The Clinical Application of Plantar Marginal Septum Cutaneous Island Flap
Wen-Cheng Lin, Dun-hern Shiao
Soft tissue defects complicated with exposure of tendons, bones, ligaments and joints of the forefoot usually require flap coverage to achieve wound closure and functional preservation. The plantar marginal septum cutaneous island flap (PMSC) was first published by Dr. Bertelli, et al in 1997.1 It served an alternative of the conventional methods to provide coverage of the forefoot. Before the development of this flap, the forefoot coverage methods remained a formidable challenge .The PMSC flap is a reversed-flow flap based on the superficial branch of the medial division of the medial plantar artery. The flap has a distal anastomosis with the lateral plantar artery, first dorsal metatarsal artery (FDMA) and lateral branch of the medial plantar artery at the level over the neck of the first metatarsal-phalangeal area. So it is a reliable flap .We have successfully used this flap to reconstruct complicated forefoot wounds in 5 cases. 4 of the harvested flaps totally survived and one was partially survived and healed by skin graft.
Masquelet AC et al. had described the vascularization of the inner border of the foot in 1988. *2 They described the anatomy of the cutaneous branches of the medial plantar artery over navicular tuberosity and according to this they designed the medialis pedis flap for heel and ankle coverage in 1990. 3 Till 1997, Jamye Augusto Bertelli, et al designed the plantar marginal septum cutaneous island flap (PMSC flap) after 25 fresh human cadaver dissections and eight successful clinical cases. *1 The advantages of this flap include (1). reliable vascular anatomy (2). wide rotational arc (3). easily dissection (4). avoid to sacrifice a main artery of the foot. (5) might gain sensitivity by anastomosis with peripheral nerve.
METHODS AND MATERIALS
Anatomy
A constant and reliable cutaneous artery supplies the plantar marginal cutaneous island flap, which arise from the medial plantar artery (Fig. 2). The medial plantar artery flow between the abduction hallucis and the flexor digitorum muscles after dividing from the posterior tibia artery. At the level of 27mm proximal to the navicular-cuneiform line, the medial plantar artery divided into lateral and medial branches (fig. 1). Then the medial branches divided into a deep branch and a superficial branch at the talus-navicular joint level. The superficial branch runs from plantar to the dorsum obliquely, then runs parallel to the superior borders of the navicular and first metatarsal bones. After goes to the peripheral area of the first metatarsal, it distally anastomoses with lateral plantar artery, first dorsal metatarsal artery (FDMA) and lateral branch of the medial plantar artery
According to the descriptions of Dr. Bertelli, there are two major cutaneous artery branches supplying the PMSC flap from the medial plantar artery system. The first one usually arise from the median plantar artery before dividing into medial and lateral branches, it closes to the level of talus-navicular line. And then anastomoses to the branches of the medial maleous artery. The second one arises from the superficial branch of the medial division of the medial plantar artery at the navicular-cuneiform line, close to the insertion of the posterior tibia tendon into the tuberosity of the navicular bone. Besides the two major cutaneous branches, there are four to six small cutaneous branches, along the first metatarsal bone, arising from superficial branch of the medial division of the medial plantar artery. (Fig. 1)
Surgical technique
There are three landmark identified for operation. (1) navicular tuberosity: insertion of the posterior tibia tendon , close to the second cutaneous branch of the PMSC flap , (2) 1cm proximal to first metatarsal bone : show the pivot point of the island flap (3) mark a straight line from (1) to (2) , it show the superficial branches of the medial division of the medial plantar artery (fig. 2 )
Preoperative evaluation of the integrity of the vessels includes the dorsalis pedis artery, FDMA, posterior tibia artery, medial plantar artery, and superficial branch of the medial division of the medial plantar artery.
