Anatomic Basis of Dorsal Finger Skin Cover

Transcription

1 JOBNAME: tihues 9# 2005 PAGE: 1 OUTPUT: Fri June 24 00:02: Prod#: BTH Techniques in Hand and Upper Extremity Surgery 9(): , 2005 Ó 2005 Lippincott Williams & Wilkins, Philadelphia S H O R T R E V I E W Anatomic Basis of Dorsal Finger Skin Cover Jefferson Braga-Silva, MD, PhD Division of Hand Surgery and Microsurgery Pontifical Catholic University of Rio Grande do Sul Porto Alegre, Brazil n ABSTRACT This study describes the anatomy of the dorsal cutaneous vascular system of 180 digits (6 thumbs, index, middle, ring, and little fingers) from 18 pairs of fresh human cadaver hands. The aim of this paper is to incorporate the anatomic data into the current way of designing the homodigital adipofascial turnover flap for cutaneous coverage of the dorsum of the finger. We have carried out an anatomic study in preserved cadaver hands to define the distance between the joint and the origin of the dorsal cutaneous branches of the proper palmar digital artery in the proximal and middle phalanx of the long fingers and for the thumb to metacarpal and interphalangeal joint. All branches of the proper digital artery that ran to the dorsal skin were then identified, and their diameters and the distances of their origins from the proximal interphalangeal joint were measured. We showed that 2 constant branches in the proximal and middle phalanx from each proper digital artery have consistent sites of origin at predictable distances from the proximal interphalangeal joint for the long fingers and the metacarpal and interphalangeal joint for the thumb. The flap survival was excellent, and no donor site complications were observed. We showed that these branches have consistent sites of origin at predictable distances from the proximal interphalangeal joint. The adipofascial turnover arterial flap has appeared as an excellent alternative to achieve early coverage of cutaneous wounds at the dorsal aspect of the fingers. Keywords: vascularization, dorsal finger, homodigital flaps, finger flaps n HISTORICAL PESPECTIVE Vascularization of dorsal skin finger adipofascial flaps constitutes an excellent option because of their thinness, good pliability, minimal donor site deformity, and the Address correspondence and reprint requests to Jefferson Braga-Silva, MD, PhD, Av Ipiranga, 6690, Centro Clínico PUC-RS, conj 216, Porto Alegre, RS CEP, Brazil. jeffmao@terra.com.br. simplicity and rapidity of the procedure. Data concerning the dorsal hand vascular system have been collected during the last decades, allowing the development of new techniques of soft tissue coverage after skin loss. Levame et al 1 showed that the vascular system of the dorsal skin cover the proximal phalanx consisted of 2 constant arteries (commissural arteries), which are direct branches of the radial and ulnar proper digital arteries (PDA), whereas the vascular supply to the skin cover dorsum of the middle phalanx arises from 1 or 2 different symmetrical branches from the radial and ulnar PDA. Oberlin and Le Quang 2 described 2 constant cutaneous dorsal branches at the level of the proximal phalanx that originate from the radial and ulnar PDA. Yousif et al described 4 constant juxtarticular cutaneous dorsal branches (2 proximal and 2 distal), which constitute the vascular system over the proximal interphalangeal joint (PIP). Strauch and Moura 4 reported 2 constant cutaneous dorsal branches originating from the PDA at the level of the metaphysis and epiphysis of the proximal and middle phalanges. Valenti et al 5 showed a constant cutaneous vascular system over the proximal phalanx arising from a dorsal branch of the PDA and a dorsal anastomotic net at the metacarpophalangeal (MP) joint level. Endo et al 6 showed that the cutaneous dorsal vascularization at the level of the MP joint is provided by the intermetacarpal arteries and that branches of the PDA constitute the vascular system of the dorsal skin cover the proximal phalanx, with the proximal branch being rare. In addition, 2 branches from the PDA supply the vascular system over the middle phalanx. Flint and Harrison 7 used a local neurovascular flap to repair loss of digital pulp based on the dorsal branches of the PDA. Several studies have described the existence of dorsal branches of the PDA in the proximal phalanx, which anastomose with the vascular system of the dorsal skin. We performed the homodigital dorsal adipofascial Volume 9, Issue 1

