Development and Characterization of 3D Printed Porous PEEK for Orthopaedic Applications
Thursday, September 30, 2021
3:30 PM-5:30 PM
BIOMED PhD Thesis Defense
Title:
Development and Characterization of 3D Printed Porous Polyetheretherketone (PEEK) for Orthopaedic Applications
Speaker:
Hannah Spece, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University
Advisors:
Steven Kurtz, PhD
Research Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University
Joseph Sarver, PhD
Teaching Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University
Details:
Additive manufacturing (AM, 3D printing) is rapidly being adopted by clinicians and researchers aiming to create affordable patient-specific medical devices and other complex structures. In orthopaedics, AM technologies have been especially beneficial for the creation of metallic porous biomaterials, which can help establish bone-implant fixation without the use of bone cement. Metal AM, however, presents considerable challenges for use in a clinical setting, and the potential disadvantages of metal in vivo have led to increased interest in nonmetallic implants. Recent advancements in AM have allowed for the printing of high temperature polymers like polyetheretherketone (PEEK) using the fused filament fabrication (FFF) process already adopted by many hospitals. While the bioinert nature of PEEK is often cited as a barrier to its use in osseointegration, the inclusion of porosity by surface modification has shown promising results for bone ingrowth, though often at the expense of mechanical properties. Establishing a strategy to create porous PEEK without detrimental post processing may help advance the possibilities for patient-specific implants created at the point of care.
In this thesis, porous PEEK created by FFF is presented and characterized to determine its potential use as a novel orthopaedic biomaterial. The porous architectures are designed using the concept of triply periodic minimal surfaces (TPMS), and design tools are provided for future TPMS-inspired materials. In Aim 1, it was demonstrated that porous PEEK designed as either a simple lattice or TPMS structure can be created via FFF. In vitro testing indicated increased preosteoblast cell activity for porous PEEK compared to nonporous, and compression testing showed that the TPMS design led to improved mechanical properties over a simple lattice. In Aim 2, the mechanical properties and degree of anisotropy induced on PEEK by the FFF printing process were explored. The elastic constants to be used in later modeling methods were determined, and relatively low anisotropy for the mechanical properties in two orientations was found. In Aim 3, models were created to relate the architecture and function of the porous PEEK. A custom MATLAB script was created to design and characterize TPMS structures, and the designer inputs were mapped to the resulting pore size and porosity. A homogenization scheme was then used to predict the properties of TPMS architectures, and a relationship between the porous characteristics and predicted elastic modulus was established. The model was validated as a part of Aim 4, in which a family of TPMS-inspired porous PEEK structures were additively manufactured and characterized. A variety of FFF porous PEEK with ranging mechanical properties was achieved, and experimental values showed good agreement with the model for the transverse loading direction, showing promise for a predictive architecture-property model for PEEK TPMS structures.
Contact Information
Natalia Broz
njb33@drexel.edu