The lumbar artery perforator based island flap: anatomical study and case reports

British Journal of Plastic Surgery (1999), 52, 541 546 1999 The British Association of Plastic Surgeons The lumbar artery perforator based island flap: anatomical study and case reports H. Kato*, M. Hasegawa, T. Takada* and S. Torii Departments of Plastic and Reconstructive Surgery, *Chubu Rosai Hospital, Nagoya; Okazaki Municipal Hospital, Okazaki; and Nagoya University School of Medicine, Nagoya, Japan SUMMARY. A lumbar artery island flap can be elevated based on a single lumbar artery. We studied the vascular anatomy using 21 specimens of lumbar arteries in 11 cadavers, and investigated the skin territory of the artery using fluorescein injection. We observed lumbar perforators emerging through the lumbar fascia at the lateral border of the erector spinae muscle, situated 5 9 cm from the midline. The diameter of the vascular bundle at the site of perforation ranged from 1 to 5 mm. Perforators of the second and fourth lumbar arteries were much more developed than others. The cutaneous territory supplied by the second lumbar artery extended from the posterior midline to the lateral border of the rectus sheath, and at least 10 cm above the anterosuperior iliac spine. We transferred four clinical flaps for coverage of ulcers on the lower back. All flaps survived and their donor site defects were closed primarily. The cadaver dissection, the injection study and our clinical success have confirmed the feasibility of lumbar artery island flaps. 1999 The British Association of Plastic Surgeons Keywords: lumbar artery, perforator, island flap, pressure sore. The blood supply from lumbar arteries has been used for flaps such as the reverse latissimus dorsi musculocutaneous flaps 1 4 and the transverse lumbosacral back flaps, 5 which are generally regarded as clinically proven and reliable flaps. However, these flaps do have some disadvantages. With the reverse latissimus dorsi musculocutaneous flap the muscle is sacrificed. 1,2,4 In the transverse lumbosacral back flap, the rotational arc of the flap is limited, and the donor-site defect cannot be closed primarily. 5 These problems would be solved if a flap based on a single lumbar artery could be established as clinically reliable. There are few anatomical reports concerning the lumbar arteries. 6 Although some reports 5,7 have described the cutaneous vascular territory of lumbar arteries, the territory nourished by a single lumbar artery has not been defined in detail. The purpose of this paper is to define the vascular anatomy of lumbar arteries and the skin territory supplied by a single lumbar artery in order to establish the feasibility of lumbar artery island flap surgery. Anatomical study The lumbar arteries are similar to the intercostal arteries. Normally there are four on each side of the body, arising from the back of the aorta and travelling behind the psoas major muscle. The upper three arteries run laterally and backwards between the quadratus lumborum muscle and the erector spinae musculature, and the last set of arteries normally run in front of the quadratus lumborum muscle. From each artery, a perforating artery branches off just lateral to the erector spinae muscles sending a few branches to the skin (Fig. 1). 5,6 These perforators are of various sizes, but Figure 1 Cross-section of lumbar region. 541

542 British Journal of Plastic Surgery Table 1 Location of the perforator at the site of penetration through the lumbar fascia Case Distance from the midline (cm) L1 L2 L3 L4 1 L 7 6 7 9 R ( ) 6 6 7 2 L 9 8 8 8 R 9 9 8 9 3 L 7 7 7 8 R 7 6 6 6 4 L 8 8 7 7 R 7 7 7 7 5 L 5 5 5 7 R 6 6 7 8 6 L 7 7 6 7 R 6 6 6 6 7 L 9 8 ( ) 9 R 9 8 8 8 8 L 8** ( ) ( ) 7 R ( ) 7* ( ) 8 9 L 7 5 7 9 10 L 7 ( ) 7 8 R 6 7 8 8 11 L 8 8 ( ) 8 R ( ) 7* ( ) 8 Max. 9 9 8 9 Min. 5 5 5 6 Mean 7.33 6.89 6.88 7.71 ( ): Lumbar artery is present but has no perforator; ( ): Lumbar artery is absent; *: Two perforators; **: Three perforators; : Subcostal artery has a perforator at the L1 area. those of the second and fourth lumbar arteries are usually much more developed. 8 They anastomose with one another and form a vascular network in the subcutaneous layer 9,10 accompanied by veins and nerves. We investigated location as well as size of perforators at the sites of penetration through the lumbar fascia, using 21 specimens of lumbar arteries in 11 cadavers (Tables 1 and 2). The sizes of perforators were expressed by the diameter of vascular bundles including artery and veins because the dissection of the perforating artery alone was difficult in preserved cadavers. The lumbar perforators penetrated the lumbar fascia at the lateral border of the erector spinae muscles surfacing to the subcutaneous tissue at points 5 9 cm (mean: 7.22 cm) from the midline. In the cases in which the erector spinae muscles were well developed, the perforators ran on the surface of the muscle from the lateral border in a medial direction before emerging through the lumbar fascia. In the cases in