The lower posterolateral thigh flap

Britzsh Journal ofP/asric Surger? ( I989), 42. 133- 139 $ 1989 The Trustees of Bntish Association of Plastic Surgeons

The lower posterolateral

thigh flap

J. K. G. LAITUNG Plastic Surgery Department, University Pinderfields Hospital, Wakefield

Hospital of South Manchester

and Yorkshire Regional Burns Centre,

Summary-The vascular basis of a new distally based flap in the distal third of the posterolateral thigh has been studied in 30 cadaver limbs. This flap is supplied mainly by direct cutaneous branches of the popliteal artery and of the lateral superior genicular artery. Its use as a distally based fasciocutaneous flap for defects of the knee is illustrated and its potential as a free flap is discussed. A classification of various flaps from the posterolateral region of the thigh is also proposed. In the light of the anatomical studies, the cutaneous blood supply of the distal posterolateral region and other regions of the thigh is reviewed.

Various methods have been described to cover an exposed knee joint; these make use of such local muscle flaps as the sartorius, gastrocnemius, vastus medialis and vastus lateralis flaps (Elsahy, 1978; Petty and Hogue, 1978 ; Arnold and Prunes-Carillo, 1981; Sanders and O’Neill, 1981; Tobin, 1985; Swartz et al., 1987). However, the upper part of the anterior aspect of the knee is a particularly difficult area since the surrounding skin and muscles are often damaged at the same time (Jackson, 1976). In contrast, the more posterior aspect of the knee and lower thigh is usually spared from direct trauma and seems a potential source of soft tissue for reconstruction of the knee. Therefore, an investigation of the vascular basis of a distally based flap from the lower posterolateral thigh has been carried out.

This area of the thigh was found to be supplied by a direct cutaneous branch of: (1) the popliteal artery in 29 of the 30 limbs (96%) (2) the lateral superior genicular artery in 26 of the 30 limbs (86:/,), (3) the third perforating artery of the profunda femoris in 5 of the 30 limbs at this level (160/o), (4) musculocutaneous perforators from vastus lateralis and biceps femoris in all limbs. The main cutaneous vessels emerge from the lateral intermuscular septum between vastus lateralis and biceps femoris (Fig. 2), entering the flap superficial to fascia lata at different levels (Table 1). Table 2 shows the number of vessels found supplying the flap: in 6096 of the limbs, both the

Anatomical investigation Dissections of 30 human cadaver limbs (10 fresh and 20 preserved) were performed. Seven of the fresh limbs were injected with ink in order to determine the origin of the cutaneous vessels and the territorial limit of the cutaneous supply. The popliteal artery was cannulated retrogradely after distal ligation and injected with blue ink. The profunda femoris artery was cannulated antegradely and injected with red ink. Depending on the level of skin staining from the popliteal injection, which usually extended about 15 cm above the lateral femoral condyle, a skin flap was raised overlying the lateral intermuscular septum between vastus lateralis and biceps femoris (Fig. I).

Fig. 1 Figure l-Left thigh: marking of flap; upper limit of ink staining approximately 15 cm above the LFC. Note posterolateral groove-landmark for the lateral intermuscular septum.

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Table 1 Distancepro.ximal to lateral ,ftimoral condyle (cm)

Vascular pedicles

Profunda femoris perforating branch Popliteal branch Lateral superior genicular branch

