title: A Biomechanical Evaluation of Auricular Cartilage Autografts in Orbital Floor Defect Repair.
abstract: OBJECTIVE
  Auricular cartilage is used as a surgical implant in the management of orbital floor fractures. However, no specific parameters exist regarding the use/limitations of this potential graft. In order to determine the mechanical efficacy of adult auricular cartilage grafts, a mechanical model was developed and studied for structural threshold size limits.
  
  
  METHODS
  Thirty-seven cadaveric auricular cartilage specimens were tested in a laboratory. A plexiglass baseplate was created with four different sized holes, defined as 1.0×, 1.2×, 1.4×, and 1.6× the mean minor axis of the specimens. Each specimen was used to bridge one hole under increasing loads until mechanical failure. Structural stiffness at three different loading stages, structural failure strength, and percent failure of the entire system for each defect size was calculated.
  
  
  RESULTS
  Specimens tested on 1.0×, 1.2×, 1.4× and 1.6× defects demonstrated 0%, 0%, 20%, and 60% system failure rates, respectively. Structural stiffness curves showed a similar trend, with ANOVA demonstrating a significant difference in mechanical properties between defect sizes (p = 0.03). The curve representing 1.6 × defect size demonstrated significantly reduced structural stiffness relative to 1.0×, 1.2×, and 1.4× curves. There was no statistical difference between 1.2× and 1.4× testing sets (p = 0.09).
  
  
  CONCLUSIONS
  A clinically significant biomechanical and functional threshold exists between 1.2×and 1.4× defect sizes. Given a mean minor axis of 2.06 cm, orbital blow-out defects <2.4 cm (1.2 × 2.06 cm) are suitable for auricular cartilage grafts; fractures >2.4 cm may require a more rigid material. Cartilage grafts that allow failure, however, may better protect the globe in subsequent injury.
authors.affiliation: Department of Otolaryngology, Vascular Birthmark Institute of New York, Lenox Hill and Manhattan Eye, Ear, and Throat Hospitals, North Shore LIJ Health System , New York, New York , USA .
authors.forename: Teresa M
authors.initials: TM
authors.lastname: O
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Richard
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Cullinane
authors.forename: David J
authors.initials: DJ
authors.lastname: Binetter
authors.forename: Aaron
authors.initials: A
authors.lastname: Fay
authors.forename: Raffi
authors.initials: R
authors.lastname: Der Sarkissian
mesh_terms: D000328:Adult; D064592:Autografts; D001696:Biomechanical Phenomena; D004425:Ear Cartilage / Q000502:physiology* / Q000637:transplantation*; D004548:Elasticity / Q000502:physiology*; D006801:Humans; D009917:Orbital Fractures / Q000601:surgery*; D019651:Plastic Surgery Procedures; D020858:Tissue and Organ Harvesting; D014182:Transplantation, Autologous
keywords: Auricular cartilage; biomechanical testing; blow-out fracture; orbital implant; orbital trauma