Letters and Communications
Transpositional Modification of the Posterior Auricular Pull-Through Flap: A New Twist
Article first published online: 14 NOV 2013
© 2013 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.
Volume 40, Issue 1, pages 79–82, January 2014
How to Cite
Carroll, B. T., Gillen, W. S. and Maher, I. A. (2014), Transpositional Modification of the Posterior Auricular Pull-Through Flap: A New Twist. Dermatologic Surgery, 40: 79–82. doi: 10.1111/dsu.12368
- Issue published online: 6 JAN 2014
- Article first published online: 14 NOV 2013
Anterior auricular reconstruction is challenging because of the immobility of the skin of the conchal bowl and antihelix. Secondary intention and full-thickness skin grafts are commonly used but can result in undesirably long healing times for those who are hearing aid dependent or use custom-fitted ear protection.[1, 2] The “flip flop” or revolving door posterior auricular pull-through flap provides a local reconstructive flap option,[1, 3, 4] but it is limited to use in areas of the ear closely associated with the scalp because of its short central pedicle. Here, we review and demonstrate the proper use of a novel transpositional sling modification of the posterior auricular pull-through flap. This modification allows for greater pedicle length, thus minimizing tension, maximizing blood supply, and preventing attenuation of lateral auricular projection.
Unlike anterior auricular skin, the skin of the posterior auricle is freely mobile.[3, 4] The vestigial auricularis posterior muscle lies deep to a loose subcutaneous layer in the posterior auricular sulcus. Arterial supply for this area is derived primarily from the posterior auricular artery, so the dominant direction of blood flow is from inferior to superior—an important point when designing and undermining the transpositional sling modification of the pull-through flap. The depth of the posterior auricular artery is variable but generally runs in proximity to the auricularis muscle. Incorporation of muscle in the pedicle guarantees ample random pattern blood supply without intraoperative arterial identification.
Modifications and Technique
The revolving door modification is harvested from skin directly posterior to the defect and, like an island pedicle flap, is based upon a central musculosubcutaneous pedicle. Its pedicle length is limited to the thickness and extensibility of the posterior auricular soft tissue, making it most suitable for defects in close proximity to the scalp and in patients with limited lateral auricular projection. The transpositional modification increases pedicle length by shifting the donor site superiorly and posterior to the retroauricular sulcus (Figure 1). With biplanar undermining, a robust and lengthy pedicle can be formed, allowing sufficient pedicle length for use on the antihelix of those with more-protuberant ears, broadening the potential uses of the pull-through flap.
The skin is incised as it would be for the revolving door technique, and the area around the flap is undermined in the immediate subdermal plane. The incision at the superior aspect of the donor site is carried through the level of the auricularis muscle. Undermining is performed in the supraperiosteal plane, inferiorly beneath the intended course of the pedicle. Vertical sharp dissection is performed, connecting the superficial and deep undermining planes on either side of the pedicle until sufficient movement is achieved. This technique of biplanar undermining forms a flexible, mobile, robust, sling-like pedicle analogous to the nasalis sling flap so familiar to dermatologic surgeons. This pedicle can be used to access defects in more-distal areas than would be possible using the revolving door modification. An appropriately sized window in the cartilage is created to prevent pedicle strangulation (Figure 2). Once the flap is elevated and undermined, it is transposed under the retroauricular sulcus. The flap is sutured into place in a standard layered manner and the secondary defect closed (Figure 3). We have found that the overnight application of a head wrap dressing is sufficient for preventing bleeding complications.
Summary and Conclusion
The transpositional sling modification of the posterior auricular pull-through flap delivers consistent results (Figure 4) and offers a solution for the limited tissue reservoirs of the anterior auricle. We have performed pull-through repairs in 13 patients over the last 2 years (8 transpositional, 5 revolving door.) Wound care in all cases was complete and sutures removed after 1 week, permitting a swift return to normal functionality for all patients. In contrast, secondary intention often involves healing times of more than 3 weeks. No complications of chondritis, infection, or tissue necrosis were observed. Most patients were given a 1-week course of tetracycline after surgery.
The indications for pull-through flaps include 1.5- to 6-cm anterior auricle defects, specifically those involving the conchal bowl and antihelix. Large areas of cartilage denuded of perichondrium should lead to consideration of use for this type of repair, as should a patient's need for shorter healing time. The revolving door modification is typically useful for repair of the conchal bowl, whereas the transpositional modification is better suited to antihelical repair and defects on protuberant ears. A reservoir of sufficient non-hair-bearing retroauricular skin is required, and other options should be considered in patients with hairlines adjoining the retroauricular sulcus. A history of radiation or surgery in the area may impede flap viability.
The revolving door modification has been described in the dermatologic surgery literature, but other modifications of the auricular pull-through flap have been reported less frequently. Transpositional modifications have been discussed in the plastic surgery literature, with placement of the donor site in the retroauricular sulcus and manual de-epithelization of the pedicle.[3, 4] This introduces two problems. First, by placing the donor site in the retroauricular sulcus and de-epithelizing the pedicle, a vertically oriented secondary defect is created in the retroauricular sulcus. Closure of this donor site pulls the auricle toward the scalp, creating asymmetry of the lateral projection of the ears. Although pedicle length is sufficient, closure of the secondary defect pins the ear back. Second, manual de-epithelization of the pedicle creates an additional step that risks trauma to the vascular pedicle, endangering flap viability.
The transpositional sling modification has several important departures from previously published reports. First, biplanar undermining efficiently creates a long, robust vascular pedicle without the need for sharp de-epithelization of the pedicle. This technique, analogous to the creation of a nasalis sling, obviates the technically demanding step of sharp pedicle de-epithelization, minimizing potential trauma. Second, shifting the donor site posterior to the retroauricular sulcus affords greater pedicle length, extending the use of transpositional sling modification to areas of the ear further from the scalp without risking auricular pinning. Third, the combination of leaving the skin overlying the pedicle intact and shifting the donor site onto the posterior auricular scalp minimizes pinning back of the auricle due to closure of the secondary defect.
In conclusion, the transpositional sling pull-through flap modification represents a safe, reliable closure option for anterior auricular defects. The familiar biplanar undermining technique expands the applications of the pull-through flap.