10 6 2

and lateral superior genicular cutaneous branches were present. The direct cutaneous branch of the popliteal artery arises about 6 cm (range 3-9 cm) above the lateral femoral condyle (Fig. 3). It gives branches to both vastus lateralis and biceps femoris on its way. The length of the vessel from its point of origin from the popliteal artery ranges from 411 cm (mean 7 cm) with a mean external diameter of 2.7 mm (range 1.O-4.0 mm) at its origin. The direct cutaneous branch of the lateral superior genicular artery arises about 2 cm above the lateral femoral condyle. On average, it is shorter (mean length 5 cm; range 3-7 cm) and smaller (mean external diameter 2 mm; range 1.0-3.0 mm) than the direct cutaneous branch of the popliteal artery. The artery bifurcates into its cutaneous branch and a branch to the genicular anastomosis (Fig. 2). Both the popliteal and lateral superior genicular branches are accompanied by venae comitantes draining into the popliteal vein, with mean external diameters of 2.4 mm and 1.6 mm respectively. In 5 limbs there were separate veins draining the flap, and in 2 of these the veins joined the profunda venous system. The direct cutaneous branch of the third profunda femoris perforating artery had an oblique downward course and was found to supply the area of the thigh at this level in only 5 limbs (Table 2, Fig. 2). popliteal

Table 2 No. of limbs

Cutaneous arteries supplyingflap

18 (6093 8 (27%) 4(13X)

2 (DP+LSG)

3 (DP + LSG + PFP) 1 (DP/LSG)

DP=direct popliteal branch. LSG = lateral superior genicular branch. PFP = profunda femoris perforating branch.

Case report A lower posterolateral

thigh flap was used successfully

in

an 89-year-old patient who had sustained a deep burn to the superior and anterior aspects of her left lower thigh and knee (Fig. 4A), involving the lower part of rectus femoris, the suprapatellar bursa and the quadriceps expansion. Excision of the burn resulted in exposure of the knee joint with a defect measuring 20 x 15 cm. An inferiorly based transposition flap was raised from the intact posterolateral aspect of the thigh, together with fascia lata which was used to reconstruct the joint capsule and quadriceps expansion. A small backcut was necessary in order to ease transposition. Most of the donor site was closed directly except for a small area that needed skin grafting (Fig. 4B, C).

The cutaneous blood supply of the thigh comes from two groups of vessels. The first group is variously referred to as “direct” or “fasciocutaneous” (Cormack and Lamberty, 1985, 1987) or “septocutaneous” (Song et al., 1984), while the second group are indirect, musculocutaneous vessels. It would be simpler to call the first group “direct” cutaneous vessels as proposed by Spalteholz in 1893 (Timmons, 1985) and again by Taylor and Palmer (1987). The term “fasciocutaneous” is then used not as a vascular hallmark but to denote the tissue composition of the flap. Cormack and Lamberty (1987) have described the regional arrangement of the cutaneous blood supply of the thigh as follows: The anteromedial region is supplied by the superficial femoral artery; the anterolateral and posterior thigh regions are supplied by the profunda femoris artery via the descending branch of the lateral circumflex artery and the cutaneous branches of its perforating arteries respectively. Occasionally, in the lower posterior thigh there is an ascending branch from the popliteal artery. In the present study, cutaneous branches from the profunda femoris perforating arteries which emerge from the lateral intermuscular septum and in between the hamstrings were found mainly in the upper two-thirds of the posterior thigh. The superficial femoral and popliteal arteries were found to supply the lower third of the thigh via the descending genicular artery and its cutaneous branches medially and via the direct popliteal and lateral superior genicular cutaneous branches posterolaterally (Figs 5A, B and 6). Likewise, the ascending cutaneous branch from the popliteal artery in the posterior thigh was only an occasional finding in this series. Thus, from the present study it appears that in

THE LOWER

POSTEROLATERAL

THIGH

FLAP

Fig. 2 Figure 2 --Left thigh: cutaneous vessels emerge from the lateral intermuscular septum and run superficial to fascia lata (fl): (a) from 3rd prqofunda femoris perforating artery. (b) from popliteal artery. (c) from lateral superior genicular artery.

Fig. 3 Figure &Left thigh: the direct popliteal and biceps femoris (bD.

cutaneous

vessel arising

from the popliteal

artery (p) emerges

between

vastus lateralis

(VI)

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OF PLASTIC SURGERY

Fig. 4 Figure &(A) Extensive burn to the left knee involving knee joint and quadriceps tendon. (B) Reconstruction with distally based lower posterolateral thigh flap: fascia lata used to reconstruct extensor mechanism and joint capsule. (C) 7 months after repair, patient can achieve nearly full extension of her knee.

