Chapter 60. Understanding flaps based on Perforators (Vasculosomes)
(Addendum to Chapter 59)
This chapter was invited from Adhish Basu, Kolkata, whose work on perforator flaps won the Kilner Essay Award (2016) of the Association of Plastic Surgeons of India. He presents a slightly different view of perforator flaps as compared to the previous chapter.
There has been a long-standing confusion towards naming traditional peninsular-design skin flaps (like the groin flap) as perforator flaps. While harvesting these flaps, the operator takes a leap of faith as the perforators that obviously provide the flap with nourishment essential for it’s survival are not visible! Although not visible, the perforators are present and therefore the flap should be called a “perforator flap”. Unfortunately, flap nomenclature has traditionally been based on flap dissection techniques rather than on their vascular basis. When Fu-Chan Wei et al described their ‘free-style perforator flap from the thigh, the dissection of perforators through the muscle was a requirement to call it a perforator flap. It was actually Ye-Guang Song and co-workers who were the first to describe a perforator flap from the thigh in 1984, years before Isao Koshima described the perforator flaps from the abdomen in 1989. The reason why Koshima is often quoted as the first one to describe perforator flaps is because of his description of intramuscular dissection of the pedicle over a long distance. The free-style concept was actually first described by Sipra Asko-Seljavaara in 1983 who proposed an exploratory skin incision for dissection of the perforator around the point where it perforates the fascia. Hence all isolated perforator flaps are actually free-style in concept. The question of whether the tissue characteristics of the donor and recipient match, needs to be addressed by any flap that is harvested, and not necessarily the flap has to be one that has its perforators skeletonized!
The vasculosome theory provides a physiological basis for harvesting perforator flaps. (Figure 1) Based on the principles of the vasculosome theory the flaps based on perforator vessels may be classified into three broad categories viz. “isolated” perforator (IP) flaps, “clustered” perforator (CP) flaps and combined perforator flaps. (Figures 2 and 3).
When a single vasculosome is harvested based on dissected and isolated perforator vessels the flap is termed an Isolated perforator flap. (Figure 2) On the other hand when one or more vasculosomes are harvested based on one or more perforators which have neither been dissected nor been isolated, the flap is termed a clustered perforator flap. (Figure 2) Both isolated and clustered perforator flaps have subtypes. While the isolated perforator flaps may be subdivided based on the length of pedicle dissected into long and short types; the clustered perforator flaps may be classified into peninsular (Latin paene = almost and insula = island) and island subtypes. An example of the peninsular clustered perforator flap is the traditional groin flap; whereas examples of the island clustered perforator flap are Behan’s keystone design island flap and the radial forearm flap (where multiple forearm vasculosomes are supplied by a long source vessel, the radial artery). The pectoralis major musculocutaneous flap when harvested as a true island flap is also an example of an island clustered perforator flap, the muscle mass being incidentally included in the flap.
If more than one vasculosome is individually harvested on isolated perforators but are eventually joined with a single source vessel, these flaps are termed chimeric perforator flaps. (Figure 3) When a flap has more than one vasculosome included with two separate feeding perforators, the flap is termed a conjoined perforator flap (previously termed Siamese flaps). (figure 3) The latter requires two sets of feeder vessels for complete survival of the flap. Peninsular clustered perforator flaps which require arterial supercharging or turbocharging for complete survival, are basically conjoined flaps.
- Wei FC, Mardini S. Free-style free flaps. Plast Reconstr Surg 2004;114(4):910–916
- Song YG, Chen GZ, Song YL. The free thigh flap: a new free flap concept based on the septocutaneous artery. Br J Plast Surg. 1984 Apr;37(2):149-59.
- Koshima I, Soeda S. Inferior epigastric artery skin flaps without rectus abdominis muscle. Br J Plast Surg 1989;42(6):645–648
- Asko-Seljavaara S. Free style free flaps. In: Programs and Abstracts of the Seventh Congress of the International Society of Reconstructive Microsurgery. New York, NY; 1983
- Basu A. Classification of flaps and application of the concept of vascular territories. In Textbook of plastic, reconstructive and aesthetic surgery, Edition: 1, Chapter: 5, Publisher: Thieme, Editors: Karoon Agrawal, 2016, pp.93 – 120
- Basu A. The vasculosome theory. Plast Reconstr Surg 2015; 135(2):449e–451e