International Journal of Surgery 7 (2009) 472–475
Contents lists available at ScienceDirect
International Journal of Surgery journal homepage: www.theijs.com
Canine lateral thoracic fasciocutaneous flap: An experimental study n Lu’o’ng b, Pha: m Thi: Ngo: c c, Hoa`ng Ma: nh An d Tri: nh Cao Minh a, *, Hoa`ng Va a
Practical and Experimental Surgery Department, Military Medical University of Vietnam, Vietnam Department of Anatomy, Military Medical University of Vietnam, Hadong, Hanoi, Vietnam c National Institute of Veterinary Research, Hanoi, Vietnam d Military Hospital, No. 103, Military Medical University of Vietnam, Hadong, Hanoi, Vietnam b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 9 February 2009 Received in revised form 12 June 2009 Accepted 21 July 2009 Available online 26 July 2009
For the purpose of reconstructive surgery training and research, we have developed a new skin flap model: canine lateral thoracic fasciocutaneous flap. Anatomical study found that the lateral thoracic arteries in dogs have similar anatomical characteristics to human’s ones. Based on these vessels, if a skin flap was designed within the vessels territory (size 5 8 cm) it could survive completely, whereas, if designed beyond the vessels territory (size 5 14 cm) would result in partial necrosis of the flap. This fasciocutaneous flap model closely simulates the human surgery and could be valuable for training and research. Furthermore, this flap could be applied in the veterinary practice for reconstruction of canine forelimbs and cervical area. Ó 2009 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.
Keyword: Canine fasciocutaneous flap
1. Introduction Creation of skin flaps is a complex procedure that requires delicate skills and a comprehensive knowledge of the anatomy and operative stages. Because of its complexity, the procedure is difficult to teach using conventional surgical instructive methods. Furthermore, despite of the common use of the skin flaps, many unresolved questions still remain and the failures of free flaps are still substantial obstacles. To solve these problems, many experimental skin flap models, using various species1–7 have been investigated. In most flap models, small animals, such as rat,8 rabbit,9,10 have been used as the experimental animals because they are cheap and readily available. These models are excellent for basic research but lack real simulation of human skin flap. As a result, in training of reconstructive surgery, students cannot receive sufficient instruction and practice with models in small animals. Porcine model3,4 might be most suitable for training of skin flap creation. However, housing pigs is complicated and inconvenient. Dogs are medium animals, equal paediatric size, quite cheap and easily obtained in some countries. Housing dogs is much more simple than housing pigs. Dog skin thickness, blood vessels size are similar to human, so canine skin flap models would be more useful for the training purpose than rodent and porcine skin flap models.
* Corresponding author. Trinh Cao Minh, Practical and Experimental Surgery Department, Military Medical University of Vietnam. K58, Hoc vien Quan y, Hadong, Hanoi, Vietnam. E-mail address:
[email protected] (T.C. Minh).
However, we are aware of few experimental skin flap models in the dog.11–14 In this study, we describe the lateral skin flap model in the dog, a new model, which could be an excellent educational and experimental model as well as clinically applicable technique. 2. Materials and methods Adult, mixed breed, Vietnamese dogs (12–15 kg), both male and female, were acclimated to their holding facility for at least 5 days before experimental manipulation. Animals were treated according to the ‘‘Principles of Laboratory Animal Care’’ (NIH publication No 86-23 revised 1985). 2.1. Part 1: anatomical study The vascular anatomy of the lateral thoracic skin area was investigated in 10 dogs (5 males and 5 females). Dogs were anesthetized with sodium pentobarbital delivered intramuscularly, hair was shaved from both flanks. Then, dogs were positioned supine on the operating table. The skin in the lateral thoracic areas of both sides was carefully dissected leaving the underlining fascia and vessels intact (Fig. 1). By preserving all the vessels, the blood supply was sufficiently maintained to enable clear visualization and photography of the vasculature. Then, the vessels were further dissected up to their origin. In Part 2 of the study, while raising skin flap, the vascular patterns of the remaining 15 dogs were also recorded and added to the anatomical study result. In most cases,
1743-9191/$ – see front matter Ó 2009 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijsu.2009.07.009
T.C. Minh et al. / International Journal of Surgery 7 (2009) 472–475
Fig. 1. The vascular anatomy of the lateral thoracic skin area. Skin was carefully dissected leaving the underlining fascia and vessels intact. (A) The suprasternal notch. (B) The midpoint between the xiphoid process and suprasternal notch. (C) The xiphoid process. (D) The lateral thoracic artery, begins branching.
