MANAGEMENT AND THERAPY OF SICKLE CELL DISEASE

NIH Publication No. 95-2117, Revised December 1995 (Third Edition) National Institutes of Health, National Heart, Lung, and Blood Institute

Chapter 16—Leg Ulcers

Between 10 and 20 percent of patients with SS disease develop debilitating leg ulcers. The ulcers usually appear between the ages of 10 and 50 years and are seen more frequently in males than in females. Leg ulcers are rare in individuals with Hb SC disease and S beta thal as well as in patients younger than age 10 years.

PATHOPHYSIOLOGY

Sickle cell ulcers usually begin as small, elevated, crusting sores on the lower third of the leg, above the ankle and over and around the medial or lateral malleolus. Occasionally, ulcers are seen over the tibial area or the dorsum of the foot. They can be single or multiple. Some heal rapidly, others persist for years, and others heal only to recur in the area of scarred tissue. In the early phase, the neighboring skin appears to be healthy, but as the ulcer persists, the surrounding skin shows hyperpigmentation with a loss of subcutaneous fat and hair follicles. These ulcers can be very painful and often are accompanied by reactive cellulitis and regional (inguinal) adenitis. Warmer temperatures, lower steady-state hemoglobin, and lower fetal hemoglobin appear to enhance ulcer formation. Once an ulcer forms, recurrence is common.

DIAGNOSIS AND LABORATORY TESTS

A general physical examination should search for other causes of leg ulcers such as varicose veins, diabetes mellitus, and collagen vascular disease. Before therapy, a radiograph of the leg is needed to establish the presence or absence of chronic changes in the underlying bone. Periosteal thickening below the ulcer is not uncommon, but underlying osteomyelitis is rare. Quantitative cultures can be taken from the base of the ulcer with the use of a dermal punch biopsy. The aim of treatment is to reduce the colony count by local cleansing or topical antibiotics.

SUGGESTED TREATMENT

Leg ulcers are very difficult to treat. There are many treatment modalities described. None of them has been proved to give consistently beneficial results. Active patient participation in the care of leg ulcers is essential because of the ulcers' chronicity. Nursing staff members can be particularly helpful in assisting patients. Patients should be encouraged to wash their legs and feet daily and to wear proper shoes and support stockings. Leg ulcer management is difficult and can be frustrating to both patient and medical and nursing staff members because therapy is often unsatisfactory. Patients should be encouraged to promptly report to the physician when they develop an ulcer. Ulcers less than 2-3 cm have a greater chance of healing. Once ulcers are persistent for more than 6 months, they become chronic, and treatment is difficult.

Ulcer Care

Wash the leg with mild soap or diluted solutions of liquid household bleach (1 tablespoon in 1 gallon of water). Then gently use gauze or a cotton swab to remove slough from the ulcer base

* Wet-to-dry dressings will help debride necrotic tissue to achieve a clean(er) base. The dressing is applied after soaking it in saline (or diluted household vinegar if a Pseudomonas infection is suspected) and allowed to dry on the ulcer. It is then removed (without moistening if possible) to debride the ulcer, and the process is repeated at intervals of 3 to 4 hours. Rest and elevation of the leg are desirable.

* Alternately, the patient can be instructed to have complete bedrest for 7 to 10 days. During the day, wet saline dressings are applied frequently. At night, dry nonstick adhesive dressing is applied and the leg is wrapped with Kerlix dressing

. * Apply cocoa butter or oil over the skin around the ulcer and massage.

* Apply topical antibiotics or antibacterial agents to help reduce local infections and to enhance the development of granulation tissue.

Once granulation tissue appears, saline dressings can be used and healing slowly ensues. Unna's Boot (Zinc Oxide-Impregnated Bandage) If healing fails to occur and the ulcer is not acutely infected, 2 to 3 weeks of Unna's boot application is recommended. The zinc oxide-impregnated bandage should be applied after cleansing (as previously described) to cover the ankle, the ulcer area, and up to about 3 inches below the knee joint. The boot should be left in place for 1 week. It provides support, protects the ulcer from trauma, and contributes to effective debridement on removal. Three or four applications may be required before there is definite evidence of healing, at which time the use of saline dressings can be continued. Antibiotics or other ointments should not be applied under the Unna's boot bandage because they may react with zinc to produce an allergic reaction.

