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Vascular anatomy of the metatarsal bones and the interosseous muscles of the foot
Journal of Plastic, Reconstructive & Aesthetic Surgery (2009) 62, 1227e1232
Vascular anatomy of the metatarsal bones and the interosseous muscles of the foot Murat Sahin Alagoz a,*, Hakan Orbay b, Ahmet Cagri Uysal b, Ayhan Comert c, Eray Tuccar c a
Department of Plastic and Reconstructive Surgery, Kocaeli University Faculty of Medicine, Kocaeli, Turkey Department of Plastıc and Reconstructıve Surgery, Nippon Medıcal School, Tokyo, Japan c Department of Anatomy, Ankara University Faculty of Medicine, Ankara, Turkey b
Received 15 July 2007; accepted 29 December 2007
KEYWORDS Metatarsal bones; Interosseous muscles; Vascular anatomy
Summary Utilization of the metatarsal bones and interosseous muscles in foot reconstruction should be based on the vascular anatomy of the metatarsal bones and interosseous muscles. We studied the vascular anatomy of the metatarsal bones and the interosseous muscles to design a split metacarpal musculoosseous flap and dorsal interosseous muscle flap. Twenty-two feet from eleven cadavers that had been embalmed in formalin were studied. Dissection was done using a dissection microscope (3.5), delineating meticulously the arcuate artery, dorsal metatarsal arteries and the small branches arising from the metatarsal arteries. The dorsal metatarsal arteries do not course at the midline of the interosseous muscles. The first dorsal metatarsal artery proceeds close to the first metatarsal bone in the first metatarsal space. While proceeding to the distal, it shoots out a branch that individually feeds the lateral head of the first dorsal metatarsal muscle and medial face of the second metatarsus, thereby feeding muscle and bone. Except for this branch, the first dorsal metatarsal gives off segmental and periosteal branches that individually feed the medial heads of the first dorsal metatarsal muscle and first metatarsal bone. The second, third and fourth metatarsal arteries proceed close to the third, fourth and fifth metatarsal bones in the metatarsal spaces. In these courses, the arteries give out segmental branches to both faces of the interosseous muscles and periosteal branches to the medial face of metatarsal bones. For defects or disease of the ankle bones, the metatarsal bones can be split at the medial border distally, and a split metatarsal musculoosseous flap, based proximally on the dorsal metatarsal artery, can be done. Distal intermetatarsal anastomoses between the dorsal and plantar vascular networks enables a split metatarsal musculoosseous flap based distally, including the dorsal metatarsal artery for bony defects of the proximal phalanx. Crown Copyright ª 2009 Published by Elsevier Ltd on behalf of British Association of Plastic, Reconstructive and Aesthetic Surgeons. All rights reserved.
* Corresponding author. Address: Department of Plastic and Reconstructive Surgery, Kocaeli University Faculty of Medicine, Fatih mah., R.Seymen Doktorlar sitesi FBlok No:3, Kurucesme, Kocaeli, Turkey. Tel.: þ90 262 226 25 83; fax: þ90 262 303 8003. E-mail address: [email protected] (M.S. Alagoz). 1748-6815/$- seefront matter Crown Copyrightª 2009Published by Elsevier Ltd on behalf of BritishAssociationofPlastic, Reconstructiveand AestheticSurgeons.Allrights reserved. doi:10.1016/j.bjps.2007.12.083
1228 The dorsum and digits of the foot are frequently affected by the microvascular and neuropathic complications of diabetes mellitus, as well as other vascular diseases. Bone and joints can be readily exposed after minor trauma or infection due to thin skin (particularly on the dorsal part). Surgical options in such cases are limited, and defects usually progress.1e3 The metatarsal bones and interosseous muscles establish foot architecture. The interosseous muscles have a subtle functional role in fine motor manipulation of the normal foot.4 Extensor digitorum brevis muscle in the foot dorsum was used as the local muscle flap for reconstruction of defects in ankle and foot dorsum.5e8 Dorsal interosseous muscles are vascularised structures that can be used in the repair of minor chronic or acute defects if extensor digitorum brevis is damaged or cannot be used. Bony defects of the foot, ankle and finger demolish foot architecture, resulting in poor functional outcomes.9,10 Conventional bone grafting is generally recommended for most bone defects with a well vascularised bed, adequate soft-tissue coverage, and absence of infection.11 Vascularised bone grafts exhibit better mechanical strength, early union, and less absorption.12e15 Studies have defined use of the muscles in the hand to treat soft tissue and bone defects of the hand and various vascularised bone grafts.16e19 In the hand, Uysal et al.20 studied vascular anatomy of the metacarpal bones and the interosseous muscles to design a split metacarpal musculosseous flap. Vascular anatomy of the interosseous muscles and metatarsal bones, as well as muscle and musculosseous flaps that can be elevated, has not been studied. Dorsal interosseous muscle can be used in the reconstruction of acute or chronic, diabetic or traumatic minor bone and/or skin defects on a reverse or proximal basis, solely or with split metatarsal bones affixed to it. We studied the vascular anatomy of the metatarsal bones and the interosseous muscles to design a split metatarsal musculosseous flap and dorsal interosseous muscle flap.
