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RECONSTRUCTIVE The Superior and Inferior Gluteal Artery Perforator Flaps Reza Ahmadzadeh, B.Sc. Leonard Bergeron, M.D., C.M., M.Sc. Maolin Tang, M.D. Steven F. Morris, M.D., M.Sc. Halifax, Nova Scotia, Canada Background: Perforator flaps have allowed reconstruction of soft-tissue defects throughout the body. The superior and inferior gluteal artery perforator flaps have been used clinically, yet the published anatomical studies describing the blood supply to the gluteal skin are inadequate. This study comprehensively evaluated the anatomical basis of these flaps to present anatomical landmarks to facilitate flap dissection. Methods: In six fresh cadavers, the integument of the gluteal region was dissected. Cutaneous perforators of the superior and inferior gluteal arteries were identified. Their course, size, location, and type (septocutaneous versus musculocutaneous) were recorded based on dissection, angiography, and photography. The surface areas of cutaneous territories and perforator zones were measured and calculated. Results: The average number of superior and inferior cutaneous perforators greater than or equal to 0.5 mm in the gluteal region was 5 ⫾ 2 and 8 ⫾ 4, respectively, with all of the superior and 99 percent of the inferior gluteal artery perforators being musculocutaneous. Their average perforator internal diameter was 0.6 ⫾ 0.1 mm. The average superior and inferior gluteal artery cutaneous vascular territory was 69 ⫾ 56 cm2 and 177 ⫾ 38 cm2, respectively. The superior gluteal perforators were found adjacent to the medial two-thirds of a line drawn from the posterior superior iliac spine to the greater trochanter. The inferior gluteal artery perforators were concentrated along a line in the middle third of the gluteal region above the gluteal crease. Conclusion: The reliable size and consistency of the superior and inferior gluteal artery perforators allow the use of pedicled and free superior and inferior gluteal artery perforator flaps in a variety of clinical situations. (Plast. Reconstr. Surg. 120: 1551, 2007.) O ne of the main goals in reconstructive surgery of soft-tissue defects is to replace “like with like.” During the evolution of flap design and transfer over the past 50 years, surgeons have gradually improved the results of reconstructive surgical procedures by selecting the best flap for a specific reconstructive challenge. Perforator flaps have become well accepted and are useful alternatives to historical reconstructive techniques.1 The musculocutaneous superior and inferior gluteal artery flaps have been previously described and may have a role in certain From the Departments of Anatomy and Neurobiology and Surgery, Dalhousie University. Received for publication December 13, 2005; accepted June 7, 2006. Presented at the 51st Annual Meeting of the Research Council of Plastic Surgery, in Dana Beach, California, May 20, 2006. Copyright ©2007 by the American Society of Plastic Surgeons DOI: 10.1097/01.prs.0000282098.61498.ee procedures. However, the sacrifice of muscle in the region and the potentially difficult dissection have limited their acceptance. The superior gluteal artery perforator (SGAP) and inferior gluteal artery perforator (IGAP) flaps have been well described clinically and are reliable flap procedures. A more detailed description of the vascular anatomy will aid surgeons in the customized design of perforator flaps in this region.2 Fujino et al.3 first used the gluteal region as a donor site in 1975. Since then, gluteal flaps based on the superior gluteal artery have advanced, as shown in the works of Blondeel4 and Allen and Tucker.5 The inferior gluteal artery free flap was first reported by Le-Quang6 in 1979 and later was used as a perforator flap by Higgins et al.7 in 2002. Potential donor sites for breast reconstruction are few. In the thin patient, the buttocks region offers a substantial amount of soft tissue that can be microsurgically transferred. Clinical works have documented the use of the superior gluteal www.PRSJournal.com 1551 Plastic and Reconstructive Surgery • November 2007 artery and the inferior gluteal