by S. William Levy, M.D.

Lower extremity amputees are frequently troubled by skin problems. Amputation at any level can be attended by distinct problems of functional loss, fitting and alignment of a prosthesis, and medical or skin disorders secondary to the use of an artificial limb.

Every amputee who wears a prosthesis experiences skin adaptation and is at risk for problems incident to the close-fitting interface. Skin is not physiologically designed to endure the enclosed environment and variety of pressures inherent in the wearing of an artificial limb.

The skin of the residual limb, for an amputee who wears a prosthesis, is subject to many abuses. Most leg prostheses have a snug-fitting socket in which air cannot circulate easily and which may trap perspiration. The socket has to provide for weight bearing and uneven loading may cause stress or chafing on localized areas of the stump skin. For example, the skin may undergo intermittent stretching from rubbing against the socket edge and the interior surface of the socket (stump socks are worn with some prostheses to reduce this friction). In addition, the skin of the stump is vulnerable to the possible irritant or allergenic action of the materials used to manufacture the prosthetic socket.

The state of the stump skin is of utmost importance to an amputee's ability to use a prosthesis. Some amputees suffer from lifelong skin complaints while others have little or no difficulty. If the normal skin condition cannot be maintained despite daily wear and tear, the prosthesis cannot be worn, no matter how accurate the fit of the socket. Hence, the amputee is not only physically incapacitated, but also mentally, socially, and economically handicapped. Maintaining stump hygiene is of utmost importance in preventing infectious or traumatic skin problems in the future of the amputee.

The term edema comes from the Greek word for swelling. It describes the abnormal condition in which an excessive amount of fluid has collected in the soft tissues in some part of the body. Usually, the supply and removal of fluid in the body are well balanced; however, amputation of a lower extremity greatly disturbs the normal pattern of blood and lymph channels and the relationship of pressures, both inside the vessels and in the surrounding tissues of the stump. Postoperative edema occurs in most cases and gradually disappears over many months following amputation.

When an amputee first begins to wear a suction-socket prosthesis, his or her skin must adapt to the entirely new environment. The amputee can expect edema; redness or hyperemia; some residual pigmentation of the skin resulting from prior capillary hemorrhage; and occasionally, some crusting of the skin of the terminal, or distal portion of the stump. These changes are usually innocuous and do not require therapy. Some abnormal swelling can be partially prevented by gradual compression of the stump tissues with an elastic bandage, or “shrinker” sock, either before the use of the prosthesis or during times – at night or at home – when the artificial limb is not being used.

Some areas can even erode, ulcerate, or become gangrenous because of impaired blood supply. The edema can embarrass the lymphatic and vascular channels and prevent necessary tissue nutrition. Treatment will then include elimination of all mechanical factors contributing to the edema, such as tightness in the socket, poor fit and poor alignment. Treatment should always be directed toward equalization of pressures for better support of the distal stump tissue. Faulty prosthetic alignment or weight gain can become the cause for skin breakdown.

Interrelated with edema is a wart-like condition of the skin of the entire distal portion of the stump, call verrucous hyperplasia, which has been seen in numerous instances.

This process appears to be secondary to an underlying vascular disorder, poor prosthetic fit and alignment, and in some instances, even bacterial infection with ulceration. This hyperplasia is seen not only in above- and below-knee amputees, but is also recognized in amputations of the fingers and toes. Some practitioners treat this condition with topical preparations and other forms of therapy, but without effect. Systemic antibiotics and other oral preparations have been of only temporary benefit. Through trial and error, we have found that external compression is the best method of treatment, in combination with adequate control of any bacterial infection or ulceration.

Using plastics or foam-rubber cushions, a temporary buildup of the distal socket wall can be achieved for better support of the residual limb. Once adequate support of the stump end is provided, the skin condition gradually disappears and does not recur. The greater the compression on the distal stump skin, the more immediate and lasting the improvement. In many instances, the socket must be redesigned to allow for sufficient backpressure on the tissues at the end of the stump. Malignant degeneration can occur and has been seen in three instances by the author. Early diagnosis and treatment is therefore of utmost importance. In some amputees, the sockets are redesigned for total contact.

Contact dermatitis and eczematization of the amputation stump skin have been seen in a small number of patients. In both above- and below-knee amputees, the disorder is usually caused by contact with chemical substances that either act as a primary irritant or trigger a specific allergic reaction.