Materials and methods Twenty-two feet from 11 cadavers that had been embalmed with formalin were studied. The cadavers, seven female and four male, had no known vascular disease and a mean age of 49 years (age range, 42e59 years). The popliteal arteries were dissected at the poplitea, and latex (40 ml) was injected manually under physiological pressure. The latex was allowed to cure overnight at room temperature as described by Reynolds.21 Dissection was done using a dissection microscope (3.5), delineating meticulously the arcuate artery, dorsal metatarsal arteries, and the small branches arising from the metatarsal arteries. The deep plantar arch and its connections with the dorsal system were excluded from the study because they have been studied in detail.22e24
Results The tibialis anterior artery is named the dorsalis pedis artery after it passes under the extensor retinaculum. The dorsalis pedis artery travels underneath the extensor
M.S. Alagoz et al. hallucis longus and curves between the extensor hallucis longus and extensor digitorum longus along the dorsum of the first interspace. Typically, the dorsalis pedis artery has three lateral arterial branches (proximal and distal tarsal arteries; arcuate artery) and two medial branches (medial tarsal arteries). The third lateral branch of the dorsalis pedis, the arcuate artery, takes off at the level of the first tarsal-metatarsal joint and travels laterally over the bases of the second, third, and fourth metatarsals. It gives off the second, third, and fourth dorsal metatarsal arteries before it joins the lateral tarsal artery. After giving off the arcuate artery, the dorsalis pedis artery enters into the proximal first intermetatarsal space, and in the process gives off the first dorsal metatarsal artery, which courses over the first dorsal interosseous muscle. After giving off the plantaris profundus branch at the basis of the first metatarsal bone, the dorsalis pedis artery continues as the first dorsal metatarsal artery. The latter proceeds close to the first metatarsal bone in the first metatarsal space. While proceeding to the distal, it shoots out a branch that individually feeds the lateral head of the first dorsal metatarsal muscle and medial face of the second metatarsus, thereby feeding muscle and bone (Figure 1). Except this branch, the first dorsal metatarsal gives off segmental branches that individually feed the medial heads of the first dorsal metatarsal muscle and first metatarsal bone (Figure 2). At the more distal level following the muscle level, the first metatarsal artery gives off medial and lateral branches that supply blood to the hallux and second digit. The arcuate artery separates from the dorsalis pedis artery in the distal part of the tarsal artery and in the vicinity of cuneiform bone. The first branch of the arcuate artery is the second metatarsal artery. Immediately after branching from the arcuate artery, this artery gives out segmental branches to both faces of the interosseous muscle. In this course, the artery proceeds close to the third metatarsal bone in the second metatarsal space. The concerned artery also gives off periosteal branches to the medial face of the third metatarsal bone. The third metatarsal artery, which is the second branch of the arcuate artery, goes close to the fourth metatarsal artery. It gives out segmental branches to the third interosseous muscle on its course, and periosteal branches to the medial face of the fourth metatarsal bone. The branches of the fourth dorsal metatarsal artery, which is the last branch of the arcuate artery, are similar to those of the third metatarsal artery; the diameter of the artery and its branches narrows in this space. The fourth metatarsal artery moves close to the fifth metatarsal bone and gives off periosteal branches to the medial part of this bone (Figure 3).
Discussion Defects of the foot dorsum, ankle and toes are usually seen after trauma or due to vascular or neuropathic diseases. Recovery of soft tissue defects in these areas, particularly those associated with bone disease, is very difficult.25 In recent diabetic neuropathy wounds and minor defects arising from trauma, the first choice is follow-up with dressing
Vascular anatomy of the foot
1229
Figure 2 The interosseous muscle dissected and removed in part. The asterisk indicates the dorsal metatarsal artery. The arrow indicates the periosteal branches nourishing the bone. Figure 1 Dorsum of the foot with the skin and the extensor tendons removed (schematic). The course of the dorsal metatarsal arteries is not at the midline of the interosseous muscles, but at the first, second, third and fourth dorsal metatarsal arteries, proceeding close to the first, third, fourth and fifth metatarsal bone. The arcuate artery is marked by an asterisk. The arrow indicates the periosteal branches piercing muscles and nourishing bones.
