Refers to thickenings in the skin in areas of repeated pressure.
Increased pressures are related to a hyperkeratotic response and that the target for treatment should be eliminating excess pressures on the foot.
They are the result of mechanical trauma to the skin culminating in hyperplasia of the epidermis.
Most commonly, friction and pressure between the bones of the foot and ill-fitting footwear cause a normal physiological response, which is proliferation of the stratum corneum.
The stratum corneum provides a barrier to mechanical injury of the skin, and the response to stress results in the release of epidermal cytokines stimulating an increase in synthesis of the stratum corneum.
Such external mechanical forces focused on a localized area of the skin, ultimately leading to impaction of the stratum corneum and the formation of a hard keratin plug, a corn, that presses painfully into the papillary dermis, which is known as a radix or nucleus.
Friction against footwear is likely to perpetuate hyperkeratosis.
A Morton toe, in which the second toe is longer than the first toe, occurs in 25% of the population, and may cause a callus of the common second metatarsal head.
Corn formation may result from long-term or repetitive motions.
Excessive leg crossing may cause callouses.
Plantar pressures are significantly higher under callused regions of the foot.
The hands and feet are important in corn formation as the bony prominences of the metacarpophalangeal and metatarsophalangeal joints often shaped to induce overlying skin friction
If the chronic mechanical defect is not repaired, hyperplasia and inflammation are common.
Irregular distribution of pressure and repetitive motion injury are considered to be the main inciting causes.
Abnormal mechanical stress leading to corns may be intrinsic or extrinsic.
Toe deformities, contractures and claw, hammer, and mallet-shaped toes, and rheumatoid arthritis may contribute to corns.
Callosities over the lateral fifth metatarsal head, may be associated with neuropathic symptoms due to compression of the underlying lateral digital nerves.
Intrinsic factors include foot deformities, abnormal foot mechanics and peripheral neuropathy.
Extrinsic factors include poorly fitting footwear and vigorous activities.
Some disorders may alter the shape or sensation of the soles of the feet.
Bony prominences and faulty foot mechanics allow clavus formation to continue.
A soft corn, or heloma molle, has macerated texture secondary to moisture., and is generally found in interdigital locations.
A periungual corn occurs near or on the edge of a nail.
Localized callosities of the soles, are called plantar callus, or plantar corn.
Callosities occurring over one or more lateral metatarsals, are termed intractable plantar keratoses.
Often present in athletes and in patients exposed to uneven friction from footwear or gait abnormalities, including elderly persons, diabetics, and amputees.
African Americans have a significantly higher rate of corns and calluses compared with non-Hispanic white and Puerto Rican participants (70% vs 58% vs 34.1%).
Elderly patients, of both genders wear shoes too narrow for their feet.
Women frequently wear shoes that are short than their feet.
Chronic arthritis can lead to foot deformities and consequent callus formation.
It may result in chronic pain, particularly in the forefoot.
Thickening may result in ulcer formation.
Inappropriately shaped or constrictive footwear in the presence of bony prominences may exacerbate corn formation.
A corn, also termed clavus, is a thickening of the skin due to intermittent pressure and frictional forces on the foot.
Calluses lack a central core, which characteristically is revealed in corns upon removal of the upper hyperkeratotic layer of skin.
Corns can occur within an area of callus.
Corns are one of the most common foot conditions in the United States, particularly amongst older persons.
It is a common disorder as a result of usage of occlusive footwear and participation in repetitive activities.
Symptoms and signs of corns and calluses include a thick, hard patch of skin, area of flaky, dry skin, pain or tenderness of the affected area.
Both narrow and short footwear can lead to the development of corns.
Most individuals acquire the risk factors for clavus formation after puberty due to use of traumatic footwear use, experience of repetitive motion injuries, and progressive foot deformities.
The potential for a maltreated corn, soft corns in particular, to develop into a life-threatening secondary infection must be considered in patients with diabetes mellitus or immunosuppression.
Chronic clavus generally occurs because of the failure to remove inciting factors.
Corns and calluses can be treated with products to chemically pare down the thickened, dead skin.
Corns are often misdiagnosed as calluses, which are also hyperkeratotic skin lesions resulting from excess friction.
Calluses develop from forces distributed over a broad area of skin, whereas corns develop from more localized forces.
Salicylic acid is the ingredient used in most corn and callus removal products.
Can be prevented by reducing or eliminating increased pressure at specific points on the hands and feet.
The medical term for the thickened skin that forms corns and calluses is hyperkeratosis.
Friction forces result in hyperkeratosis, both clinically and histologically.
Hyperkeratotic lesions of the foot that include corns and calluses have been reported to affect 20-65% of people aged 65 or older.
Corns hard and soft are caused by pressure from unyielding structures.
A callus refers to a diffuse, flattened area of thick skin.
A corn is a thick, localized area that usually has a conical or circular shape.
Corns, also known as helomas or clavi.
Corns sometimes have a dry, waxy, or translucent appearance.
A callus is also known as a tyloma.
Corns and calluses occur on the feet and sometimes the fingers.
Corns are often painful.
Common locations for corns are: the bottom of the foot, the metatarsal arch, on the outside of the fifth toe, where it rubs against the shoe, between the fourth and fifth toes.
Corns between the toes are often whitish and messy; this is sometimes called a “soft corn”.
The more common “hard corn” is found in other locations.
Thickening of the skin occurs as a natural defense mechanism that strengthens the skin in areas of friction or excessive pressure.
Abnormal anatomy of the feet, such as hammertoe or other toe deformities, can lead to corn or callus formation as can bony prominences in the feet.
Footwear that is too short or too tight or that exerts friction at specific points can also cause skin thickening that leads to corns and calluses.
Abnormalities in gait or movement that result in increased pressure and can also be the cause.
Finger calluses may develop in response to using tools, playing musical instruments such as the guitar, or using work equipment that exerts pressure at specific sites.
People of all ages can be affected but they are particularly common in people over 65 years of age.
Corns and calluses have been shown to affect 20%-65% of people 65 years or older.
Risk factors are:
abnormalities in anatomy of the feet or toes
abnormalities in gait
poorly fitting shoes
using equipment, tools, or instruments that exert pressure on specific locations on the fingers
certain occupations, such as farmers or garden workers.
Conditions associated with corn formation include:
Advanced patient age
Use of a brace or orthopedic stabilizing product
Keratoderma palmaris et plantaris
Tethered spinal cord syndrome
Vascular occlusion syndromes
Diabetes mellitus with associated peripheral neuropathy
Diagnosis can be made by observing the characteristic changes in the skin.
Treated with medicated products to chemically pare down the thickened, dead skin.
These products all share the same active ingredient — salicylic acid, a keratolytic, which means it dissolves the protein keratin that makes up most of both the corn and the thick layer of dead skin.
Salicylic-acid treatments are available in different forms including
All of these treatments allow the dead tissue to be trimmed or peeled away.
Surgical removal of corns is rarely necessary.
Surgery for corns may involve shaving the underlying bone or correcting any deformity that is causing undue pressure or friction on the skin.
Calluses and corns can often be prevented by reducing or eliminating the circumstances that lead to increased pressure at specific points on the hands and feet.