Auricular ReconstructionUsing Porous

Polyethylene ImplantTechnique Scott Stephan, MDa,*, John Reinisch, MDb

KEYWORDS

� Auricular reconstruction � Porous polyethylene � Implant � Ear

KEY POINTS

� Porous high-density polyethylene as an alloplast in microtia reconstruction offers an excellentframework for auricular reconstruction.

� Advantages include earlier reconstruction, fewer procedures, avoidance of donor site morbidity,shorter learning curve, and improved size and contour match.

� Results ultimately depend on soft tissue envelope, and choice of technique is best decided accord-ing to surgeon expertise and patient preference.

INTRODUCTION

Creation of an external ear remains one of themost challenging dilemmas for reconstructive sur-geons. Between the thin soft tissue envelope sur-rounding an intricate, flexible frameworkprojecting off the mastoid, success in recreatingnative anatomy depends as much on the patient’ssoft tissue characteristics as it does on surgicaltechnique.

The choice of material for creating the architec-ture and framework of the ear has long been atopic of debate and continues to evolve. Stagedautologous cartilage reconstruction remains themost widely used technique in microtia repair,1

but many surgeons have turned to alloplasts toavoid donor site morbidity, begin reconstructionat an earlier age, reduce the number of total sur-geries, increase the predictability of their results,improve on the inherent structural limitations of

Disclosure: The authors have nothing to disclose.a Department of Otolaryngology, Head and Neck SurgMedical Center East, South Tower, 1211 Medical Center Dgery, University of Southern California, 1450 San Pablo StrAngeles, CA 90089, USA* Corresponding author.E-mail address: Stephan@vanderbilt.edu

Facial Plast Surg Clin N Am 26 (2018) 69–85https://doi.org/10.1016/j.fsc.2017.09.0091064-7406/18/� 2017 Elsevier Inc. All rights reserved.

autologous rib, and to tailor to individual patients’needs (ie, low-lying hairline, bilateral microtia).This article broadly discusses the considerationsfor alloplast-based ear reconstruction, details aseries of evolving technical advancements, andexpands on the description of the surgical proced-ure outlined in the authors’ previous work.2

AURICULAR ALLOPLASTS

The ideal alloplast for auricular reconstructionwould be cost-effective, safely implantable, resis-tant to infection and repeated trauma, and beeasily customized to approximate the contralateralnative ear.

Since 1891, more than 40 different frameworkmaterials have been described in the ear, includingalloplasts such as ivory, wire mesh, nylon, and sil-icone.3,4 Silicone was initially viewed as a prom-ising prospect, particularly for its ability to mimic

ery, Vanderbilt University Medical Center, 7th Floorrive, Nashville, TN 37232, USA; b Department of Sur-eet, Healthcare Consultation Center 4 Suite 6200, Los

facialplastic.theclinics.com

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the flexibility and structure of native auricular carti-lage, but a high extrusion rate when placed underthin skin flaps was ultimately problematic.5

First described for partial auricular reconstruc-tion by Berghaus and colleagues19 in 1983, poroushigh-density polyethylene (pHDPE), originally mar-keted as Medpor (Stryker, Kalamazoo, MI) has along record of successful, safe use as an implant-able framework. Other companies now offersimilar pHDPE ear implants, such as Omnipore(Matrix Surgical USA, Atlanta, GA) and Su-Por(Poriferous, Newnan, GA). pHDPE is a modestlyflexible, biocompatible material made of high-density polyethylene with interconnected pores(100–200 mm diameter) that show structural stabil-ity and the ability to support soft tissue ingrowth.6,7

As a porous material, this facilitates collagendeposition and vascular ingrowth, which in turnprotects against extrusion and infection, and al-lows systemic drug delivery to the implant.8 Struc-turally, pHDPE is robust enough to withstand therepeated microtrauma expected of an ear, but iseasily shapeable with a scalpel, and separatepieces may be soldered together with high-temperature cautery. The authors’ experiencewith customization with drill technique is reviewedlater.The basic paradigm for microtia reconstruction

using a pHDPE implant involves implantation of afused two-piece framework, completely coveredwith a large temporoparietal fascia (TPF) flap andresurfaced with a mixture of skin grafts and localflaps. This procedure has been described asboth single stage5 and multistage.4,9–11

CONSIDERATIONS FOR HIGH-DENSITYPOROUS POLYETHYLENE

One advantage of alloplast reconstruction is theavoidance of a chest wall donor site. Becausethe quantity and quality of the patient’s rib carti-lage is not a factor, patients do not need to waitfor chest wall maturity for costal cartilage harvest,and may undergo reconstruction at an earlier age.The youngest child implanted in the authors’ expe-rience was 2.5 years old, with preferred timing be-tween 3 and 6 years of age. pHDPE is available asa preformed 2-piece implant, and a straightfor-ward technique allows a shorter learning curvefor new surgeons. Modern modifications to theprocedure have resulted in comparable complica-tion rates with autologous cartilage, and cosmeticoutcomes can be excellent in experiencedhands.4,12 Microtia reconstruction with porouspolyethylene may be performed after or at thesame time as canal atresia surgery if the patientis deemed a suitable candidate for canalplasty.