2 JOBNAME: tihues 9# 2005 PAGE: 2 OUTPUT: Fri June 24 00:02: Braga-Silva FIGURE 1. Schematic representation of the intermetacarpal arteries. arterial flap elevation for finger dorsum wounds, as described by Lai et al. 8 We have confirmed the existence of 2 constant dorsal branches originating from the proper PDA in the proximal and middle phalanx. More importantly, we have shown that these branches arise at predictable sites, near the PIP joint. We also showed symmetry of the dorsal branches of the ulnar and radial PDA of each finger. 9 Our results strongly support the feasibility of using flaps based on the dorsal cutaneous branches, which can reliably be found at fixed distances from the PIP joint. 10 We did not note any marked venous insufficiency in the flaps or in the fingers. The flap is drained by small vena concomitants that follow the arterial branches. The digit is well drained by the palmar venous system, which assures the venous return when the major dorsal system has been interrupted Options of Skin Cover of Dorsal Finger Rose made use of a flap supplied by the PDA as donor site for the cutaneous coverage of the dorsal aspect of FIGURE 2. Deepithelization of the flap. the digits. We do not believe that approaching a PDA for the cutaneous coverage of the dorsal aspect of the digits is appropriate once there are other possibilities that prevent using a digital artery. 14 In relation to the dorsal intermetacarpal flaps, and among those who used them for treating losses of substance in the dorsal aspects of the digits, Earley showed this flap in 11 cases of losses of substance at the level of the proximal phalanx in 1989; he emphasized that this kind of reconstruction would not be reliable for distal losses to the PIP joint 15,16 (Fig. 1). On the other hand, other authors 17 have reported that the dorsal metacarpal flap with extended pedicle, based on the dorsal anastomosis at the level of the proximal phalanx allows for cutaneous coverage of the tip of the long fingers. The present study corroborates the anatomic findings of this study about the existence of dorsal branches at the level of the proximal phalanx. F1 2 Techniques in Hand and Upper Extremity Surgery

3 JOBNAME: tihues 9# 2005 PAGE: OUTPUT: Fri June 24 00:02: Anatomic Basis of Dorsal Finger Skin Cover FIGURE 4. Dorsal cutaneous branch of the proper palmar digital artery (PDA) to the metacarpophalangeal joint (MP), for the thumb. DCB, dorsal cutaneous branch; ET, extensor tendon. a kite flap for the cutaneous coverage of the thumb based on the second dorsal intermetacarpal artery, with several advantages. 21 Some investigations of the anatomic variations of this arterial system were carried out. 22 The aim of the present study is to demonstrate how our anatomic findings influenced our designing of the flap and to report on our experience in the use of the homodigital adipofascial turnover arterial flap. FIGURE. Transposition of the flap to the neighboring finger. In relation to the heterodigital de-epithelialised flaps, Pakian is distinguished as the first to use a dorsal deepithelialised flap (crossed-finger method) 18 (Figs. 2 F2; F and ). However, the main disadvantages of this reconstruction are that early mobilization is made impossible, and there is the need of another surgery for the separation of the digits. Atasoy 19 showed the reversed cross-finger subcutaneous flap with excellent results. Foucher, Merle, and Debry, in 1982, published the experiment with the deepithelialized flap described by Pakian. They pointed out the inclusion of epidermic cysts in the donor site as a complication. 20 In the present study, this kind of complication was not observed because the anterior surface of the flap went to a posterior surface, with no detection of epidermic cysts. Foucher described Anatomic Data One hundred eighty digits from 18 fresh cadavers (6 hands) were dissected in the Fer-à-Moulin Laboratoire (Paris, France) between January 1998 and March The age range of the cadavers was 47 to 76 years (mean 58 years), and 16 were male and two, female. Ten were white. No thumb, index, middle, ring, or little fingers were absent in the cadavers. The anatomic dissections were carried out by the same person who injected 5 ml of colored latex (Neoprene) into the humeral artery until FIGURE 5. Dorsal cutaneous branch (DCB) of the proper palmar digital artery (PDA) for the long fingers. PIP, proximal interphalangeal joint. Volume 9, Issue

