Medical Therapy
Nonsurgical treatment of microtia is primarily with prosthetic replacement. This method of treatment has the advantage of providing an ear with a very natural appearance and should be offered to the patient or their parents as an alternative to surgical reconstruction. Prosthetic replacement may be the best alternative in a person with complete anotia because reconstruction of the lobule is a challenging task and is often met with less than optimal results.
Disadvantages of prosthetic reconstruction include the fact that it must be attached to the side of the head. Adhesives may be used, but these have limited strength. Osseointegrated implants to the temporal bone may be joined to a metal framework, which is then connected to the prosthesis by means of magnets. This is a somewhat more secure option than adhesives but is not without problems. The prosthesis is expensive and also wears out, needing frequent replacement. The prosthetic has a tendency to fade when exposed to sunlight or seawater. Obviously, a prosthetic is insensate and feels like an unnatural appendage or ornament rather than part of a patient's own body. The potential also exists for social embarrassment if the prosthesis becomes unglued or detached in public.
Surgical Therapy
The mainstay of surgical therapy for microtia reconstruction has been costal cartilage rib grafting. This is typically a 3-4 stage procedure, whereby the ear is created from local tissue flaps and a cartilage framework carved from rib cartilage.
The first stage involves the carving of rib cartilage into the shape of an external ear and placing the graft into a pocket created in the skin overlying the temporal bone. In the second stage, a Z-plasty is performed, which rotates the auricular remnant inferiorly, creating a lobule. The third stage elevates the cartilage graft off the temporal bone, creating a postauricular sulcus with a split-thickness skin graft. These 3 stages are spaced at 6-month intervals to allow for reestablishment of blood supply between procedures. A fourth stage may be added later to create a neotragus.
Another option with microtia reconstruction is the use of porous polyethylene (Medpor as seen in the image below) as the framework. Proponents for the use of this alloplastic option cite the ability to start the reconstruction at an earlier age, as young as age 3. This is possible because one does not need to wait for rib cartilage to achieve appropriate size. Another advantage is avoiding the pain and potential deformity of the rib donor site. The reconstruction may be completed in 2 stages, as opposed to 4 with the rib option.
The final cosmetic result may be superior with alloplasts because framework projection is easier to achieve, the need to sculpt is limited, and the alloplast does not resorb. On the other hand, a danger of extrusion or infection exists with alloplast that is only rarely seen with cartilage. The first stage of alloplastic reconstruction generally takes longer to perform but is associated with a shorter hospital stay. Shaving half the head is necessary, in order to make a long transverse incision to lift a temporoparietal flap. This may result in areas of temporary or permanent alopecia.
As with reconstruction using cartilage, a template from the normal ear is used. The auricular framework is constructed from 2 components, which are trimmed to fit the template. The 2 components are welded together using thermal cautery or are sutured together with permanent suture. A temporoparietal flap measuring 12 X 12 cm is harvested through a long horizontal incision 6 cm superior to the future cephalic border of the helical rim. The temporoparietal flap covers the alloplast, and a full-thickness skin graft is placed on the flap. Split-thickness grafts are preferred in heavier and older patients owing to improved rates of take. Small split-thickness grafts may be obtained from the ipsilateral scalp with minimal risk of visible scarring.
The second stage consists of lobule transposition, very similar to the second stage performed with rib cartilage. A third and fourth stage, as needed with the rib cartilage technique, are generally not needed with the alloplast option.
In the authors’ practice, families are presented with both options and are allowed to decide which option they prefer based on their understanding of the risks and benefits. Patients with prior atresia repair are encouraged to pursue the alloplast option.
Preoperative Details
Timing of reconstruction using rib is based on 2 primary factors. First, a sufficient amount of costal cartilage must exist, specifically the synchondrosis of the fifth through seventh ribs. Second, in unilateral microtia repairs, the normal ear must be at least 85% of normal adult size. Typically, sufficient size is achieved in most children by the time they are aged 5-6 years.
A retrospective study by Moon et al suggested that three-dimensional (3-D) CT scanning of the rib cage is an effective means of preoperatively evaluating the size of the eighth costal cartilage prior to its use in microtia-related ear reconstruction. The study, which involved 97 patients, found that costal cartilage lengths assessed with 3-D CT scanning correlated well with those determined intraoperatively. [4]
If the alloplastic option is considered, the patient should be evaluated for a palpable superficial temporal pulse, in order to predict adequate blood supply to the temporoparietal flap. Patients as young as age 3 may be considered for this option, and slight overcorrection of the framework should be carried out in younger patients to allow for future ear growth on the normal side.
