Microtia Repair: The Firmin 2 Stage Technique

Chapter Authors
Dr. Mai Thy Truong, MD, Clinical Associate Professor of Otolaryngology — Head & Neck Surgery (OHNS) and, by courtesy, of Pediatrics, Fellowship Director of Pediatric Otolaryngology
Kay Chang, MD
Professor of Otolaryngology — Head & Neck Surgery (OHNS) and, by courtesy, of Pediatrics

The classes of microtia according to pinna size and subunits affected. For the purpose of this classification, the subunits of the pinna are helix, antihelix, scapha, tragus, antitragus, concha, and lobule. Class 1: a small ear with all of the subunits present, although some may be abnormally shaped; Class 2: a small ear with missing subunits; Class 3: a classic peanut ear with no recognizable subunits except for the lobule; Class 4: anotia (the complete absence of a pinna). Microtia surgery involves multiple stages. Some surgeons employ two stages, others employ three or more. Stages are usually spaced by 3 to 4 months at a minimum. In this chapter, we illustrate a two-staged technique as described by Dr. Francoise Firmin. Foundations from Dr. Burt Brent's four-staged technique and Dr. Satoru Nagata's two-staged technique can be appreciated.
Stage 1 initiates with planning the placement of the reconstructed ear. Standing at the head of the bed, a ruler is used to mark the inferior point of the lobule in symmetry with the nonmicrotia ear. In bilateral microtia, the commissures of the eye and mouth are used as reference points, with the new pinna placed as high as permitted by the demarcation of non–hair-bearing retroauricular skin.
The distances from the lateral canthus of the eye to the root of the helix (X), and the lateral commissure of the mouth and the anterior point of the lobule (Y), are measured on the unaffected side. These measurements are used for placement of the reconstructed ear. The superficial temporal artery is identified with Doppler and marked.
The rotation of the ear. The pinna has a polarity, or an axis of rotation. First, on the nonmicrotia side, the slope of the nose is drawn on the face, and the angle of the pinna is drawn, as determined by the longest measurement of the pinna. The angle between these is measured. On the microtia side, the slope of the nose is repeated, the angle is measured, and the axis of the reconstructed ear is drawn on the face. This becomes a guide for the planned rotation of the reconstructed ear.
Markings for the planned placement of the reconstructed ear are kept in view throughout the procedure.
Harvest of rib cartilage is planned from the sixth to ninth cartilage. The ninth cartilage is obtained when prominent. In this technique, cartilage is harvested from the ipsilateral side of the microtia ear.
The typical plan for the harvested cartilage for microtia reconstruction of the left ear: The floating eighth rib often serves as the helical rim and, when robust, can also be used for the antihelix. The synchondrosis of the sixth and seventh ribs often provides the base plate. Extra pieces of cartilage serve to become the P1 (Projection 1) piece as described by Dr. Firmin, and banked pieces for the elevation of the ear in the second stage. Banked cartilage pieces are placed in a pocket of the subcutaneous skin of the chest closure secured to the dermis.
The helix is often carved from the eighth rib cartilage, and is shaped to sit flat on the base plate. The center is gouged to create a curved surface and allow for ease of curvature.
The base plate is prepared by removing the perichondrium on the anterior surface. It is kept intact on the posterior surface. Often, marks are made on the cartilage to delineate the placement of the antihelix and the scapha in the correct orientation. This can be done by inking the cartilage based on a drawing of the opposite ear drawn on X-ray film. The X-ray film is then flipped to show the mirror image, and drawn on paper. The paper is then dipped in water-soluble ink, and stamped on the cartilage. Carving begins with reducing the lobule and gouging the scapha. Then, the triangular fossa can be deepened. Posteriorly, the edge of the cartilage is beveled so that the back surface of the ear is sloped.
The tragus–antitragus complex is a challenging three-dimensional entity that has convexities and concavities. The intertragal notch is the thinnest portion.
The antihelix is first to be placed on the baseplate.
A silicone block is used to secure the cartilage as the individual pieces are constructed together. Double-ended 5.0-steel sutures are used to suture the cartilage. Steel suture is preferred to prevent future migration of cartilage pieces when exposed the tensile strength of the skin. Double-ended steel sutures can be made by hand threading 5.0-steel wire through the eyelet of small, straight cutting needles.
View of the undersurface: the cartilage construct is lifted away from the silicone block, the needles cut, and the wire sutures are twisted together, trimmed, and ends turned down onto the undersurface of the cartilage. As each cartilage piece is added to the construct, the silicone block provides the stability needed for suturing.
Once the antihelix is placed, the P1 piece is secured to the baseplate in preparation for the helix. The P1 piece allows for the crus of the helix to drop to a lower plane while providing stabilization to the curve of the helix.
The helix is then secured with steel sutures.
The tragus–antitragus complex is placed and secured to the baseplate and the P1 elevation piece.
An anterior view allows appreciation of the appropriate contours of the ear construct.
Preparation of the skin for a type 2 skin approach as described by Dr. Firmin. This approach is often chosen for class 3 microtia when the inferior portion of the microtia remnant will be used to make the lobule of the new pinna. With the planned outline for the ear reconstruction drawn relative to the microtia ear, the ear is pulled until a natural point is found where the lobule meets the planned incision with the least amount of tension on the remnant. This is where the lobule will be transposed. The X marks the point where the lobular skin meets the planned point of transposition.