4 JOBNAME: tihues 9# 2005 PAGE: 4 OUTPUT: Fri June 24 00:02: Braga-Silva FIGURE 6. Dorsal cutaneous branch (DCB) of the proper palmar digital artery (PDA) to the proximal (PP) and middle phalanx (MP) for the long fingers. PIP, proximal interphalangeal joint. FIGURE 7. Arterial flap: skin deepidermization. FIGURE 9. Arterial flap: final aspect. the dorsal hand was colored. The latex was then allowed to polymerize for 24 hours, and the cadavers were positioned in a dorsal decubitus position with the arms abduced to 90 degrees, the elbows extended, and the forearms and hands in pronation. A dorsal incision was made from the metacarpophalangeal joint to the base of the nail of each finger, and the dorsal skin was dissected in a palmar direction. The lengths of the radial and ulnar margins of the proximal and middle phalanges of each finger were measured. Direct visualization of the dorsal arterial branches of the PDA was then possible (Fig. 4). All branches of the PDA that ran to the dorsal skin were then identified (Figs. 5 and 6), and their diameters and the distances of their origins from the PIP joint were measured. The diameter of the ulnar and radial PDA was also measured at the point where the second dorsal branch arose, and all anatomic variations were registered. Dissections and observations were carried out with the aid of loupe magnification. Parametric statistical analysis was carried out, and 95% confidence intervals were calculated. There was no statistical difference between the positions of origin of the radial dorsal branches and their corresponding ulnar branches. Thus, the sites of origin of the second and third dorsal cutaneous branches of the proper TABLE 1. Donor Sites and Average Size of the Flaps Donor Site FIGURE 8. Arterial flap: adipofascial flap transposed over the defect. 4 Proximal phalanx (long fingers) Middle phalanx (long fingers) Metacarpal (thumb) Proximal phalanx (thumb) Techniques in Hand and Upper Extremity Surgery Number of Flaps No. (%) Length Width (mm) F4 F5; F6

5 JOBNAME: tihues 9# 2005 PAGE: 5 OUTPUT: Fri June 24 00:02: Anatomic Basis of Dorsal Finger Skin Cover FIGURE 10. Loss of dorsal skin over the distal phalanx of the index finger. PDA in the proximal phalanx and the first and second branches in the middle phalanx are consistent and symmetrical. The first dorsal branch was found in only 6 of the 18 cadavers, and when found in 1 finger, it was found in all the other fingers of the same cadaver. For the thumb, a dorsal branch of each PDA at the level of both the MP and interphalangeal (IP) joints was a constant finding. In all cases, these dorsal branches anastomose with each other at the level of the joint line. Clinical Data Between March 1999 and January 2004, 56 homodigital adipofascial turnover flaps were raised in 54 patients, all of them for loss of the cutaneous coverage on the finger dorsum of the middle and distal phalanx of the long fingers and proximal and distal phalanx of the thumb. The age range was 5 to 60 years (mean 27 years). The dominant hand was affected in 44 patients. The mechanisms of injury were burning (55%), crushing (40%), and human biting (5%) for the long fingers and crushing FIGURE 12. Adipofascial flap transposed over the defect. (64.%) and infection (5.7%) for the thumb. The digits most often involved were the middle and thumb (25%), followed by the ring finger (21.5%), the index, and the little finger (14.2%). Defects were located at the middle (54.8%) and distal phalanges (45.2%) for the long fingers, and for the thumb proximal (64.%) and distal phalanges (5.7%). n TECHNIQUE Once the defect had been defined, the skin overlying the flap was carefully incised down to the dermal layer in an H shape and undermined without the adipose component. When planning the length of the flap, we included the size of the defect, the portion that would not be laterally incised (the pedicle of the flap), and an additional 10 mm to compensate the loss of effective length observed when the flap is turned over. Because the cutaneous dorsal branches of the PDA arise near the PIP joint, this portion must always be preserved. Care was taken to preserve the skin on the lateral border of the digits ( Fig. 7). Proximal and lateral incisions in the subcutis were carried out, and the flap was raised including all tissue F7 FIGURE 11. The adipofascial flap on the proximal phalanx. FIGURE 1. Skin graft on the arterial flap. Volume 9, Issue 5

