Skin Health and Stump Hygiene1 GILBERT H. BARNES, M.D.2 Literally the word "hygiene" connotes a loss of its protective properties. Among indi­ state or condition of health. But adequate hy­ viduals in certain occupations, we frequently giene, or good health, of the human skin pre­ see both manifestations of such skin reaction. sents a complex problem involving much more Housewives, mechanics, laboratory workers, than a casual acquaintance with soap and and others whose work exposes certain areas water, the concept which usually comes to of the body, particularly the hands and arms, mind when hygiene is mentioned. The func­ to prolonged soaking in solutions and solvents, tional state of our human integument is pretty or even in plain water, are prone to recurrent much taken for granted by most of us. We skin irritation and breakdown. In such cases, know that this two-square-yard covering will, the chemical and physiological properties of in most cases, repair itself in event of local the skin are altered to such a degree that the injury, provided infection is avoided. Cheer­ skin's built-in protective functions are no fully we dissolve it in strong chemical solu­ longer effective. Even in the absence of pro­ tions. We broil it in the summer sun until it longed soaking, the skin may be injured locally peels off like old birch bark. We allow it to be by contact with an irritant, such as a strong rubbed and blistered in tight shoes for vanity's acid, or with a sensitizing agent, such as sake. As a nation, we spend millions of dollars poison ivy. on elaborate sun-tan lotions guaranteed to All of these considerations similarly pertain produce in it the beautiful brown of the abo­ to amputees who wear some type of prosthesis rigine and at the same time an equal fortune (Fig. 1), most of which are attached to the on lotions and creams which promise to stump by means of a snugly fitted socket bleach it out to the shade of a sheltered lily. which excludes circulating air and traps the Even though the skin has remarkable powers accumulated sweat against the skin. In the of restoration, the conditions of use are occa­ lower-extremity amputee, the effect is aggra­ sionally too damaging, or the opportunities vated by the added factor of weight-bearing for healing between periods of use are too and uneven loading on localized areas of the brief for repair and maintenance. In such in­ stump skin, especially in the adductor region stances, there may be an acute breakdown of of the stump and at other points of contact the skin with a severe inflammatory reaction, with the socket rim. Weight-bearing is at­ tended by other mechanical stresses, espe­ or the process may be a gradual one, with a cially intermittent stretching of the skin and progressive deterioration of the skin and a friction from rubbing against the socket edge 1 and interior surface. The latter results in two Based on a lecture presented before the University important and harmful effects on the skin— of California Pilot School in Lower-Extremity Pros­ thetics, August 25, 1955, at the U.S. Naval Hospital, heat, and abrasion of the skin surface, which Oakland, California. in time can, by steady attrition, become highly 2 Clinical Instructor in Dermatology, School of destructive. Over a long period of time, heat Medicine, University of California Medical Center, alone may be capable of causing profound San Francisco, and member of the Study Group on changes in the metabolism of living tissues. Dermatology, Lower-Extremity Amputee Research The stump skin of the amputee is especially Project, University of California, Berkeley and San vulnerable to the possible irritant or allergic Francisco. 4 SKIN HEALTH AND HYGIENE 5 action of various materials that compose the socket of the artificial leg. In this situation, then, the state of health of the stump skin is of the utmost importance in determin­ ing whether or not the prosthesis can be tolerated. If the skin can­ not be maintained in a good func­ tional condition in spite of daily wear and tear, then the weight- bearing prosthesis cannot be worn, no matter how accurate the fit of the socket may be. It is the purpose of this article to review some of the basic prin­ ciples of skin biochemistry and physiology concerned in the main­ tenance of good hygiene in the stump area. Included are some re­ marks relative to the use of certain disinfectant agents in skin cleans­ ing, and to some of the natural skin defenses against bacterial in­ vasion, because these topics also are germane to the principal subject with which this article is concerned. THE SKIN AS A VITAL ORGAN Man cannot live without his en­ velope of skin any more than he can exist without his heart or his liver. It might seem at first