changes and reconstruction with split-thickness skin graft.1,3 Due to the vascular structure of the area, if minor defects are secondary to a neuropathic disease or if bones and tendons are exposed due to trauma, methods of dressing, primary closure, and reconstruction with a graft usually fail and the defect may expand.26 Local random flaps have limited reach and can be unreliable, particularly if the area around the wound has been traumatized or is chronically scarred.27 Local muscle flaps are preferred to free flaps if the defect is small (3e6 cm) and within reach of the local muscle flap.28 Pedicled muscle flaps, the next option on the reconstructive ladder, were first routinely advocated by Ger29 in the late 1960s as a solution for coverage of advanced stasis ulcers, post-traumatic wounds, and diabetic ulcers in the lower extremities. Ger suggested that rotation of well-vascularised muscle to cover soft tissue defects increased wound healing because of improved local blood flow. There are many muscle flaps used locally in the plantar area of the foot, but the only local muscle that is commonly used in the dorsal area is extensor digitorum brevis because
Figure 3 Dorsum of the foot with the skin and extensor tendons removed. The first, second, third and fourth dorsal metatarsal arteries proceed close to the first, third, fourth and fifth metatarsal bone.
1230 its vascular structure is well known and it is readily available.23,30,31 This muscle is commonly used in the treatment of minor defects. Based on the vascular anatomy we described, dorsal interosseous muscles are good alternatives that can be used to repair minor defects that require local muscle flaps. In defects caused by microangiopathy or other vascular failures in diabetic patients, the disease can also involve the vessel that feeds the flap (possibility of foot ischaemia due to interruption of foot collateral circulation). In patients with critical foot ischaemia presenting with a defect suitable for the discussed flap, prior foot revascularisation is essential (needed in about 40% of cases) to salvage the foot. Alternative treatments should be instigated in defects induced in this way (e.g. free transfer, amputation).32 The common characteristic of the dorsal interosseous muscles of the foot is that they are fed via segmental branches originating from the dorsal metatarsal artery passing from their locale. The common feature of these arteries is that they originate from the dorsalis pedis, and that they are connected with the plantar vascular network through two perforators (proximal perforating arteries, distal perforating arteries) originating from the plantar arch. This vascular connection has been studied in detail.22e24 The perforators concerned are located in the proximal and distal parts of each interosseous space. Therefore, in the case of injury to vascular structures resulting from trauma in the dorsal part of the foot or diabetic neuropathy (in isolated neuropathic wounds), these muscles can be easily fed through the perforators coming from the plantar area. Fasciocutaneous flaps based on the first dorsal metatarsal artery of the foot dorsum have been used on proximal and distal bases.33 If defects of the ankle and foot dorsum require a muscle flap, it is suggested in this study that interosseous muscles that can be lifted on a proximal basis can be elevated individually or in combination depending on defect size. The major supply to flaps that are to be elevated on a proximal basis is dorsal metatarsal arteries. In defects in more proximal areas, the dorsalis pedis artery can be incorporated into dissection, and the pedicle elongated. If the dorsalis pedis is known to be injured, the muscle should be fed by perforators coming from the plantar area. For defects in distal areas (proximal parts of toes, web spaces), circulation of the muscle to be elevated should be provided by distal plantar perforators. It was reported in various series that the first dorsal metatarsal artery was not located in 9.4e18% of cases. This flap cannot be elevated from the first metatarsal artery.34e36 Vascularised bone grafts are well recognized; they demonstrate better mechanical strength, early union, and less absorption.14 Peterson et al15 demonstrated feeding of metatarsal heads to use the head parts of the metatarsus as vascular bone grafts. According to this study, the metatarsal heads had two arterial sources, i.e. the dorsal metatarsal arteries (arising from the dorsalis pedis artery) and the plantar metatarsal arteries (branches of the posterior tibial artery). These two vessels typically anastomose at two sites near the metatarsal heads, forming a vascular ring and providing an extensive extraosseous arterial network around the metatarsal heads. Small arterial branches
M.S. Alagoz et al.