RGD Peptide Matrix (Argidene Gel (trademark)) A topical viscous gel can enhance healing, providing the extracellular matrix for physical support, the macromolecular scaffold to facilitate the migration of fibroblasts, and endothelial cells and keratinocytes to the wound sites. The gel is applied to cover the wound once a week, and an Unna boot is applied. The procedure is repeated until healing begins.

Transfusions

Blood transfusions can be used when the ulcer does not heal or it progresses with persistent hyperpigmentation and induration of the surrounding skin. Transfusions should be given to raise the hemoglobin to at least 10 g/dL and to reduce Hb S to less than 30 percent. If the ulcer does not heal after 6 months, transfusions should be discontinued. If healing does occur, transfusions should be gradually discontinued.

Skin Grafts

Skin grafts may be tried for nonhealing recalcitrant leg ulcers and for the patient who does not comply with prolonged medical management. Before plastic surgery, it is necessary to reduce the colony count of bacteria in the ulcer base to less than 10(5)/g of tissue by both debridement and the use of local antibiotics. The patient should be hospitalized and prepared for anesthesia with transfusions (see Chapter 10, Transfusion). Skin grafting can be performed under general or spinal anesthesia. A split thickness graft from the thigh area is recommended. The leg should be immobilized. The patient may be hospitalized for 1 to 2 weeks following surgery. Free Flaps (Free Tissue Transfer) Free flaps can be used for patients with chronic leg ulcers that persist for several years. With the advent of microsurgery, free flap grafts may become the procedure of choice for providing sufficient soft tissue for coverage of large recalcitrant ulcers. Flaps include the use of latissimus dorsi muscle, temporoparietal fascia, and split omentum. These procedures are a method of primary treatment.

Patients need meticulous preoperative preparation, aggressive blood transfusion, and continued transfusion in the postoperative period of 3 to 4 months to maintain Hb S at less than 30 percent. In the postoperative period, the leg should be protected from external trauma and edema. Leg elevation, bedrest, and the use of elastic stockings are encouraged. The patient should protect the free flap area with proper shoes such as soft boots to avoid scratching the area. The area around the flap should be well lubricated with baby oil and massaged at least once a day.

CONCLUSIONS

If the patient is unwilling to wait the long periods required for the trials of medical treatment, skin grafting may be the procedure of choice for chronic ulcers. If a breakdown of the graft occurs, a repeat procedure is encouraged. When ulcers heal, the scarred tissue is easily injured. Foot exercise and elevation of the foot are important to improve circulation. Continued cooperation among the patient, the surgeon, and the primary physician is necessary for successful results.

BIBLIOGRAPHY

Hall MG. Progress in the management of leg ulcers in sickle cell disease. In: Scott R (ed). Advances in the pathophysiology, diagnosis, and treatment of sickle cell disease. New York: Alan R. Liss, Inc., 1982;83-9.

Hallbook T, Lanner E. Serum-zinc and healing of venous leg ulcers. Lancet 1972;2:780-2. Koshy M, Entsuah R, Koranda A, et al. Leg ulcers in patients with sickle cell disease. Blood 1989;74:1403.

Thompson N, Ell PJ. Dermal overgrafting in the treatment of venous stasis ulcers. Plast Reconstr Surg 1974;54:290-9.

Weinzweig N, Schuler J, Marschall M, et al. Lower limb salvage by microvascular free tissue transfer in patients with homozygous sickle cell disease. Plast Reconstr Surg, in press.

Wethers D, Ramirez G, Koshy M, et al. Accelerated healing of chronic sickle cell leg ulcers treated with RGD peptide matrix. Blood 1994;84(Nov 6):1775-9.

Wolfort FG, Krizek TJ. Skin ulceration in sickle cell anemia. Plast Reconstr Surg 1969;43:71-7.

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