Thus, patients can have their atresia and microtiareconstructions completed in a single stage beforeentering primary school, which is an importantperiod of cognitive awareness and self-concept.13–15 There are also aesthetic and tech-nical considerations as to why pHDPE auricularreconstruction is better earlier than later in the au-thors’ experience: the TPF flap used to cover theimplant is the blood supply to the overlying hair fol-licles and becomes thicker as the child ap-proaches late adolescence to teenage years,perhaps as a factor of increased hair density andcaliber with puberty. When done at an early age,the TPF is thin and more pliable, allowing it toeasily contour to the architecture of the implant un-der negative pressure, yielding superior detail.There is significantly less bleeding and better visu-alization of surgical planes in younger childrenthan in adolescents and adults. Also, the dermallayer of the harvested full-thickness skin graftsused to cover the TPF flap is also inherentlythinner.Although salvage surgery using autologous rib

with adjunctive procedures has beendescribed,16,17 it is not common and the outcomesare widely variable. In contrast, the pHDPEimplant–based approach is versatile; it serves asan excellent primary option in many cases or canbe used as salvage surgery after failed autologousrib, burn cases, auricular avulsion, or situations ofsignificant scarring of the mastoid skin area, pro-vided that a well-vascularized fascial flap is stillavailable for framework coverage.

TECHNIQUE

The authors’ reconstructive approach is describedlater, adapted from the single-stage technique firstdescribed by the senior author and modified overthe years to the current iteration.3,5 The emphasis isonmicrotia reconstruction, but the principles remaingeneralized for auricular reconstruction broadly.

PREP

The patient is orotracheally intubated and the bedrotated 180�. Hair over the temporoparietal areaon the surgical side is shaved to allow properDoppler identification of the vascular anatomy.The course of the superficial temporal artery ismapped using vascular Doppler and a permanentskin marker. The anterior and posterior branchesof the superficial temporal artery (STA) are markedand, if possible, any superior anastomosing ar-cade between the 2 ends distally (Fig. 1).It can be helpful to identify the main trunk of the

STA as it courses near the auricular remnant. In

Fig. 1. Identification of landmarks and flap design.Yellow lines indicate skin incisions. Vertical dimensionof the TPF flap is measured from the proposed supe-rior border of the neo-external auditory canal extend-ing vertically toward the vertex of the scalp. Theanterior/posterior dimension is slightly narrower, ex-tending to the temporal hairline to incorporate theanterior branch of the STA (demarcated in red). Thebase of the TPF flap is kept wide to maintain venousdrainage in the mastoid region. (From Owen S,Wang T, Stephan S. Alloplastic reconstruction of themicrotic ear. Operat Tech Otolaryngol Head NeckSurg 2017;28(2):98; with permission.)

Fig. 2. Radiograph film tailored to dimensions of thecontralateral ear with surface landmarks of the lateralbrow, lateral canthus, malar-orbital groove, alar-facialgroove, and oral commissure used to orient the newear on the opposite side with respect to locationand axis. Intra-auricular details such as the superiorand inferior crura as well as the shape of the conchalbowl are cut as single lines through the film.

Auricular Reconstruction Using Porous Polyethylene 71

severe cases of microtia, the vessel can originatefrom the post-auricular artery rather than beingthe terminal branch of the external cartodi vessel.In these cases the vessel begins behind the lobeand courses underneath the microtic cartilageputting the vessel in danger during removal ofthe cartilage remnant.

The anticipated course of the frontal branch ofthe facial nerve is also delineated using the Pitan-guy line principle, using the mastoid tip as the infe-rior point of reference in place of the lobule.

Using a piece of radiograph film (or the clearplastic guard from a surgical face mask), the posi-tion and size of the contralateral normal ear aremarked relative to the oral commissure, nasalalar groove, orbitomalar groove, lateral canthus,and lateral brow Fig. 2. The radiograph film canbe sterilized for later use on the field, or the plasticmask sheet can be covered by sterile translucent

dressings. The dimensions of the new ear arebased on the contralateral normal ear, taking intoconsideration the patient’s age at the time ofsurgery and anticipated future growth. In addition,notes are taken of specific details and unique fea-tures found on the normal ear that will be custom-ized during the molding and soldering of theimplant later in the procedure.

Careful preoperative assessment of the patient’sage, contralateral ear dimensions in the setting ofunilateral microtia, as well as the dimensions oftheir gender-matched parent’s ear are essential toachieving symmetry between the reconstructedpHDPE ear and the normal ear. The pHDPE willnot increase in size so an adult-sized ear must becreated at the time of surgery. In a forensic studyof normative data for ear growth in more than 800patients, at 4 to 5 years of age, ear vertical lengthwas approximately 90% (girls) and 84% to 86%(boys) of the relevant values recorded in individuals18 to 30 years old.18 Therefore, adding a 10% to15% increase in height from the contralateral earin a 4-year-old patient (about 5–7 mm) is a reason-able estimation; using dimensions from the parentscan alsobeadouble check (Fig. 3). A case exampleof a boy 3 years and 2 months old who underwentpHDPE microtia reconstruction with modestadjustment in size for future growth shows the abil-ity to accurately compensate for this dynamic evenin very young patients (Fig. 4).

