Anatomical study. Clinical study. R. Ogawa, H. Hyakusoku, M. Murakami, R. Aoki, K. Tanuma* and D. G. Pennington?

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1 British Journal of Plastic Surgery (2002) 55, I The British Association of Plastic Surgeons doi: /bjps PLASTIC SURGERY An anatomical and clinical study of the dorsal intercostal cutaneous perforators, and application to free microvascular augmented subdermal vascular network (ma-svn) flaps R. Ogawa, H. Hyakusoku, M. Murakami, R. Aoki, K. Tanuma* and D. G. Pennington? Departments of Plastic and Reconstructive Surgery, and *Anatomy, Nippon Medical School, Tokyo, Japan; and tdepartment of Plastic, Reconstructive and Hand Surgery, Royal Prince Alfred Hospital, Sydney, Australia SUMMARY. We report a two-part anatomical and clinical study whose aim was to map the dominant dorsal intercostal cutaneous perforators (DICPs), which are useful for microvascular augmentation of flaps raised from the skin of the back called subdermal vascular network (SVN) flaps, and to test their reliability in the clinical setting. In the anatomical arm of the study, using preserved cadavers, we macroscopically confirmed the location of DICPs, and performed microangiography of the dorsal skin to find each dominant DICE In the clinical arm of the study, we confirmed the location of the dominant DICP during microvascular augmented SVN flap transfer. Postoperatively, posteroanterior radiographs of the chest were taken to locate vessel clips used to ligate the DICPs. The combined study results showed that the dominant DICP is the sixth or seventh in most instances, but there are some anatomical variations. If no dominant DICP is found in the sixth or seventh spaces, at least one DICP that is of sufficient calibre for microvascular augmentation can usually be found in the general vicinity, such as the fifth, eighth or ninth spaces. The clinical application of microvascular augmented SVN flaps, both pedicled and free, is presented The British Association of Plastic Surgeons Keywords: anatomical study, clinical study, dorsal intercostal cutaneous perforator, subdermal vascular network flap. The concept of microvascular augmented subdermal vascular network (SVN) (sometimes called 'super-thin') flaps for the reconstruction of cervical scar contractures was first reported by Hyakusoku and Gao in These very thin flaps are useful for the reconstruction of contour-sensitive areas, such as the face and neck. 2,3 The original flap had a narrow skin pedicle with the thickness of a fasciocutaneous flap, and a widely thinned flap area, with microvascular augmentation provided by an artery and vein in its distal part. Usually the circumflex cervical vessels were used for augmentation. Since January 1998, we have used SVN flaps augmented with dorsal intercostal cutaneous perforators (DICPs) to reconstruct post-burn cervical scar contractures. However, the relationship between the position and the size of DICPs has not previously been clarified. This study reports the location of dominant DICPs, which were identified anatomically and clinically. In the anatomical study, using preserved cadavers, the location of the DICPs was confirmed macroscopically, and microangiography of the dorsal skin to find each dominant DICP was performed. In the clinical study, the location of the dominant DICP was confirmed intraoperatively during the transfer of a microvascular augmented SVN (ma-svn) flap. Postoperative posteroanterior radiographs of the chest were taken to find the vessel clips that were used to ligate the DICPs. In this study, the xth intercostal perforator is the perforator between the superior border of the xth rib and the superior border of the x+ lth rib. Therefore, the xth intercostal perforator is not always the perforator of the xth intercostal artery. The term 'DICP' includes both the perforating artery and the vein. The term 'DICPs' means more than one perforating artery and vein together. Materials and methods Anatomical study We raised 30 dorsal cutaneous flaps bilaterally in 15 cadavers. First, a thoracotomy was performed with the cadaver in the supine position. The aorta was clamped at the top of the heart and at the celiac trunk bifurcation. Next, the left common carotid and left subclavian arteries were clamped. Arterial injection was carried out using a cannula placed in the brachiocephalic trunk. The contrast medium was 30% barium sulphate diluted in water. The cadaver was then placed in cold storage for 24 h to allow the injectant to solidify. With the cadaver in the prone position, a skin incision was made in the centre of the back, and bilateral dorsal cutaneous flaps were elevated over the fascia. The location of each DICP was confirmed macroscopically. A microangiogram was then performed to determine the area of skin supplied. Clinical study Since January 1998 we have used SVN flaps augmented with DICP vessels to reconstruct post-bum cervical scar contractures in eight patients. These ma-svn flaps were 396

