Aust. N.Z. J . Surg. (1994) 64, 145-146 145

EDITORIAL COMMENT

FASCIOCUTANEOUS FLAPS IN LOWER LIMB RECONSTRUCTION

With their article in this issue on fasciocutaneous flaps in lower limb reconstruction,’ Felix Behan and his col- leagues not only raise new flaps but new questions and some eyebrows. The capricious outcome of flaps to the lower leg has long bedevilled surgeons and led to the concept that the lower leg has by nature a peculiar and notoriously poor blood supply. After sporadic failed sorties into the lower leg, plastic surgeons’ egos frequently needed convalescence in the more forgiving waters of zones such as the head and neck, and trunk, where flaps raised in apparently the exact same manner as in the lower leg, regularly survived.

Historically, the staged techniques of the tube pedicle and cross leg flaps were unpredictable, cumbersome and extremely costly. Ralph Ger’s introduction of the muscle flaps heralded a new beginning.’ For muscles, at least, the blood supply had a known and predictable source, often at a site distant from the zone of injury. Skin even as islands could be piggy-backed with the muscle. Because of the limited muscle length and the proximal blood supply this concept has found its niche for proximal lower leg and knee defects. Distally based muscle flaps nourished by reverse flow3 for distal defects have not proved consistently reliable. Even proximally based flaps have high complication rates particularly for closure of traumatic defect^.^

The free microvascular flap offered the potential for a final solution. However, all reported series confirm that survival figures in the lower leg are appreciably worse than for any other zone in the body. The magnitude of these microvascular procedures alone is often daunting and the donor flaps rarely satisfy the needs of the defect from a thickness and textural viewpoint.

Ponten’s remarkably simple concept of fasciocuta- neous nourishment of the skin of the lower leg5 explained the hitherto mysterious death of the purely cutaneous flaps that had been traditionally raised superficial to the deep fascia, according to the customs of the face, neck, thorax and abdomen. Surprisingly, scalp flaps had always been raised in the subfascial (galeal) plane and large, narrow based flaps were commonplace but the analogy to the limbs was not recognized. Behan was the earliest to appreciate the significance of the deep fascia in head and neck reconstruction and described its importance in the viability of the forehead flap as early as 1973.6 Although these newly described fasciocutaneous flaps of the lower leg proved remarkably viable, the source of their blood supply and venous drainage was assumed to be from a proximal descending source such as the descending genicular vessels and long saphenous system, respectively. The sanctity of this broad proximal base still posed restrictions on their applications and the more distal the defect the longer the flap needed to be. The

secondary defect was often considerably larger than the primary one being repaired. To increase the arc of rota- tion island fasciocutaneous flaps were designed, based proximally and distally on the known major vessels of the limb. Yoshimura et al. used peroneal perforator^,^ Wee, Morrison and Shen, and Torii et al. used anterior tibial artery perforators8-10 and Hong et al. used perfora- tors from the posterior tibial vessels. II These authors realized that the source vessels supplying the fasciocuta- neous plane were local perforators from the named major vessels via the fascioseptal spaces between the muscles. This anatomy was elucidated and described in great detail by Cormack and Lamberti, and Carriquiry et al. 1 2 ~ 1 3 These island fasciocutaneous flaps pedicled proximally or dis- tally require division of a major vessel and this remains a deterrent to their use, especially for traumatic defects where vascular damage may be coexistent. Taylor and Palmer’s injection studies of the lower limb vessels also confirmed the source of these perforators in the fasciosep- tal spaces and pointed out, like Cormack and Lamberti, that one vascular territory linked at the fasciocutaneous horizontal plane with its neighbour in a dynamic way through what they termed ‘choke’ vessels, such that any two adjacent territories could be nourished by a single perf~rator.’~ Taylor chose the word ‘angiosome’ to de- scribe the three dimensional linkage in both the horizontal and vertical dimensions. Several years before this, Behan had by injection studies demonstrated and described the linkage of one axial pattern vascular temtory with another and coined the term ‘angiotome’ to complement the well understood territory of the dermat~me.’~

Thatte’s venous pedicle flapsI6 as well as the arterial- ized free venous flaps of Honda et al. and Inoue17.18 are fasciocutaneous in nature and add a further dimension for closure of lower limb defects by transferring appropriate local tissue, but their reliability is by no means certain. The fasciocutaneous turnover flaps also described by ThatteI9 stretch one’s credulity but obviously survive. These are further examples of fasciocutaneous flaps sur- viving on septofascial perforators.

