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

M F Griffin,Y Premakumar,M Szarko,A M Seifalian,P E M Butler

doi:10.1007/s10439-016-1688-1

Abstract

Currently, autologous cartilage provides the gold standard for auricular reconstruction. However, synthetic biomaterials offer a number of advantages for ear reconstruction including decreased donor site morbidity and earlier surgery. Critical to implant success is the material’s mechanical properties as this affects biocompatibility and extrusion. The aim of this study was to determine the biomechanical properties of human auricular cartilage. Auricular cartilage from fifteen cadavers was indented with displacement of 1 mm/s and load of 300 g to obtain a Young’s modulus in compression. Histological analysis of the auricle was conducted according to glycoprotein, collagen, and elastin content. The compression modulus was calculated for each part of the auricle with the tragus at 1.67 ± 0.61 MPa, antitragus 1.79 ± 0.56 MPa, concha 2.08 ± 0.70 MPa, antihelix 1.71 ± 0.63 MPa, and helix 1.41 ± 0.67 MPa. The concha showed to have a significantly greater Young’s Elastic Modulus than the helix in compression (p < 0.05). The histological analysis demonstrated that the auricle has a homogenous structure in terms of chondrocyte morphology, extracellular matrix and elastin content. This study provides new information on the compressive mechanical properties and histological analysis of the human auricular cartilage, allowing surgeons to have a better understanding of suitable replacements. This study has provided a reference, by which cartilage replacements should be developed for auricular reconstruction.Electronic supplementary materialThe online version of this article (doi:10.1007/s10439-016-1688-1) contains supplementary material, which is available to authorized users.

Highlights

Microtia, translated from the Greek, means ‘little ear’ and is the medical word used to describe a small or absent ear in newborn babies.[11]
There are a number of complications with this reconstructive technique,[11] including the surgery must be delayed until the child is 6–10 years,[16] associated cartilage donor site risks including pneumothorax and chest wall deformities[7] and rib cartilage can warp over time.[2,7,18,23]
The mechanical properties of the auricular cartilage have not been extensively studied to date

Summary

Introduction

Microtia, translated from the Greek, means ‘little ear’ and is the medical word used to describe a small or absent ear in newborn babies.[11] Affecting one in 6000 live births, microtia can appear in isolation or as a feature of other syndromes such as Hemifacial microsomia or Treacher collins syndrome.[11] Currently, the gold standard surgical technique for ear reconstruction is using autologous rib cartilage.[16]. The first stage involves carving and joining together the rib cartilage to create a framework to replicate a new ear.[16]. There are a number of complications with this reconstructive technique,[11] including the surgery must be delayed until the child is 6–10 years,[16] associated cartilage donor site risks including pneumothorax and chest wall deformities[7] and rib cartilage can warp over time.[2,7,18,23] In the motivation to avoid extracting costal cartilage and provide earlier surgical intervention, alloplastic materials are currently being used to reconstruct the ear. Synthetic biomaterials offer a number of advantages including the mass production of implants with various predetermined shapes and sizes enabling ‘off-the-shelf’ products and decreased donor site morbidity.[2,3]

Objectives

Methods

Results

Conclusion