Can The Medial Plantar Artery Flap Be Beneficial For Diabetic Heel Ulcers?

Author(s): 
Ronald J. Belczyk, DPM, AACFAS, Lee C. Rogers, DPM, and George Andros, MD

The diabetic ulcer, particularly involving the heel, remains a challenge for the foot surgeon. When these ulcers occur in the neuropathic patient with adequate circulation, the medial plantar artery flap can serve as a useful tool for the management of these defects.

   Heel ulcers are notoriously difficult to treat because of their late clinical presentation, which often involves large skin and soft tissue defects, extension to bone and insufficient local tissue for closure. Frequently, simpler treatment options have failed. In this presentation, the wounds have not responded to a trial of offloading or have healed with unstable scars and are now subject to recurrent ulceration due to being on a pressure bearing location.

   Full thickness soft tissue defects in this location can lead to exposure of deep structures including the plantar fascia, Achilles tendon or calcaneus. When left exposed for a period of time, these structures can become desiccated or infected. Since further delay results in worsening of the ulcer, the use of the medial plantar artery flap has become an interesting alternative over the last few years for soft tissue coverage of heel ulcerations.

   Although local flaps — such as the advancement, rotation and transposition flaps comprised of skin and subcutaneous tissue — can promote healing of smaller defects, larger ulcers such as those that occur in the heel are better treated with flaps of vascularized tissue comprised of muscle, subcutaneous tissue and skin. These are the pediculated fasciocutaneous or myocutaneous flaps such as the medial plantar artery flap.

A Closer Look At The Advantages Of The Medial Plantar Artery Flap

As opposed to a local flap, the medial plantar artery flap has an anatomically recognizable arteriovenous system, which permits a greater arc of mobility, a longer length to width ratio and increased flap perfusion. Although there is increased risk to vascularity if the dissection is extensive, there is no need for microvascular anastomosis. The medial plantar artery flap is indicated for ulcers 3 cm or less in diameter around the perimeter of the heel.

   When the ulceration is greater than 3 cm and is located at the central aspect of the heel, then one can use an island medial plantar artery flap.1 This entails raising a flap from a pedicle devoid of skin and typically only consists of nutrient artery and vein. The medial plantar artery flap has increased mobility and can cover the posterior part of the weightbearing heel.2,3

   The vascularity of this flap is based on the medial branch of the plantar arterial system, which arises from the posterior tibial artery and its extension, the common plantar artery. The lateral plantar artery is part of the primary pedal arch, which connects to the dorsal circulation of the foot via the deep plantar artery into the dorsalis pedis artery.

   In contrast, the medial plantar artery is an end artery. The abductor hallucis muscle is associated with this artery and lies on the first metatarsal. One can harvest this muscle as a myocutaneous flap. After constructing this flap, either as a fasciocutaneous or myocutaneous flap, one can adapt it to the treatment of hindfoot defects.

   The use of this flap is part of an overall strategy for the management of complex heel ulcerations that require debridement, eradication of infection and adequate wound bed preparation. Once one has sufficiently prepared the ulceration, then the patient is ready for construction of the medial plantar artery flap.

   However, because of the variability of the flap, one should obtain a detailed angiogram prior to the procedure to confirm adequacy of both the dorsal and plantar circulation. Doing so helps to ensure the foot circulation will not be compromised with mobilization of the medial plantar artery. This commonly requires complex angiographic imaging with multiple views of the foot and selective arterial catheterization. Often, it is useful to supplement angiographic imaging with Doppler studies.

   Contraindications or precautions to performing this procedure include: small ulcerations that one can treat with simpler methods; vascular insufficiency; complicated renal or cardiac issues; non-ambulatory status; severe infection; an unsalvageable foot; trauma to the instep; and a non-adherent patient.

A Comprehensive Guide To Performing The Procedure

The surgeon can perform the procedure with the patient in the supine or prone position. Measure the defect and mark the flap on the non-weightbearing instep area with the maximum length parallel to the medial plantar artery. Intraoperative Doppler assessment can assist with incision placement. Mark the course of the medial plantar artery.

   Plan the length and width of the desired flap in reverse using a cloth pattern over the defect and transposing it to lie over the marked artery. In many instances, it is difficult to include the vessels exactly in the center. Usually, the pattern lies toward the medial margin of the flap. The exposure is with an incision through the skin, subcutaneous tissue and the plantar fascia. The flap does not include the plantar lateral aspect of the foot. Keep the distal extent of the flap 2 cm behind the metatarsal heads.

   Next, it is important to visualize the common plantar artery and the bifurcation of the medial and lateral plantar arteries. The medial plantar neurovascular bundle is located in between the abductor hallucis (ADH) muscle and the flexor digitorum brevis (FDB) muscle.4 Retract the abductor hallucis muscle toward the first metatarsal medially or transect the muscle to permit visualization of the medial plantar artery.

   The surgeon will encounter the neurovascular bundle toward the proximal aspect of the septum. Then identify the division of the common plantar artery and elevate the vascular pedicle with overlying tissue. Incise the distal margin and cut the slips of the plantar aponeurosis. Take care not to injure the common nerve trunk to the toes. Continue the dissection until you emerge from the tarsal tunnel. Proximal dissection of the neurovascular bundle requires the division of the abductor hallucis muscle and vascular branches to the muscle. The use of a bipolar electrocautery is helpful.