Behan’s article in this issue surprises us with his intuitive daring and conviction. He proposes an angio- tome concept closely paralleling the neurologically deter- mined dermatomes. He has learned his art not in the halls of academia but in the bazaar and, reminiscent of the mystical energy paths of the Chinese acupuncturists, he plucks perforators from these lifelines with a magician’s regularity. Like the conjurer he has not fully shown us the secret of his trick so that his audience remains frustrated by the gaps that limit their ability to play the stand-in or put on a rival show. He can close almost any defect by rotation or advancement of immediately adjacent tissue based on the most meagre of perforators. The axis

146 MORRISON

of these perforators is along the dermatome-angiotome line but this is a rather nebulous street directory. Are these axes along the line of the underlying vessels from which we know these perforators ultimately derive, and through which intermuscular septa1 space are they emerg- ing? He points out the importance of the cutaneous nerves and it is well known that a large vessel perforator of the anterior tibial artery accompanies the superficial peroneal nerve, but is this so for the saphenous and sural? He states that the saphenous and sural nerves are not divided: are these nerves therefore guides to the perforators? His flap size is not necessarily related to defect size as in case 3, Fig. 3 where an 8 X 3 cm defect is closed with a 20 X 6cm flap; in case 5 , a 4 cm ulcer is closed by a flap 28 X 12 cm. What determines its size, how many perforators and what calibre are necessary to sustain them? How far will these perforators lengthen by direct advancement as many of his flaps simply advance towards the midline without rotation. Are we all possessed of the same courageous stuff as Behan that lets him raise half of the integument of the limb on the expectation that he will find a perfora- tor to support it?

Two other somewhat mystical concepts are mentioned: intrinsic expansion, which allows closure of larger defects than expected, and hyperaemia due to circumferential division of the skin and deep fascia, which improves the perfusion of his flaps. This latter and very exciting observation is ‘confirmed’ by nuclear scans. Again we are tantalized by the offer of a separate article to explain it.

Behan’s remarkable success rate in the minefield of the lower leg tells its own story. With the exception of the acute injury, he has possibly eliminated the need for free flaps. By stretching his fasciocutaneous concepts and perforators to their limits he has brought back the mystique, the art and the daring into plastic surgery. We look forward to his further publications.

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REFERENCES Behan FC, Terrill PJ, Ashton MW. Fasciocutaneous island flaps in lower limb reconstruction using dermatomal pre- cincts. Aust. N.Z. J. Surg. 1994; 64: 155-166. Ger R. The management of pretibial skin loss. Surgery

Townsend PLG. An inferiorly based soleus muscle flap. Br. J. Plast. Surg. 1978; 31: 210-13. Neale HW, Stem PJ, Kreilein JG, Gregory RO, Webster L. Complications of muscle-flap transposition for traumatic defects of the leg. P last. Reconstr. Surg. 1983; 7 2 5 12-16. Ponten B. The fasciocutaneous flap: Its use in soft tissue

1968; 63: 757-63.

defects of the lower leg. Br. J. Plast. Surg. 1981; 34:

6. Behan FC, Wilson JSP. The vascular basis of laterally based forehead island flaps and their clinical applications. In: Proceedings of Second Congress of the European Section of the International Confederation of Plastic and Recon- structive Surgery, Madrid, 1973.

7. Yoshimura M, Imura S, Simamura K, Yamauchi S, Nomura S. Peroneal flap for reconstruction in the extremity. Plast. Reconstr. Surg. 1984; 74: 402.

8. Wee JTK. Reconstruction of the lower leg and foot with the reversed-pedicled anterior tibial flap: Preliminary report of a new fasciocutaneous flap. Br. J. Plast. Surg. 1986; 39:

9. Momson WA, Shen TY. Anterior tibial artery flap: Anatomy and case report. Br. J. Plast. Surg. 1987; 40: 230-5.

10. Torii S, Namiki Y, Hayashi Y. Anterolateral leg island flap. Br. J . Plast. Surg. 1987; 40: 236-40.

11. Hong G, Steffens K, Wang FB. Reconstruction of the lower leg and foot with the reverse pedicled posterior tibial fasciocutaneous flap. Br. J. Plast. Surg. 1989; 42: 512-16.

12. Cormack G, Lamberti B. A classification of fascio-cutaneous flaps according to their patterns of vascularisation. Br. J. Plast. Surg. 1984; 37: 80-7.

13. Carriquiry C. Costa A, Vasconez LO. An anatomic study of the septocutaneous vessels of the leg. Plast. Reconstr. Surg. 1985; 76: 354-63.

14. Taylor GI, Palmer JH. The vascular temtories (angiosomes) of the body: Experimental study and clinical application. Br. J. Plast. Surg. 1987; 40: 113.

15. Behan FC, Wilson JSP. The principle of the angiotome, a system of linked axial pattern flaps. In: Hueston J (ed.) Transactions of the Sixth International Congress of Plastic and Reconstructive Surgery, Paris, 1975.

16. Thatte RL, Thatte MR, Kumta SM, Purdhit SK, Deshpande SN, Thatte RN. Cephalic venous flaps: A series of 8 cases and a preliminary report on the use of *Tc labelled RBCs to study the saphenous venous flap in dogs. Br. J. Plast. Surg. 1989; 42: 193-8.

17. Honda T, Nomura S, Yamauchi S. Shimamura K, Yoshimura M. The possible applications of a composite skin and subcutaneous vein graft in the replantation of amputated digits. Br. J. Plast. Surg. 1984; 37: 607-12.

18. Inoue G, Madea N. Arterialized venous flap coverage for skin defects of the hand or foot. J. Reconstr. Microsurg.

19. Thatte RL, Patil D, Talwar P. De-epithelialised ‘turn over’ axial-pattern flaps in the lower extremity. Br. J. Plast. Surg.

215-20.

327-37.

1988; 4: 259-64.

1983; 36: 327-33.

Department of Surgery St Vincent’s Hospital Fitzroy, Victoria, Australia

WA MORRISON