Fig. 3. For a 7-year-old girl with unilateral left micro-tia reconstruction, measurements of the normal rightear (AD) as well as that of her mother’s right ear areshown at the bottom of the image. Using this infor-mation, the proposed left ear (AS) size is then de-signed and the pHDPE implant customized to whatwill be her predicted adult-sized ear.

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Likewise, a perfectly symmetric ear that ismoderately malpositioned may be an even greaterdisfigurement and distraction than the original

Fig. 4. (A) Child seen before left ear reconstruction at 3 ystruction with modest adjust in vertical height; (C) sameheight symmetry. (From Reinisch J. Ear reconstruction inpermission.)

microtia. Of the facial landmarks used for orienta-tion, the lateral brow, lateral canthus, malar-orbitalgroove, and alar groove are the most trustworthyin patients with some degree of craniofacial micro-somia, because the first and second branchial archmalformations disproportionately affect the lowerfacial skeleton. The patient’s eyes, nose, andmouthare kept visible but coveredwith an occlusive trans-parent dressing to remain out of the sterile field. Thehead is prepped with betadine solution, and theauricular remnant, incisions, and skin graft donorsites injected with local anesthetic.The scalp incisions used to approach the TPF

flap elevation are varied, with multiple approachesdescribed. The authors favor elevation of the flapentirely from below, using only the incision in thepostauricular area of the microtic ear correspond-ing with the position of the new helical rim. Thisincision is made on the postauricular componentof the portion of the ear that is present (Fig. 5). Inpatients with low-set hairlines, up to a third orhalf of this incision along its superior margin maybe in hair-bearing skin. Whatever component ofthe anteriorly based mastoid skin flap containshair is discarded. Therefore, the surgeon doesnot have to compromise either the placement ofthe implant or the final aesthetics of a hairy earbased on the patient’s preoperative mastoid hair-line position. To improve exposure, a curvilinearhorizontal incision over the superior portion ofthe TPF flap can be added; this additional incisioncan help visualize the distal most portion of theanterior branch as it travels just posterior to thefrontal branch of facial nerve. It can also be helpfulin harvesting the distal flap to obtain the recom-mended length. These two approaches allowadequate access to elevate a wide TPF flap witha lighted retractor or head light.

ears and 2 months; (B) 10 months after left ear recon-patient see at 20 years of age with good interauralyoung children. Facial Plast Surg 2015;31:602; with

Fig. 5. Elevation of the TPF flap is done through thepostauricular incision only using needle tip electro-cautery and a headlight or lighted retractor.

Fig. 6. Alternative scalp incisions. The Yor zigzag inci-sion can be used for better access and visualization,but carry a higher risk for focal alopecia. (FromOwen S, Wang T, Stephan S. Alloplastic reconstructionof the microtic ear. Operat Tech Otolaryngol HeadNeck Surg 2017;28(2):99; with permission.)

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Other approaches include a Y incision extendingsuperiorly from the mastoid area, as well as a largeZ to expose the TPF. Each of these allow muchbetter visualization and access to the fascia butcarry the risk of patchy alopecia near incisional bi-furcations or the apex of a triangular flap. The TPFprovides vascular perforators to the dermal plexusthat supply the follicles; any incisions through thedermal plexus can compromise perfusion throughthis layer from the occipital, supraorbital, andcontralateral STA vascular watersheds (Fig. 6).

Next, the remnant microtic cartilage is excised.This stage is performed by meticulous elevationof a very thin anteriorly based skin flap off themicrotic cartilage, then coming under the cartilagemass and excising it. This flap frequently requiresadditional thinning when laying onto the pHDPEframework for optimal definition. The inferiorportion of this flap typically has the lobule remnantattached to it initially. For improved soft tissuecoverage, particularly with a malpositioned lobule,this flap may be amputated and used as a free skingraft. Amputation allows for improved ability tothin the skin; reserves that high-quality skin foruse in the most aesthetically important areas (heli-cal rim, scaphoid, antihelical flold (AHF) fossa tri-angularis) instead of the conchal bowl, which cantolerate darker skin if needed; and provides moreflexibility in orientation. When removing theremnant microtic cartilage from the mastoid area,care must be taken not to injure a potentiallyanomalous course of the main trunk of the super-ficial temporal vascular pedicle that aberrantlycourses under the cartilage. This possibility canbe particularly relevant when removing excessivemastoid soft tissue down to the periosteal layerto create a deeper conchal bowl or in the settingof combined atresia-microtia cases in which theotologist requires subperiosteal elevation toexpose the mastoid bone. Careful Dopplerassessment of the vascular pedicle’s trajectory

immediately before surgery can help identify theseanomalous cases.

