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Microsurgery

Perforator flaps

By Rami Mossad Ibrahim, Magnus Obinah, Magnus Balslev Avnstorp, Peter Stemann, Birgitte Jul Kiil and Christian Kaare Paaskesen Stud. Med.

Introduction

In this chapter you will learn the basic principles about perforator flaps, the nomenclature, the pre-operative patient assessment, and get an overview of the procedure by clinical photos and illustrations.

Background

In 1989 Koshima and Soeda published the first case report on perforator flaps for reconstruction in two patients. They isolated a cutanous flap based on the inferior epigastric artery for successful reconstruction of a large groin defect in the oral floor, leaving the rectus abdominis muscle intact. Since then several other perforator flaps have been found and used for reconstruction.

Definition

Perforator flap: A flap based on an isolated vascularized pedicle arising from the deep vascular system. A perforator flap normally consists of skin and/or subcutaneous fat tissue, but may consist of only scarpa’s fascia and subcutaneous fat tissue. The perforators may course either through or in between the deep tissues such as muscle.

Nomenclature

The 29th of September 2001, a consensus meeting was held in Gent, Belgium.

Perforator flaps were categorized as follows:

  1. Free perforator flaps (Dissected using microsurgery techniques)
  2. Pedicled perforator flaps
    1. Transposition flaps
    2. Propeller flaps (90-180 degree rotation flaps)

Classification of Perforator Types

Perforator flaps may be classified in several different ways. One classification is by the way the perforator courses from the source vessel to the deeper fascia and skin plexus; Either directly to the skin, through the intermuscular septum, through the muscle, as a branch of another larger vessel to muscle or skin. The flap is usually named after the specific perforating vessel.

Direct cutaneous perforator: Courses directly from source vessel to the skin, passing only through the deep fascia.

Direct Septocutaneous perforator: Courses through intermuscular septum before piercing the deep fascia to the skin.

Direct Cutaneous branch of muscular vessel: Courses directly to the skin from a vessel ending in a muscle without perforating either septa or muscle.

Perforating cutaneous branch of muscular vessel: As a sidebranch of a muscular vessel courses through the muscle before perforating to the skin.

Musculocutaneous perforator:Courses through muscle before piercing the deep fascia to supply the overlying skin.

Angiosomes

Angiosomes are three-dimensional territories from bone to skin, supplied by named arteries travelling with veins and nerves in a neurovascular bundle. Angiosomes consist of arteriosomes (the arterial blood supply) and venosomes (the venous drainage) that are connected for optimal blood circulation.

In the dermal and subdermal tissues, angiosomes are connected either by vessels with a reduced-caliber arteries called ”choke” anastomoses or by the so-called the “true” anastomoses, that regulate blood flow to the skin without any change in caliber.

Choke vessels provide an initial resistance to blood flow between base and the tip of a flap, but when a flap is delayed by strategic division of cutaneous perforators, they dilate to the dimensions of true anastomoses, thus enhancing the circulation to the distal flap.

Indications for microsurgical flaps

Classic indications are reconstruction of defects following cancer resections or traumatic injuries in cases where local flaps are not sufficient or consist of relevant tissues for adequate reconstruction. I.e. breast reconstruction following mastectomy and radiation therapy or mandibular reconstruction using a free fibula bone graft. Follow links in the beginning of this chapter for the specific perforator flap.

Contraindications for microsurgical flaps

Severely ill patients where the patient will not survive intensive longer surgery.

A relative contraindication may be massive tumor masses where no salvage surgery is available, but in these cases debulking followed by a flap for cover of defect may be a choice.

Pre-operative assessment

It is important to do a proper full patient assesment from top to toe before surgery. This includes a profound assessment of specific anatomical region to be resected / trauma induced defect for useful recipient arteries and veins. Aswell as a profound assessment of donor site for skin quality and blood perfusion. A full set of blood samples including INR in case of blood thinning medication must also be preformed.

CT angiography must also be preformed to determine the exact location of the optimal perforating artery.

Depending on the case, different assessments must be made.

In case of carcinoma:

  • Tumor location, size, bone involvement,
  • Nearby vessels for anastomosis,
  • Functional aspect i.e. when reconstructing tongue, CT scan or MR scan.

In case of trauma:

  • Size and depth of laceration,
  • Bone fractures,
  • Infection,
  • Nerve involvement,
  • Functional aspect i.e. reconstruction of breasts,
  • Nearby vessels for anastomosis.

Also remember pre-operative information to patient, this includes placement of scares(depending on the specific perforator flap) as well as risk of infection, bleeding, hematoma, flap necrosis, seroma, swelling, change in shape and size, affection of donor- and recipient area.

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