2 An anatomical study of dorsal intercostal cutaneous perforators 397 occipito-cervico-dorsal (OCD) flaps, superficial cervical artery (SCA) flaps and free scapular flaps (Fig. 1). At operation, each flap was elevated from the periphery to expose the perforators. The perforator to be used for anastomosis was confirmed, and its anatomical position was recorded. After each operation, posteroanterior radiographs of the chest were taken to locate the vessel clips that were used to ligate the DICE Results Anatomical results A total of 30 flaps were raised in 15 cadavers. In 16 flaps the dominant DICP was the seventh intercostal OCD-SVN flap SCA-SVN flap free scapular-svn flap perforator, and in eight flaps it was the sixth intercostal perforator. In two flaps the seventh and sixth intercostal perforators were almost equal in size ( mm internal diameter). However, in the remaining four flaps, neither the seventh nor the sixth DICP could be identified, and the dominant DICPs were the fifth and the eighth DICPs (Figs 2 and 3). These dominant DICPs existed symmetrically in the cadavers in which they were found. Clinical results In all eight clinical cases the flaps survived completely and the scar contractures were released (Table 1). In four patients the dominant DICP was the seventh intercostal perforator, and in three patients it was the sixth intercostal perforator (Fig. 4). In one patient the dominant DICP was the ninth intercostal perforator. Perforators that could be used for anastomosis averaged mm in internal diameter; the pedicle lengths averaged cm. Case reports Arterial network of occipital artery and transverse cervical artery Superficial cervical artery Circumflex scapular artery Figure 1--The various DICP augmented SVN flaps: the occipitocervico-dorsal flap (OCD flap), the superficial cervical artery flap (SCA flap) and the free scapular flap. Patient 1 - Sixth DICP augmented OCD-SVN flap A 46-year-old female suffered an extensive burn to 85% of her total body surface area in a suicide attempt. After primary surgery consisting of debridement and free skin grafting, she presented with severe scar contracture of the anterior neck (Fig. 5A). A microvascular augmented OCD-SVN flap was Figure 2 Microangiogram of a cadaver, clearly showing the seventh and sixth DICPs. Pins show thc position of ribs. Figure 3--The seventh DICP of the cadaver shown in Figure 2. This DICP has an internal diameter of 0.6 mm, and a pediclc length of 4.2 cm. Table 1 Results of the clinical study; in four cases the dominant DICP was the seventh intercostal perforator and in three cases it was the sixth intercostal perforator Case Age (years)/sex Recipient site Flap size (cm) Position of augmented D1CP 1 46/F right OCD sixth intercostal 2 51/M right SCA seventh intercostal 3 41/M left free scapular 24 x 9 seventh intercostal 4 59/M right SCA 26 9 seventh intercostal 5 29/M left OCD 35 x 11 sixth intercostal 6 35/F left free scapular 15 8 sixth intercostal 7 5 I/F left OCD ninth intercostal 8 35/F left OCD 35 x 19 seventh intercostal

3 398 British Journal of Plastic Surgery Figure 4---Case 3. Postoperative posteroanterior radiographs of the chest (A) taken to find the vessel clips that were used to ligate the DICE and (B) the vessel clip that was used to ligate the DICP is shown in the seventh intercostal space. Figure 5--Case 1. (A) Preoperative view showing severe contracture of the neck. (B) Design of the sixth DICP and circumflex scapular vessel augmented OCD-SVN flap; because this flap was designed in an area that had received meshed skin grafts, and was very large, two microvessels were used for augmentation. (C) Postoperative view 1 year after transfer of a free groin flap. There is no recurrence of the scar contracture. used to reconstruct the anterior neck and chin (Fig. 5B). During the operation, a DICP was found in the sixth intercostal space. Both this DICP and the circumflex scapular artery and vein were used to augment the blood supply of the OCD-SVN flap. They were anastomosed to the transverse cervical artery and vein and the facial artery and vein, respectively. The flap survived completely and the neck contracture was released. At a later date, a free groin flap was transferred to the chin, which the OCD-SVN flap could not cover. No recurrence of the scar contracture was observed 1 year later (Fig. 5C). Patient 2 - Seventh DICP augmented SCA-SVN flap A 51-year-old male suffered an extensive burn of 50% of his total body surface area. After skin grafting of the acute burn, the patient developed severe scar contracture of the anterior neck (Fig. 6A). A DICP augmented SCA-SVN flap was transferred 2 months after the primary operation (Fig. 6B). In this operation, a dominant DICP was found in the seventh intercostal space (Fig. 6C) and used to augment the distal portion of the flap by anastomosis with the facial vessels. The flap survived completely, and the reconstructive result is shown in Figures 6D,E. Patient 3 - Seventh DICP augmented free scapular-svn flap A 41-year-old male suffered severe burns to 40% of his total body surface area. After emergency skin grafting, he developed severe scar contracture of the anterior neck. First, a secondinternal-thoracic-perforator augmented SVN flap was transferred, but this left some residual scar contracture on the chin (Fig. 7A). The patient requested further reconstruction for hypertrophic scar contracture of the chin and cheek. Therefore, a DICP augmented free scapular-svn flap was transferred (Fig. 7B). At operation, a DICP was found in the seventh intercostal space and anastomosed with the facial vessels. The flap survived completely and the contracture was fully released (Fig. 7C).

