Plantar Skin Flaps On Diabetic Ulcers: Are They Worth It?
Yes, the authors say skin flaps can be a viable option if conservative wound care fails. They emphasize that flaps can provide a unique match to the soft tissue properties of weightbearing areas and facilitate healing in wounds with exposed bone and tendon.
By Gary P. Jolly, DPM, and Thomas Zgonis, DPM
Historically, the treatment of chronic foot wounds has centered around aggressive debridement, pressure reduction and, lately, the application of wound healing accelerators such as various growth factors. More recently, the use of reconstructive procedures has been gaining support among reconstructive foot and ankle surgeons as an alternative to traditional offloading endeavors in this subset of patients since these reconstructive procedures seem to hasten the process of wound closure.
Does the use of both random and pedicle skin flaps offer any advantages over conservative wound management? The answer is somewhat ambiguous.
When it comes to wounds in nonweightbearing areas such as the arch or the side of the foot, one may allow these to close by secondary intention without complication. Similarly, partial thickness wounds on the plantar surface of the foot may also be allowed to close by secondary intention. However, when dealing with a wound on a weightbearing area that penetrates to the fascia or beyond, it is much less likely to close by secondary intention and yield a stable and durable envelope because of the physical properties of the resulting scar.
Taking A Closer Look At The
Soft Tissue Properties Of The Sole
Several flaps have been described as alternatives to healing by secondary intention. These flaps can be raised on the foot and leg, and used to repair defects on the weightbearing and nonweightbearing surfaces of the foot. The advantage of these flaps over healing by secondary intention is that their tissue properties closely resemble those of the lost tissue, and they will move harmonically with the surrounding soft tissue during weightbearing.
The weightbearing areas of the foot are covered with a soft tissue envelope that is unique in its design and allows for the resolution of shear as well as axial loads. The glabrous skin of the sole is significantly thicker than the skin that covers the rest of the body. Given the sole’s thicker stratum corneum, penetrating injuries are largely avoided. Attaching the dermis of this area of skin to the fascial layer are a series of stout bands called the mooring ligaments. These mooring ligaments resist shear and prevent avulsion of the weightbearing skin during periods of activity. Located between these ligaments are fat bodies that are arranged in columns. These fat bodies provide a hydrostatic cushion and aid in shock absorption during foot strike. The skin, mooring ligaments and fat bodies form a functional unit with remarkably unique properties. Therefore, their loss requires replacement with tissue that has similar properties.1
Unfortunately, when wounds in this area close by secondary intention, the resultant scar is thick, inelastic and unable to move harmonically with the surrounding soft tissue. This dramatic difference in the elasticity and plasticity between the scar and the surrounding tissue results in the production of marginal strain during weightbearing and likely leads to microtears at the edge of the scar. Since the scar is immovable, it is subjected to increased friction during weightbearing, and the absence of sweat glands in scar tissue increases that area’s coefficient of friction.
When full thickness defects of the weightbearing areas of the foot are closed primarily with either local or pedicle flaps, the replacement tissue is composed of skin, mooring ligaments and columnar fat bodies. As a result, the replacement tissue is able to move in concert with the surrounding tissue. An additional advantage to flaps is that they retain functional sweat glands, which help to lubricate the skin and reduce friction.