artery musculocutaneous flaps. More recently, enthusiasm for perforator flaps has led to many reports of SGAP and IGAP perforator flaps.4,7–9 Although the SGAP flap has been extensively used, the IGAP flap has been used less widely. There is a lack of detailed anatomical information regarding the location and properties of gluteal artery perforators, which has slowed the adoption of perforator flaps in the area. The goal of this study was to objectively and comprehensively document the surgical anatomy of the superior and inferior gluteal artery perforator flaps with regard to vessel diameter, length, and cutaneous territory. MATERIALS AND METHODS Whole-body lead oxide and gelatin arterial injection studies were carried out in six fresh human cadavers (12 specimens) using the technique described by Tang et al.10 For the purpose of this study, the gluteal area is defined superiorly by the iliac crest, inferiorly by the inferior gluteal fold, laterally by the trochanter, and medially by the midline. These landmarks were identified and the integument was dissected. Cutaneous perforators were labeled with radiopaque markers. Radiographs, photographs, and dissection notes were used to document the dissection at each stage. By means of angiography, photography, and dissection notes, the exact course and source artery of individual perforators were described. The length, diameter, type (musculocutaneous or septocutaneous), and source artery of each perforator were identified. Vessel measurements were obtained directly on the original angiogram. The radiographs were assembled using Adobe Photoshop CS (Adobe Systems, Inc., San Jose, Calif.), and the cutaneous territories of specific perforators were determined. The cutaneous vascular territory of a specific perforating cutaneous blood vessel was defined as the region supplied by a specific vessel between adjacent territories separated by choke anastomotic vessels. Scion Image Beta 4.02 (Scion Corporation, Frederick, Md.) was used to measure cutaneous vascular territories and average perforator zones (the cutaneous territory of a single cutaneous perforator). Average perforator zones were determined by dividing the area of each vascular territory by the number of its cutaneous perforators. RESULTS Regional Vascular Anatomy The superior and inferior gluteal arteries are both terminal branches of the internal iliac artery 1552 Fig. 1. Medial view of the left pelvic region of a human cadaver injected with lead oxide and gelatin. The superior and inferior gluteal arties are terminal branches of the internal iliac artery. 1, external iliac artery; 2, internal iliac artery; 3, lateral sacral artery; 4, umbilical artery; 5, obturator nerve; 6, obturator artery; 7, superior gluteal artery; 8, inferior gluteal artery; 9, internal pudendal artery; S1 through S4, anterior rami of sacral spinal nerves. (Fig. 1). They both exit the pelvis through the greater sciatic foramen. The superior gluteal artery passes superior to the piriformis muscle. It then gives off a deep branch that runs laterally in between the gluteus medius muscle and the iliac bone. The superior gluteal artery enters the gluteus maximus muscle to supply its upper portion and to send perforators to the overlying skin. The inferior gluteal artery travels inferior to the piriformis muscle. It is accompanied by the internal pudendal vessels, the pudendal nerve, the posterior femoral cutaneous nerve (posterior cutaneous nerve of the thigh), and the sciatic nerve. The inferior gluteal artery supplies the lower half of the gluteus maximus and also provides perforators to the overlying gluteal skin. The descending branch of the inferior gluteal artery, when present, accompanies the posterior femoral cutaneous nerve. Local Vascular Anatomy Both the superior and inferior gluteal arteries are major contributors to the blood supply of the skin in the gluteal region (Fig. 2). Other source arteries such as the lumbar artery, deep circumflex iliac artery, lateral sacral arteries, obturator artery, internal pudendal artery, femoral artery, profunda femoris artery, and medial and lateral circumflex femoral arteries also contribute to the blood