which erector spinae muscles had atrophied, the perforators ran through the fascia from the lateral border of the muscle in a lateral direction before penetrating the fascia. Thus, the location of the perforator at the site of penetration through the lumbar fascia, which was recorded as the distance from the midline, did not seem to depend on the development of the erector spinae muscles. Although each lumbar artery usually had a perforating branch, some lumbar arteries had no perforator. All of the fourth lumbar arteries had perforators. Three of the first lumbar arteries (14.3%), two of the second lumbar arteries (9.3%) and five of the third lumbar arteries (23.8%) had no perforator. Although Table 2 most of the lumbar arteries were present even when they had no perforator, the first lumbar artery was absent in two sides (9.5%) and in these instances the subcostal artery gave off a perforator in the area of the first lumbar artery. In case 8, the first lumbar artery had three perforators, which compensated for the absence of perforators from the second and third lumbar arteries. In two of the four cases which had all but the perforator from the third lumbar artery, the second lumbar artery had two perforators in the area of the second and third. This sort of compensation, however, was not always present. The size of the vascular bundle was largest at the site of the fourth lumbar artery perforator, followed by the second lumbar artery. After the perforators pierced the lumbar fascia, they gave off arteries medially and laterally to supply the dorsal skin. In summary, the fourth lumbar artery was superior to other lumbar arteries in that the size of the perforator was the largest and it was the most reliably present. The next best was the second lumbar artery. Injection study Diameter of the vascular bundle (mm) Case L1 L2 L3 L4 1 L 2 4 2 4 R 4 2 4 2 L 4 2 4 2 R 4 3 3 2 3 L 1 4 3 4 R 2 3 4 3 4 L 3 3 4 5 R 2 4 2 2 5 L 2 3 3 2 R 4 2 4 2 6 L 1 4 2 2 R 3 3 2 4 7 L 4 3 3 R 2 3 4 4 8 L 3 4 R 4 2 9 L 1 1 1 3 10 L 2 4 4 R 3 4 2 4 11 L 4 4 4 R 2 4 Max. 4 4 4 5 Min. 1 1 1 2 Mean 2.61 3.16 2.88 3.24 Vascular bundle includes a perforating artery and venae comitantes. We injected fluorescein into the second lumbar artery in one clinical case. The skin territory supplied by the single lumbar artery extended from the posterior midline to the lateral border of the ipsilateral rectus sheath, and at least 10 cm above the anterosuperior iliac spine (Fig. 2). Operative techniques The sites of the lumbar artery perforators can be detected by using a Doppler ultrasound probe. The

Lumbar artery perforator island flap 543 Figure 2 (A) Distribution of the vascular territory of the second lumbar artery as delineated by fluorescein injection. (B) Diagram showing the vascular territory. lumbar artery perforator based island flap can be elevated based on any of these arteries. The most suitable lumbar artery perforator is selected according to the location of the ulcer. The flap is designed transversely or obliquely from the posterior midline down to the anterosuperior iliac spine to include the vascular pedicle in the flap. The distal edge of the flap can be placed as far anteriorly as the midaxillary line if required by the size and location of the ulcer (Fig. 3). Because the source lumbar artery travels obliquely and anteriorly from the lateral edge of the erector spinae muscles and then deep beneath the transverse process of a vertebra, the rotational arc cannot be widened even if further dissection were to be performed. When a wider rotational arc is needed, the pivot point can be placed in the vicinity of a transverse process by incising the erector spinae muscles. However, this manoeuvre cannot be adopted when using the fourth lumbar artery perforator because the lumbar artery runs in front of the quadratus lumborum muscle. When the rotational arc does not need to be large, the pivot point may be placed where the perforating artery emerges through the lumbar fascia. Skin incision should begin from the distal margin, and proceed proximally, including the lumbar fascia in the flap, until the pedicle is identified. The vascular pedicle is dissected only until sufficient mobility is gained to mobilise the flap adequately. The flap is passed to the defect either through a subcutaneous tunnel or by placement in an incision between the defect and donor site. The donor site defect can be closed primarily when the flap is less than 8 cm wide. Patient data We have treated four patients using the lumbar artery perforator based island flaps (Table 3). Three cases had pressure ulcers which occurred following spinal cord injuries. One had a radiation ulcer induced by surgery and radiation therapy for a malignant tumour of the soft tissue 21 years previously. The sites of ulcers were in the midline in two cases, the posterior iliac crest in one case and the paravertebral region in