6 JOBNAME: tihues 9# 2005 PAGE: 6 OUTPUT: Fri June 24 00:02: Braga-Silva FIGURE 14. Result. F8 F9 T1 F10 ÿ 14 between the dermis and the paratendon. The flap was then turned back on its attached base to reach the opposite end of the defect ( Fig. 8). After the flap had been fixed to the defect, the skin over the donor site was repositioned over the paratendon, and a split-thickness skin graft was applied to the raw surface of the turnover flap ( Fig. 9). The hand was immobilized for 5 to 7 days after the operation. We had observed that all defects in the middle and distal phalanges could be covered with flaps based on the third (the last branch of proximal phalanx) or on the fourth (the first branch of the middle phalanx) cutaneous dorsal branches of the PDA. To cover extensive areas of both middle and distal phalanges, the flap length can be marked to include the subcutaneous tissue over the MP joint and, sometimes, a portion of the dorsal metacarpal surface, based on the anastomosis between the dorsal vascular system of the proximal phalanx and the dorsal metacarpal vessels. The adipofascial turnover arterial flap was able to fit wounds at the dorsal aspect of the finger in all patients. All flaps easily reached the extremity of the defects, and no signs of vascular compromise were observed in the cases that the tourniquet was intentionally released before the end of the procedure. The length of the flaps varied according to the size of the defects and the donor sites. Table 1 shows the average size of the flaps ( Figs ). In the present modified technique, the use of data on the dorsal vascularization of the finger, on the predictable sites of emergence of the dorsal branches, and on their symmetrical presentation, based on our anatomic study, permitted a predictable and reliable flap design. The range of motion FIGURE 15. Vascularization of the dorsal thumb, dorsal branches at the level of the metacarpal and interphalangeal joint. TABLE 2. Average Joint Range of Motion (Active Flexion/Extension Deficit) (Degrees) Thumb Index Middle Ring Little MP 80/0 80/0 80/0 80/0 80/ÿ10 PIP 80/ÿ5 80/ÿ10 90/ÿ10 85/ÿ5 80/ÿ15 DIP 50/ÿ10 60/0 70/0 50/ÿ10 FIGURE 16. Loss of dorsal skin over proximal phalanx of the thumb. 6 Techniques in Hand and Upper Extremity Surgery