Using the superior scalp incision, the temporo-parietal area is widely undermined in a subcu-taneous plane, with care taken not to violateeither the TPF beneath or the hair follicles above.Once widely exposed, an inferiorly based TPFflap measuring approximately 10.5 � 13.0 cm isincised and elevated off the underlying deep tem-poral fascia (investing temporalis muscle) and theperiosteum in the portion superior to the tempo-ral line. Approximately one-third of the flap is su-perior to the temporal line, making it in practice acombination TPF extended by superficial parietalgaleal aponeurosis. The base of the flap is keptwide (approximately 6 cm) to maximize inclusionof secondary vascular supply from the postauric-ular artery, early branches off the occipital artery,and the mastoid emissary vein. Although preser-ving every bit of the secondary vascular supplyfrom this mastoid region is not always possible,every attempt is made to ensure the flap is asrobust as possible with a redundant vascularsupply (Fig. 7). Care is taken to preserve andinclude both the anterior and posterior branches

Fig. 7. Latex-injected cadaver dissections show thesecondary vascular supply to the extended TPF flapfrom the mastoid region. If the base of the TPF flapis kept wide (w6 cm), several other vascular structurescan be included in the mastoid area. (A) The postaur-icular artery and vein are located within 4 cm of anarea posterior to the ear canal, as well as earlybranches (Br.) off the transverse portion of the occip-ital artery that course superiorly to the mastoid re-gion. (B) Mastoid emissary vein is large, drainsintracranial to the sigmoid sinus, and can often beincorporated if the flap base is kept wide.

Fig. 8. (A) Postauricular incision made first and carti-lage remnant removed leaving thin anteriorly basedskin flap. (B) TPF flap elevation requires meticulousseparation of subcutaneous fat away from superficialsurface of TPF. (FromOwen S, Wang T, Stephan S. Allo-plastic reconstruction of the microtic ear. Operat TechOtolaryngol Head Neck Surg 2017;28(2):99; withpermission.)

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of the superficial temporal artery, using electro-cautery on a low setting to avoid thermal damageto the microvasculature. It is critical to include theloose areolar tissue on the deep surface of theTPF. This loose tissue will rest against the under-surface of the skin grafts and permit the skin toglide over the underlying structure, resisting softtissue trauma and implant exposure. The flap isthen reflected inferiorly through the superiorportion of the posterior auricular incision(Figs. 8 and 9).Next, the 2-piece pHDPE framework is sculpted

and fused. The 2 separate implant pieces areplaced in a 60-mL syringe of betadine, and placedunder negative pressure to push antiseptic solu-tion through the entire implant, not just coatingthe surface. The implant is tailored to the appro-priate dimensions to match the contralateral ear.This process may be aided with the radiographfilm template made from the contralateral ear.The pHDPE implant may be customized intrao-peratively to appropriately mirror the patient’snative anatomy. The implants are easily carved

with a scalpel, and the 2 preformed componentsare then fused with high-heat ophthalmic cautery.The tragal extension and some portion of thelobule are routinely amputated in microtia cases;for auricular avulsion, anotia, or other completeear reconstructions, the entire lobule can be pre-served. The tragal portion is brittle and difficultto wrap with the TPF flap without blunting thebowl. The amputated pieces can be cut intomany smaller fragments used to reinforce theimplant. In particular, the union of the superiorand inferior crura of the AHF to the helical rim re-quires reinforcement to avoid fracture and sublux-ation. Other modifications to the pHDPEframework can also be done, such as deepeningof the conchal bowl and making the uniform heli-cal rim irregular to provide a more natural appear-ance, as needed (Figs. 10 and 11).Before placement of the implant, 2 flat suction

drains are placed through the posterior mastoid

Fig. 9. (A) Vessels within thin TPF flap can be identi-fied by transillumination. (B) TPF flap is deliveredthrough a bipedicled scalp flap to the mastoid area.(From Owen S, Wang T, Stephan S. Alloplastic recon-struction of the microtic ear. Operat Tech OtolaryngolHead Neck Surg 2017;28(2):100; with permission.)

Fig. 10. (A) pHDPE implants come in 2 pieces to allowsurgeons to adjust ear size as needed. There are slightvariations by company on the shape of the preformedear base, with some offering ready-made braces tobuttress the helical rim (middle implant), as well asdifferent arcs of curvature of the antihelical foldand the crura. (B) The 2 pieces are soldered togetherwith ophthalmic cautery. (C) Further modifications us-ing a scalpel can be done for optimization. (FromOwen S, Wang T, Stephan S. Alloplastic reconstructionof the microtic ear. Operat Tech Otolaryngol HeadNeck Surg 2017;28(2):100; with permission.)

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hair-bearing skin, with one deep to the pHDPEconstruct and the second in the posterior portionof the temporoparietal scalp donor site. Theimplant is then placed in the correct anatomicorientation, axis, and projection on the mastoidarea and draped with the TPF flap. Confirmationof correct position is key at this stage becausethe implant cannot be adjusted easily after theflap is placed under negative pressure. The radio-graph template created at the beginning of theprocedure is used at this time to ensure correctplacement. If projection needs to be altered,some excess of the implant can be shaved offthe undersurface of the fused implant, or solderedon to it if needed at the inferior aspect, forexample, for greater projection in the setting of aseverely hypoplastic sloping temporal bone. Theflap is oriented with the loose areolar layer facingaway from the framework and then looselysecured to the mastoid fascia with a 5-0 polydiox-anone suture. Strong fixation of the framework tothe mastoid is avoided to maintain mobility of theear, a feature needed to help absorb trauma and

resist framework fracture or soft tissue injury. If anative canal exists or a neocanal is being createdduring combined microtia-atresia surgery, thenthe implant position must be more fixated to themastoid in order to avoid obstruction of themeatus by potential framework descent, even if itis subtle. A narrow strip of deep temporal fasciais raised and reflected through a window made inthe base of the TPF serving as an inferiorly based

Fig. 11. Excess fragments of pHDPE such as shavings and amputated tragus/lobule component are used as mate-rial to reinforce the junctions between the 2 pieces. Finished product shows areas of reinforcement to preventimplant fractures. Helical root extension is amputated in cases with a canal or concurrent atresia surgery. Notethat the implant is impregnated with iodine antiseptic solution. (A) Lateral surface of the implant; limited solder-ing or scalpel manipulation as possible (B) Medial (deep) surface of implant; primary area for soldering to rein-force. (From Owen S, Wang T, Stephan S. Alloplastic reconstruction of the microtic ear. Operat Tech OtolaryngolHead Neck Surg 2017;28(2):101; with permission.)