   One should preserve perivascular fat surrounding the pedicle. The typical length of the pedicle is about 4 to 5 cm and the arc of rotation is at the sustentaculum tali. If additional length is required, then release the abductor hallucis muscle and the flexor retinaculum. Also, dividing the lateral plantar vessels can also increase the length of the flap although this is not advised since the lateral plantar artery is the dominant supply of the foot.

   One should consider other flap options such as the reverse sural artery flap when needing to cover the Achilles tendon. Incise the lateral margin and the lateral portion of the plantar aponeurosis. The dissection proceeds to the flexor digitorum brevis muscle to include the septum between the flexor digitorum brevis and the abductor hallucis. Divide the proximal attachment of the plantar aponeurosis. One would not typically include muscle since it does not have a significant myocutaneous supply.

   After mobilizing the flap, extend an incision to the ulcer or tunnel beneath the skin. A tunnel is not required or preferred since this places tension on the pedicle. Rotate the flap 90 to 180 degrees. Once the flap is transposed into the defect, secure it with a single layer closure and utilize a suction drain. Close the donor defect with a split thickness skin graft (STSG). The split thickness skin graft will only take if you preserve the peritenon over the fascia. In some cases, one may excise the fascia and place the split thickness skin graft over the underlying intrinsic muscles. Surgeons can also use the split thickness skin graft over the pedicle to prevent compression from primary skin closure.

Additional Considerations With The Medial Plantar Artery Flap

Considerations to incorporate the fascia or muscle are based on the need for a thicker flap, which can be helpful when closing defects on the weightbearing surface. However, there are advantages to leaving the fascia intact such as preserving the function of the plantar fascia. Inclusion of the plantar fascia into the flap may result in swiveling of the reconstructed heel pad. A thick flap may not be ideal for non-weightbearing areas. Excluding the fascia, adding triangles and defatting the flap can result in a thinner flap.5

   Some other pearls for the procedure include delaying the flap and adjunctive use of external fixation. When performing the proximally based medial plantar artery flap, adequate antegrade flow is necessary prior to division. Mobilization of the flap can be delayed in the clinical scenario in which adequate vascularity to the flap is in question. Flap delay interrupts a portion of the blood supply in a preliminary stage prior to tissue transfer. The purpose of delay is to augment the surviving portion of the flap.

   There are two schools of thought regarding the pathophysiology of the delay phenomenon. The first holds that delay subjects tissue to ischemic conditions so it is able to survive with less vascular inflow. The second believes that delay actually increases vascularity by dilating reduced caliber “choke” anastomotic vessels and stimulating additional vascular ingrowths. The use of external fixation permits immobilization, flap and vascular surveillance, access to wound care and offloads both the pedicle and the flap.

   Some potential complications of this procedure include delayed wound healing of the flap, decreased sensation, hyperkeratosis, flap/skin necrosis, venous congestion, donor site complications, infection and the need for additional surgery. Also, the surgeon should exercise caution with routine use of this flap as future midfoot collapse may occur and initiate ulceration through the skin grafted site.

In Summary

Diabetic ulcers involving the heel can be quite challenging. Emerging literature and surgical experience suggest that the medial plantar artery flap can provide distinct advantages and serve as a viable option for covering diabetic heel defects.

   Dr. Belczyk is a Fellow of the American College of Foot and Ankle Surgeons, and is board qualified in both foot surgery and reconstructive rearfoot/ankle surgery by the American Board of Podiatric Surgery. He is a consultant physician at the Amputation Prevention Center at Valley Presbyterian Hospital in Van Nuys, Calif.

   Dr. Rogers is the Associate Medical Director of the Amputation Prevention Center at Valley Presbyterian Hospital in Los Angeles. He is the Chair of the Foot Care Council for the American Diabetes Association. Dr. Rogers has more than 50 publications in press or in print on diabetic foot disorders including several book chapters.

   Dr. Andros is the Medical Director of the Amputation Prevention Center at Valley Presbyterian Hospital in Los Angeles. He is a board-certified vascular surgeon with over 40 years experience and is a renowned specialist in the revascularization of diabetic limbs. Dr. Andros serves as the Co-Director of the Diabetic Foot Global Conference and is a member of the American Diabetes Association and the Society for Vascular Surgery.

References

1. Koshima I, Narushima M, Mihara M, et al. Island medial plantar artery perforator flap for reconstruction of plantar defects. Ann Plast Surg. 2007; 59(5):558-562.
2. Baker GL, Newton ED, Franklin JD. Fasciocutaneous island flap based on the medial plantar artery: clinical applications for leg, ankle, and forefoot. Plast Reconstr Surg. 1990; 85(1):47-58; discussion 59-60.
3. Skef Z, Ecker HA, Jr., Graham WP, 3rd. Heel coverage by a plantar myocutaneous island pedicle flap. J Trauma. 1983; 23(6):466-472.
4. Macchi V, Tiengo C, Porzionato A, et al. Correlation between the course of the medial plantar artery and the morphology of the abductor hallucis muscle. Clin Anat. 2005; 18(8):580-588.
5. Ulkur E, Acikel C, Karagoz H, Celikoz B. Refinements of medial plantar flap used for covering nonweightbearing ankle and posterior heel defects requiring thin flaps. Ann Plast Surg. 2005; 55(4):371-373.

Additional References

6. Mourougayan V. Medial plantar artery (instep flap) flap. Ann Plast Surg. 2006; 56(2):160-163.
7. Schwarz RJ, Negrini JF. Medial plantar artery island flap for heel reconstruction. Ann Plast Surg. 2006; 57(6):658-661.
8. Schwarz R. Reverse medial plantar artery flap. Lepr Rev. 2006; 77(1):69-75.

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