The ear forms during the weeks of 4-8 of Gestation and takes the form of adult shape as a fetus. By the age of 8 years it is 80% adult size. The External Ear or Pinna consists of five anatomical subunits that make up the complex contours of the ear.: the Base, The Helix, The Anti-helix, Tragus, Anti-tragus.
In Microtia the development of the external ear is compromised and there are varying degrees of expression of the ear subunits. This ranges from no ear cartilage that resembles normality to parts of ear cartilage that resemble normality. The goal of ear reconstruction is to create all the subunits of the ear in a harmonious way.
Microtia can be classified in a number of ways based on the external appearance or surgical approach.
Our preference is to classify according to Francoise Firmin surgical classification. Type 1, Type 2, Type 3a, Type 3b.
Classically Microtia has been classified as Lobular or Conchal (Nagata Classification). Lobular Microtia is where only cartilage and skin remnant is present.
Conchal Microtia is where the concha is developed and where the tragus-anti-tragus may be developed but the rest of the contours are absent. This is further sub-classified as small Conchal or Conchal type.
The external ear has historically been reconstructed using the child’s own costal cartilage (rib) which is considered an Autologous reconstruction. Autologous reconstruction has the advantage of lower infection rate and superior aesthetic outcomes. Today this is still the preferred option. At the recent International Society for Auricular Reconstruction conference (September 2014, Paris) 90% of surgeons are using costal cartilage.
There are 4 names in ear reconstruction that are world pioneers. Tanzer who first used rib for ears, followed by Dr. Burt Brent, Dr. Saturo Nagata and Dr. Francoise Firmin. Dr. Francoise Firmin has performed thousands of ear reconstruction using first the Brent method followed by the Nagata method. Dr. Firmin has revolutionised her own ear reconstruction approach performing a two-stage reconstruction with modifications from the Nagata method.
Dr.’s Vandervord and Zoumaras have both trained with Francoise Firmin and use her technique in ear reconstruction.
Medpor is a synthetic implant made from polyethylene in the shape of the contours of the ear. It is sculpted to more closely resemble an external ear. The main advantage is that the reconstruction can occur at a younger age (age 5) and no rib harvest is required. The main disadvantages are that because it is a foreign material (Alloplastic), infection rates and extrusion rates are higher. It also means that if you have a failed Medpor reconstruction then costal cartilage reconstruction is not possible.
A prosthetic ear involves the prosthetist producing an external ear made out of silicone that resembles the contralateral ear. The principles of the procedure follow that of a Branemark dental implant. First a titanium screw/peg is positioned in the mastoid bone. Once osseo integration has occurred the abutment is externalized and the prosthetic ear attached. The disadvantages are that the prosthesis needs to be adjusted every two years due to colour changes of the prosthesis and the facial skin. The prosthesis needs to be unclipped from the abutment nightly. This type of reconstruction is reserved for those that have failed autologous or alloplastic reconstruction and in elderly patients and patients who have poor local skin conditions. It is often a last resort reconstructive option.