We use Doppler probe to confirm the alignment of the major artery and avoid the original vessel injury. After general or epidural anesthesia applies, adequate debridement should be performed and then operation turn to locate the three landmarks. According to the size of the skin defect of the wound, the proposed flap size and shape are designed. Its distal limit point is the landmark (1): navicular tuberosity. The axis of the flap is located at the junction between the dorsal and the plantar skin. We harvest the flap by incising the skin from the landmark (1) to landmark (2) under tourniquet usage. The incised skin is undermined bilaterally just above the adipofascial layer, which is 0.5 cm dorsal and plantar to the landmark (3). The required flap is incised through the plantar margin skin, the abduct hallucis muscle is firstly exposured. The fascia of the abduct hallucis muscle is incised and retracted dorsally to expose the vascular pedicle of t
he superficial branch, we ligate the proximal pedicle now or later. The deep fascia, including cutaneous branches of the superficial branch, just beneath the flap must be elevated firmly attaches to the flap. The dissection in depth is performed closed to the navicular tuberosity and includes the deep fascia. After dorsal flap margin skin incising, the flap is progressively raised and retracted from plantar to dorsal, and from proximal to the pivot point. Be careful to dissect the pivot point area, avoid to injury the distal base, which anastomoses with the lateral plantar artery, FDMA and lateral branch of the medial plantar artery. The donor site is covered by skin graft. Sometimes, a small skin graft is necessary for the bulking pivot point.
Case Reports
From Sep.1997 to Aug. 1998 5 patients of forefoot skin defects were reconstructed with this flap and covered with spit thickness skin graft. 4 of them had a total survival of flaps and 1had partial necrosis of flap and healed secondarily. They are all male, and age ranged from 21year-old to 45 year-old with an average at 33. 3 of them were burn wounds and one was crushing injury, the last one was a diabetic patient with a chronic wound over 1st metatarsal head. The flap size ranged from 6 cm2 to 15 cm2 with an average at 9. Follow up time from 6 months to 15 months with an average at 11 months. Most of the flaps survived well, and the poor result appeared at the diabetic patient. Which flap survived poor, most of skin necrosis but underline tissue was well and the wound healed secondarily. (Table 1)(Fig 3)
Discussion
To restore form and function of the complicated forefoot wound remain great challenge to plastic surgeons. Some authors has ever provided several solutions of the forefoot reconstruction, but the disadvantages remained at these solutions .Toe fillet flap is an easy and safe procedure offering a well vascularized, innervated soft tissue to cover distal foot area. *4 However, toes sacrifice is unavoidable. The reverse FDMA flaps and reverse dorsalis pedis flap possess the disadvantages of the donor site morbidity and vascular variation. *5-6 Distally based extensor digitorum brevis muscle flap must sacrifice the muscle belly and bulking rotational arc, which limit it’s effect. *7 The Y-V vessel lengthening of the reverse medial plantar flap, distally based on the lateral plantar artery, was described by D. Martin et. al in 1994.This flap can cover the any area of the foot because the wildly arc of rotation *8 ( Martin D, Legaillard P, Bakhach). But it must sacrifice the posterior tibia artery at the bifurcation of the medial and lateral plantar arteries . Besides above , The V-Y plantar flap *9, cross-leg and free flap are the other methods for forefoot reconstruction .
Recently , the Vacuum-Assisted Closure (V.A.C.) **, a new device developed via the use of negative pressure to promote the healing of the tissue defect , may effect to forefoot complicated wound . But it is cost .
The first clinical applications of the PMSC flap to cover the forefoot skin defect are conducted Jayme Augusto Bertelli et al. al. in 1997 . This flap is distally based on the reverse arterial inflow from the superficial branch of the medial division of the medial plantar artery via the distal communicating arterial net , including the FDMA , the medial plantar artery and the lateral division of the medial plantar artery .It has the advantages of predictable vessel pedicle , widely rotational arc , easily dissection , and no sacrifice of a main artery of the foot .In addition , the sensitivity of the flap can be preserved by anastomosis with a branch of the saphenous nerve , which into the flap from the navicular tuberosity , with the peripheral nerve such as branches of the plantar nerve or the deep peroneal nerve . We feel the PMSC flap is an easy and safe procedure to manage the complicated forefoot wound . It preserve a reliable method , which is unnecessary microsurgery and without sacrificing main trunk artery .
References
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8.Grabb;s Encyclopedia of the flaps 1848-1850
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12. Morykwas MJ; Argenta LC; Shelton-Brown EI et al. Vacuum-assisted closure: a new method for wound control and treatment:animal studies and basic foundation. Ann Plast Surg 1997;38(6):553-62 .