Figure 4 Rotational arch of the split metatarsal musculoosseous flap (schematic). p: flap based proximally for defects in the proximal region; d: flap based distally for defects in the distal region.
of this network run distally on the metatarsal cortex to enter the bone of the metatarsal head. In our cadaver dissections, the dorsal metatarsal arteries exhibited an indistinct pattern of segmental periosteal nourishment throughout their course in the dorsal interosseous muscles, and anastomoses with the plantar arteries were via perforators. Preservation of muscle would prevent damage to the dorsal metatarsal artery and to the periosteal branches supplying the first metatarsal bones from the lateral and medial borders, and the other metatarsal bones from the medial border. Preservation of the muscle around the artery, when compared to dissection of the artery as an island flap, facilitates and shortens the duration of flap elevation, as noted in this study. Meticulous dissection of the dorsal metatarsal artery, maintaining a sufficient cuff of soft tissue around the artery, can nourish the split metatarsal bone if the periosteal branches are isolated and preserved, but can prolong flap elevation time. For defects or any disease of the ankle bones, the metatarsal bones can be split at the medial border distally, and a split metatarsal musculoosseous flap, based proximally on the dorsal metatarsal artery, can be done (Figure 4). Distal intermetatarsal anastomoses between the dorsal and plantar vascular networks enables a split metatarsal musculoosseous flap based distally, including the dorsal metatarsal artery for the bony defects of the
Vascular anatomy of the foot
Figure 5 Rotational arch of the split metatarsal musculoosseous flap. p: flap based proximally for defects in the proximal region; d: flap based distally for defects in the distal region.
proximal phalanx (Figure 5). Venous supercharging should be tried using a vein graft if it is suspected that venous failure may develop. Functional loss from these proximally or distally based flaps may cause restriction of abduction of the toes.
References 1. Tosun Z, Ozkan A, Karac ¸or Z, et al. Delaying the reverse sural flap provides predictable results for complicated wounds in diabetic foot. Ann Plast Surg 2005 Aug;55:169e73. 2. Demirtas Y, Ayhan S, Sariguney Y, et al. Distally based lateral and medial leg adipofascial flaps: need for caution with old, diabetic patients. Plast Reconstr Surg 2006 Jan; 117:272e6. 3. Yildirim S, Akan M, Ako ¨z T. Soft-tissue reconstruction of the foot with distally based neurocutaneous flaps in diabetic patients. Ann Plast Surg 2002 Mar;48:258e64. 4. Kalin PJ, Hirsch BE. The origins and function of the interosseous muscles of the foot. J Anat 1987 Jun;152:83e91. 5. Pai CH, Lin GT, Lin SY, et al. Extensor digitorum brevis rotational muscle flap for lower leg and ankle coverage. J Trauma 2000;49:1012e6. 6. Hirase Y, Kojima T, Fukumoto K, et al. Indication and practice of reverse flow extensor digitorum brevis muscle flap transfer. Ann Plast Surg 2003;51:273e7. 7. Landi A, Sorangi O, Monteleone M. The extensor digitorum brevis muscle island flap for soft tissue loss around the ankle; case report. Plast Reconstr Surg 1985;75:892e7. 8. Leitner DW, Gordon L, Buncke HJ. The extensor digitorum brevis as a muscle island flap. Plast Reconstr Surg 1985;76: 777e80.