THE LOWER

territories-note

POSTEROLATERAL

overlap.

THIGH

(A) Posterolateral.

FLAP

(B) Poiterio;

view.

Fig. 6 Figure bSchematic’diagram showing the branches of the popliteal artery and genicular anastomosis. (Reproduced with kind permission from W. B. Saunders and the American Journnl qfSiurgery)

most cases the cutaneous blood supply of the upper two-thirds of the thigh is derived from both the superficial femoral and profunda femoris arteries, and that of the lower third from the superficial femoral and popliteal arteries (Fig. 7). Undoubtedly, however, overlap does occur between the latter and the profunda femoris cutaneous supply. The findings in this study are consistent with the pictorial representation of the cutaneous supply of this area of the thigh by Manchot (1889, 1983) and more recently by Taylor and Palmer (1987). Some confusion exists in the naming of various free flaps in the posterolateral region of the thigh. The profunda femoris artery has four perforating arteries, the fourth being its terminal branch. Maruyama et al. (1984) called a free flap based on the cutaneous branch of the first perforating artery “the lateral thigh fasciocutaneous flap”. This has been renamed “the superior posterolateral thigh flap” by O’Brien and Morrison (1987). Similarly, a free flap based on the cutaneous branch of the third perforating artery has been named “the posterior thigh flap” (Song et al., 1984) “the lateral thigh flap” (Baek, 1983) and “the posterolateral thigh flap” (O’Brien and Morrison, 1987). Nappi et al.

BRITISH JOURNAL

Fig. 7 Figure 7-Schematic supply of the thigh.

representation

of the cutaneous

blood

OF PLASTIC SURGERY

(1986) described the use of a “posterolateral thigh free flap” to release a burn contracture of the face. No anatomical details were given of its vascular supply although an illustration showed this flap sited in the distal third of the thigh. For simplicity, anew nomenclature is put forward (Table 3). The lower posterolateral thigh region can be used as a donor site for a distally based flap to cover most of the front of the knee. For this purpose, it is based on the direct cutaneous branches of the popliteal artery and lateral superior genicular artery, but not on that of the third perforating artery of the profunda femoris because of the higher point of emergence of its direct cutaneous branch. The strong layer of fascia lata makes it ideal for concomitant reconstruction of the quadriceps expansion and for use as part of a “fasciofat” flap. This region is also a potential donor site for a free flap as shown in the selective arterial injection study (Fig. 8A, B). Both the direct popliteal and

Fig. 8 Figure 8-_(A) Free lower posterolateral thigh flap (direct popliteal cutaneous of flap after selective injection of the direct popliteal cutaneous branch.

artery

being injected

with contrast).

(B) Radiograph

THE LOWER

POSTEROLATERAL

THIGH

FLAP

Table 3 Posterolateral thigh&p Superior Middle Lowelr

I st profunda femoris perforating artery 3rd profunda femoris perforating artery Direct popliteal and lateral superior genicular arteries

lateral superior genicular cutaneous vessels are easil,y accessible and suitable in length and calibre for microvascular anastomosis. It is a relatively thin fasciocutaneous flap, its thickness ranging from 0.5 cm anteriorly to 2 cm posteriorly. The cosmetic defect of the donor site obviously depends on the size of flap raised (maximal size at least 20 x 10 cm) and on whether primary closure is achieved. This problem would be avoided if a fasciofat instead of a fasciocutaneous flap was used. Acknowledgements My thanks go to Mr J. S. Watson. Consultant Plastic Surgeon at the University Hospital of South Manchester. for allowing me to operate on his patient and for encouraging me to perform this study. to the Departments of Anatomy at the Universities of Manchester and Leeds for providing the materials for the dissections, to the Departments of Medical Illustration at the University Hospital of South Manchester and at Bradford University: and to Mr M. J. Timmons, Consultant Plastic Surgeson at St Luke’s Hospital, Bradford, for his helpful advice and criticisms.