the dominant vascular supply of the chest wall lateral-lower area is the lateral thoracic artery. 2.2. Part 2: flap model viability study In the second part, the viability of lateral thoracic skin flaps with different sizes, 5 8 cm and 5 14 cm, was assessed in 15 animals (7 males and 8 females). Dogs were prepared in the same manner as in Part 1 and operated under clean condition but not sterilized. Group 1 consisted of 15 skin flaps, size 5 8 cm, created on the right or left flanks of studied animal. Flaps were designed with the cranial border drawn perpendicularly to the midline and approximate the midpoint between the xiphoid process and suprasternal notch, the dorsal border is the right posterior axillary line. By this design, flaps were elevated based on the lateral thoracic arteries and positioned entirely inside vascular territories of lateral thoracic arteries. As a result, entire flap is axial pattern (Fig. 2). Whereas, group 2 consisted of 15 skin flaps, size 5 14 cm, created on the opposite flanks of studied animal. Flap design is similar to group 1 except the caudal border was extended beyond the vascular territory of the lateral thoracic artery. By this design, 2/3 flap is axial pattern and 1/3 flap is random pattern (Fig. 2).
473
Fig. 3. Elevation of the canine lateral thoracic skin flap. Flap was elevated from the caudal side to the cranial side, vascular pedicle (A) was dissected up to its origin (B) in the axillary fossa.
All flaps were elevated in the same manner. After the skin along the flap borders had been incised, lateral thoracic arteries were identified, then underlining fasciae were cut and attached to the skin by several stitches. Lateral thoracic skin flaps were then elevated from the caudal side to the cranial side. Using surgical loupes, vascular pedicles were dissected up to their origin in the axillary fossa (Fig. 3). After checking the vital signs and countering arteries spasm, flaps were re-sutured in position using interrupted 6/0 nylon sutures. Animals were allowed to recover and were given access to food and water ad libitum. Antibiotics and other medicines were not used in this study. Flap survival and necrosis were determined at postoperative day 6th by the method described previously.6,7 In brief, both outer and inner sides of the flap were checked. Skin necrosis was defined grossly by typical signs of tissue injury on the outer side: black color, dehydration, eschar formation, and on the inner side, no vasculature. Survival and necrotic portions were then outlined on a transparent template, and then cut and weighed on an analytic scale, to determine the percentage of survival using the following formula: Survival percentage ¼ weight of survival area/total weight of entire area (survival and necrotic). All data are presented as mean SD in the text and figures. The Student t-test was used to compare two means. Statistical significance was set at a P < 0.05 level.
3. Results 3.1. Part 1: anatomical findings In 25 animals of the whole study, 50 lateral thoracic arteries from both sides were observed. Three distinct vasculature patterns were recognized. The occurrence rates for each pattern are given in Table 1. The vasculature pattern 1, which was shown in Fig. 1, was the most prominent: 46/50 cases (92%). In this pattern, the lateral
Table 1 Occurrence rate of vascular patterns.
Fig. 2. Lateral thoracic skin flaps design. Flaps were created in opposite sides of animal based on lateral thoracic arteries. (A) The suprasternal notch. (B) The midpoint between the xiphoid process and suprasternal notch. (C) The xiphoid process. (G1) Group 1’s flaps, size 5 8 cm. (G2) Group 2’s flaps, size 5 14 cm.
Vasculature pattern
Number
Percentage
Pattern 1 Pattern 2 Pattern 3 Total
46 1 3 50
92 2 6
474
T.C. Minh et al. / International Journal of Surgery 7 (2009) 472–475
Table 2 Number of used and excluded flaps in Part 2. Group
Number of flaps Excluded flaps
Used for study
Technical error Abnormal vasculature Group 1 15 Group 2 15 Total 30
2 2
3 3
13 12 25
thoracic arteries originated from the axillary arteries, run caudally and begin branching at the level of the midpoint between the xiphoid process and suprasternal notch. The skin flaps based on this vasculature would have pedicle consisted of artery, vein, and nerve, the pedicle length is approximately 10 cm (Fig. 4). The diameter of artery and vein in the pedicle is sufficient for microsurgery (1–1.5 mm). Other vasculature patterns were found in 4/50 cases. All in the right side of animals. The lateral thoracic artery was completely absent in one case (Pattern 2). In the 3 case remained (Pattern 3), the lateral thoracic arteries were small and short. The skin in this area was supplied by the intercostal vessels instead. 3.2. Part 2: flap model viability Table 2 shows the number of used and excluded flaps in Part 2 of this study. In group 1 (flap size 5 8 cm), 2/15 flaps were excluded due to the technical error in flap elevation procedure, and 13/15 flaps were used for flap survival assessment. The average survival rate (mean SD) was 95.7 4.5 percent (Fig. 5). In group 2 (flap size 5 14 cm), 3/15 flaps were excluded due to abnormal vasculature, 12/15 flaps were used for flap survival assessment. The average survival rate (mean SD) was 78.3 6.5 percent (Fig. 5). In comparison with the survival rate of group 1 (Fig. 6), it was significantly lower (P < 0.05). 4. Discussion