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soft tissue sling. This fascial strip is wrappedaround the inferior crus of the framework beforecovering the implant with the TPF flap.The TPF flap is shrink-wrapped around the

implant using negative pressure from the firstdrain. The second drain is for removal of any se-rous fluid from the TPF flap donor site (Fig. 12).The anteriorly based skin flap is draped over the

TPF, or amputated and positioned as a free skingraft. The lobule remnant typically requiresinferior-posterior transposition, which is accom-plished by sectioning it from the anteriorly basedskin flap and transposing it based on a narrowanteriorly based pedicle (Fig. 13).If the ipsilateral mastoid skin is not of sufficient

surface area to cover the entire lateral surface ofthe new ear, a full-thickness skin graft is harvestedfrom the contralateral postauricular sulcus. Thisgraft provides the best color and texture matchfor the most aesthetically important parts of thereconstruction. A larger skin graft harvested fromthe inguinal region is typically required to coverthe back of the ear. Care must be taken toadequately thin this graft, because it can be thick,even in children. Of note, the graft should also be

harvested as laterally as possible to prevent the in-clusion of skin prone to grow pubic hair after pu-berty. Other donor site options include centrallower abdominal skin, medial upper extremity, orsupraclavicular fossa.These harvested grafts are then combined to

cover the new ear. The grafts will heal to resemblethe original color and skin type from their donor re-gions. Because of this, the authors recommend thatthe ipsilateral auricular/mastoid skin be used on thelateral surface of the ear, with any gaps covered bythe contralateral posterior auricular sulcus graft.The inguinal graft should be used primarily to resur-face the new postauricular sulcus, because of itssuboptimal color match. If possible, it is best toavoid inguinal skin anywhere on the helical rim,with the junction of the inguinal skin graft and themore favorable lateral surface grafts tucked behindon the medial surface of the auricle (Fig. 14).For those reconstructions requiring a tragus, a

small amount of the remnant ear cartilage istailored into a tragal graft. This cartilage graft isthen covered by the anteriormost portion of theanteriorly based preauricular skin flap. If this flapneeds to be amputated for preferred lateral

Fig. 12. (A) TPF flap draped over implant without suc-tion. Anteriorly based skin flap has already beenamputated. (B) Suction activated and flap shrink-wrapped around pHDPE framework. (From Owen S,Wang T, Stephan S. Alloplastic reconstruction of themicrotic ear. Operat Tech Otolaryngol Head NeckSurg 2017;28(2):101; with permission.)

Fig. 13. Neotragus can be made by securing a carti-lage graft tailored from previously resected microticremnant to the anteriorly based mastoid skin flap(point A). The lobule can be partially split to setback inferiorly and hold the inferior portion of theTPF-wrapped implant like a sling (point B).

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surface coverage, then a sufficient anterior portionis left attached to the preauricular skin to fold overa cartilage graft, braced temporarily with a needle,and secured using a 4-0 plain gut suture on astraight needle (see Fig. 13). Skin graft donor sitesare closed, and skin grafts are attached to eachother using absorbable gut suture. With the drainson suction, the auricle is coated with a thin layer ofantibiotic ointment, gauze is tucked into concav-ities of the bowl, scaphoid, and fossa triangularis,and then the entire ear is covered in a custom sil-icone cast to prevent seroma, hematoma, orshearing trauma that may compromise skin graftviability during neovascularization. The siliconemold is secured to the scalp and skin with interrup-ted Prolene stitches. A Glasscock cup dressing isthen applied to help prevent the weight of the sili-cone molding from pulling the auricle down. Pres-sure on the silicone mold should be avoided.Mastoid-style gauze pressure dressing is appliedover the TPF donor site to prevent seromaformation.

Immediately following extubation, all suctiondrains are removed (Figs. 15 and 16).

AFTERCARE

The gauze pressure dressing is removed after 3days and the parietal region inspected for seroma.The silicone mold is removed in clinic at 11 to 14days. A new silicone mold is created in clinic foruse behind the ear to maintain projection andavoid sulcus blunting against the forces of woundcontracture. Patients wear this all night for 4months. The silicone should not be worn duringthe day as the weight of the mold can contributeto inferior descent of the ear. Parents are askedto sleep with their children in the bed for the firstfew weeks to ensure that they do not roll ontothe reconstructed ear. Aquaphor, Vaseline, orother moisturizing ointment is used until the woundedges and grafts cease to crust or scab.