1.19 Jackson, D. Ma&. (1976). Burns into joints. Burns, 2,90. Manchot, C. (I 889). Die Hautarterien des Menschlichen Kiirpers. Leipzig: F. C. W. Vogel. Manchot, C. (1983). The Cutaneous Arteries of the Human Bodr. Translated by Ristic. J. and Morain. W. D. New York’ .._. Springer-Veriag. Maruvama. Y.. Ohnishi. K. and Takeuchi. S. ( 1984). The later:21 thigh fasciocutaneous flap in the repair of ischial and trochanteric defects. British Journalof‘Plastic Surgery. 37,103. Nappi, J. F., Lubbers, L. M. and Carl, 9. A. (1986). Composite tissue transfer in burn patients. Clinics in Plasric Surgery, 13, 137. O’Brien, 9. McG. and Morrison, W. A. (1987). Reconstructhv Microsurgery. Edinburgh: Churchill Livingstone. Petty, C. T. and Hogue, R. J., Jr. (1978). Closure of an exposed knee joint by use of a sartorius muscle flap: Case report. Plastic and Reconstructive Surgery. 62. 458. Sanders, R. and O’Neill, T. (1981). The gastrocnemius myocutaneous flap used as a cover for the exposed knee prosthesis. Journal ef Bone and Joinr Surgery. 639. 383. Song, Y. G., Chen, G. Z. and Song, Y. L. (1984). The free thigh flap: a new free flap concept based on the septocutaneous artery. British JournalofPlastic Surgery? 37, 149. Swartz, W. M., Ramasastry, S. S., McGill, J. R. and Noonan, J. D. (1987). Distally based vastus lateralis muscle flap for coverage of wounds about the knee. Plastic and Reconstructiw I.

I

u1

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Tavlor. G. I. and Palmer. J. H. (1987). The vascular territoripc . (angiosomes) of the body: experimental study and clinical applications. British JournalofPlastic Surgery, 40. 113. Timmons, M. J. (1985). Landmarks in the anatomical study of the blood supply of the skin. British JournalofPlastic Surgery, 38. 197. Tobin, G. R. (1985). Vastus medialis myocutaneous and myocutaneous-tendinous composite flaps. Plastic and Reconstructive Surgery. 75. 677. .l”

The Author References Arnold, P. G. and Prunes-Carillo, F. (1981). Vastus medialis muscle flap for functional closure of the extended knee joint. Playtic and Reconstructire Surgery, 68. 69. Baek. S. M. (1983). Two new cutaneous free flaps: the medial and lateral thigh flaps. Plastic and Rrconstructhw Surger,v. 71. 354. Cormack, G. C. and Lamberty, 9. G. H. (1985). The blood supply of thigh skin. Plastic and Reconstructioe Surgerv. 75.342. Corma& G. C. and Lamberty, 9. G. H. (1587). The Arterial AnatomyqfSkin Flaps. Edinburgh: Churchili Livmgstone. Elsahy, N. 1. (1978). Cover of the exposed knee joint by the lateral head of the gastrocnemius. British Journal qf Plastic Surgery. 31. 136.

J. K. G. Laitung, MB, ChB, FRCSEd, Research Registrar. Regional Burns Centre, Pinderfields Hospital. Wakefield; Honorary Research Fellow. Burns and Plastic Surgery Research Unit. Bradford University, Yorkshire; formerly Registrar in Plastic Surgery, University Hospital of South Manchester. Requests

for reprints

to the author at Wakefield.

Paper received 28 June 1988 Accepted 17 October 1988. This paper Association

was presented at the Winter meeting of the British of Plastic Surgeons, December 1987.