Intraoperative Details
Rib Option
See the list below:
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Stage 1 reconstruction: Construction of the cartilaginous framework
In forming the helix of the auricular cartilage, the cartilage of the eighth rib is sutured to the carved portion of the sixth and seventh ribs. For attachment of the eighth rib cartilage, 4-0 clear nylon is used.
The root of the helix no longer is extended into the conchal bowl because the root of the helix is usually resected during the creation of the external meatus. Repositioning of the helical graft allows more of the eighth rib to be used for the posterior inferior helix, achieving improved helical relief.
In dissecting a skin pocket to receive the rib cartilage graft, limiting the amount of dissection is important. Undermining of skin should be carried out only 3-4 cm peripheral to the proposed location of the new ear. Overaggressive undermining may result in compromise of the blood supply or promote formation of a hematoma. Too large of a pocket also results in blunting of the angle between the helical rim and the side of the head, resulting in less-than-desired relief.
The incision is made near the anterior edge of the malformed auricular cartilage remnant. A small amount of cartilage is left anterior to the incision to act as a tragus during stage 4 reconstruction. After making the incision, the natural tendency is for dissection to proceed in the sub–SMAS plane or in the thin plane that exists between the temporoparietal fascia and the temporalis fascia. However, the appropriate plane of dissection for auricular reconstruction is the plane between the temporoparietal fascia and the subdermal plexus. When in the proper surgical plane, the surgeon should be able to observe a thin layer of fat adhering to the deep layer of the dermis. This fatty layer should be removed with careful sharp dissection. Peripherally and superiorly, hair follicles are visualized and clipped at this time. Dissection into the deep layer of the dermis compromises blood supply and reduces the pliability of the skin.
Skin pliability may be improved by intraoperative tissue expansion or by mechanical stretching of the skin. Bleeding from the subdermal plexus is controlled with bipolar cautery. Avoiding the use of epinephrine in the skin flap is important to monitor blanching. Should blanching occur at the time of skin closure, sutures are removed, further dissection is performed, and intraoperative tissue expansion is repeated with moist gauze sponges.
A wedge of extra cartilage is banked deep to the scalp superiorly. This will be used as a pedicled buttress during stage 3 to aid in auricular projection. Once the rib cartilage graft has been inserted into the pocket, the incision is closed over 2 small suction drains. A 5-0 mild chromic suture for skin closure is used, avoiding the need for suture removal in less-than-cooperative children.
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Stage 2 reconstruction: Creation of the lobule
Typically, 6 months following stage 1 of the repair, the patient is ready for stage 2. The second stage involves transposition of the lobule using a Z-plasty technique. With the classic grade 3 microtia deformity, the patient usually has a well developed, although improperly positioned, lobule. Superior to this lobule is a variable amount of malformed cartilage, typically covered by a roll of redundant skin. At the time of lobule transposition, this roll of redundant skin is left attached to the lobule. This skin roll may be incorporated into the inferior helix. The result is a smoother, more natural transition from lobule to helix.
The inferior pole of the cartilage framework is delivered, and the lobule is filleted open, allowing the lobule to be wrapped around the cartilage. This avoids the problem of the lobule acquiring a "pasted on" appearance. A 2-0 nylon suture is used to approximate the posterior skin of the lobule to the deep surface of the inferior pole of the cartilage framework, thus accentuating the inferior portion of the postauricular sulcus.
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Stage 3 reconstruction: Creation of the postauricular sulcus
During this stage, an incision is made from the root of the helix anteriorly, along the top of the ear, and posteriorly into the junction of the lobule with the postauricular skin. This creates a near-total circumferential incision of the skin covering the lateral surface of the cartilaginous framework. Care must be taken when creating this incision to ensure that adequate blood supply remains to the auricular skin. Typically, if a sufficient period of time has passed since the initial placement of the cartilaginous graft (typically, a minimum of 1 y), the skin then receives most of its blood supply from the underlying cartilage and its perichondrium. If at any point the blood supply appears to be compromised, the incision is not extended as far anteriorly.
The cartilaginous graft is then elevated off the mastoid periosteum. Typically, elevation is performed to a point where the auricle is hinged anteriorly by its attachment to the preauricular skin. A sulcus is thereby created to accept a split-thickness skin graft.
Projection of the auricle is accentuated by using the previously banked cartilage from stage 1. This cartilage is left attached to the SMAS layer and raised as an inferiorly based flap. The cartilage is wedged into the depths of the new postauricular sulcus, and secured with 4-0 Vicryl suture.