supply of the gluteal region (Fig. 2). How- Volume 120, Number 6 • Gluteal Artery Perforator Flaps Table 1. Properties of the Superior and Inferior Gluteal Arteries Regional blood supply No. of cutaneous perforators Average perforator size, mm Cutaneous vascular territory, cm2 Perforator zone, cm2 Fig. 2. Angiogram of the integument of the left side of the cadaver from the L3 level to the midthigh region, dissected after medial incision. The gluteal region is outlined in red. Note that the superior and inferior gluteal artery vascular territories occupy most of the gluteal region. G, greater trochanter; P, posterior superior iliac spine; LA, lumbar artery; DCIA, deep circumflex iliac artery; LSA, lateral sacral arteries; SGA, superior gluteal artery; IGA, inferior gluteal artery; IPA, internal pudendal artery; LCFA, lateral circumflex femoral artery; PFA, profunda femoris artery. ever, the frequency of their contribution, their cutaneous territory, and the number of their perforators in the region is minor when compared with the major contribution of superior and inferior gluteal arteries. On average, we found 5 ⫾ 2 cutaneous perforators arising from the superior gluteal artery and 8 ⫾ 4 cutaneous perforators arising from the inferior gluteal artery. All of the superior gluteal artery perforators and 99 percent of the inferior gluteal artery perforators were musculocutaneous. All of the inferior gluteal musculocutaneous perforators and 50 percent of the superior gluteal musculocutaneous perforators passed through the gluteus maximus muscle, and the remaining 50 percent of the superior gluteal musculocutaneous perforators passed through the gluteus medius muscle. The average diameter of the perforators arising from the superior and inferior gluteal artery was similar at 0.6 ⫾ 0.1 mm. The average pedicle length from the deep fascia was 23 ⫾ 11 mm and 21 ⫾ 11 mm for perforators arising from the superior and inferior glu- Superior Gluteal Artery Inferior Gluteal Artery Internal iliac artery Internal iliac artery 5⫾2 8⫾4 0.6 ⫾ 1 0.6 ⫾ 1 69 ⫾ 56 21 ⫾ 8 177 ⫾ 38 24 ⫾ 13 teal arteries, respectively. The average cutaneous vascular territory for the superior gluteal artery and the inferior gluteal artery in the gluteal region was found to be 69 ⫾ 56 cm2 and 177 ⫾ 38 cm2, respectively. Each perforator of the superior gluteal artery supplies an area (perforator zone) of 21 ⫾ 8 cm2, and each perforator of the inferior gluteal artery supplies 24 ⫾ 13 cm2 (Table 1). The superior gluteal artery perforators were generally more vertical and the inferior gluteal artery perforators were generally more horizontal or oblique as they passed through the muscle. Most of the superior gluteal artery perforators were located adjacent to the medial two-thirds of a line drawn from the posterior superior iliac spine to the greater trochanter. The inferior gluteal artery perforators were mostly located in the horizontal middle third of the gluteal region parallel to the gluteal crease. Inferior gluteal artery perforators were also found at approximately 5 cm superior to the lateral third of the gluteal crease (Fig. 3). Landmarks for SGAP Dissection Based on our study, the following landmarks could be used to locate the SGAP and IGAP perforators and design a viable skin paddle (Figs. 4 and 5). To locate SGAP perforators, a line is drawn from the posterior superior iliac spine to the greater trochanter. Perforators are usually found adjacent to the medial two-thirds of the drawn line. A skin paddle is positioned over the most suitable perforator. In general, the more lateral the perforator, the longer the pedicle. Landmarks for IGAP Dissection A line is drawn from the greater trochanter to the middle of the distance between the posterior superior iliac spine and the medial border of the gluteal crease (Figs. 4 and 5). Perforators are located on the marked areas. A skin paddle is positioned over a desirable (size and position-wise) 1553 Plastic and Reconstructive Surgery • November 2007 100 years, including the impressive works of Manchot11 and Salmon.12 As surgery evolves, the need for specific anatomical information continually changes. Thus, with the