Title
Exploring the Correlation Between Functional Gradients in Material Properties and Solute Diffusion Across the Osteochondral Interface
Author
Cazier, Jordi (TU Delft Mechanical, Maritime and Materials Engineering)
Contributor
van Osch, G.J.V.M. (mentor) 
Mirzaali, Mohammad J. (mentor)
Degree granting institution
Delft University of Technology
Programme
Biomedical Engineering
Date
2023-09-21
Abstract
The solute transport across the osteochondral (OC) interface is of crucial metabolic importance for a normal function of articular cartilage, and, therefore, for the OC interface as a whole. A better understanding how the mechanical- and physiological properties of the OC interface affect the solute transport across the OC interface could lead to new insights in repair strategies. The aim of this master’s thesis was to investigate how graded mechanical- and/or physiological properties of the OC interface affect the solute transport across the OC interface.
A combination of computational modelling and experimental diffusion tests on GelMA-based hydrogel plugs was used to approach the goal. Regarding the computational model, first, a multi-zone biphasic-solute finite element model that accurately replicates axial solute transport across the OC interface was designed and validated. Second, a power law function was used to apply several gradients on the initial values of the solid volume fraction (SVF), diffusion coefficient, and elastic modulus across the OC interface to study the effect of each parameter on the solute diffusion across the OC interface. On the experimental front, attempts were made to 3D-print GelMA-based hydrogel plugs but all failed. Alternatively, five groups (n = 3) of hydrogel plugs were created, each of which underwent different UV curing time, by casting GelMA into cylindrical plugs. Axial diffusion of an alizarin red solution through the hydrogel samples was recorded using a digital camera.
The results of the computational model show that only the SVF plays a small role in the height of the equilibrium concentration reached in the subchondral bone layer. However, the influence of both the SVF and diffusion coefficient on the time when the equilibrium concentration is reached in the subchondral bone is considerably large. It is shown that the elastic modulus has a negligible influence on the solute transport. Regarding the experimental diffusion tests, air bubbles and/or sincere light reflections made all but six hydrogel plugs unusable for further analysis. A relationship between sample thickness and diffusion is observed in the remaining hydrogel samples. The results of the SVF computational model and experimental diffusion tests were compared, but sufficient experimental data was lacking to draw any solid conclusions from this comparison.
This master’s thesis provides a new computational model of the OC interface which allows the implementation of graded parameters across the OC interface. It is concluded that the current experimental set-up is not suitable for obtaining consistent data on solute transport across hydrogel plugs. Suggestions to improve the experimental set-up are made.
Subject
Functional Gradients
Finite Element Method
Finite Element Analysis
Osteochondral Interface
Diffusion
Computational modelling
To reference this document use:
http://resolver.tudelft.nl/uuid:abf70d73-71b0-43ca-805f-b894481f2fa8
Embargo date
2025-09-21
Part of collection
Student theses
Document type
master thesis
Rights
© 2023 Jordi Cazier