A full-thickness skin graft is then harvested, typically from the groin or "bikini line" area. Split-thickness grafts are used in patients heavier than about 50-60 kg. The graft is used to cover the remaining mastoid periosteum and posterior portion of the auricular cartilage. The graft is pie-crusted and sewn in place using a running 4-0 chromic suture. Several quilting sutures are also placed through the graft to help adhere the graft to the underlying tissues. A tie-down bolster is then placed over the graft and is left in place for 6-7 days.
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Stage 4 reconstruction: Creation of a tragus
If sufficient tissues remain from the auricular remnant, these can be used to create a tragus. Typically, a tragus needs to be created de novo. This is easily accomplished by using a composite graft from the opposite ear. A skin-cartilage graft is harvested from the antihelix and conchal bowl of the normal ear.
A J-shaped incision as described by Aguilar is made anterior to the location of the external auditory meatus (assuming the patient is a candidate for external auditory canal [EAC] reconstruction). [5] The cartilage is then placed into this incision, and the skin portion of the graft is sutured anteriorly. A horizontal mattress suture is then placed through the preauricular skin and into the cartilage graft, pulling it forward and creating the tragal eminence.
Often, minor refinements to this technique are necessary. When EAC reconstruction is undertaken, the auricle may require some repositioning.
Alloplast Option
See the list below:
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Stage 1 reconstruction: Placement and covering of the framework
Once a template from the normal ear has been made and the appropriate location determined for ear placement on the malformed side, the ipsilateral side of the head is shaved up to the vertex of the scalp. The superficial temporal artery is palpated or Dopplered. The side of the head and face and the skin graft donor area are then prepared and draped. The skin graft should measure 4 cm by 12 cm, and the donor site is closed primarily with a subcuticular closure.
A 12 cm horizontal incision is made on the scalp, 6-8 cm superior to the remnant. The incision should not extend through the underlying fascia. The skin is lifted off the fascia, preserving hair follicles and identifying viable arterial and venous branches. A second incision is made in a curvilinear fashion at, or slightly peripheral to, the hairline, taking care not to jeopardize the underlying fascia. The superficial temporal artery should be ligated and divided at its frontal branch, taking care not to injure the temporal nerve.
The goal is to lift a temporoparietal flap measuring 12 x 12 cm. Once the incisions in the fascia have been made, the flap is then elevated in a superior to inferior manner and passed through the inferior, curvilinear incision. Care is taken not to injure the superficial temporal, occipital, or postauricular vessels as they enter the flap. The flap is then irrigated with saline.
The alloplastic framework is then assembled, using the template as a guide. Excess plastic material is trimmed off, and the 2 components are fixed together using a thermal cautery or 4-0 clear nylon suture. A small notch is cut in the medial side of the framework to allow a drain to pass through without pushing the framework off the side of the head. The framework is then soaked in dilute Betadine solution.
The curvilinear incision at the hairline has essentially described an antero-inferiorly based flap. This flap should now be elevated in the subcuticular plane, making a pocket into which the framework will fit. One must not "button hole" the skin. Dissection is carried out beyond the remnant cartilage and lobule. The cartilage is dissected out and discarded.
The framework is now placed into the pocket. A small suction drain is placed inferiorly through the skin and passed deep to the framework through the notch made for that purpose. The temporoparietal flap is draped over the framework, and the drain is placed on suction. One should note the presence of air leaks, and repair them with 4-0 chromic sutures. The drain is then secured on the skin. Note that neither the framework nor the flap is sutured in place.
The skin graft is then trimmed and inset in the usual fashion with 4-0 chromic suture. A second suction drain is placed under the skin and runs from a point just superior to the framework up to the vertex of the head. Whereas the first drain functions to conform the temporoparietal flap to the framework, the second acts to conform the skin graft to the temporoparietal flap, as well as to prevent the accumulation of fluid under the scalp. The scalp incision closure must therefore be airtight. A subcuticular closure is used. No bolster is placed on the skin graft, but a cup type dressing (Glasscock) with a Velcro strap is used to protect the operative site.
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Stage 2 reconstruction: Creation of the lobule
As soon as 4 months following stage 1 of the repair, the patient may be ready for stage 2. As with the rib cartilage option, the second stage involves transposition of the lobule using a Z-plasty technique.
The inferior pole of the framework is delivered, taking care not to expose the plastic. The lobule is filleted open, allowing the lobule to be wrapped around the framework. A 2-0 nylon suture is usually not needed to approximate the posterior skin of the lobule to the deep surface of the inferior pole of the cartilage framework because the postauricular sulcus has already been formed at stage 1.