DISCUSSION

Despite the popularity of autologous rib, pHDPEremains an excellent framework reconstructiveoption for ear surgeons. The primary advantagesremain the avoidance of chest wall donor site

Fig. 14. (A) Inguinal donor full-thickness skin graft(FTSG) donor site closed primarily. Medial thighsplit-thickness skin graft donor site used to linenew canal during combined atresia surgery. (B)FTSG cover TPF flap. Lateral surface of ear coveredby combination of previously amputated ipsilateralmastoid skin flap, contralateral postauricular FTSG,and remnant lobule. Inguinal skin only used formedial surface. Tragal reconstruction completedwith small piece of remnant microtic cartilage. Pa-tient also underwent canal atresiaplasty at thesame time. (From Owen S, Wang T, Stephan S. Allo-plastic reconstruction of the microtic ear. OperatTech Otolaryngol Head Neck Surg 2017;28(2):102;with permission.)

Fig. 15. Pink silicone mold covers the ear with aGlasscock cup dressing lifting mold slightly to sup-port it. Gauze head wrap for pressure over TPF donorsite. (From Owen S, Wang T, Stephan S. Alloplasticreconstruction of the microtic ear. Operat Tech Oto-laryngol Head Neck Surg 2017;28(2):102; withpermission.)

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morbidity, fewer stages, more consistent results,and the ability to perform an earlier repair. Inmost cases, this may be completed before thechild starts school, minimizing the social impactof congenital deformity. Earlier repairs generallyresult in improved tissue healing and a morecosmetically appealing result.Although it is easy to focus on choice of frame-

work material as the key ingredient for success,outcomes depend mainly on soft tissuecoverage.4 The use of tissue expanders to allowcomplete coverage of the implant with preauricu-lar tissue has been described as a viable option

for soft tissue coverage. This technique has notbeen adopted by the authors because of theaddition of an operative stage, potential tissueexpander complications, the pain associatedwith expansion for children, and the fact thatpHDPE often becomes exposed under a skinflap unless it is covered by an intervening fasciaflap.The ability to perform an entire repair in a single

stage results in less recovery time, repetitive expo-sure to anesthesia, and care by patients and fam-ilies. Preformed pHDPE implants allow lessoperative time carving rib frameworks, more pre-dictability in the outcome, and an easier learningcurve with respect to the framework design. How-ever, microtia reconstruction in general requiresmeticulous attention to detail and superb soft tis-sue technique, regardless of what paradigm isused. As with any implantable material, there isconcern for biofilm formation, infection, implantfracture, and extrusion. Although common in theearly experience with pHDPE, modern techniqueshave significantly improved complication rates,which are now comparable with those of

Fig. 16. (A, B) Primary reconstructions without canal atresia surgery. (C) Primary repair with combined atresia sur-gery. (D) Prior rib reconstruction revised with pHDPE approach. (From Owen S, Wang T, Stephan S. Alloplasticreconstruction of the microtic ear. Operat Tech Otolaryngol Head Neck Surg 2017;28(2):103; with permission.)

Table 1Comparison of complication rates of poroushigh-density polyethylene ear reconstructionsdone by the senior author early in the seriesversus later in the series with implementation

Auricular Reconstruction Using Porous Polyethylene 79

autologous rib techniques in experiencedhands.4,12 One study at a high-volume centerexamining long-term follow-up data elucidatedno clear benefits to either autologous rib or pHDPEreconstruction.11 Their conclusions were thatpHDPE reconstructions had fewer operationsand better size and contour match. Autologousrib advantages include better color match anddecreased risk of extrusion.11

The senior author’s experience implementingthese changes over 28 years and their impact onrates of exposure, infection, and fractures is re-flected in the notable trend toward reduced compli-cation rate highlighted in Table 1. Several criticaladvancements in technique and materials that areresponsible for this trend are discussed here.

of several key technique advancements

1993–1995 2008–2013

Procedures 25 487

ImplantFractures (%)

28 1.5–8.7

ImplantExposures (%)

44 4.3

Infections (%) 4 1.1

From Reinisch J. Ear reconstruction in young children.Facial Plast Surg 2015;31:601; with permission.

RELIABILITY OF POROUS IMPLANTS

Early implant trials attempted the use of multipledifferent materials. Silicone was favored initiallyfor its ability to mimic the flexibility of the nativeear cartilage, but high exposure rates ultimatelyleft it undesirable.5 Polyethylene has a longhistory of biocompatibility, and the addition ofmicropores allows for vascular and soft tissueingrowth. This advancement dramatically

improved resistance to infection and exposure.19

Romo and colleagues9 reported a 4% complica-tion rate in 250 cases over an 11-year period, andAustrian surgeons with 78 cases report an extru-sion rate of 2.6%.20 The senior author’s ownexperience from 2008 to 2013 detailed in Table 1is very similar. Other smaller-volume studiesreport complication rates between 0% and12%.10,11

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It follows that maintenance of the implant’sporosity is important to the overall success, safety,and longevity of this technique. The junior author’spreliminary investigations into this has yieldedsome interesting laboratory findings whenanalyzing electron microscopy images of pHDPE(Medpor samples) cut with a surgical scalpel astraditionally done, and compared with effects onporosity from soldering (as typically done forfusion of the 2-part implant), or sculpting thepHDPE with a drill using either a cutting bur or adiamond bur Fig. 17.The overall porosity of the implant is decreased

by any manipulation technique, but visual inspec-tion shows only a modest decrease in porosityfrom baseline when pHDPE is cut with a scalpel,and only slightly worse than that when modifiedwith a cutting bur using irrigation. However, allporosity seemed to be eliminated after solderingor diamond bur manipulation. Although the solder-ing is necessary to fuse the 2-piece implanttogether, minimizing the amount of soldering inthe areas most prone to exposure is prudent. Clin-ical experience has shown the inferior portion ofthe helical rim where it fuses with the lobule

