This lecture will provide a case-based discussion of closure of large maxillary oncologic defects that require not only removal of a portion of the maxilla, but also skin that overlies the tumor. Surgeries of various levels of difficulty will be discussed, as will the thought processes behind reconstruction decisions.

Flap options for closure include local flaps and distant flaps. Research shows that perfusion decreases to 10% after elevation of a single pedicle flap or 40% after raising a bipedicle flap. Staged development of flaps (separating the time between raising the flap and placement of the flap in its recipient site by utilizing techniques such as a tube flap) help to combat this decrease in blood supply by neovascularization. However, staged techniques are not usually practical for our maxillectomy patients due to a large defect into the nasal cavity/maxillary recess that needs to be closed at the time of the original surgery.

Before surgery, the skin surrounding the maxillectomy site is manipulated to assess lines of tension and the directions the skin may be most easily moved. Local flaps, also called subdermal plexus flaps, can be categorized as advancement and rotating flaps. Advancement flaps involve advancement, rather than rotation, of tissue adjacent to the defect to close the site. Rotating flaps pivot around a point central to their base into the defect. Advancement flaps can be created by making a single incision away from but parallel to the defect, resulting in a bipedicle flap.
The bipedicle flap is limited in the distance it can move since it is still attached to the skin on two sides. The donor site is either closed after undermining or it is left to heal by second intention if tension is too great at the donor site. In general, the total length of the flap should be no more than twice the width of the flap. The single pedicle flap is formed by two releasing incisions that are equal in length to the defect. The main disadvantage of an advancement flap is that any tension will be directly transferred to the site of the incision.

 Rotating flaps can be further categorized into the following options:
• Rotation flap- semicircular flap that rotates into the adjacent recipient bed.
• Transposition flap- rectangular pedicle graft commonly rotated within 90 degrees of the wound axis.
• Interpolation flap- rectangular flap rotated into a nearby but not immediately adjacent defect.

A portion of the flap passes over the skin between donor and recipient beds (redundant portion excised once healed). The axial pattern flap is a type of distant flap that is centered over, and takes with it, a specific artery to allow for a longer flap with less likelihood of flap necrosis due to loss of blood supply.

Reference
Pavletic, MM. Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd ed. Wiley Blackwell, Hoboken, NJ. 2010.

Questions?
Contact me at jlewis@vdsvets.com