recent enthusiasm for perforator flaps, precise anatomical studies are required to carefully document cutaneous perforators suitable for flap harvest. In this study, we have described the cutaneous territories supplying the gluteal region. We specifically looked at the superior and inferior gluteal arteries and provided landmarks to perforators arising from these arteries. Fig. 3. Angiogram of the integument of the left gluteal region. The superior and inferior gluteal artery vascular territories are outlined in blue and red, respectively. The yellow line indicates the glutealcrease.Superiorglutealarteryperforatorsareusuallylocated along the superior two-thirds of a line drawn from the posterior superior iliac spine (P) to the greater trochanter (G). The inferior gluteal artery perforators are usually located in the middle third of the gluteal region above the gluteal crease, and also at approximately 5 cm superior to the lateral third of the gluteal crease. Fig. 4. Landmarks to locate inferior (a) or superior (b) gluteal artery perforators. Cross marks (x) are at the posterior superior iliac spine and the greater trochanter. perforator and dissection proceeds as for a standard perforator flap. DISCUSSION The study of the blood supply of the skin of the human body has been carried out for over 1554 SGAP The SGAP flap5 is the most used gluteal artery perforator flap. Fujino et al.3 reported in 1975 and 197613 the use of the gluteal region for breast reconstruction. In 1988, Kroll and Rosenfield14 documented the first use of local skin flaps based on unspecified perforators in the gluteal area. Koshima et al.15 showed that a flap in this area can be nourished even by one perforator. SGAP flaps have been used since for sacral pressure sores,8 breast reconstruction,4,5,9 breast augmentation,16 and closure of lumbosacral myelomeningoceles.17 Musculocutaneous flaps3,13,18 and perforators flaps4,5,8,9,16,17,19 –22 based on the superior gluteal artery have been described. Nevertheless, clinical studies of this region4,5,7–9,14,16,17,19 –23 far outnumber the few anatomical studies15 documenting its cutaneous blood supply. In their clinical/anatomical study, Koshima et al.15 described the perforators in the gluteal region of five fresh cadavers after injecting barium into the internal iliac arteries using the arterial embalming method. They found 20 to 25 perforators in each gluteal region but did not specify the number of perforators based on each source arteries. They reported that the main cutaneous vessels of the gluteal region arise from the superior and inferior gluteal artery, which is consistent with our findings, and explained that the perforators of the superior gluteal artery are located mostly in the superolateral gluteal region. No previous anatomical study exists regarding the size of the cutaneous vascular territory and perforator zones of the superior gluteal artery. Previous clinical reports have documented5 flap sizes as large as 12 ⫻ 32 cm2, although donor sites larger than 10 cm in diameter after harvesting flaps tend to be more difficult to close primarily. Our anatomical findings for the superior gluteal artery perforators support clinical reports in terms of perforator and skin paddle location. The ability to identify and trace back individual per- Volume 120, Number 6 • Gluteal Artery Perforator Flaps Fig. 5. Superior gluteal artery perforator flap (left) and inferior gluteal artery perforator flap (right) raised on respective perforators. forators of the gluteal region with angiography has allowed better demonstration of the relationship of the SGAP with regards to other cutaneous vascular territories (Fig. 2). The total gluteal perforator count (Table 1) is lower than that found by Koshima. This might be explained by more precise characterization of perforators with the lead oxide technique10 or by anatomical variation. IGAP The inferior gluteal artery is the other dominant blood supply to the gluteal region. Surprisingly, very little clinical and anatomical information is available. Le-Quang6 was the first to describe the use of an inferior gluteal musculocutaneous free flap in 1979. Pedicled IGAP flaps