title: 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 collagen 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 are 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.
  
  
  METHODS
  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 quasistatic 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 two-term hyperelastic soft tissue constitutive models successfully fit both human and porcine nonlinear elastic behavior (mean R(2) fit >0.95).
  
  
  CONCLUSIONS
  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.
  
  
  METHODS
  NA
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Division of Pediatric Otolaryngology, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: David A
authors.initials: DA
authors.lastname: Zopf
authors.affiliation: Department of Biomedical Engineering, Department of Mechanical Engineering and Department of Surgery, University of Michigan, Ann Arbor, Michigan, U.S.A.
authors.forename: Colleen L
authors.initials: CL
authors.lastname: Flanagan
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Division of Pediatric Otolaryngology, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Hassan B
authors.initials: HB
authors.lastname: Nasser
authors.affiliation: Department of Biomedical Engineering, Department of Mechanical Engineering and Department of Surgery, University of Michigan, Ann Arbor, Michigan, U.S.A.
authors.forename: Anna G
authors.initials: AG
authors.lastname: Mitsak
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Division of Pediatric Otolaryngology, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Farhan S
authors.initials: FS
authors.lastname: Huq
authors.affiliation: Department of Biomedical Engineering, Department of Mechanical Engineering and Department of Surgery, University of Michigan, Ann Arbor, Michigan, U.S.A.
authors.forename: Vishnu
authors.initials: V
authors.lastname: Rajendran
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Division of Pediatric Otolaryngology, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Glenn E
authors.initials: GE
authors.lastname: Green
authors.affiliation: Department of Biomedical Engineering, Department of Mechanical Engineering and Department of Surgery, University of Michigan, Ann Arbor, Michigan, U.S.A.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Hollister
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001696:Biomechanical Phenomena; D001706:Biopsy; D002102:Cadaver; D004425:Ear Cartilage / Q000166:cytology* / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013552:Swine
keywords: Auricular cartilage; auricular tissue engineering; biomechanics; cartilage computational modeling; nonlinear elasticity