Additive Manufacturing of Polyetheretherketone for Intervertebral Devices

Thursday, July 18, 2019

10:00 AM-12:00 PM

BIOMED PhD Research Proposal

Title:
Additive Manufacturing of Polyetheretherketone for Intervertebral Devices: Evaluating the Impact of Process Parameters in Interfacial Bonding Strength for Fused Filament Fabricated PEEK

Speaker:
Cemile Basgul, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University

Advisor:
Steven M. Kurtz, PhD
Research Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Details:
Spinal cages are load bearing surgical implants used when there is a need for stabilization of the spine due to back pain caused by degenerative disc disease and spondylolisthesis. Polyetheretherketone (PEEK) intervertebral cages were introduced as an alternative to titanium spinal cages to overcome the disadvantages, such as radiopacity and excessive stiffness, which causes subsidence in the healthy vertebrae. However, aside from its being radiolucent and a closer elastic modulus to the cortical bone than titanium, PEEK’s hydrophobicity inhibits osseointegration, which may result in unsatisfactory outcomes of fusion.

There have been efforts to introduce modifications to PEEK to create surface porosity and hence improve osseointegration. However, traditional manufacturing techniques is restricted to certain areas of outer surfaces. The need of customization in the design and fast reproducibility of intervertebral devices can be satisfied by additive manufacturing (AM). Fused filament fabrication (FFF) is one of the AM techniques that has been investigated to manufacture spinal implants, including spinal cages. FFF was shown as a feasible manufacturing method for PEEK spinal cages; however, interlayer delamination was shown as the failure mechanism under load. Layer adhesion is important and directly related to FFF constructs’ mechanical properties. Interfacial bonding between the deposited layers is crucial for FFF PEEK implants, especially when they are exposed to daily loads in the body, such as spinal cages. Poor layer adhesion is related to uncontrolled cooling conditions of the printed parts on the heated bed and therefore might be improved by overall parametric optimization.

Modeling for parameter optimization was investigated before for low temperature polymers, such as polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). PEEK, however, is a high temperature biomaterial with a melting temperature over 300℃, and was not the focus of the research before in this field. This thesis aims to provide a direct assessment of the interfacial strength of 3D printed PEEK spinal cages and will establish a quantitative model for an interlayer debonding phenomenon that has been stated for the fused filament fabrication of PEEK. Use of the model will allow for optimizing the parameters for FFF PEEK cages, providing crucial insights into a thermally-controlled environment of PEEK printing. This approach may be leveraged for modifying FFF technologies to achieve better interlayer strength for PEEK spinal cages, as well as other biomedical applications for PEEK.

Contact Information

Ken Barbee
215-895-1335
barbee@drexel.edu