Fig. 17. Electronmicroscopy of control andmanipulated pHin all forms of manipulation, but minimally with scalpel cutsicant lossofporosity seenwith solderingordiamonddrilling.Arrows show some residual porosity. (C) After solderingwithtion. (E) After cutter drill with irrigation. Arrow indicates m

framework to be most vulnerable in this regard(especially in early recovery), because it is coveredby the distal portion of the TPF flap and venousdrainage must travel against gravity. Therefore,the safest technique to maintain porosity duringframework modification is to use a scalpel andkeep soldering to a minimum, and potentiallyonly on the medial surfaces of the framework.

COVERAGE OF THE ENTIRE FRAMEWORKWITH THE VASCULARIZEDTEMPOROPARIETAL FASCIA FLAP

In the early days of pHDPE ear reconstructions, onlyportions of the framework were covered with theTPF.The lowerhalf of the implantwasplaceddirectlyunder the hairlessmastoid skin, similar to how autol-ogous rib reconstructions are now done. However,pHDPE requires more vascularized soft tissuecoverage than autologous rib. In the early years,most exposures occurred at the sites covered underthemastoid skin inferior to the portion of the implantcovered by the more vascularized fascia.21 The dra-matic decrease in exposure rate before andafter thistechnical advancement is highlighted in Table 1.

DPE samples (Medpor). Note that the porosity is altered, and modestly with a cutter drill with irrigation. Signif-(A)NormalpHDPE (control sample). (B)After scalpel cut.ophthalmic cautery. (D) After diamond drill with irriga-aintained porosity, arrowhead shows implant spicules.

Auricular Reconstruction Using Porous Polyethylene 81

INCLUSION OF THE SUBGALEAL (AREOLAR)FASCIA WITH THE TEMPOROPARIETALFASCIA FLAP

Traveling with the superficial temporal vessels is asensory nerve making the TPF-covered earimplant sensate, a critical requirement for long-term viability and exposure prevention. However,if the overlying soft tissue is densely adherent tothe implant, there is a much greater risk for expo-sure with normal auricular wear and tear. Overtime the TPF undergoes tissue deposition andvascular ingrowth into the framework, whichalso makes it more adherent. Therefore, inclusionof the subgaleal loose areolar fascia with the har-vest is important to avoid this problem. The looseareolar fascia is harvested off the superficial sur-face of the deep temporal fascia along with theflap. When transposed, this loose fascia nowfaces superficially and serves as a glide plane be-tween the overlying skin grafts and the adherentTPF to resist soft tissue trauma and abrasion(Fig. 18).4

Fig. 18. Skin should be able to glide with the loose areopHDPE implant. Notice how the skin envelope glides over tallows some degree of protection from abrasion and bluresultant ear skin is sensate to fine touch. (From Owen Smicrotic ear. Operat Tech Otolaryngol Head Neck Surg 20

REINFORCEMENT OF THE pHDPEFRAMEWORK

In the senior author’s experience, early breakageof the implant, from rates as high as 25% in thefirst few years of practice, encouraged reinforce-ment along the superior portion of the implant.21

These modifications reduced the fracture rate to1.5% of ears without canals and 8.7% in earswith canals in a total of 487 patients operated onbetween 2008 and 2013 with average follow-upof 1.5 years. Weak areas of the framework maybe structurally bolstered by soldering the extraimplant pieces carved off from the lobule or un-used tragal extension to the weakest points offusion using high-temperature battery cautery.The most critical area to re-enforce is betweenthe superior crus and lateral helical rim.

OCCIPITAL PARIETAL FLAP

Although the TPF is the ideal choice for primaryreconstruction using a pHDPE implant, another

lar tissue over the TPF flap, which is adherent to thehe framework between images (A) and (B). This abilitynt trauma. The TPF flap carries sensory fibers and the, Wang T, Stephan S. Alloplastic reconstruction of the17;28(2):104; with permission.)

Stephan & Reinisch82

regional flap is available if needed:– the occipitalparietal (OCP) flap based on the axial supply ofthe occipital artery and vein. Anatomically, theOCP flap is the superficial occipito-parietal fasciathat is the posterior continuation of the TPF, allpart of the epicranial aponeurosis (or galea apo-neurotica). This flap can be used in the setting ofrevision after a failed TPF-based reconstructionusing a pHDPE implant, serving as a plan B if prob-lems occur. There are other scenarios in which anOCP flap is necessary: if the superficial temporalvessels or the TPF are compromised from priorscarring, burn, or surgery; when previously bankedrib cartilage over the main STA bifurcation createsundue risk for vascular compromise or excessiveflap thickness; if there is a malpositioned bone-anchored abutment for hearing appliances orprosthesis. The OCP flap is comparable with theTPF in thickness and pliability, also has a paired

Fig. 19. Latex-injected cadaver dissections show recommenheight for a TPF starts at the native conchal bowl or, in thetransposed by flipping it down to the ear area like turninsurement begins approximately 1 cm below the nuchal linabruptly make a right-angle turn superiorly and penetrateThe OCP flap is relocated to the ear area in a similar way aswith the axis of pivot located at the nuchal line.

sensory nerve with it, and typically yields similaraesthetic results to the TPF. However, the OCPflap harvest can be more challenging because itis further away from the mastoid region and re-quires a longer flap with more dissection belowthe nuchal line to allow for rotation and transposi-tion (Fig. 19).