Postoperative Details
Rib Option
See the list below:
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Stage 1
The 2 small butterfly drains placed intraoperatively superiorly and inferiorly in the skin pocket are attached to vacuum blood collection tubes, which are changed every 2-4 hours. After 1-2 days, the drains are removed when output becomes straw colored and when less than 2-3 cc per 8-hour period is collected. A larger suction drain is placed in the chest. The chest incision is covered with surgical tape. Children remain in the hospital for 48-72 hours, primarily for pain control.
Postoperative pain is related primarily to the rib donor site, and this is reduced by a more limited dissection in this area. A bulky noncompressive mastoid-type dressing is placed over the reconstructed ear and is usually not changed until postoperative day 2. The suture lines are covered with antibiotic ointment twice daily for a week. Absorbable, minimally reactive sutures are placed in small children, obviating the need for suture removal. Patients may wet the suture lines beginning on postoperative day 2.
A protective cup ear dressing with a Velcro strap may be used for more active children until healing is complete. This is particularly useful to prevent harming the reconstructed ear at night while sleeping. After all surgical procedures, patients are advised to limit strenuous activity for approximately 2 weeks.
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Stage 2: This is probably the stage associated with the least postoperative morbidity. Most importantly, the suture lines must be kept clean and covered with antibiotic ointment for approximately one week.
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Stage 3: Routine suture care is indicated after this stage as well.
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Stage 4: Because a composite graft is obtained from the normal ear, both ears cause some discomfort postoperatively; the patient may need to use protective occlusive dressings temporarily. Routine suture line care is indicated here as well.
Alloplast Option
See the list below:
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Stage 1: The patient is admitted for 24-72 hours, depending on how comfortable the parents are with drain care. Drains are removed 3-7 days after surgery. The drains are somewhat larger (3-4 mm diameter) for the alloplast option. The cup dressing stays in place day and night for 2 weeks and then is worn at night for an additional 2 weeks.
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Stage 2: Again, this is probably the stage associated with the least postoperative morbidity. Most importantly, the suture lines must be kept clean and covered with antibiotic ointment for approximately one week.
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Managing unwanted hair: Although many hair follicles typically are clipped and removed during stages 1 and 3, persistent hair growth around the upper scapha and helix continues to be a problem in some patients. Some patients simply clip the hairs short. Electrolysis is not well tolerated in the pediatric age group. Laser hair removal using light directed at the hair pigments has been successful; nevertheless, more than one treatment is generally required.
Follow-up
Patients are seen preoperatively, at 1 week postoperatively, and as needed thereafter.
Complications
A literature review by Long et al found the average overall rate of complications in microtia-related ear reconstruction with autogenous cartilage to be 16.2%. The review, which included 60 studies (9415 patients total), also found that the use of two- or multiple-stage techniques with or without preexpansion of tissue did not significantly impact the complication rate, nor did the use of simultaneous midear reconstruction. [6]
Rib option
The most frightening common complication with the rib cartilage microtia repair is skin loss. For this reason, the surgeon is doubly careful to avoid damaging the subdermal plexus or stretching the skin unduly. The field is never injected with epinephrine-containing solutions so that blanching of the skin may be monitored accurately. Fortunately, when skin loss occurs, it is usually limited in scope and can be managed adequately with the excision of small portions of exposed cartilage and aggressive wound care. These areas usually heal by secondary intent.
Occasionally, portions of the skin graft are lost. If the underlying perichondrium is still intact, a new graft may be placed successfully. For larger areas of skin loss, a local flap procedure needs to be performed. The temporoparietal flap is a good choice because it is thin, pliable, and in close proximity. After turning down the flap and covering the exposed cartilage, the flap is grafted onto skin. Although the grafted skin has a poor match of color, texture, and thickness, these differences tend to minimize with time.
Resorption of the cartilage graft may occur if the cartilage is denuded of perichondrium during the harvesting stage or during the formation of the framework.
Dislocation of the cartilage elements of the framework may occur, especially if the helix is not secured adequately onto the cartilage base. For this reason, multiple permanent sutures are used. Because wire has a tendency to extrude or become infected, it no longer is used. Despite the possibility of suture failure, the potential for cartilage dislocation is small because the graft has been secured within a precise confined pocket of skin.
Keloid and hypertrophic scar formation are problematic because they defy any satisfactory correction and are difficult to predict. Although surgical resection of the scarred tissue may be attempted, the results are likely to be disappointing. Local injection of long-acting steroid compounds may be attempted.