have been used for ischial pressure sores,7 and free IGAP flaps have been used for breast reconstruction.9 Despite these IGAP reports, no comprehensive description of the number of perforators and their characteristics exists. In their study, Koshima et al.15 reported that the perforators of the inferior gluteal artery are located in the inferomedial and inferolateral areas of the gluteal region. Our findings provide detailed anatomical information concerning the characteristics (Table 1) and location of IGAPs (Fig. 2) that are relevant to perforator flap design in this region. The descending branch of the inferior gluteal artery has been used clinically to perfuse flaps.24 –26 Its anatomy has been variably reported in the literature. Hurwitz et al.25 and Paletta et al.26 found this branch to be consistently present. However, Cormack and Lamberty27 found that it was present in 25 percent of specimens and Rubin et al.28 did not find this branch to be consistent. Windhofer et al.29 documented the presence of the descending inferior gluteal artery branch to be 90 percent, and they described its relationship to the posterior femoral cutaneous nerve. They mentioned that when this branch was absent, the cutaneous branch came from either the lateral or medial circumflex or profunda femoris artery. We found the descending branch of the inferior gluteal artery to be present in 33 percent of cases. This illustrates the variability of this branch and should probably mandate the imaging of this branch before designing a flap on this pedicle. SGAP versus IGAP Table 1 demonstrates similar characteristics between the SGAPs and IGAPs. Of interest is the larger cutaneous territory of the inferior gluteal artery. This might be of clinical significance when a bulky flap needs to be raised in the gluteal region, such as for breast reconstruction. However, Guerra et al.9 used the IGAP flap in six cases for breast reconstruction but found that the exposure of the sciatic nerve could cause prolonged postoperative dysesthesia when compared with the SGAP flap. The SGAP flap has been previously described in the reconstruction of trochanteric and sacral defects. Its short pedicle has prevented its use in the repair of ischial defects. This shortcoming prompted Higgins et al.7 to use an inferior gluteal artery perforator flap to cover an ischial pressure sore. CONCLUSIONS Both the inferior and superior gluteal arteries supply cutaneous vascular territories that can be harvested as valuable flaps. This study comprehensively describes the anatomy of the SGAPs and IGAPs. Clinical studies will confirm the dynamic cutaneous vascular territory of these arteries that 1555 Plastic and Reconstructive Surgery • November 2007 will predictably be larger than our observations, because of the role of physiologic anastomoses. The inferior gluteal artery has a more generous cutaneous territory compared with the superior gluteal artery. Dissection of the IGAP flap tends to be easier; however, proximity to the sciatic and femoral cutaneous nerves may result in painful paresthesias postoperatively. Both of these flaps are useful options for breast reconstruction and for local reconstruction in the sacral, hip, and perineal areas. Steven F. Morris, M.D., M.Sc. Division of Plastic Surgery, Room 4443 1796 Summer Street Halifax, Nova Scotia B3H 3A7, Canada [email protected] DISCLOSURE The authors have no financial interest in the products, devices, or drugs mentioned in this article. REFERENCES 1. Blondeel, P. N., Morris, S. F., Hallock, G. G., and Neligan, P. C. Perforator Flaps: Anatomy, Technique & Clinical Applications. St. Louis: Quality Medical, 2005. 2. Geddes, C. R., Morris, S. F., and Neligan, P. C. Perforator flaps: Evolution, classification, and applications. Ann. Plast. Surg. 50: 90, 2003. 3. Fujino, T., Harasina, T., and Aoyagi, F. Reconstruction for aplasia of the breast and pectoral region by microvascular transfer of a free flap from the buttock. Plast. Reconstr. Surg. 56: 178, 1975. 4. Blondeel, P. N. The sensate free superior gluteal artery perforator (S-GAP) flap: A valuable alternative in autologous breast reconstruction. Br. J. Plast. Surg. 52: 185, 1999. 