Biomechanical evaluation of human and porcine Auricular cartilage

Abstract

Objective The mechanical properties of normal auricular cartilage provide a benchmark against which to characterize changes in auricular structure/function due to genetic defects creating phenotypic abnormalities in collage subtypes. Such properties also provide inputs/targets for auricular reconstruction scaffold design. Several studies report the biomechanical properties for septal, costal, and articular cartilage. However, analogous data for auricular cartilage is lacking. Therefore, our aim in this study was to characterize both whole ear and auricular cartilage mechanics by mechanically testing specimens and fitting the results to nonlinear constitutive models. Study Design Mechanical testing of whole ears and auricular cartilage punch biopsies. Methods Whole human cadaveric ear and auricular cartilage punch biopsies from both porcine and human cartilage were subjected to whole ear helix down compression and quasi-static unconfined compression tests. Common hyperelastic constitutive laws (widely used to characterize soft tissue mechanics) were evaluated for their ability to represent the stress-strain behavior of auricular cartilage. Results Load displacement curves for whole ear testing exhibited compliant linear behavior until after significant displacement where nonlinear stiffening occurred. All five commonly used 2-term hyperelastic soft tissue constitutive models successfully fit both human and porcine nonlinear elastic behavior (mean R2 fit greater than 0.95). Conclusion Auricular cartilage exhibits nonlinear strain stiffening elastic behavior that is similar to other soft tissues in the body. The whole ear exhibits compliant behavior with strain stiffening at high displacement. The constants from the hyperelastic model fits provide quantitative baselines for both human and porcine (a commonly used animal model for auricular tissue engineering) auricular mechanics.

Mechanical and biochemical mapping of human auricular cartilage for reliable assessment of tissue-engineered constructs

“…Since AUR cartilage displays a different tissue composition and architecture to articular cartilage, it cannot be assumed that models used for articular cartilage would yield relevant results for AUR. Only very recently, a first model has been proposed for AUR cartilage (Zopf et al, 2015).…”

“…The structure-function relationship linking composition and architecture to mechanical competency has been established for these cartilage subtypes (Humzah and Soames, 1988; Mow and Guo, 2002). The mechanical properties of AUR cartilage are, however, sparsely investigated (Naumann et al, 2002), and limited data are available for human cartilage Zopf et al, 2015). Unlike hyaline and fibrocartilage, AUR cartilage contains large amounts of elastin (ELN) fibers.…”

Biomechanical Characterisation of the Human Auricular Cartilages; Implications for Tissue Engineering

“…The maximum tensile strength and young’s modulus under tension was calculated with an observed young’s modulus of 5.02 ± 0.04 MPa 4. Similarly, Zopf et al evaluated the biomechanical auricular cartilage of four patients, observing that the whole ear exhibited nonlinear strain-stiffening elastic behaviour that is similar to other soft tissues in the body 24. To date one study has evaluated the mechanical properties of fresh auricular tissue based on the different region of the auricle.…”

Influence of backside loading on the floating mass transducer: An in vitro experimental study

“…In addition, the FMT was glued to cylinders of cartilage of equivalent sizes, that is 1.0 mm in diameter and 1.0 mm or 1.5 mm of length. All cartilage was harvested from a commercially obtained pig ear and was kept well hydrated with saline distributed by an aerosol can throughout the measurements . Moreover, the commercially available alloplastic Round Window Soft‐Coupler (RWSC) (RW‐Soft‐Coupler ® , MedEl, Innsbruck, Austria) was glued with its base to the rear side of the FMT.…”