1231 9. Yazar S, Lin CH, Wei FC. One-stage reconstruction of composite bone and soft-tissue defects in traumatic lower extremities. Plast Reconstr Surg 2004 Nov;114:1457e66. 10. Tamai S, Fukui A, Shimizu T, et al. Thumb reconstruction with an iliac bone graft and a dorsalis pedis flap transplant including the extensor digitorum brevis muscle for restoring opposition: a case report. Microsurgery 1983;4:81e6. 11. Bieber EJ, Wood MB. Bone reconstruction. Clin Plast Surg 1986; 13:645e55. 12. Hayashi A, Maruyama Y, Okajima Y, et al. Vascularized iliac based on a pedicle of upper lumbar vessels for anterior fusion of the thoraco-lumbar spine. Br J Plast Surg 1994; 47:425e30. 13. Davis PK, Mazur JM, Coleman GN. A torsional strength comparison of vascularized and non vascularized bone grafts. J Biomech 1982;15:875e80. 14. Cutting CB, McCarthy JG. Comparison of residual osseous mass between vascularised and non-vascularised onlay bone transfers. Plast Reconstr Surg 1983;73:672e5. 15. Petersen WJ, Lankes JM, Paulsen F, et al. The arterial supply of the lesser metatarsal heads: a vascular injection study in human cadavers. Foot Ankle Int 2002 Jun;23:491e5. 16. Foucher G, Genechten F, Merle N, et al. A compound radial artery forearm flap in hand surgery: an original modification of the Chinese forearm flap. Br J Plast Surg 1984;37:139e48. 17. Biemer E, Stock W. Total thumb reconstruction: a one stage reconstruction using an osteocutaneous forearm flap. Br J Plast Surg 1983;36:52e5. 18. Galsson DW, Lovie MJ. The ulnar island flap in hand and forearm reconstruction. Br J Plast Surg 1988;41:349e53. 19. Costa H, Comba S, Martins A, et al. Further experience with the posterior interosseous flap. Br J Plast Surg 1991;44:449e55. 20. Uysal AC, Alagoz MS, Tuccar E, et al. Vascular anatomy of the metacarpal bones and the interosseous muscles. Ann Plast Surg 2003;51:63e8. 21. Reynolds DG. Silicon rubber techniques for microvascular studies. Lab Manage 1968;6:24. 22. Attinger CE, Evans KK, Bulan E, et al. Angiosomes of the foot and ankle and clinical implications for limb salvage: reconstruction, incisions, and revascularization. Plast Reconstr Surg 2006;117:261se93. 23. Lee JH, Dauber W. Anatomic study of the dorsalis pedis-first dorsal metatarsal artery. Ann Plast Surg 1997;38:50e5. 24. Ozer MA, Govsa F, Bilge O. Anatomic study of the deep plantar arch. Clin Anat 2005;18:434e42. 25. Weinzweig N, Davies BW. Foot and ankle reconstruction using the radial forearm flap: a review of 25 cases. Plast Reconstr Surg 1998 Nov;102:1999e2005. 26. Butler CE, Chevray P. Retrograde-flow medial plantar island flap reconstruction of distal forefoot, toe, and webspace defects. Ann Plast Surg 2002 Aug;49:196e201. 27. Selmanpakoglu N, Guler M, Sengezer M, et al. Reconstruction of foot defects due to mine explosion using muscle flaps. Microsurgery 1998;18:182e8. 28. Attinger CE, Ducic I, Cooper P, et al. The role of intrinsic muscle flaps of the foot for bone coverage in foot and ankle defects in diabetic and nondiabetic patients. Plast Reconstr Surg 2002;110:1047e54. 29. Ger R. The operative treatment of the advanced stasis ulcer: a preliminary communication. Am J Surg 1966;111:659e63. 30. Gibstein LA, Abramson DL, Sampson CE, et al. Musculofascial flaps based on the dorsalis pedis vascular pedicle for coverage of the foot and ankle. Ann Plast Surg 1996;37:152e7. 31. Kurata S, Hashimoto H, Terashi H, et al. Reconstruction of the distal foot dorsum with a distally based extensor digitorum brevis muscle flap. Ann Plast Surg 1992;29:76. 32. Dellon AL. Diabetic neuropathy: medical and surgical approaches. Clin Podiatr Med Surg 2007 Jul;24:425e48.
1232 33. Senyuva C, Yucel A, Fassio E, et al. Reverse first dorsal metatarsal artery adipofascial flap. Ann Plast Surg 1996;36:158e61. 34. Governa M, Barisoni D. Distally based dorsalis pedis island flap for a distal lateral electric burn of the big toe. Burns 1996;22: 641e3.
M.S. Alagoz et al. 35. Lippert H. Variability of hand and foot arteries. Handchir Mikrochir Plast Chir 1984;16:254e8. 36. May JW, Chait LA, Cohen BE, et al. Free neurovascular flap from the first web of the foot in hand reconstruction. J Hand Surg 1977;2:387e93.
