Investigation of Modular Taper Material and Design Factors
Thursday, June 25, 2020
9:00 AM-11:00 AM
BIOMED PhD Thesis Defense
Title:
Investigation of Modular Taper Material and Design Factors That Affect Mechanically-Assisted Crevice Corrosion at the Femoral Head-Stem Interfaces in Total Hip Arthroplasties
Speaker:
Sevi Berna Kocagoz, 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:
Modularity in total hip arthroplasty (THA) designs allows intraoperative flexibility for the surgeon to adapt leg length and femoral offset to the individual anatomy and gives the option to keep a well-fixed femoral stem and revise femoral head and acetabulum, as needed. The clinical use of these designs led to increased reports of adverse local tissue reactions (ALTRs) to the release of metallic material, and corrosion at the modular tapers became a clinical concern. Taper corrosion poses a clinical risk for all components that employ any modular connection. There is a need to systematically investigate the factors that increase the risk of taper corrosion.
The process leading to corrosion and metallic particle release from modular connections is known as mechanically assisted crevice corrosion (MACC). The severity of MACC at tapers depends on a combination of mechanical, electrochemical, geometrical, material, and solution conditions. The goals for this doctoral research were to:
1. Investigate the difference of visual fretting-corrosion damage in the femoral head-stem taper in a matched cohort study comparing total hip arthroplasty with ceramic femoral heads and CoCrMo femoral heads.
2. Develop a method for measuring taper angle clearance. Use developed method to measure retrievals and compare taper corrosion between ceramic and CoCr heads in retrievals using a matched cohort study design as a function of taper angle clearance.
3. Develop and validate a quantitative method to estimate volumetric material lost from the taper surfaces. Use developed method to measure retrievals and compare taper corrosion between ceramic and CoCr heads in retrievals using a matched cohort study design as a function of volumetric material loss.
4. Investigate fretting-corrosion behavior of PEEK-metal interfaces and compare with metal-metal interfaces using a previously developed in vitro pin-on-disk fretting-corrosion test system. Mitigation of taper fretting-corrosion using alternative materials.
The key findings of this research have shown that there was no correlation between taper angle clearance and volumetric material loss. There was a significant correlation between femoral head material and volumetric material loss. Using ceramic heads reduced the total volumetric material loss from femoral head-stem taper junctions. The volumetric material loss from femoral head taper surfaces was higher compared to their mated femoral stem taper surfaces in THAs using CoCrMo alloy femoral heads. Lastly, the fretting currents generated between PEEK-metal material couples was lower compared to metal-metal material couples tested in vitro using a tribocorrosion pin-on-disk test setup.
Contact Information
Natalia Broz
njb33@drexel.edu