5. Allen, R. J., and Tucker, C., Jr. Superior gluteal artery perforator free flap for breast reconstruction. Plast. Reconstr. Surg. 95: 1207, 1995. 6. Le-Quang, C. Two new flaps proceedings from aesthetic surgery: The lateral mammary flap and the inferior gluteal flap. In Transactions of the 7th International Congress of Plastic and Reconstructive Surgery, Rio de Janeiro, Brazil, May of 1979. 7. Higgins, J. P., Orlando, G. S., and Blondeel, P. N. Ischial pressure sore reconstruction using an inferior gluteal artery perforator (IGAP) flap. Br. J. Plast. Surg. 55: 83, 2002. 8. Verpaele, A. M., Blondeel, P. N., Van Landuyt, K., et al. The superior gluteal artery perforator flap: An additional tool in the treatment of sacral pressure sores. Br. J. Plast. Surg. 52: 385, 1999. 9. Guerra, A. B., Metzinger, S. E., Bidros, R. S., et al. Breast reconstruction with gluteal artery perforator (GAP) flaps: A critical analysis of 142 cases. Ann. Plast. Surg. 52: 118, 2004. 10. Tang, M., Geddes, C. R., Yang, D., et al. Modified lead oxidegelatin injection technique for vascular studies. J. Clin. Anat. 1: 73, 2002. 1556 11. Manchot, C. Die Hautarterien des Menschlichen Korpers. Leipzig: Vogel, 1889. 12. Salmon, M. Arteries of the Skin. Paris: Masson, 1936. 13. Fujino, T., Harashina, T., and Enomoto, K. Primary breast reconstruction after a standard radical mastectomy by a free flap transfer: Case report. Plast. Reconstr. Surg. 58: 371, 1976. 14. Kroll, S. S., and Rosenfield, L. Perforator-based flaps for low posterior midline defects. Plast. Reconstr. Surg. 81: 561, 1988. 15. Koshima, I., Moriguchi, T., Soeda, S., et al. The gluteal perforator-based flap for repair of sacral pressure sores. Plast. Reconstr. Surg. 91: 678, 1993. 16. Allen, R. J., and Heitland, A. S. Autogenous augmentation mammaplasty with microsurgical tissue transfer. Plast. Reconstr. Surg. 112: 91, 2003. 17. Duffy, F. J., Jr., Weprin, B. E., and Swift, D. M. A new approach to closure of large lumbosacral myelomeningoceles: The superior gluteal artery perforator flap. Plast. Reconstr. Surg. 114: 1864, 2004. 18. Shaw, W. W. Breast reconstruction by superior gluteal microvascular free flaps without silicone implants. Plast. Reconstr. Surg. 72: 490, 1983. 19. Guerra, A. B., Soueid, N., Metzinger, S. E., et al. Simultaneous bilateral breast reconstruction with superior gluteal artery perforator (SGAP) flaps. Ann. Plast. Surg. 53: 305, 2004. 20. DellaCroce, F. J., and Sullivan, S. K. Application and refinement of the superior gluteal artery perforator free flap for bilateral simultaneous breast reconstruction. Plast. Reconstr. Surg. 116: 97, 2005. 21. Leow, M., Lim, J., and Lim, T. C. The superior gluteal artery perforator flap for the closure of sacral sores. Singapore Med. J. 45: 37, 2004. 22. Hamdi, M., Blondeel, P., Van Landuyt, K., et al. Bilateral autogenous breast reconstruction using perforator free flaps: A single center’s experience. Plast. Reconstr. Surg. 114: 83, 2004. 23. Gurunluoglu, R., Spanio, S., Rainer, C., et al. Skin expansion before breast reconstruction with the superior gluteal artery perforator flap improves aesthetic outcome. Ann. Plast. Surg. 50: 475, 2003. 24. Hurwitz, D. J. Closure of a large defect of the pelvic cavity by an extended compound myocutaneous flap based on the inferior gluteal artery. Br. J. Plast. Surg. 33: 256, 1980. 25. Hurwitz, D. J., Swartz, W. M., and Mathes, S. J. The gluteal thigh flap: A reliable, sensate flap for the closure of buttock and perineal wounds. Plast. Reconstr. Surg. 68: 521, 1981. 26. Paletta, C., Bartell, T., and Shehadi, S. Applications of the posterior thigh flap. Ann. Plast. Surg. 30: 41, 1993. 27. Cormack, G. C., and Lamberty, B. G. The blood supply of thigh skin. Plast. Reconstr. Surg. 75: 342, 1985. 28. Rubin, J. A., Whetzel, T. P., and Stevenson, T. R. The posterior thigh fasciocutaneous flap: Vascular anatomy and clinical application. Plast. Reconstr. Surg. 95: 1228, 1995. 29. Windhofer, C., Brenner, E., Moriggl, B., et al. Relationship between the descending branch of the inferior gluteal artery and the posterior femoral cutaneous nerve applicable to flap surgery. Surg. Radiol. Anat. 24: 253, 2002.