Vascular anatomy of the metatarsal bones and the interosseous muscles of the foot Murat Sahin Alagoz a,*, Hakan Orbay b, Ahmet Cagri Uysal b, Ayhan Comert c, Eray Tuccar c a
Department of Plastic and Reconstructive Surgery, Kocaeli University Faculty of Medicine, Kocaeli, Turkey Department of Plastıc and Reconstructıve Surgery, Nippon Medıcal School, Tokyo, Japan c Department of Anatomy, Ankara University Faculty of Medicine, Ankara, Turkey b
Received 15 July 2007; accepted 29 December 2007
KEYWORDS Metatarsal bones; Interosseous muscles; Vascular anatomy
Summary Utilization of the metatarsal bones and interosseous muscles in foot reconstruction should be based on the vascular anatomy of the metatarsal bones and interosseous muscles. We studied the vascular anatomy of the metatarsal bones and the interosseous muscles to design a split metacarpal musculoosseous flap and dorsal interosseous muscle flap. Twenty-two feet from eleven cadavers that had been embalmed in formalin were studied. Dissection was done using a dissection microscope (3.5), delineating meticulously the arcuate artery, dorsal metatarsal arteries and the small branches arising from the metatarsal arteries. The dorsal metatarsal arteries do not course at the midline of the interosseous muscles. The first dorsal metatarsal artery proceeds close to the first metatarsal bone in the first metatarsal space. While proceeding to the distal, it shoots out a branch that individually feeds the lateral head of the first dorsal metatarsal muscle and medial face of the second metatarsus, thereby feeding muscle and bone. Except for this branch, the first dorsal metatarsal gives off segmental and periosteal branches that individually feed the medial heads of the first dorsal metatarsal muscle and first metatarsal bone. The second, third and fourth metatarsal arteries proceed close to the third, fourth and fifth metatarsal bones in the metatarsal spaces. In these courses, the arteries give out segmental branches to both faces of the interosseous muscles and periosteal branches to the medial face of metatarsal bones. For defects or disease of the ankle bones, the metatarsal bones can be split at the medial border distally, and a split metatarsal musculoosseous flap, based proximally on the dorsal metatarsal artery, can be done. Distal intermetatarsal anastomoses between the dorsal and plantar vascular networks enables a split metatarsal musculoosseous flap based distally, including the dorsal metatarsal artery for bony defects of the proximal phalanx. Crown Copyright ª 2009 Published by Elsevier Ltd on behalf of British Association of Plastic, Reconstructive and Aesthetic Surgeons. All rights reserved.
* Corresponding author. Address: Department of Plastic and Reconstructive Surgery, Kocaeli University Faculty of Medicine, Fatih mah., R.Seymen Doktorlar sitesi FBlok No:3, Kurucesme, Kocaeli, Turkey. Tel.: þ90 262 226 25 83; fax: þ90 262 303 8003. E-mail address: [email protected] (M.S. Alagoz). 1748-6815/$- seefront matter Crown Copyrightª 2009Published by Elsevier Ltd on behalf of BritishAssociationofPlastic, Reconstructiveand AestheticSurgeons.Allrights reserved. doi:10.1016/j.bjps.2007.12.083
1228 The dorsum and digits of the foot are frequently affected by the microvascular and neuropathic complications of diabetes mellitus, as well as other vascular diseases. Bone and joints can be readily exposed after minor trauma or infection due to thin skin (particularly on the dorsal part). Surgical options in such cases are limited, and defects usually progress.1e3 The metatarsal bones and interosseous muscles establish foot architecture. The interosseous muscles have a subtle functional role in fine motor manipulation of the normal foot.4 Extensor digitorum brevis muscle in the foot dorsum was used as the local muscle flap for reconstruction of defects in ankle and foot dorsum.5e8 Dorsal interosseous muscles are vascularised structures that can be used in the repair of minor chronic or acute defects if extensor digitorum brevis is damaged or cannot be used. Bony defects of the foot, ankle and finger demolish foot architecture, resulting in poor functional outcomes.9,10 Conventional bone grafting is generally recommended for most bone defects with a well vascularised bed, adequate soft-tissue coverage, and absence of infection.11 Vascularised bone grafts exhibit better mechanical strength, early union, and less absorption.12e15 Studies have defined use of the muscles in the hand to treat soft tissue and bone defects of the hand and various vascularised bone grafts.16e19 In the hand, Uysal et al.20 studied vascular anatomy of the metacarpal bones and the interosseous muscles to design a split metacarpal musculosseous flap. Vascular anatomy of the interosseous muscles and metatarsal bones, as well as muscle and musculosseous flaps that can be elevated, has not been studied. Dorsal interosseous muscle can be used in the reconstruction of acute or chronic, diabetic or traumatic minor bone and/or skin defects on a reverse or proximal basis, solely or with split metatarsal bones affixed to it. We studied the vascular anatomy of the metatarsal bones and the interosseous muscles to design a split metatarsal musculosseous flap and dorsal interosseous muscle flap.