HARVEST OF A WIDE-BASEDTEMPOROPARIETAL FASCIA FLAP

The TPF flap shows variability of both arterial andvenous flow in up to 37% of patients.22 Theauthors recommend the use of Doppler ultraso-nography intraoperatively to confirm arterial sup-ply patterns, and keeping as wide a base to theTPF flap as possible to improve venous andlymphatic outflow and inclusion of potential contri-butions from the posterior auricular, emissary, and

ded dimensions of a TPF flap and an OCP flap. Verticalcase of microtia, the proposed conchal bowl. The TPF isg a page in a book. The OCP flap vertical height mea-e (green dashed line) where the main occipital vesselsthe deep cervical fascia investing the trapezius muscle.the TPF flip maneuver but also requires some rotation

Auricular Reconstruction Using Porous Polyethylene 83

occipital vessels (see Fig. 7). Narrowing of the TPFpedicle base to include exclusively the main trunkof the superficial temporal vessels can be temptingintraoperatively, because the flap is much moremobile and can drape more easily over the implantwith less potential folding in the sulcus area. How-ever, this narrowing comes at the cost of the sec-ondary vascularity provided from the mastoidregion, which in our estimation is important tomaintain.

Cadavericstudiesusing latex injectionof thegalealvasculature by these authors helped to corroboratethe clinical experience on recommended flap dimen-sions used over the years (see Fig. 19). A pHDPEimplant tailored to normative adult dimensions(implant sized to 53� 31mm to accommodate addi-tions of soft tissue envelope and lobule generating a60 � 33 mm adult ear of normative dimensions)18 iscovered by a raised TPF flap placed under negativepressure. The flaps were made smaller and smalleruntil minimum dimensions required to maintain anegative pressure seal were determined. This mini-mum size for both TPF and OCP flaps helped guidethe recommendations listed in the table. These in-vestigations also showed what portions of the TPFflap cover the different subunits of the auricularframework (Figs. 20 and 21). The inferior helicalrim, midhelical rim, and antitragus are the locationsthat can have the highest risk for exposure over thelong term. Verifying excellent vascularity of the flap

Fig. 20. Single stage, outpatient pHDPE ear reconstruction

along these key locations and maintaining the sec-ondary blood supply from the mastoid region canhelp prevent future problems.

FUTURE DEVELOPMENTS

Several exciting areas of innovation are emergingin alloplast-based auricular reconstruction.Customized implants made from computed to-mography or MRI data of the contralateral ear offerthe prospect of an identical match and havealready been used in the setting of unilateralmicrotia. What remains to be seen is whether thesignificant increase in cost of creating this three-dimensional (3D) printed replica is balanced by aclearly demonstrable aesthetic improvement.Similar to rib reconstruction, the difference be-tween a less than average result and an excellentoutcome often depends not on the frameworkbut on the soft tissue that is covering it. Oneadvantage of the 3D customized implant is that itis a single structure not requiring fusion, whichsaves operative time and theoretically is strongerthan the fused 2-piece implant.

Alloplast microtia frameworks may also have arole in stem cell–based auricular reconstruction.One of the great challenges facing rib microtia sur-geons is the many inflammatory mediators andcontractile forces that surround the autologous ribframework through themultitudeof stages involved

. (A) Preoperative. (B) One year postoperative.

Fig. 21. Referral case with implant exposure following scalp tissue expander and placement of the implant underthe expanded skin only. (A) Pre-op with arrow showing site of exposure at the helical rim. The STA was injuredduring the original placement of the expander. (B) Salvage done using occipital galeal flap (OCP) and replace-ment of the implant. Seen 3 years after OCP flap over new implant.

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over time. These factors influence how muchresorption may occur, leading to loss of detail,projection, and architecture. For those scientiststrialing tissue-engineered auricular frameworks inanimal models, these inflammatory and contractileforces oftendecimate thearchitecture andstrengthof the cartilage. pHDPE could be used as theprimary stage, covering it with TPF and skin graftsin the standard fashion, while the chondrocytesharvested from the auricular remnant are culturedand prepared on scaffolds as many researchershave tried. The difference is that this bioengineeredautologous cartilage framework could be swappedwith the pHDPE implant in a second stage into aready-made precontracted soft tissue envelope.The alloplast plays its part in bearing the brunt ofsoft tissue contracture and then makes way for anautologous, flexible framework to be inserted.

SUMMARY

The use of pHDPE as an alloplast in microtiareconstruction offers an excellent framework forpediatric reconstructive surgeons. Advantagesinclude earlier reconstruction, fewer procedures,

avoidance of donor site morbidity, shorterlearning curve, and improved size and contourmatch. Results ultimately depend on soft tissueenvelope, and choice of technique is bestdecided according to surgeon expertise and pa-tient preference.

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