Although the word microtia (micro-otia) literally translates as “small ear,” the clinical condition presents as anything from an ear that presents with minor deformities but with all major landmarks present, to a severely malformed ear that presents with few identifiable landmarks [1]. The remnants of the auricle may be displaced, and the condition is often associated with aural atresia, hearing loss, and craniofacial syndromes [2]. Risk factors for developing microtia include embryonic vascular disruption; environmental factors such as maternal age, illness, or medication; or genetic pathways [3].
Options for the rehabilitation of microtia have included plastic surgical reconstruction and craniofacial prosthetics with or without the use of osseointegrated implant retention mechanisms [4]. The use of autogenous rib cartilage for the reconstruction was described by Tanzer [5], and his method has formed the basis for most current surgical options. Two widely used and successful techniques based on autogenous rib grafts have been proposed by Brent [6, 7] and Nagata [8]. The Brent technique is based on the original surgical approach used by Tanzer but uses four surgical stages instead of the original six. The procedures include the fabrication of the auricular framework with costal cartilage followed by transposition of the lobule, elevation of the framework, and reconstruction of the tragus. The number of stages needed for reconstruction has often been cited as a deficiency of the technique as, in practice, the number of surgical procedures including revision procedures can often reach seven or eight. Although the Nagata technique also uses autogenous rib cartilage, it differs from the Brent technique by proposing two stages which combine framework harvesting and contouring, tragus reconstruction, and lobule transposition in one procedure followed by framework elevation at the second stage. This reduces the number of surgeries significantly; however, the procedure has been shown to result in an increased rate of complications including flap necrosis, framework extrusion or resorption, and increased donor site complications. Even in successfully treated cases with either technique, there is often an esthetic compromise resulting from the lack of definition of the concha and surrounding structures.
Advances in biomedical engineering may eliminate some of the problems with the surgical reconstruction of auricular defects. Current experiments are focused on the creation of tissue-engineered cartilage that has improved elasticity compared to harvested rib cartilage [9]. The advantage of this technique is that it allows a precise framework to be created in the laboratory rather than sculpting the cartilage in the operating room, and it also reduces the surgical invasiveness of the reconstruction [10].
An alternative approach to the treatment of microtia has been to use a prosthetic material to replace the missing or malformed portions of the ear. The use of artificial prostheses to restore facial structures has been recorded since ancient times [11], and the use of leather, fabrics, clay, and metal as prosthetic materials and retention mechanisms have all been reported [12]. The improvement in dental materials in the twentieth century allowed for increasingly realistic prosthetics; however, many of the newer materials did not possess the durability required of a long-term prosthetic restoration, nor a reliable method to attach it to a defect. The evolution of advanced silicone elastomers and the introduction of osseointegrated craniofacial implants [13] as a method of prosthetic attachment have improved the issues with durability, cosmetics, and retention. Because of the favorable conditions at the mastoid region, the success rate of osseointegrated implants retaining auricular prostheses or bone-anchored hearing aids has been exceptionally high with success rates above 95% [14].
The use of craniofacial prosthetics for the rehabilitation of microtia often results in superior esthetic results with a minimal number of surgical procedures; however, there are several marked deficiencies with this approach, chief amongst which is the removable nature of the reconstruction. The daily maintenance procedures which include careful debridement of the supporting structures with a brush and detergent can also be complicated for patients with limited mobility [15]. Despite the high success rates of auricular implants, there are multiple issues that arise with the tissue and the prostheses themselves. Local tissue reactions from erythema through granulation tissue have been noted [16]. Studies have also shown that the remake rate of an auricular prosthesis due to poor fit or discoloration is approximately 14 months. Other complications that may arise are loss of retention of the attachment clips, loosening of bar screw or abutments, separation of the retention clips or acrylic base from the silicone, and rupture of the silicone [17]. Also important is the fact that the removal of residual tissues for the placement of osseointegrated craniofacial prostheses often eliminates the possibility of future plastic surgery reconstruction.
In many cases, the ultimate choice of rehabilitation is determined by the experiences and the expertise of the treating physicians, and because of the limited number of rehabilitation centers, the cost, and the time involved in either reconstructive method, many patients choose their treatment options by what is available locally rather than explore all available treatments. A careful consideration of the position and size of the auricular remnants and the long-term needs and desires of the patient should be included in the decision-making process prior to the selection and implementation of a therapeutic protocol. The following case presentation illustrates the different results attained in a patient who had both a plastic surgical reconstruction followed by an osseointegrated craniofacial prosthesis.