7 JOBNAME: tihues 9# 2005 PAGE: 7 OUTPUT: Fri June 24 00:02: Anatomic Basis of Dorsal Finger Skin Cover FIGURE 17. The adipofascial flap on the first metacarpal. of the digits measured 6 months after the injury is shown T2 F15 ÿ 19 in Table 2 ( Figs ). n CONTRAINDICATIONS In case of severe circumferential crush injuries or partial degloving injuries, the use of this flap may be questioned. The digit must be carefully evaluated. The proper management should be individualized. The zone where the dorsal branches are located has to be marked out, and the most suitable vessel included in the base of the flap chosen, preoperatively, according to the defect. FIGURE 18. Adipofascial flap transposed over the defect. FIGURE 19. Result. n COMPLICATIONS As a consequence, no necrosis of the skin over the donor site was found. Neither postoperative infection in donor or recipient sites nor residual edema on the digits was perceived in this series. In one patient, a 15% loss of the grafted skin was observed. Two patients manifested dissatisfaction with the conspicuous scar on the donor site of the flap. The sensitive branches are sectioned during the elevation of this flap. The sensibility is similar to any area that has received a partial-thickness skin graft. We did not observe any remarkable tendon adhesion in our series. Dorsal skin slough was not observed in the donor site. n ACKNOWLEDGMENTS Our thanks to Professor Elizamari M. Rodrigues for the English version of this study. n REFERENCES 1. Levame JH, Otero C, Berdugo G. Vascularisation artérielle des téguments de la face dorsale de la main et des doigts. Ann Chir Plast. 1967;12: Oberlin C, Le Quang G.Étude anatomique de la vascularisation du lambeau en drapeau. Ann Chir Main. 1985;4: Yousif NJ, Cunningham MW, Sanger JR, et al. The vascular supply to the PIP joint. J Hand Surg. 1985;10A: Strauch B, Moura W. Arterial system of the fingers. J Hand Surg. 1990;15A: Valenti P, Masquelet AC, Bégué T. Anatomic basis of a dorso-commissural flap from the 2nd, rd and 4th intermetacarpal spaces. Surg Radiol Anat. 1990;12: Endo T, Kojima T, Hirase Y. Vascular anatomy of the finger dorsum and a new idea for coverage of the finger pulp defect that restores sensation. J Hand Surg. 1992;17A: Flint MH, Harrinson SH. A local neurovascular flap to repair loss of the digital pulp. Br J Plast Surg. 1965;18: Lai CS, Lin S, Yang C, et al. The adipofascial turn-over flap for complicated dorsal skin defects of the hand and finger. Br J Plast Surg. 1991;44: Braga-Silva J, Kuyven CR, Fallopa F, et al. An anatomical study of the dorsal cutaneous branches of the digital arteries. J Hand Surg. 2002;27B: Volume 9, Issue 7

8 JOBNAME: tihues 9# 2005 PAGE: 8 OUTPUT: Fri June 24 00:0: Braga-Silva 10. Braga-Silva J, Kuyven CR, Albertoni W, et al. The adipofascial turn-over flap for coverage of the dorsum of the finger: a modified surgical technique. J Hand Surg. 2004;29A: Lucas GL. The pattern of venous drainage of the digits. J Hand Surg. 1984;9A: Madelenat P, De La Caffinière JY. Le drainage veineux des doigts. Arch Anat Pathol. 1971;19: Nyström A, Drasek-Ascher G, Fridén J, et al. The palmar digital venous anatomy. Scand J Plast Reconstr Hand Surg. 1990;24: Rose EH. Local arterialized island flap coverage of difficult hand defects preserving donor digit sensibility. Plast Reconstr Surg. 198;72: Earley MJ. The arterial supply of the thumb, first web and index finger and its surgical application. J Hand Surg. 1986; 11B: Earley MJ. The second dorsal metacarpal artery neurovascular island flap. J Hand Surg. 1989;14B: Karacalar A, Özcan M. A new approach to the reverse dorsal metacarpal artery flap. J Hand Surg. 1997;22A: Pakian AI. The reversed dermis flap. Br J Plast Surg. 1978; 1: Atasoy E. Reversed cross-finger subcutaneous flap. J Hand Surg. 1982;7: Foucher G, Merle M, Debry R. Le lambeau désépidermisé retourné. Ann Chir Main. 1982;1: Foucher G, Braum JB. A new island flap in surgery of the hand. Plast Reconstr Surg. 1979;6: Dautel G, Merle M, Borrelly J, et al. Variations anatomiques du réseau vasculaire de la première commissure dorsale. Applications au lambeau cerfvolant. Ann Chir Main. 1989;8: Techniques in Hand and Upper Extremity Surgery