544 British Journal of Plastic Surgery Discussion Figure 3 Design of the lumbar artery perforator based island flap. the last case. The midline ulcers were on the fifth lumbar vertebra and on the fourth to fifth lumbar vertebra. The paravertebral ulcer was just lateral to the midline, and extended vertically from the first to the third lumbar vertebra. All patients were male, and their ages ranged from 45 to 60 years. Results We used the first, second and fourth lumbar arteries. The sizes of the flaps used ranged from 5.5 14 cm to 8 27 cm. The distal end of three flaps lay over the midaxillary line, and one reached the anterior axillary line. All flaps survived completely. Only one flap (Case 2) showed temporary congestion, but healing was uneventful. All the donor site defects were closed primarily. Case reports Case 2 (Fig. 4) A 60-year-old man who had kyphosis in his lumbar spine suffered from a pressure ulcer on the midline of his lower back after spinal cord injury. The ulcer was covered with a 6 13 cm island flap based on the second lumbar artery perforator. The distal end of the flap extended over the midaxillary line. The atrophied erector spinae was partially incised so that a long pedicle might be obtained. The flap survived completely, without complication. Case 3 (Fig. 5) A 54-year-old man with paraplegia due to spinal cord injury had a pressure ulcer on his posterior iliac crest. After debridement, the defect was covered with a 5.5 14 cm island flap based on the fourth lumbar artery perforator. The distal end of the flap extended to the midaxillary line. Although the flap showed congestion, it survived completely. The blood supply to the skin from lumbar arteries has been used in flaps such as reverse latissimus dorsi musculocutaneous flaps 1 4 and transverse lumbosacral back flaps, 5 which have some disadvantages. The muscle is sacrificed with the reverse latissimus dorsi musculocutaneous flap. 1,2,4 In the transverse lumbosacral back flap, the rotational arc of the flap is limited, and the donor site defect cannot be closed primarily. 5 The lumbar artery perforator based island flap, on the other hand, has advantages because it is a fasciocutaneous flap based on a single artery. First of all, it does not sacrifice any muscle. Secondly, it has a large rotational arc. And finally, its donor site can be closed primarily. The perforator based flaps reported by Kroll and Rosenfield 11 were elevated from the lumbar region, but the vascular anatomy was not described in detail. The lumbar artery perforator flap differs from the flaps described by Kroll and Rosenfield in that the former has a single vascular pedicle which may be dissected up to the lumbar artery itself. Knowledge of vascular anatomy and the skin territories supplied by arteries is essential for flap surgery. Cadaver dissection showed that an artery suitable for lumbar artery island flap surgery does exist. The location of the perforator can be detected relatively easily by searching in the vicinity of the lateral border of the erector spinae, using a Doppler ultrasound probe. Although some reports 5,7 have described the skin territories of lumbar arteries, the territory supplied by a single lumbar artery has not been described in detail. Cormack and Lamberty 7 described the composite area of all the posterior cutaneous perforators, but the territory supplied by a single artery was unclear. The experimental work by Hill et al 5 described the width of the territory, but the length of the area was unclear. Kroll and Rosenfield 11 used perforator based flaps on the back and the buttocks with success because the sizes of the perforators were suited for these regions. In their clinical cases, a relatively large flap was elevated successfully, although the size of the flap was not defined. Our injection study showed that the skin territory supplied by the second lumbar artery alone was from the posterior midline to the lateral border of the rectus sheath, and at least 10 cm above the anterior superior iliac spine. This result may be helpful in determining the skin territory supplied by a single lumbar artery, although the size of the area may vary due to size variation in the lumbar arteries. Table 3 Patient summary Case Age Cause Site of ulcer Size of flap Lumbar artery (years) (cm) 1 58 Pressure ulcer Midline 6.5 13.5 1st 2 60 Pressure ulcer Midline 6 13 2nd 3 54 Pressure ulcer Posterior iliac crest 5.5 14 4th 4 45 Radiation ulcer Paravertebral 8 27 1st

Lumbar artery perforator island flap 545 Figure 4 Case 2. (A) Pressure ulcers on the midline of the lower back and on the sacrum. (B) Design of the lumbar artery perforator based island flap based on the second lumbar artery (after the sacral pressure sore was treated with a local flap). (C) Elevation of the flap. The erector spinae muscles were partially incised. The arrow shows the vascular pedicle. (D) Four months later. Figure 5 Case 3. (A) Pressure ulcer on the posterior iliac crest and the design of the lumbar artery perforator based island flap based on the fourth lumbar artery. (B) Key to Figure 5A. (C) Elevation of the flap. (D) Inset of the flap. The flap showed slight congestion.

