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