Microvascular Transfer of The Compound Dorsalis Pedis Skin Flap With Second Metatarsal for Mandible and Floor of Mouth Reconstruction

R. M. ZUKER

R. T. MANKTELOW

Perhaps one of the most significant contributions to head and neck reconstruction is the use of the free composite osteocutaneous flap (1, 2, 3, 4, 5, 6, 7, 8). The dorsalis pedis flap (9, 10), when used with the second metatarsal, can reconstruct not only the floor of the mouth but also up to 8 cm of the mandible itself with vascularized tissue.

INDICATIONS

Reconstruction of head and neck defects is most difficult following composite resections. There are occasions when no bony reconstruction of any kind is mandatory, such as hemi-mandibular resections. We believe reconstruction with vascularized bone provides the patient with the best reconstructive alternative. Thus, a hemimandibular resection would be a relative indication.

Anterior segment defects, on the other hand, leave the patient with a significant functional and aesthetic deformity that requires reconstruction. Conventional techniques often fall short of providing adequate, lasting bone for both contour restoration and function. Problems may ensue with mastication, the production of intelligible speech, and drooling. The dorsalis pedis flap with the metatarsal, when osteotomized, provides an excellent reconstructive tool for the anterior segment defect, one that cannot be provided by any other available means of reconstruction. The anterior segment composite resection, then, does provide an absolute indication for the compound dorsalis pedis skin and metatarsal flap, provided that the bony defect can be reconstructed with the 7 to 8 cm of metatarsal available.

Among advantages of the flap are that it provides vascularized bone for difficult reconstructive problems such as anterior segment defects. It also provides thin, pliable tissue for mucosal resurfacing, a long vascular pedicle, and a donor site that is remote from the recipient site, which may have been radiated.

FLAP DESIGN AND DIMENSIONS

With postoperative lingual swelling, the pedicle could be compromised seriously if its position were between the tongue and mandible. Thus, it is better to have the vascular pedicle external to the mandible. The most likely site of recipient vasculature is identified. Because the position of the vessels should be external to the mandible, it is best to use the contralateral foot. Routine angiography is not necessary if adequate independent dorsalis pedis and posterior tibial pulses are present.

The boundaries of the skin flap include the extensor retinaculum proximally, the interdigital web spaces distally, and 1 cm on either side of the extensor hallucis longus (medially) and extensor digiti quinti (laterally). The second metatarsal then lies beneath the central segment of the skin flap (see Fig. 207.2B).

OPERATIVE TECHNIQUE

The operation is carried out in three parts. The tumor (Fig. 207.1A) is resected along with the anterior segment of mandible. Usually, a lip-splitting approach is used (Fig. 207.1B). A radical neck dissection is often necessary, and the recipient vasculature is prepared on this side. We have used virtually all the branches of the external carotid artery to revascularize this flap. Usually, however, the superior thyroid or facial vessels, if available, are used. To assist in the mandibular reconstruction, the mandible that has been resected is measured on either side of the midline and its angle at the
anterior segment is estimated. A template of this resected segment may be useful in planning the osteotomy of the second metatarsal.

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