Otoplasty

Anatomy and Physiology

Before surgical correction of the ear, a fundamental understanding of the embryology and anatomy is necessary.  Development of the ear begins with the otic placode which presents during the 3rd week of gestation. Cartilage formation is present in week 7.  The hillocks of His fuse by week 12 and the antihelix then furls between weeks 12 to 16. Finally, the helix furls at 6 months. The hillocks of His are numbered one to six, and they include tragus, helical crus, helix, antihelix, antitragus, and lobule.[3]  The first three hillocks derive from the first pharyngeal arch, and the hillocks 4, 5, and 6 derive from the second pharyngeal arch.

Indications

To understand the indications for performing otoplasty, one must appreciate facial analysis.  The pinna is ideally positioned approximately 15 to 20 mm from the helical rim to the scalp. Prominauris, which is the main indication for performing otoplasty, is seen when the auriculocephalic angle is greater than 30 degrees.  The ideal auriculocephalic angle ranges from 20 to 30 degrees. Additionally, the vertical height of the ear should be approximately six centimeters.[4]  The width of the external ear should accordingly be about 55% of his length, averaging about 35 millimeters.  The distance between the lateral helix to mastoid skin should be approximately 2 to 2.5 centimeters.[5]  Upon further facial analysis, parallel lines can be drawn in the plane of the nasal dorsum and the long axis of the ear.  The external ear should have about 15 degrees of posterior rotation from the vertical plane. The length of the ear should be equal to the length of the nose from the nasion to the subnasale.  Also, the superior edge of the ear should lie at the level of the eyebrow, and the inferior edge should lie at the level of the nasal ala. The conchomastoid angle should be approximately 90 degrees, and the conchoscaphalic angle should be 90 degrees.[4]  The skin of the external ear is tightly adherent to the underlying cartilage anteriorly and loosely attached posteriorly.

Innervation of the external ear is elaborate and involves multiple cranial nerves which include: auriculotemporal nerve from the trigeminal nerve, facial nerve, glossopharyngeal nerve, Arnold’s nerve from the vagus nerve, and nerves from the second and third cervical plexus.[5]  As a result, adequate local anesthesia can be difficult to achieve.  The external ear receives vascular supply by the superficial temporal artery, the posterior auricular artery, and the lesser occipital arteries.  Prominauris is the primary indication for otoplasty, and as such is seen in approximately 5% of Caucasians.[6]  This auricular condition can be inherited in an autosomal dominant fashion, and many patients report a family history.  The etiology of prominauris is related to two main factors which are a poorly developed antihelical fold and excessive conchal cartilage.  The most common cause is the poorly developed antihelical fold with excessive conchal cartilage being the second most common cause. The surgery should be performed at 5 to 6 years old when the ear has reached 90% of its adult size, and the cartilage has increased in stiffness.

Technique or Treatment

The Mustarde technique treats the underdeveloped antihelical fold.  When examining the ear the surgeon should apply gentle pressure to form the planned antihelical fold.  Then mattress suture points should be marked 8 mm on each side of the new antihelical fold. Hydrodissection with local anesthetic is critical to promote anesthesia and hemostasis; 1% local lidocaine with epinephrine 1 to 100,000 is typically an acceptable local anesthetic. Cartilage tattoo can be performed with methylene blue to mark the cartilage site of suturing.  A postauricular incision is made to provide access for the sutures. There is an option to score the cartilage which can help weaken it to ensure that the cartilage loses its elasticity. The horizontal mattress sutures should include three separate sutures from superior to inferior about 10 mm apart.[2]  The Furnas technique focuses on correcting excessive conchal cartilage.  This technique involves using roughly four permanent conchomastoid sutures. These sutures need to go through the lateral perichondrium to the mastoid periosteum while avoiding the anterior conchal skin.[1]  The Davis technique, which involves removing conchal cartilage to treat excessive cartilage, may also be a surgical option.[5]  The postoperative dressing should include a xeroform gauze which is tightly packed around the external ear followed by padding with fluffs and a mastoid dressing which does not cover the eyes. Most dressings should be removed on postoperative day one to ensure that there is no hematoma.

Complications

Complications largely divide into early and late complications.  Early complications involve hematoma, bleeding, postoperative infections including perichondritis, dehiscence, and necrosis of the skin.  The most worrisome postoperative complication is a hematoma. Hematoma formation can lead to cartilage and skin necrosis. If not addressed immediately, the hematoma can progress to infection which could worsen cartilage necrosis and lead to cauliflower deformity. Cartilage necrosis can also result from over tightening of the sutures and sometimes excessive pressure from the dressing. Postoperative hematomas are usually seen between one to three days after surgery. Pain is one of the main symptoms and should prompt a timely examination.

Other late complications include excessive scarring suture extrusion, hypersensitivity, and most importantly poor aesthetic outcomes. Unsatisfactory aesthetic outcomes are the most common complication of otoplasty.[5]  The aesthetic complications are notable. The telephone ear deformity is related to the overcorrection of the middle mattress suture relative to the superior and inferior sutures.  The reverse telephone ear results from over tightening the inferior and superior Mustarde sutures. The vertical post deformity is a result of improperly placed sutures which leaves a sharp vertical fold in the antihelix.  The hidden helix complication is another result of overtightening the Mustarde sutures so that the antihelix is not visible from an anterior facial view.[5]

Clinical Significance

A proper understanding of the diagnosis, indications, and surgical techniques will lead to positive outcomes in otoplasty.

Enhancing Healthcare Team Outcomes

The correction of prominauris has traditionally been under the specialties of plastic surgery and otolaryngology. Although otoplasty is typically an outpatient procedure, it still requires a team approach. The child’s pediatrician most often refers these patients to the surgeon, which requires an understanding of the diagnosis and direct communication with the surgical practice, as well as knowledge of the appropriate timing of referral and repair. If a wound infection and subsequent perichondritis were to develop, consulting with an infectious disease pharmacist may also be warranted to help guide antibiotic selection. The earlier a complication is recognized, the better the prognosis and subsequent cosmetic outcome (Level V).