Varnishes, lacquers, various plastics, and resins may be used in finishing the socket of the leg prosthesis. We have learned that such materials are capable of producing primary irritation or true allergic sensitization. We have also had to analyze the different conditions of heat, humidity, and friction within the socket, since these can be related to the intensity of the reaction. Epoxy resins are frequently used to improve the appearance of a socket and to render it impervious to external agents. These resins, if not completely cured in their manufacture, may trigger a primary-irritant dermatitis, as well as a specific allergic reaction, with intense itching and oozing or redness of the skin. Some amputees have various pads, such as foam-rubber cushions, on the bottoms of their sockets and these can be potential irritants. A number of the cements and volatile substances (such as T-161 cement) used to repair prostheses or sockets are also capable of producing an irritant reaction or allergic sensitization. Any of these cements can produce a dermatitis of the stump skin after weeks, months, or even years of continued use. In some instances, we have found only by a carefully taken history that beginning the use of a new cream, lubricant, or cleansing agent coincided with the onset of the itching or dermatitis. Patch tests can be informative in pinpointing specific substances as causes of dermatitis. In those instances where the irritant is not easily identified and patch tests have been inconclusive, temporary symptomatic therapy may alleviate the condition. Cool or cold compresses, bland anti-itch lotions, and the topical use of corticosteriod preparations have been most beneficial in my experience.

Eczematization of the stump skin has been in a number of instances as a persistent, weeping, itching area of dermatitis over the distal portion of the stump. The lesions are at times dry and scaly while at other times they become moist without apparent reason. Edema, even of short duration, is capable of producing such eczematization distally, as is seen in a static eczema of the ankles or legs. The condition often fluctuates over a period of weeks or months and may be a source of anxiety to the amputee. In some patients, we have been able to elicit a significant history of recurrent allergic or atopic eczema; sometimes-active eczema lesions can be identified on other portions of the body. For other amputees, the eczema has been secondary to poor fit or alignment of the prosthesis, or to edema and congestion of the terminal portion of the stump, so alleviating these problems can clear the condition. Symptomatic treatment with mid-range topical steroid preparations can be effective, but the condition frequently recurs unless its cause is eliminated.

Bacterial infections are usually worse in the summer when the weather means increased warmth and moisture from perspiration, which, in turn, promotes maceration of the skin within the socket. This favors invasion of the hair follicles by bacteria, and folliculitis, furuncles, or boils may develop. This condition is frequently aggravated by the use of a stump sock or socket. Ordinarily, the process is not serious, but sometimes it can progress to the formation of large deep boils, spreading cellulitus, or an eczematous weeping and crusted superficial pyoderma, making it impossible to use the artificial limb. These can also be the result of poor hygiene of the stump or of the socket itself.

The stump skin has also been found to harbor a bacterial flora more abundant than that found in the skin of the normal, or contra lateral, leg. Hence, in a number of patients, a chronic recurrent folliculitis was virtually cured by having the amputee adhere to a routine antiseptic hygiene program. Treatment can include wet dressings, incision and drainage of abscesses after localization, oral or parenteral use of antibacterial or antibiotic substances, or the local application of bactericides, such as topical Polysporin, Erythromycin, Mupirocin, or topical Clindamycin.

Superficial fungal infections usually appear only on the part of the stump or thigh enclosed by the socket. These infections of the stump skin may be difficult to eradicate completely because of the moisture, warmth, and maceration within the prosthetic socket. The diagnosis can be confirmed either by culture or by microscopic demonstration of the fungal filaments within scales or blisters removed from a given lesion. Therapy includes application of fungistatic or fungicidal creams and powders for an extended period. Oral antifungal agents may be beneficial in treating recurrent fungal infections that have not responded to topical therapy.

Intertriginous dermatitis is an inflammation or irritation of those skin surfaces that are in constant apposition and between which there is hypersecretion and retention of sweat. This usually occurs in the inguinal or crural areas, but on occasion it also occurs in the folds at the end of the stump where two surfaces of the skin rub each other and where the protective layer of keratin is removed by friction. It can result in thickened, lichenified, or pigmented skin; even painful fissures and secondary infection with eczematization can be found. Hygienic measures to cleanse the opposing folds and the use of drying powders or lotions are beneficial. In some instances, only refitting and realigning the prosthesis can correct this.