Materials and methods Twenty-two feet from 11 cadavers that had been embalmed with formalin were studied. The cadavers, seven female and four male, had no known vascular disease and a mean age of 49 years (age range, 42e59 years). The popliteal arteries were dissected at the poplitea, and latex (40 ml) was injected manually under physiological pressure. The latex was allowed to cure overnight at room temperature as described by Reynolds.21 Dissection was done using a dissection microscope (3.5), delineating meticulously the arcuate artery, dorsal metatarsal arteries, and the small branches arising from the metatarsal arteries. The deep plantar arch and its connections with the dorsal system were excluded from the study because they have been studied in detail.22e24
Results The tibialis anterior artery is named the dorsalis pedis artery after it passes under the extensor retinaculum. The dorsalis pedis artery travels underneath the extensor
M.S. Alagoz et al. hallucis longus and curves between the extensor hallucis longus and extensor digitorum longus along the dorsum of the first interspace. Typically, the dorsalis pedis artery has three lateral arterial branches (proximal and distal tarsal arteries; arcuate artery) and two medial branches (medial tarsal arteries). The third lateral branch of the dorsalis pedis, the arcuate artery, takes off at the level of the first tarsal-metatarsal joint and travels laterally over the bases of the second, third, and fourth metatarsals. It gives off the second, third, and fourth dorsal metatarsal arteries before it joins the lateral tarsal artery. After giving off the arcuate artery, the dorsalis pedis artery enters into the proximal first intermetatarsal space, and in the process gives off the first dorsal metatarsal artery, which courses over the first dorsal interosseous muscle. After giving off the plantaris profundus branch at the basis of the first metatarsal bone, the dorsalis pedis artery continues as the first dorsal metatarsal artery. The latter proceeds close to the first metatarsal bone in the first metatarsal space. While proceeding to the distal, it shoots out a branch that individually feeds the lateral head of the first dorsal metatarsal muscle and medial face of the second metatarsus, thereby feeding muscle and bone (Figure 1). Except this branch, the first dorsal metatarsal gives off segmental branches that individually feed the medial heads of the first dorsal metatarsal muscle and first metatarsal bone (Figure 2). At the more distal level following the muscle level, the first metatarsal artery gives off medial and lateral branches that supply blood to the hallux and second digit. The arcuate artery separates from the dorsalis pedis artery in the distal part of the tarsal artery and in the vicinity of cuneiform bone. The first branch of the arcuate artery is the second metatarsal artery. Immediately after branching from the arcuate artery, this artery gives out segmental branches to both faces of the interosseous muscle. In this course, the artery proceeds close to the third metatarsal bone in the second metatarsal space. The concerned artery also gives off periosteal branches to the medial face of the third metatarsal bone. The third metatarsal artery, which is the second branch of the arcuate artery, goes close to the fourth metatarsal artery. It gives out segmental branches to the third interosseous muscle on its course, and periosteal branches to the medial face of the fourth metatarsal bone. The branches of the fourth dorsal metatarsal artery, which is the last branch of the arcuate artery, are similar to those of the third metatarsal artery; the diameter of the artery and its branches narrows in this space. The fourth metatarsal artery moves close to the fifth metatarsal bone and gives off periosteal branches to the medial part of this bone (Figure 3).
Discussion Defects of the foot dorsum, ankle and toes are usually seen after trauma or due to vascular or neuropathic diseases. Recovery of soft tissue defects in these areas, particularly those associated with bone disease, is very difficult.25 In recent diabetic neuropathy wounds and minor defects arising from trauma, the first choice is follow-up with dressing
Vascular anatomy of the foot
1229
Figure 2 The interosseous muscle dissected and removed in part. The asterisk indicates the dorsal metatarsal artery. The arrow indicates the periosteal branches nourishing the bone. Figure 1 Dorsum of the foot with the skin and the extensor tendons removed (schematic). The course of the dorsal metatarsal arteries is not at the midline of the interosseous muscles, but at the first, second, third and fourth dorsal metatarsal arteries, proceeding close to the first, third, fourth and fifth metatarsal bone. The arcuate artery is marked by an asterisk. The arrow indicates the periosteal branches piercing muscles and nourishing bones.
changes and reconstruction with split-thickness skin graft.1,3 Due to the vascular structure of the area, if minor defects are secondary to a neuropathic disease or if bones and tendons are exposed due to trauma, methods of dressing, primary closure, and reconstruction with a graft usually fail and the defect may expand.26 Local random flaps have limited reach and can be unreliable, particularly if the area around the wound has been traumatized or is chronically scarred.27 Local muscle flaps are preferred to free flaps if the defect is small (3e6 cm) and within reach of the local muscle flap.28 Pedicled muscle flaps, the next option on the reconstructive ladder, were first routinely advocated by Ger29 in the late 1960s as a solution for coverage of advanced stasis ulcers, post-traumatic wounds, and diabetic ulcers in the lower extremities. Ger suggested that rotation of well-vascularised muscle to cover soft tissue defects increased wound healing because of improved local blood flow. There are many muscle flaps used locally in the plantar area of the foot, but the only local muscle that is commonly used in the dorsal area is extensor digitorum brevis because
Figure 3 Dorsum of the foot with the skin and extensor tendons removed. The first, second, third and fourth dorsal metatarsal arteries proceed close to the first, third, fourth and fifth metatarsal bone.
