2023 Volume No 46 – pages 40-56
Title: Relationship between microscale shear modulus, composition, and structure in porcine, canine, and human temporomandibular-joint cartilage: relevance to disease and degeneration |
Authors: D Yoon, S Peralta, N Fiani, GS Reeve, I Cohen, LJ Bonassar |
Address: Meinig School of Biomedical Engineering, Sibley School of Mechanical and Aerospace Engineering, 149 Weill Hall, Cornell University, Ithaca, NY, 14853, USA |
E-mail: lb244 at cornell.edu |
Abstract: Fully understanding the complex mechanical function of temporomandibular joint (TMJ) cartilage and the compositional and structural organization that underlie it is a persistent challenge. Changes to composition, structure, and mechanics take place in naturally occurring disease in humans and canines as well as in disease models, such as in pigs. This study combined histology, Fourier transform infrared (FTIR) microscopy, Fast Fourier transform (FFT), and confocal elastography to quantify the relationship between the microscale composition, structure, and shear mechanics of porcine, canine, and human TMJ cartilage. All three species had distinct zonal mechanics and similarly high stiffness of 105~106 Pa in the hypertrophic zone. Notably, porcine tissue had a thick, compliant fibrous zone (~ 200 µm) (G* < 104 Pa) that was absent in canine and human tissue. The hypertrophic zone of all three species had high proteoglycan content, while the surface regions showed higher collagen content and fiber orientation. Small changes (two-fold) in composition led to large changes (twenty-fold) in modulus. Structural orientation of the fibers showed that high fiber orientation led to more compliant tissue mechanics while the angle of orientation was not predictive of the shear mechanics. The relationship between local composition, structure, and mechanics were similar in all three species. Despite this similarity, the immature pigs used most frequently in disease models have a very thick compliant surface region, the presence of which is likely to alter the degenerative process. |
Keywords: Elastography, rigidity percolation, Fourier Transform Infrared microscopy, collagen, proteoglycan, extracellular matrix, Fast Fourier Transform image analysis. |
Publication date: November 1st 2023 |
Article download: Pages 40-56 (PDF file) |
