidation

Subject(s)

Intervertebral disk prostheses; Implants, Artificial

Disciplines

Biomedical Engineering and Bioengineering | Orthotics and Prosthetics

Abstract

HYDRAFIL™ is a poly(vinyl alcohol)/poly(ethylene glycol)-based hydrogel nucleus pulposus replacement device that is injected in situ and has demonstrated efficacy in lowering the prevalence and pain associated with back. In this work, we developed a method to analyze HYDRAFIL™ polymer composition using (TGA) and characterized intermolecular bonding interactions within the hydrogel through (FTIR). To function as a permanent implant for nucleus pulposus replacement, HYDRAFIL™ must be stable when exposed to a multitude of degradation pathways, namely, thermal, chemical, and mechanical. We subjected HYDRAFIL™ to accelerated thermal and chemical degradation pathways and described compositional, physical and chemical property changes using a kinetic framework. HYDRAFIL™ exhibited evidence of degradation when subject to extreme, atypical conditions, but proved to be stable in response to clinically and physiologically relevant pathways of degradation. To assess mechanical degradation, we generated HYDRAFIL™ particulates using cryogenic milling to mimic long-term mechanical wear particulates Morphological changes and shape descriptors were evaluated when HYDRAFIL™ was cryogenically milled under different cooling phases and grinding cycles. Particulates were evaluated in a rabbit model and showed excellent biocompatibility and safety, even within the spinal canal.

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