Repair of medial canthal defects can often be difficult. Deep defects are better treated with local flaps, as skin grafts will not provide enough thickness to the area. However, a thick flap may need to be debulked later. In this video, a median forehead flap is used to repair a medial canthal defect after Mohs excision of a basal cell carcinoma. Medial canthal basal cell carcinomas are at a higher risk of recurrence, so I prefer a Mohs surgeon to remove these (if one is available in your community). A second stage procedure is performed for this patient to revise the flap. For a written transcript of this video, please see below:
This is Richard Allen at the University of Iowa. This video demonstrates repair of a medial canthal defect via a median forehead flap and the subsequent revision of the flap. The patient is s/p Mohs excision of a basal cell carcinoma. The entire canalicular system and puncta of the upper and lower lid were also removed. The dermatologist was concerned of involvement of the underlying periosteum and bone and marked the area. A chisel is then used to make an incision around the area of concern and the bone is removed for evaluation by the pathologist. This bone proved to have no involvement of the cancer. If there had been evidence of invasion of the bone, the patient would have undergone subsequent radiation therapy. Some surgeons would argue against bone removal as this may allow a path of low resistance for incompletely excised cancer to invade the nose.
The periosteum of the posterior lacrimal crest is engaged with a 4-0 Vicryl suture. This suture then engages the medial portion of the upper and lower tarsus. Tying this suture completes reconstruction of the posterior lamella. The anterior lamellar defect with then be reconstructed with the median forehead flap.
An incision is made along the planned median forehead flap with a 15 blade. Marks have also been made in the wrinkles of the forehead to aid in the subsequent closure of the donor site. A needle tip cautery is then used to dissect along the surface of the periosteum. This is performed to an area 2 cm above the root of the nose. Inferior to this area, the dissection will be performed subperiosteally with a freer periosteal elevator to allow identification and preservation of any of the neurovascular bundles. The mobilization of the flap is completed and the flap is transposed into the defect. The donor site is then widely undermined along the surface of the periosteum. The donor site is then closed with deep interrupted 4-0 Vicryl sutures followed by superficial 5-0 prolene sutures placed in a vertical mattress fashion.
Attention is then directed to the flap where deep sutures are placed through the periosteum followed by engaging the posterior surface of the flap. This will aid in seating the flap into the defect. Two sutures are placed for this purpose with 5-0 Vicryl suture. Deep sutures are then placed along the closure with 5-0 Vicryl sutures. The redundant portion of the flap is inspected and a dog-ear is excised. It is important not to cut into the flap too much as this could compromise the vascular supply of the flap. The skin is then closed with a combination of 5-0 and 6-0 Prolene suture. At the conclusion of the case, the flap covers the defect adequately.
The patient then returns in approximately two months for revision of the flap. The thick portions superiorly and inferiorly have been marked with a marking pen. The 15 blade is used to make an incision along the superior portion of the flap. The flap in the marked thick area is undermined and the subcutaneous fat is excised. Basically this thins the flap to just the dermis and epidermis. As a result of the thinning, a redundant portion of the skin is demonstrated. A marking pen is used to mark this redundant tissue and the tissue is excised with scissors. This results in adequate thinning along the superior portion of the flap. This is closed with deep interrupted 5-0 Vicryl sutures followed by superficial interrupted 5-0 Prolene sutures. Attention is then directed to the thickened inferior portion of the flap. A 15 blade is used to incise the inferior border of the flap. The flap is raised and the subcutaneous fat is excised with scissors. The redundant skin is then excised. The flap appears to be thinned appropriately and the flap is resutured into position with superficial 6-0 Prolene sutures. At the conclusion of the case, the revision of the flap appears appropriate. Antibiotic ointment is placed over the incisions. A gentle patch is placed for two days and the patient will return in one week for suture removal.
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