HEALTH AND MEDICAL PRODUCTS:CORN AND CALLUS FOOTTR EATMENTS

CORN AND CALLUS FOOTTR EATMENTS

Callus (keratosis) formation is usually an excessive accumulation of dead skin cells that harden and form a thickened hyperkeratosis epidermal lesion of an area of the foot. The appearance of a callus on skin is often considered a defense mechanism to protect the foot against excessive or abnormal pressure and friction. They usually occur on areas experiencing underlying mechanical stress, including the ball of the foot (where meta- tarsal foot bones bear human body weight), the heel, and/or the under- side of the big toe (hallux). They may, however, form over any bony foot prominence. A callus may be asymptomatic (have no pain) or manifest as a burning pain, dull ache, sharp shooting or pinching pain, or a bruising sensation. While calluses may be simple thickenings of the epidermal skin (developing as cutaneous horns, heel fissures, pinch/spin calluses, or tylomas), they may in some cases have a deep-seated central “core,” known as a nucleation. This particular type of callus is usually located on the ball of the foot (often corresponding to a prominence of the underlying bone) and can be especially painful to pressure. This condition is referred to by medical professionals (e.g., podiatrists) as an intractable plantar keratosis. Some common causes of callus formation are high- heeled shoes, obesity, abnormalities of walking gait, fat feet and high- arched feet, excessively long or displaced metatarsal bones, bony prominences, hammer toe deformity, loss (atrophy) of fat pad on the underside of the foot, and short Achilles tendon.

Corns, similar to calluses, are also hyperkeratoses (increased amount of built-up skin) of epidermal foot skin that vary in both location and appearance. They are a thickening and hardening of the dead surface layer of the skin in response to pressure, and they usually form on the toes, where the bone is prominent and presses the skin against the shoe, ground, or other bones. As the corn thickens by the recurrent rub of mechanical friction, it produces irritation in the underlying skin tissue, which may or may not involve bony structures of the toe, and becomes swollen, reddened, and painful. There also may be a deep-seated nucleation, in which the corn is thickest and most painful where the core presses on an underlying nerve. Common locations where corns form are the top surface of the toe, at the tip of the toe, and between the toes. Although there are five basic types of corns (hard corns, soft corns, seed corns, vascular corns, and fibrous corns), the two most common types are hard and soft corns. Hard corns, known as hellomadura, appear as small concentrated areas of hard skin, usually within a wider area of thickened skin or callus, and can be symptoms of feet or toes not functioning properly. Soft corns, known as hellomamolles or kissing corns, tend to be whitish and rubbery in texture and appear between toes, where the skin is moist from sweat or from inadequate drying. Common causes of corns include tight-fitting shoes, deformed or crooked toes, tight socks and stockings, a seam or stitch inside the shoe that rubs against the toe, an excessively loose shoe that leads to foot sliding and abnormal pressure, and prolonged walking on a downward slope.

Home remedy and over-the-counter nonmedicated products for callus and corn treatment usually include changing of footwear to allow for proper fit and extra room in the toe box (toe area), adding cushioning to existing footwear to reduce or remove excess pressure, friction, and irritation between the skin and foot bones or between toes and surrounding footwear, use of a pumice stone or other abrasive material to reduce callus or corn thickness (for calluses in concert with maintaining moist and supple foot skin with regular warm water foot soaking and application of moisturizers), application of nonmedicated pads around the callus or corn to relieve pressure, and/or application of moleskin over areas that tend to callus or lead to corn formation. However, many over-the- counter callus- and/or corn-removing medicated treatments include the active ingredient salicylic acid. The aim of these treatments is to remove the area of hard skin from the foot by applying a corrosive material (in a plaster- or rubber-based medicated cushion vehicle) to the affected area approximately every forty-eight hours as needed for up to fourteen days.

Salicylic acid [2-hydroxybenzoic acid; C6H4(OH)CO2H] is a colorless crystalline organic carboxylic acid derived from the bark of the white wil- low tree and wintergreen leaves (in the form of methyl salicylate) and also prepared synthetically from phenol. The large molecule size permits this beta hydroxy acid to remain on the surface of the skin, allowing it to more effectively penetrate and exfoliate within the callus or corn. Known to have keratolytic actions, salicylic acid (often in over-the-counter con- centrations of 40 percent) removes the outer layers of hardened skin from the foot, thereby reducing or removing the acute painful symptoms related to the presence of calluses or corns. Often, surrounding skin is protected from unnecessary corrosion with agents such as petroleum jelly during callus or corn salicylic acid treatment.

Specialized over-the-counter ointment treatments for calluses and feet with dry, cracked skin may include (instead of salicylic acid) an endoprotease in a white petroleum jelly vehicle base. Known to improve the soft- ness and density of the callus, the endoprotease breaks the ten end peptide bonds on the protein chains of callus tissue, leaving the normal skin unaffected (as normal skin does not contain this type of long-chain protein). Once treated, a gentle rubbing action with a wet washcloth is sufficient to gradually exfoliate callus tissue.