4 An anatomical study of dorsal intercostal cutaneous perforators 399 Figure 6--Case 2. (A) Preoperative view; after an extensive burn, this patient developed severe scar contracture of the anterior neck. (B) Design of the microvascularaugmented SCA-SVNflap, which was transferred 2 months after the primary operation. (C) The seventh DICP was used to augment the distal portion of the flap. (D,E) Postoperative appearance at 2 years showing no recurrence of the scar contracture. Discussion Very thin flaps are desirable in contour-sensitive areas, such as the neck.l Previous studies have demonstrated the safety and efficacy of one-stage super-thin pedicled and free flaps, 2-5 which have been primarily thinned to the level of the S V N. 6 Very long or very large examples of these flaps may suffer from distal necrosis, 3'5 which has prompted studies into microvascular augmentation (or super-charging) of such flaps. 2 Microvascular augmentation is extremely useful for ensuring the complete survival of large SVN flaps whose width-to-length ratio exceeds 1 : 2 or those flaps that are designed across the dorsal midline. 4'5 In the past, the circumflex scapular artery and vein have been found to be useful augmentation vessels for anastomosis with the contralateral facial artery and vein. Most of the patients in earlier studies of SVN flaps had suffered extensive burns. In some of these patients it was impossible to design a flap to include the circumflex scapular vessels because of scarring from earlier skin grafts. In other cases, a very large SVN flap required double augmentation to ensure complete survival. Such cases prompted this study, to determine whether the DICPs could be used as augmentation vessels. Moreover, we hoped to use these perforators as augmentation vessels in both free and pedicled scapular flaps and in a thinned version of the SVN flap. However, the dominant vessels and anatomical stability have not yet been fully clarified in free flaps. The major sources of arterial blood supply to the skin of the central part of the back are the dorsal cutaneous, lateral cutaneous and anterior cutaneous branches of the intercostal arteries (Fig. 8). 7'8 Each dorsal cutaneous branch is divided into a medial branch and a lateral branch. 8 The medial branch is found 1-5 cm from the midline, and the lateral branch is found 5-8 cm from the midline. We have used this lateral branch of the dorsal cutaneous branch for microvascular augmentation of the SVN flap, and we have called this the D I C E This area is

5 400 British Journal of Plastic Surgery medial cutaneous branch teh 2P 3(~Anterior cutaneous branch Figure 8---Diagram of a lower intercostal space, illustrating the artery. We have called this lateral branch of the dorsal cutaneous branch the DICE and we have used it for microvascular augmentation of the SVN flap. Figure 9--Diagram of the seventh DICE which is found 5-8 cm from the midline of the seventh intercostal space. This area is around the triangle of auscultation. Figure 7~Case 3. (A) Appearance 3 years after primary reconstruction using a second internal thoracic perforator augmented SVN flap. The patient requested treatment of the hypertrophic scar contracture of the chin and cheek. (B) A DICP augmented free scapular SVN flap was transferred secondarily, with direct closure of the donor site. (C) Appearance 1 year after secondary reconstruction. The flap survived completely and the hypertrophic scar contracture of the chin and cheek was fully released. around the triangle of auscultation (Fig. 9). For anatomical reasons, we do not use the medial branch. The DICPs supply the longissimus and iliocostalis muscles before reaching the trapezius and latissimus dorsi muscles, which they penetrate to reach the overlying skin. s The relationship between the position and the size of the DICPs has not yet been clarified. According to Cormack and Lamberty, 'they are best developed from T6 downwards and branches pierce the superficial muscles at a variable distance') In 1984, Nakajima et al reported the infrascapular fasciocutaneous flap, whose vascular pedicle is the sixth DICP. 6'9 Our results show that the seventh or the sixth DICP is dominant in the

