A Guide To Closure Techniques For Open Wounds
The soft tissue envelope of the foot resists severe mechanical stresses on a daily basis and protects the underlying structures from injury. However, an injury to the foot or a chronic ulcer can cause a defect in the soft tissues and presents a daunting challenge for the foot and ankle specialist. When the defect is on the sole of the foot, the injury may be disastrous. Historically, soft tissue lesions have been treated conservatively via various techniques of offloading, local wound care, molded shoes, inserts and orthoses. While some wounds lend themselves well to non-operative treatment, there are many wounds that either refuse to close or close with a resultant scar that is so unstable that recurrence of the ulcer is all but assured. Since the 1980s, there has been an emerging body of literature reporting on outcomes from reconstruction of the soft tissues of the foot. Historically, these procedures were the domain of the plastic surgeon, but as the training of foot and ankle surgeons has increased in duration and scope, these procedures are now being taught in a podiatric surgical fellowship. The ability of a surgeon to close a wound, which has been open for months and sometimes years, gives new hope to many patients and their families, whose lives revolve around the long-term treatment of these wounds. The majority of foot and ankle wounds are seen in the diabetic population, and many of the comorbidities associated with diabetes (such as peripheral vascular disease, Charcot neuroarthropathy and the loss of protective threshold) make it quite challenging to close wounds in these individuals. Since many of the ulcers are linked to acquired deformities associated with Charcot neuroarthropathy, one must integrate soft tissue reconstruction and the management of Charcot deformities into any treatment plan. Competency in using multiplanar external fixators is essential in treating these complex patients. How Do Skin Grafts Facilitate Closure? Soft tissue reconstruction of the foot and ankle includes the use of skin grafts, local flaps and pedicle flaps. The use of free flaps, once essential in the treatment of defects of the hindfoot and ankle, has waned with the advent of reverse flow neurocutaneous flaps harvested from the lower leg. Let’s begin by taking a closer look at skin grafts. Skin grafting provides fast and easy coverage of wounds. Split thickness skin grafts are harvested tangentially and include the epidermis and, depending on the thickness, elements of the dermis. You would use a power instrument called a dermatome to harvest the graft. Postoperatively, you would cover the donor site with Vaseline impregnated gauze that is allowed to slough as epithelialization progresses beneath it. The graft’s survival is dependent on its rapid revascularization. Inosculation of skin grafts by vascular buds usually begins by the fifth postoperative day and proceeds until venous drainage of the graft has been established (usually by the second week). During the first 48 hours postoperatively, fibrin is laid down between the graft and the bed. Doing so helps anchor the graft to the donor site. The axiom is thin split thickness grafts “take” better than full thickness grafts because the thinness of the graft allows for easier imbibition and a more rapid inosculation. To prevent slough, you must ensure close adherence of the skin graft to the recipient site and protection from shear.1-3 When it comes to the diabetic foot, split thickness skin grafts are used frequently in nonweightbearing areas or to cover donor sites of locally raised flaps. However, one should avoid using skin grafts in areas that are subjected to significant stress. Also keep in mind that a split thickness skin graft will not prevent contraction of a wound. Full thickness skin grafts are harvested by excision and include the epidermis and dermis. Using full thickness grafts will prevent the wound from undergoing further contraction. Full thickness skin grafts are usually harvested from areas where there is a skin redundancy. These areas include the flexor surfaces of joints, such as the wrist, the sinus tarsi or the inguinal fold. One may also harvest full thickness skin grafts from the lateral thigh. When you take a full thickness skin graft, you should close the donor site primarily. Skin grafts will fail if there is active bleeding or transudation below the graft.