lateral portion of the lower part. In our study, they are dominant supply to this area in 46/50 cases (92%) observed. However, in the study of G. Ian Taylor et al.19 they did not emphasize these arteries in dogs, even though they underline these arteries in cat, rabbit, and rat. The reason for different findings might be they investigate method using Lead Oxide–Gelatin mixture injection on dead animals, whereas our method using dissection on living animals, carefully preserving all the vessels. By this way, the blood supply was sufficiently maintained to enable clear visualization and photography of the smaller vasculature than the Lead Oxide injection method. Data from Part 2 indicate that when a flap was designed inside the vascular territory of the lateral thoracic artery – size 5 8 cm, it could survive completely (Fig. 5). Whereas, if a flap was designed beyond the vascular territory of the lateral thoracic artery – size 5 14 cm, it could not survive completely and the distal portion was necrotic (Fig. 5). Size 5 14 cm mean about one-third of flap (the distal portion) was extended to the next vascular territory and
Comparision of survival rates 100
Survival rate (
in area)
Skin flaps based on lateral thoracic arteries have been reported in several species including human,15,16 cat,1 rat,17 mouse18 but to our knowledge, we are not aware of any similar canine skin flap model which has been reported. Data from Part 1 indicate that the lateral thoracic arteries in dogs have similar anatomical characteristics to human’s ones.15,16 They are tributaries of the second portion of the axillary arteries. In the upper part of the chest, the lateral thoracic arteries do not give any branch. After descending to the lower part of the chest, they give multiple branches which supply the skin and fascia of the
Fig. 5. Flap viability with different designs. Flap designed inside the vascular territory of the lateral thoracic artery survives completely, whereas, if designed beyond the vascular territory of the lateral thoracic artery, the distal portion was necrotic. (A) The suprasternal notch. (B) The midpoint between the xiphoid process and suprasternal notch. (C) The xiphoid process. (G1) Group 1’s flaps, size 5 8 cm. (G2) Group 2’s flaps, size 5 14 cm.
80
95.7
78.3 60
40
20
0
1 Fig. 4. Length and component of the canine lateral thoracic skin flap pedicle. Flap pedicles have length of approximate 10 cm and composed of artery (A), vein (V) and nerve (N).
Fig. 6. Comparison of survival rates. Group 1: survival rate (mean SD) was 95.7 4,5 percent. Group 2: survival rate (mean SD) was 78.3 6.5 percent, significantly lower (P < 0.05).
T.C. Minh et al. / International Journal of Surgery 7 (2009) 472–475
this portion cannot survive well. This finding is different with the finding in other experiments which had been carried out in mice by the author.11,12 In mice, a flap with two adjacent vascular territories could survive well without delay procedure. Result from this study suggests that the choke vessels system in dogs might not as developed as the system in mice. If someone would like to make a skin flap with more than one vascular territory in dogs, the delay procedure should be performed. As have been mentioned in Introduction, the canine lateral thoracic skin flap could be a valuable model for reconstructive surgery training. By raising this flap, the trainee could differentiate layers of flap: skin, subcutaneous, fascia which are very similar to human. Students could also assess the vital signs of flap such as bleeding, pedicle pulsation comparable to clinical situation. Furthermore, raising this flap is a technical challenging, 2/15 flaps had been excluded due to the technical error, so this model could be used not only for training of students but also for training of inexperienced surgeons. The model is also suitable for microsurgery training, the vessels diameter are approximately 1–1.5 mm, sufficient for anastomoses with microsurgery technique. As for research purpose, this model is not suitable for studies involving direct arterial drug infusion into the pedicles, because there is no suitable arterial branch necessary for the cannulation. However, it could be used for studies involving delay phenomenon and choke vessels. Finally, besides of education and research values, the canine lateral thoracic skin flap could have a real clinical value in veterinary surgery. With the pedicle length of approximately 10 cm, one could make an island flap, freely turn around, easily reach the forelimb and cervical area. Then, the donor defect could be closed primarily. 5. Conclusions This study is an introduction to the vasculature anatomy of the canine lateral thoracic arteries. Based on the anatomical finding, a new fasciocutaneous flap model has been developed. This flap model could be used for reconstructive surgery and microsurgery training as well as for experimental research. Finally, the canine lateral thoracic fasciocutaneous flap could be used as an island flap for reconstruction of forelimb and cervical defect in veterinary practice. Conflict of interest There is no conflict of interest to declare. Funding The research was funded by ourself.
