Comparison of two contrast-enhancing staining agents for use in X-ray imaging and digital volume correlation measurements across the cartilage-bone interface

Sarah Davis; Aikaterina Karali; Tim Balcaen; Jurgita Zekonyte; Maïté Pétré; Marta Roldo; Greet Kerckhofs; Gordon Blunn

doi:10.1016/j.jmbbm.2024.106414

Comparison of two contrast-enhancing staining agents for use in X-ray imaging and digital volume correlation measurements across the cartilage-bone interface

J Mech Behav Biomed Mater. 2024 Apr:152:106414. doi: 10.1016/j.jmbbm.2024.106414. Epub 2024 Jan 20.

Authors

Sarah Davis¹, Aikaterina Karali², Tim Balcaen³, Jurgita Zekonyte², Maïté Pétré⁴, Marta Roldo⁵, Greet Kerckhofs⁶, Gordon Blunn⁵

Affiliations

¹ School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK; School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK. Electronic address: sarah.davis@port.ac.uk.
² School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK.
³ Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Leuven, Belgium.
⁴ Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Heverlee, Belgium.
⁵ School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK.
⁶ Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Department of Materials Engineering, KU Leuven, Heverlee, Belgium; Prometheus, Division for Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium.

PMID: 38277908
DOI: 10.1016/j.jmbbm.2024.106414

Abstract

Objective: The pathogenesis of osteoarthritis (OA) is associated with subchondral bone changes, which is linked to abnormal strain distribution in the overlying articular cartilage. This highlights the importance of understanding mechanical interaction at the cartilage-bone interface. The aim of this study is to compare solutions of two contrast-enhancing staining agents (CESA) for combining high-resolution Contrast-Enhanced X-ray microfocus Computed Tomography (CECT) with Digital Volume Correlation (DVC) for full-field strain measurements at the cartilage-bone interface.

Design: Bovine osteochondral plugs were stained with phosphotungstic acid (PTA) in 70% ethanol or 1:2 hafnium-substituted Wells-Dawson polyoxometalate (Hf-WD POM) in PBS. Mechanical properties were assessed using micromechanical probing and nanoindentation. Strain uncertainties (from CECT data) were evaluated following two consecutive unloaded scans. Residual strains were computed following unconfined compression (ex situ) testing.

Results: PTA and Hf-WD POM enabled the visualisation of structural features in cartilage, allowing DVC computation on the CECT data. Residual strains up to ∼10,000 μɛ were detected up to the tidemark. Nanoindentation showed that PTA-staining caused an average ∼6-fold increase in articular cartilage stiffness, a ∼19-fold increase in reduced modulus and ∼7-fold increase in hardness, whereas Hf-WD POM-stained specimens had mechanical properties similar to pre-stain tissue. Micromechanical probing showed a 77% increase in cartilage surface stiffness after PTA-staining, in comparison to a 16% increase in stiffness after staining with Hf-WD POM.

Conclusion: Hf-WD POM is a more suitable CESA solution compared to PTA for CECT imaging combined with DVC as it allowed visualisation of structural features in the cartilage tissue whilst more closely maintaining tissue mechanical properties.

Keywords: Cartilage mechanics; Cartilage-bone interface; Contrast-enhanced X-ray computed tomography; Digital volume correlation.

Publication types

Comparative Study

MeSH terms

Animals
Cartilage, Articular* / pathology
Cattle
Contrast Media*
Staining and Labeling
Tomography, X-Ray Computed / methods
X-Rays

Substances

Contrast Media