PhD Dissertation Defense for Andrew Miller
Advisor: Robert Guldberg, PhD (Georgia Institute of Technology)
Ken Gall, PhD (Duke University)
Johnna Temenoff, PhD (Georgia Institute of Technology)
Meisha Shofner, PhD (Georgia Institute of Technology)
Nick Willett, PhD (Emory University)
Fatigue and Cyclic Loading of 3D Printed Soft Polymers for Orthopedic Applications
The use of soft, synthetic materials for soft tissue replacement in load-bearing, orthopedic applications has been largely unsuccessful due to a lack of adequate materials with sufficient fatigue and wear resistance. Silicone was once purported to be suitable for this purpose, and has been used in applications ranging from radial head implants to intervertebral disc replacements. However, the long term results for these devices demonstrated that there was significant room for improvement, with complications including implant fracture, deformation, and wear. More recently, there has been a surge in devices based on polycarbonate urethane (PCU), which has gained traction due to its relative biocompatibility, compliant nature, viscoelastic properties, as well as it’s durability as seen through preclinical device testing. Despite its promising nature, caution is warranted as the long-term clinical results of PCU devices have yet to be seen. Considering past difficulties, there is a clear need for a better fundamental understanding of the fatigue resistance of soft, synthetic polymers for such applications. Therefore, the purpose of this thesis was to develop useful processing-structure-property relationships for relevant soft polymers under fatigue loading in order to assist in the use and success of such polymers in load-bearing orthopedic applications.