No discussion of the hands and feet would be complete without consideration of the nails and cuticles. Even though the nails are made of nonliving keratin, they are the source of
considerable cosmetic attention. Manicures, pedicures, artificial nails, nail polish application, etc. are all popular activities. Certainly, the nails add glamour and enhance the appearance of the hands and feet. In certain cultures, the fingernails are used to designate class status. For example, Greek males allow their little fingernail to grow longer than the rest to show that they work at a desk job rather than performing manual labor, since a long little fingernail cannot be maintained if people use their hands to make a living. Similarly, women in United States use long nails for much the same purpose. Since the nails are made of nonliving tissue, their cosmetic needs are much different than any of the other body areas previously discussed.
Anatomy and Physiology
The nail is a thin plate of nonliving keratin designed to protect the tip of the finger and toes. The nail is produced by a group of cells designated as the nail matrix that lies approximately one-quarter inch below the visible nail. The nail matrix cells are formed at birth and cannot regenerate following injury. For this reason, trauma to the nail matrix can result in a permanently deformed nail that cannot repair and will not grow normally. One of the most important structures adjoining the nail from a dermatologic standpoint is the cuticle. The cuticle is a like a rubber gasket forming a watertight seal between the nonliving nail and the skin of the fingertip. Damage to the cuticle results in water, chemicals, or anything the hand touches reaching the nail matrix cells. It is for this reason that dermatologists recommend that the cuticle not be dislodged, pushed back, trimmed, or manipulated in any way. Many of the abnormalities and diseases of the nail tissue can be traced back to a damaged cuticle.
Common Dermatologic Disease Considerations
Nail abnormalities and disease are extremely hard to treat because the visible nail cannot be repaired; only the growth of new nail can be influenced. In most individuals, it takes six months to grow a new fingernail and one year to grow a new toenail. This means that creation of a new nail to replace a damaged nail is a long process requiring patience before the effects of successful treatment are visible. The common nail problem is loosening of the nail plate from the nail bed, a condition known as onycholysis. Onycholysis is usually traumatic in nature and is more common in individuals who wear artificial nails in the form of sculptures or tips. The bond between the artificial nail and the natural nail is stronger than the bond between the natural nail and the underlying skin. This means that the natural nail plate will rip from the skin causing pain and swelling of the finger. The natural nail now appears white, because the nail is no longer attached to the pink flesh, and a space is created beneath the nail plate and the skin where infection can occur. Onycholysis is the most common condition predating a nail fungal infection.
Fungal infections of the nail, medically known as tinea unguinum, are extremely common with advancing age. It is estimated that 80% of persons age 80 or older will develop a nail fungal infection. The infection becomes more common with advancing age as the immune system’s ability to protect against a fungal invader is diminished. The same fungus that causes infection of the feet also causes nail fungus, as mentioned previously during our discussion of foot diseases. Nail fungal infections of the hands and feet are very difficult to treat since medication cannot be administered to the nonliving nail. The site of the nail fungal infection is not actually the nail itself, but the living tissues beneath the nail. This makes topical treatment minimally effective because any topically applied medication must penetrate the hard nail plate to reach the infected tissues below. For this reason, fungal nail infections are traditionally treated orally with medications that
must be taken for three months. The oral medication allows an antifungal to be incorporated into the newly grown nail, forming a barrier for the advancing fungal infection. The old infected nail is then cut away to physically remove the infected nail plate, and eventually the treated nail, resistant to fungal invasion, is formed. However, the nail containing the oral antifungal medication is removed with further nail growth and reinfection commonly occurs.
Nail fungus is actually transmitted through fungal spores which are extremely resistant to destruction. Traditional disinfectants used to clean manicure and pedicure instruments are ineffective against the spores, thus fungal disease can be transmitted through nail salons. Nail fungus is also not susceptible to triclosan or other antibacterial agents traditionally used in soaps and cleansers. Thus, the best protection against a nail fungus infection is an intact nail and surrounding cuticle.
Another common nail problem is peeling and cracking of the nail plate. While these are largely cosmetic concerns, they can result in pain and leave the nail weakened to infection. Nail peeling and cracking are more common with advancing age. This may be due to decreased blood flow to the cells of the nail matrix from arthritis or blood vessel disease or due to declining nutritional intake. The body certainly recognizes that the nails are not essential to maintain life, thus under times of stress or illness nail growth is not optimal. However, there are conditions where nutrients may not be absorbed from the intestinal tract that becomes more common with advancing age. One of these nutrients is biotin. Biotin is necessary for hard nails and may not be properly absorbed. For this reason, one of the main treatments for peeling, cracking nails is an oral biotin supplement. Nail dehydration may contribute as well, but this topic is addressed under skin and nail care needs.
There are a variety of inherited or acquired nail deformities for which no treatment exists. For this reason, many dermatologists run the other way when a patient presents with nail problems. Probably the common somewhat treatable nail deformity is psoriasis. As we discussed previously, psoriasis is the production of too much poor quality skin too quickly. Psoriasis of the nail is similar in that the nail that is produced is also poor quality such that little chunks of the nail plate fall out leaving tiny holes or pits. Thus, the hallmark of nail psoriasis is pitted nails. The nails improve slowly as the body psoriasis improves, but methods of camouflaging the problem with nail polish or artificial nails are a more rapid solution. Most dermatologic nail conditions are best treated in the short term with cosmetic techniques, which are beyond the scope of this text.
Hygiene Needs
As mentioned previously, the most important way to keep the nail plate healthy is to leave the cuticle undisturbed. For some, this answer is almost too simple. The nail is designed to take care of itself, and any manipulation interferes with the perfect design. Typically, hand hygiene and nail hygiene are taken care of simultaneously with good hand washing.
The most common infection that affects the nail is known as a paronychia. A paronychia is actually an infection of the skin surrounding the nail to include the cuticle. Here the cuticle is disrupted and water enters the tissue around the nail. This forms a warm, dark, moist space perfect for the growth of yeast organisms. The yeast breakdown the skin and make an environment appropriate for bacterial infection, which occurs secondarily. The bacteria then multiply and produce pain and pus. Use of antibacterial cleansers containing triclosan are very helpful in preventing a paronychial infection along with good moisturization of the tissues around the nail to prevent cracking. Oral antibiotics are usually required to treat nail and cuticle infections of this type.
Skin and Nail Care Needs
Moisturizing the nail and the cuticle are important to prevent disease. Usually these structures are moisturized at the same time the hands are moisturized, but there are some key differences to consider. The outer stratum corneum layer of the skin of the hands is replaced every two weeks, but the nails are nonliving, thus, any dehydration damage inflicted is permanent. Remoisturizing the nails can be minimally enhanced with urea and lactic acid, which increase the water binding sites on the nail keratin, but their effect is temporary until the next hand washing. Also, too much urea and lactic acid can over soften the nail plate, making it more susceptible to fracture. Water is the main plasticizer of the nail plate and it should not be removed with aggressive cleansing.