Infection may occur despite meticulous sterile technique and perioperative antibiotic therapy. Most infections are small and well localized. In some cases, local wound care and a week-long course of oral antibiotics may be necessary. Occasionally, a retained suture needs to be removed.
Alloplast option
Exposure and infection of the framework are more worrisome complications for reconstructions using an alloplast than those using rib cartilage. Plastic implants may develop colonization with bacterial biofilms upon exposure, and the ensuing infections may be difficult, if not impossible, to treat without explantation of the framework. Fractures and exposures have been reported to occur as often as 44%. [7] Smaller (< 1 cm) exposures may be successfully closed with local transposition flaps after a 1-mm rim of skin is débrided from the defect. Advancement and rotation flaps are not as successful.
If the framework becomes grossly infected, the implant is removed. Reconstruction using rib cartilage can be attempted later, giving the soft tissues time to regain some pliability and a healthy blood supply. Reconstruction using another Medpor implant may also be considered, but it is recommended that a 60-mL tissue expander be inserted through the previously existing scalp scar once healing has occurred. After several weeks of expansion, the expander is removed and the new alloplast is inserted.
Outcome and Prognosis
Under ideal conditions, a surgeon with some degree of artistic ability who uses sound judgment can expect a good result after adequately spaced stages. Nevertheless, much of the prognosis depends on factors beyond the surgeon's immediate control, such as skin pliability, scar tissue formation, and the resolution of edema.
A study by Park and Park indicated that in microtia patients with constricted ear features, reconstructive surgery that completely replaces remnant cartilage with costal cartilage and maximally saves remnant skin produces better aesthetic results than procedures that preserve remnant cartilage. Using a four-point Likert scale to measure aesthetic outcomes, the investigators found the average score for cartilage-replacement surgery to be 3.36 (between good and excellent), compared with 2.56 for cartilage-preservation procedures (between fair and good). [8]
Future and Controversies
Surgeons are constantly attempting to improve results with microtia repair.
Chin et al have described modifications to the rib cartilage framework to [9] augment the definition. They describe a Y-shaped piece of cartilage to augment the superior and inferior crus of the antihelix, as well as blocks of cartilage to reconstruct the tragus during stage 1.
Jiang et al [10] have describe a 2-stage technique using rib cartilage, which makes use of a retroauricular fascial flap to cover the rib graft posteriorly during stage 1. Conchal excavation and tragal reconstruction are accomplished in stage 2.
Chen et al [11] have made use of a second stage in which an ultrathin split-thickness skin graft is left attached to the helix to cover the raw surface created by elevating the framework. This results in fewer visible suture lines. A temporoparietal flap is raised during this stage to cover a cartilage block that adds projection to the auricle.
Readers are referred to these references for more details.
The greatest morbidity with the rib cartilage technique is at the harvest site. The postoperative pain, the thoracic scar, and the occasional concavity produced in the chest area have motivated surgeons to seek an adequate alternative. The use of porous alloplastic material has proven to be effective, but concerns persist about its long-term viability and the propensity for exposure and infection.
Prosthetic ears, with or without osteointegrated fixation, are popular with some physicians. Although these prosthetics are remarkably natural in appearance, they have several drawbacks. These include limited longevity, lack of sensation, and unnatural feel. Prosthetics should probably not be considered a first-line remedy for microtia.
Cadaveric (homograft) or animal (xenograft) cartilage has been demonstrated to have high resorption rates that make them unacceptable for preserving the delicate architecture of the reconstructed ear. In addition, concern exists about the transmission of HIV or slow viral diseases.
Seeding autologous cartilage onto a biologic framework to grow tissue in a foreign host is now possible. An auricular cartilage framework was grown in a nude mouse, whose picture was circulated widely by the lay press. Nevertheless, problems remain with such technologies, primarily because the new cartilage lacks the skeletal strength to withstand the contracting forces of the skin pocket and the subsequent scar formation.
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Grade 4 microtia (anotia). Note the absence of cartilage.
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Grade 3 microtia: the most common type.
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Grade 2 microtia.
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Grade 1 microtia.
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Framework components of porous polyethylene.
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Cartilage framework carved and assembled for stage 1.
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Appearance at completion of stage 1, rib technique.
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Incisions for stage 2.
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Postoperative appearance, stage 3. A bolster is in place over the skin graft.
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Appearance after stage 4.
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Early result after stage 1 reconstruction with porous polyethylene.
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Early result after stage 2 reconstruction with porous polyethylene.