Cysts

In association with the wearing of an artificial limb, continued rubbing and shearing action are capable of producing traumatic epidermoid cysts in the skin of the residual limb. These usually occur in above knee amputees at the edges of areas covered by the prosthesis, but have also been seen in other areas and in below knee amputees. Under most circumstances, the cysts do not appear until a patient has worn the prosthesis for months or even years. Some individuals are more prone to these, especially those who have had acne or have active acne lesions at the time.
Characteristically, the cysts start as small follicular keratin plugs that develop in the skin of the inguinal fold, along the upper edge of the prosthesis, and in the adductor area of the thigh in the above knee amputee where the rubbing and pressure are greatest. Similar small plugs may appear over the inferior portion of the buttock where the posterior brim, or ischial seat, of the prosthesis rubs. Some of the plugs may become deeply implanted and develop into cysts.

The lesions may be tiny in the early phase but may become quite large, especially if they are inflamed or infected. They are seen as round or oval swellings deep within the skin; with slow enlargement, they become sensitive to the touch. The skin may erode or ulcerate over the top of the swelling. If irritation is allowed to continue from the rub of the prosthesis, the nodular swellings may suddenly burst and discharge a bloody fluid or even pus. The discharge may open a sinus, become chronic, and hence, make it impossible for the patient to use the prosthesis. Scars are frequently seen after the cysts have healed and the inflammatory process has subsided. Intercommunicating sinuses can even develop between lesions. Similar lesions have been described on the hands and fingers after trauma, as well as in other rub areas. The surface keratin and the opidermis become implanted, a keratin plug forms, and its underlying skin is displaced into the deeper level of the tissue. They can remain quiet for a long period, or, with secondary bacterial infection, can become abscessed and produce the characteristic clinical picture with pain, drainage, and inflammation.

Either surgical incision and drainage or excision of the chronic, isolated, uninfected cyst may give temporary relief, but there is no completely satisfactory method of treatment. In the acutely infected phase, hot compresses and antibiotics are indicated. As the process localizes, then incision and drainage may be beneficial for a short time. The chronic problem can often be improved or successfully eliminated by proper fit and alignment of the prosthesis or by use of a gel liner or prosthetic sock. Trial and error may be required to find the most comfortable mix of prosthetic materials for a particular patient. All the therapeutic measures tried so far, including surgical incision and drainage, excision and grafting, topical therapy, and oral and topical antifungal therapy, have been only palliative. To reduce the detrimental effects of shear and pressure, we have found the most successful measures to be the use of socket liners and multiple socks, such as the Daw sheath combination or the Alpha liner, among other sheaths and gel liners that are appropriate. Improvement in prosthetic fit, with its resulting reduction of shearing forces, is the most promising approach to the problem.

Tumors and ulcers

Tumors of the stump skin can be benign or malignant. We have seen simple benign cutaneous tags and papillomas and have treated a number of different cutaneous horns on the stump skin. Chronic ulcers of the stump are frequent and may result from bacterial infection. Or they may result from poor cutaneous nutrition secondary to an underlying vascular disorder or localized pressures and trauma from a poorly fitting prosthesis. Malignant tumors can develop within old stump ulcerations; thus, every effort should be made to treat the ulceration before it becomes chronic. Practitioners must look for the cause of the ulceration in almost every instance. With repeated infection and ulceration of the skin, the amputation scar may adhere to the underlying tissues, which invites even further erosion and ulceration.

People with diabetes have numerous skin problems that require the combined contributions of the prosthetist, medical specialist, and dermatologist. Recognizing and treating skin lesions of the stumps of diabetic amputees cannot be overemphasized. Frequently, circulation is impaired; stasis dermatitis and swelling, or edema, are common; and the skin may be atrophic, or thinned, and easily injured. Occasionally, bacterial and fungal infections occur and ulcers are slow to heal, with secondary bacterial infection being difficult to control.

The artificial limb places heavy demands on the skin of a residual limb. Even a minor skin eruption may become, through neglect or mistreatment, an extensive disorder that will seriously threaten the amputee's mental, social, and economic rehabilitation. The importance of early recognition and treatment of skin lesions on the stumps of amputees cannot be overemphasized.

References are available upon request by fax at 865/525-7917.

This article is reprinted with permission of Dr. Levy and BioMechanics magazine, April 1999, pages 45-54.

About the Author

Dr. William Levy is Clinical Professor of Dermatology at the University of California. He has been a central medical advisor and consultant to California Blue Shield and Medicare for the past 30 year. His book, “Skin Problems of Amputees,” published in 1993, is widely accepted and individual chapters on this subject were published in 1992, 1993, 1995, and 1998 for three international textbooks.

Last updated: 08/18/2014
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