The skin is then divided and a pocket is dissected in the lobule to allow insertion of the cartilage framework. Best results are obtained when the cartilage inserts well into the lobule, near the tip.
As the lobule is turned to its new location, an X-ray template of the base plate can be used to check the insertion of the lobule.
The posterior skin is incised to allow the transposition of the lobule to the new location.
The retroauricular skin is then dissected, and the cartilage remnant is removed from the microtia ear. This skin will drape over the cartilage construct, so care must be used to maintain the skin vascularity and the same thickness throughout.
The cartilage remnant is removed. In many cases, dissection of the cartilage remnant is not a trivial dissection and requires a meticulous degloving of the cartilage while maintaining skin flap integrity and vascularity.
Skin dissection must go beyond the planed placement of the ear to allow for the skin to drape over the contours of the construct, and allow for placement of a posterior drain.
The transposed lobule is then sutured in place posteriorly, known as the “adhesion of the lobule,” with a 4-0 absorbable suture.
The cartilage construct is inserted into the lobule and placed under the skin. Drains are placed anteriorly and posteriorly to allow suction of the skin to aid resection of excess skin. Typically, 10F Blake drains are used, under low suction, classically maintaining suction with test tubes.
Excess skin is excised. Incisions are hidden in the natural junction of subunits, and trifurcations of the closure are avoided if possible.
The skin is closed with 6.0 nylon sutures, and the drains are kept to suction for 3 to 5 days. Postoperatively, test tubes are changed every 3 to 4 hours to maintain suction while the construct heals.
Stage 2: elevation of the ear. The initial step of stage 2 involves planning the retroauricular incision. Care must be taken to be off the edge of the cartilage framework. A releasing incision is designed to allow advancement of the retroauricular skin.
Elevation of the superior flap. It is essential to elevate only skin and leave the fascia and periosteum overlying the cortex intact.
Elevation of the inferior flap. At this step, the areolar tissue overlying the mastoid can be thinned to deepen the sulcus.
In preparation for creation of a postauricular sulcus, the auricular construct is elevated. It is essential not to interrupt the enveloping tissue surrounding the cartilage. Any exposure of cartilage will likely lead to wound dehiscence, as the skin graft will not integrate with the cartilage.
A thin split-thickness skin graft (STSG) is harvested from the hair-bearing scalp as this yields the best texture and color match for the ear. In addition, the donor site will be hidden by hair growth. The typical graft measurement is 5 × 10 cm. Some surgeons harvest skin grafts from the abdomen, groin, arm, or thigh. The graft must be cleaned of hair with gentle wipes from a wet gauze.
Projection of the ear is achieved through cartilage placed in tunnels, a Type D elevation technique as described by Dr. Firmin. Additionally, cartilage can be tunneled under the antihelix to deepen the conchal bowl (not shown here). This cartilage was banked in a subcutaneous pocket of the chest site during stage 1 and reopened in stage 2.
To position the incision behind the pinna and to reduce the size of the skin graft needed, the retroauricular skin flap is advanced and tacked down to the mastoid fascia using 4–0 absorbable suture.
The inferior flap is similarly advanced and the resulting overlap of the skin flaps is resected and sutured closed. An axial view shows the newly created posterior auricular sulcus which must be covered with the skin graft.
The skin graft is tacked at the superior and inferior aspects of the ear and the anterior rim of the graft is trimmed to give a fresh margin conforming to the shape of the incision. An axial view illustrates how this first skin graft is used to drape the posterior surface of the ear to the sulcus.
The skin graft is sewn to the anterior margin leaving some of the suture tails long to anchor a bolster once the skin graft is in place. When draping the skin graft toward the postauricular sulcus, it is sometimes necessary to trim a wedge to achieve optimal contour as the skin drapes behind the ear.
Excess skin graft not needed for the posterior surface of the pinna is trimmed and saved to cover the mastoid defect. This creates a suture line in the sulcus so that the graft does not cross the sulcus. Grafts which cross the sulcus tend to blunt, whereas the suture line tends to create a deeper and more natural sulcus.
The posterior surface of the construct is covered with skin graft and sutured to the sulcus, leaving a triangular defect on the mastoid that needs skin coverage.
The excess skin is placed over the mastoid defect and secured with clamps before it is cut to shape and sutured in place (STSG 2).
At the completion of stage 2, the ear is elevated, and the postauricular sulcus is created from two pieces of STSG. Bolster sutures are in place.
To adhere the skin grafts to the opposing surfaces, some surgeons use either a bolster or a mini-flap drain (e.g., 7 or 10 Fr). Bolsters or drains are left in for 4 days. The skin graft donor site along the scalp is often covered with a topical hemostatic dressing and nonocclusive gauze dressing.

 

Dr. Jackler and Ms. Gralapp retain copyright for all of their original illustrations which appear in this online atlas.  We encourage use of our illustrations for educational purposes, but copyright permission should be sought before publication or commercial use. To request permission for publication or commercial use please contact Christine Gralapp (eyeart@chrisgralapp.com, https://www.chrisgralapp.com).