thought that the cutaneous covering of the body performs about the same function as the leather cover of a baseball —and very little more. Actually, the biochemical and physiological Fig. 1. Injury to the stump skin. The gremlins symbolize some of activities of the skin are every bit the common types of damage that may be inflicted upon the stump as complex as are those of the liver. skin inside the socket of a prosthesis. Injury may be incurred mechan­ The respiratory rate of the main ically when parts of the socket abrade the skin or burrow into it. The materials of the socket, coming in intimate contact with the skin, cellular portion of the epidermis, sometimes act as irritants or as sensitizing agents to create a local based on oxygen-uptake studies and dermatitis. glycolysis measurements, has been computed to be from two to ten times as high and use is the part it plays in mechanical sup­ as the rates of other body tissues. port of the soft tissues of the stump. It pro­ The skin possesses many properties vital to vides a tough, elastic outer covering with a health and life itself. Of particular interest to tensile strength of up to 2 kg. per sq. mm. Fur­ us from the standpoint of prosthetic design thermore, this covering has a tremendous 6 BARNES capacity for repairing itself after injury and greater length in the following portions of this for strengthening itself at points of mechanical paper. stress, such as those occurring on the lower- extremity stump in association with the wear­ THE ANATOMY OF THE SKIN ing of an artificial limb. A familiar example Plate I shows in semidiagrammatic form the of this is the "lichenification," or leatherlike principal structures of the skin concerned in thickening of the skin over the ischial tuber­ stump hygiene. The skin is seen to consist of osity and in the adductor region of the thigh. two distinct layers—the epidermis and the We know that "calluses," or localized thick­ dermis, or true skin. These two layers are enings of the horny outermost layer of the joined by a system of fingerlike projections, skin, will form at points of repeated pressure. the rete pegs, which protrude down from the Sometimes a BB-shotlike condensation of epidermis and interlock with the papillae, horny material will develop over a pressure which project up from the dermis. This device point, producing the well-known "corn." All furnishes a relatively large surface area at the of these thickening processes illustrate the dermal-epidermal junction, thus providing a defensive reaction of the skin to abnormal strong bond between the two layers. mechanical stress by elaborating a natural The most superficial layer of the epidermis cushion from its cellular elements. is the so-called "horny layer," consisting of a Mechanical protection, however, is only material called "keratin," which is very simi­ one of many important services which the skin lar to animal horn. Scattered over the surface performs. Its function in the conservation of of the skin are numerous deep pockets, called water and electrolytes, those ionized salts "follicles," into which sebaceous, or oil, glands which constitute an essential part of the body discharge their contents. From the follicles fluids, is nearly as indispensable as is the func­ protrude the hairs of the skin. tion of the kidneys. The skin is extremely Two other types of glands in the skin have important in the regulation of the body tem­ an important bearing on the subject of stump perature within relatively narrow limits. It hygiene. They are the eccrine, or small sweat possesses certain important electrical and glands, which lie in coils near the base of the chemical properties. It is also the first barrier, dermis, and the apocrine, or large sweat and one of the chief defenses of the body, glands (not shown in Plate I), which are simi­ larly situated but are more localized in dis­ against infectious diseases. tribution than are the eccrine glands. The Many other properties of the skin that are watery sweat secretions pass to the surface of less immediate importance to the problem of the skin by way of the sweat ducts, dis­ of stump hygiene nevertheless have a bearing charging on the surface through the sweat-duct on human health and welfare. For example, opening, or pore. we rely on the sensory organs of the skin for a Deep to the dermis lies the subcutaneous good part of our information about the world zone. Here, cushioned in masses of fat cells, around us. Through nerve endings at or near are the large blood vessels which serve the skin. the surface, the body receives the outside en­ From the arteries, smaller vessels rise, becom­ vironmental stimuli of heat, cold, pain, and ing narrower as they branch, until they ter­ touch.