6 An anatomical study of dorsal intercostal cutaneous perforators 401 majority of patients. The perforators are usually big enough for microvascular anastomosis. However, we came across some cases where no perforators could be found in either the seventh or the sixth intercostal spaces. In these cases we found other DICPs, such as the ninth, that were big enough for microvascular anastomosis. The clinical findings confirmed those of our anatomical study. Intercostal perforators are useful for microvascular augmentation of not only pedicled OCD- or SCA-SVN flaps but also free scapular-svn flaps, although further investigation into the extension of flap survival area by using these vessels for augmentation in SVN free flaps is required. In conclusion, augmentation of the distal area of large flaps or narrow-pedicled flaps, such as SVN flaps, by anastomosis of DICPs is useful to ensure complete flap survival. We investigated the relationship between the position and the size of DICPs in cadavers, and subsequently used this information to microvascularly augment SVN flaps in clinical cases. We conclude that the dominant DICP is the sixth or seventh in most cases. The vessels are of sufficient calibre for microvascular anastomosis. However, in a minority of cases, useful DICPs do not exist in the sixth or the seventh intercostal space. In these instances, a dominant perforator can usually be found nearby, such as in the ninth intercostal space. It is expected that this study will expand the clinical application of both pedicled and free OCD- and SCA- SVN flaps, and may also expand the useful area of the free scapular flap. References 1. Hyakusoku H, Gao J-H. The 'super-thin' flap. Br J Plast Surg 1994; 47: Hyakusoku H, Pennington D-G, Gao J-H. Microvascular augmentation of the super-thin occipito-cervico-dorsal flap. Br J Plast Surg 1994; 47: Gao J-H, Hyakusoku H, Wang C-M, Aoki R. A study of survival on random pattern flaps with narrow pedicle - comparison of thinned flaps of various pedicle width and between thinned flaps and conventional thick flaps. J Jpn Plast Reconstr Surg 2000; 20: Hyakusoku H, Takizawa Y, Murakami M, Gao J-H, Takekashi A, Fumiiri M. Versatility of the free or pedicted superficial cervical artery skin flaps in head and neck burns. Burns 1993; 19: Gao J-H, Hyakusoku H, Aoki R, Wang C-M. An experimental study on the survival of random pattern flaps with a narrow skin pedicle in pigs - comparison of survival and blood supply in thick flaps with various pedicle widths. J Jpn Plast Reconstr Surg 1999; 19: Nakajima H, Fujino T, Adachi S. A new concept of vascular supply to the skin and classification of skin flaps according to their vascularization. Ann Plast Surg 1986; 16: Hendel PM, Hattner RS, Rodrigo J, Buncke HJ. The functional vascular anatomy of rib. Plast Reconstr Surg 1982; 70: Cormack GC, Lamberty BGH. The Arterial Anatomy of Skin Flaps. Edinburgh: Churchill Livingstone, 1994: Nakajima H, Fujino T. Island fasciocutaneous flaps of dorsal trunk and their application to myocutaneous flap. Keio J Med 1984; 33: The Authors Rei Ogawa Hiko Hyakusoku Masahiro Murakami Ritsu Aoki Department of Plastic and Reconstructive Surgery, Kumiko Tanuma Department of Anatomy, Nippon Medical School, Sendagi Bunkyo-ku, Tokyo , Japan. David G. Pennington Department of Plastic, Reconstructive and Hand Surgery, Royal Prince Alfred Hospital, Sydney, Australia. Correspondence to Dr Rei Ogawa. Paper received 28 November Accepted 22 February 2002.