1230 its vascular structure is well known and it is readily available.23,30,31 This muscle is commonly used in the treatment of minor defects. Based on the vascular anatomy we described, dorsal interosseous muscles are good alternatives that can be used to repair minor defects that require local muscle flaps. In defects caused by microangiopathy or other vascular failures in diabetic patients, the disease can also involve the vessel that feeds the flap (possibility of foot ischaemia due to interruption of foot collateral circulation). In patients with critical foot ischaemia presenting with a defect suitable for the discussed flap, prior foot revascularisation is essential (needed in about 40% of cases) to salvage the foot. Alternative treatments should be instigated in defects induced in this way (e.g. free transfer, amputation).32 The common characteristic of the dorsal interosseous muscles of the foot is that they are fed via segmental branches originating from the dorsal metatarsal artery passing from their locale. The common feature of these arteries is that they originate from the dorsalis pedis, and that they are connected with the plantar vascular network through two perforators (proximal perforating arteries, distal perforating arteries) originating from the plantar arch. This vascular connection has been studied in detail.22e24 The perforators concerned are located in the proximal and distal parts of each interosseous space. Therefore, in the case of injury to vascular structures resulting from trauma in the dorsal part of the foot or diabetic neuropathy (in isolated neuropathic wounds), these muscles can be easily fed through the perforators coming from the plantar area. Fasciocutaneous flaps based on the first dorsal metatarsal artery of the foot dorsum have been used on proximal and distal bases.33 If defects of the ankle and foot dorsum require a muscle flap, it is suggested in this study that interosseous muscles that can be lifted on a proximal basis can be elevated individually or in combination depending on defect size. The major supply to flaps that are to be elevated on a proximal basis is dorsal metatarsal arteries. In defects in more proximal areas, the dorsalis pedis artery can be incorporated into dissection, and the pedicle elongated. If the dorsalis pedis is known to be injured, the muscle should be fed by perforators coming from the plantar area. For defects in distal areas (proximal parts of toes, web spaces), circulation of the muscle to be elevated should be provided by distal plantar perforators. It was reported in various series that the first dorsal metatarsal artery was not located in 9.4e18% of cases. This flap cannot be elevated from the first metatarsal artery.34e36 Vascularised bone grafts are well recognized; they demonstrate better mechanical strength, early union, and less absorption.14 Peterson et al15 demonstrated feeding of metatarsal heads to use the head parts of the metatarsus as vascular bone grafts. According to this study, the metatarsal heads had two arterial sources, i.e. the dorsal metatarsal arteries (arising from the dorsalis pedis artery) and the plantar metatarsal arteries (branches of the posterior tibial artery). These two vessels typically anastomose at two sites near the metatarsal heads, forming a vascular ring and providing an extensive extraosseous arterial network around the metatarsal heads. Small arterial branches
M.S. Alagoz et al.
Figure 4 Rotational arch of the split metatarsal musculoosseous flap (schematic). p: flap based proximally for defects in the proximal region; d: flap based distally for defects in the distal region.
of this network run distally on the metatarsal cortex to enter the bone of the metatarsal head. In our cadaver dissections, the dorsal metatarsal arteries exhibited an indistinct pattern of segmental periosteal nourishment throughout their course in the dorsal interosseous muscles, and anastomoses with the plantar arteries were via perforators. Preservation of muscle would prevent damage to the dorsal metatarsal artery and to the periosteal branches supplying the first metatarsal bones from the lateral and medial borders, and the other metatarsal bones from the medial border. Preservation of the muscle around the artery, when compared to dissection of the artery as an island flap, facilitates and shortens the duration of flap elevation, as noted in this study. Meticulous dissection of the dorsal metatarsal artery, maintaining a sufficient cuff of soft tissue around the artery, can nourish the split metatarsal bone if the periosteal branches are isolated and preserved, but can prolong flap elevation time. For defects or any disease of the ankle bones, the metatarsal bones can be split at the medial border distally, and a split metatarsal musculoosseous flap, based proximally on the dorsal metatarsal artery, can be done (Figure 4). Distal intermetatarsal anastomoses between the dorsal and plantar vascular networks enables a split metatarsal musculoosseous flap based distally, including the dorsal metatarsal artery for the bony defects of the
Vascular anatomy of the foot
Figure 5 Rotational arch of the split metatarsal musculoosseous flap. p: flap based proximally for defects in the proximal region; d: flap based distally for defects in the distal region.
proximal phalanx (Figure 5). Venous supercharging should be tried using a vein graft if it is suspected that venous failure may develop. Functional loss from these proximally or distally based flaps may cause restriction of abduction of the toes.
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