475
Ethical approval Ethical approval was given by the Vietnam Military Medical University according to the ‘‘Principles of Laboratory Animal Care’’ (NIH publication No 86-23 revised 1985). References 1. Benzioni H, Shahar R, Yudelevich S, Shipov A, Milgram J. Lateral thoracic artery axial pattern flap in cats. Vet Surg 2009 Jan;38(1):112–6. 2. Bristol DG. Skin grafts and skin flaps in the horse. Vet Clin North Am Equine Pract 2005 Apr;21(1):125–44. 3. Kerrigan CL, Zelt RG, Thomson JG, Diano E. The pig as an experimental animal in plastic surgery research for the study of skin flaps, myocutaneous flaps and fasciocutaneous flaps. Lab Anim Sci 1986 Aug;36(4):408–12. 4. Kuo YR, Sacks JM, Lee WP, Wu WS, Kueh NS, Yao SF, et al. Porcine heterotopic composite tissue allograft transplantation using a large animal model for preclinical studies. Chang Gung Med J 2006 May–Jun;29(3):268–74. 5. Miesner MD. Bovine surgery of the skin. Vet Clin North Am Food Anim Pract 2008 Nov;24(3):517–26, vii. 6. Minh TC, Ichioka S, Harii K, Shibata M, Ando J, Nakatsuka T. Dorsal bipedicled island skin flap: a new flap model in mice. Scand J Plast Reconstr Surg Hand Surg 2002;36(5):262–7. 7. Minh TC, Ichioka S, Nakatsuka T, Kawai J, Shibata M, Ando J, et al. Effect of hyperthermic preconditioning on the survival of ischemia-reperfused skin flaps: a new skin-flap model in the mouse. J Reconstr Microsurg 2002 Feb;18(2):115–9. 8. Zhang F, Sones WD, Lineaweaver WC. Microsurgical flap models in the rat. J Reconstr Microsurg 2001 Apr;17(3):211–21. 9. Akyu¨rek M, Safak T, Kayikçiog˘lu A, Keçik A, Ilgit E. A new experimental flap model in the rabbit: scapular osteomyocutaneous flap. J Reconstr Microsurg 1998 May;14(4):245–50. 10. Giessler GA, Friedrich PF, Shin RH, Bishop AT. The superficial inferior epigastric artery fascia flap in the rabbit. Microsurgery 2007;27(6):560–4. 11. Aper R, Smeak D. Complications and outcome after thoracodorsal axial pattern flap reconstruction of forelimb skin defects in 10 dogs, 1989–2001. Vet Surg 2003 Jul–Aug;32(4):378–84. 12. Halfacree ZJ, Baines SJ, Lipscomb VJ, Grierson J, Summers BA, Brockman DJ. Use of a latissimus dorsi myocutaneous flap for one-stage reconstruction of the thoracic wall after en bloc resection of primary rib chondrosarcoma in five dogs. Vet Surg 2007 Aug;36(6):587–92. 13. Pavletic MM. Canine axial pattern flaps, using the omocervical, thoracodorsal, and deep circumflex iliac direct cutaneous arteries. Am J Vet Res 1981 Mar;42(3):391–406. 14. Reetz JA, Seiler G, Mayhew PD, Holt DE. Ultrasonographic and color-flow Doppler ultrasonographic assessment of direct cutaneous arteries used for axial pattern skin flaps in dogs. J Am Vet Med Assoc 2006 May 1;228(9):1361–5. 15. Schwabegger AH, Herczeg E, Piza H. The lateral thoracic fasciocutaneous island flap for treatment of recurrent hidradenitis axillaris suppurativa and other axillary skin defects. Br J Plast Surg 2000 Dec;53(8):676–8. 16. Yuen AP, Ng RW. Surgical techniques and results of lateral thoracic cutaneous, myocutaneous, and conjoint flaps for head and neck reconstruction. Laryngoscope 2007 Feb;117(2):288–94. 17. Syed SA, Tasaki Y, Fujii T, Murakami R, Kobayashi K. Cutaneous vascular anatomy of the thoracic region of the dorsum and its role in flap design in the rat. Ann Plast Surg 1992 Nov;29(5):420–4. 18. Tatlidede S, McCormack MC, Eberlin KR, Nguyen JT, Randolph MA, Austen Jr WG. A novel murine island skin flap for ischemic preconditioning. J Surg Res 2008 Jun 20 [Epub ahead of print]. 19. Taylor G Ian, Minabe Toshiharu. The angiosomes of the mammals and other vertebrates. Plast Reconstr Surg 1992 Feb;89(2):181–215.