546 British Journal of Plastic Surgery enables it to be used for lower back, as well as thoracic spinal region and posterior costal region reconstructions (Fig. 6). Acknowledgements We thank Yasuo Sugiura and Miya Kobayashi, Professor and Associate Professor of the Department of Anatomy at Nagoya University, for their valuable support in providing the anatomic specimens. Figure 6 Rotational arc of the lumbar artery perforator based island flap. How large a flap can be sustained by a single perforator? Our largest flap measured 8 27 cm in size, and its distal portion extended over the midaxillary line. When a larger flap is needed, the flap may be designed so that the axis of the flap runs obliquely from the midline down to the anterior superior iliac spine, because the lumbar arteries anastomose with each other and form a vascular network. 9,10 Our clinical success has proved that a relatively large flap with a distal margin extending over the midaxillary line can be safely elevated. In addition, our injection study suggests that it is possible to raise a wider flap of approximately 10 cm. Venous drainage of the flap depends on the lumbar vein. We experienced temporary venous congestion in one case (Case 2), resulting from a kink in the pedicle. There were no venous drainage problems in the other cases. Based on our study, the venous drainage through the lumbar vein appears to be reliable. We partially incised the erector spinae to obtain a greater rotational arc in two cases, including Case 1, but this procedure is applicable only to paraplegic patients whose muscles have atrophied and lost function. This procedure should not be performed on a patient who is capable of walking. Because the lumbar artery island flap has a single pedicle, it has a large arc of rotation. This mobility References 1. McCraw JB, Penix JO, Baker JW. Repair of major defects of the chest wall and spine with the latissimus dorsi myocutaneous flap. Plast Reconstr Surg 1978; 62: 197 206. 2. Bostwick J III, Scheflan M, Nahai F, Jurkiewicz MJ. The reverse latissimus dorsi muscle and musculocutaneous flap: anatomical and clinical considerations. Plast Reconstr Surg 1980; 65: 395 9. 3. Muldowney JB, Magi E, Hein K, Birdsell D. The reverse latissimus dorsi myocutaneous flap with functional preservation report of a case. Ann Plast Surg 1981; 7: 150 1. 4. Stevenson TR, Rohrich RJ, Pollock RA, Dingman RO, Bostwick J III. More experience with the reverse latissimus dorsi musculocutaneous flap: precise location of blood supply. Plast Reconstr Surg 1984; 74: 237 43. 5. Hill HL, Brown RG, Jurkiewicz MJ. The transverse lumbosacral back flap. Plast Reconstr Surg 1978; 62: 177 84. 6. Williams PL, Warwick R. The lumbar arteries. In: Gray s Anatomy, 36th ed. Edinburgh: Churchill Livingstone, 1980; 719. 7. Cormack GC, Lamberty BGH. The lumbar and sacral arteries. In: The Arterial Anatomy of Skin Flaps. Edinburgh: Churchill Livingstone, 1994; 156 8, 224 5. 8. Salmon M. The lumbosacral region. In: Taylor GI, Tempest MN (eds), Arteries of the Skin. London: Churchill Livingstone, 1988; 89 93. 9. Taylor GI. Foreword. In: Taylor GI, Tempest MN (eds), Arteries of the Skin. London: Churchill Livingstone, 1988; i xxxii. 10. Koshima I, Moriguchi T, Soeda S, Kawata S, Ohta S, Ikeda A. The gluteal perforator-based flap for repair of sacral pressure sores. Plast Reconstr Surg 1993; 91: 678 83. 11. Kroll SS, Rosenfield L. Perforator-based flaps for low posterior midline defects. Plast Reconstr Surg 1988; 81: 561 6. The Authors Hisakazu Kato MD, Tohru Takada MD, Department of Plastic and Reconstructive Surgery, Chubu Rosai Hospital, 1 10 6 Komei, Minato-ku, Nagoya 455 8530, Japan. Morimasa Hasegawa MD, Department of Plastic and Reconstructive Surgery, Okazaki Municipal Hospital, 2 2 Wakamiya-cho, Okazaki 444 8553, Japan. Shuhei Torii MD, Department of Plastic and Reconstructive Surgery, Nagoya University, School of Medicine, 65 Tsurumai, Syouwa-ku, Nagoya 466 8560, Japan. Correspondence to Dr H. Kato. Paper received 19 October 1998. Accepted 8 February 1999.