Hard and soft corns and calluses Definition,Causes and treatment

Definition

Corns and calluses are variously known as hyperkeratosis, clavus, heloma and tyloma, but all essentially describe the same condition – a local thickening of the epidermis as a result of intermittent pressure meeting with constant resistance over some bony prominence on the foot

Causes

The irritation caused by this rubbing increases the blood supply, bringing

extra nutrition to the basal layers of the epidermis, resulting in increased

proliferation of cells and thickened areas of hard, insoluble mass. Pressure on

nerve endings in the dermis causes pain.

Hard corns

form on the outer aspects of the toes as a result of rubbing against shoes

Soft corns

usually occur between the toes and are softened by the presence of moisture (sweat).

Calluses

are more diffuse areas of thickening on the sole or the side of the foot.

Treatment

Epidermabrasion

Epidermabrasion is a physical process that removes horny skin using a mechanical aid. Several gently abrasive materials and appliances are available,including emery boards, foot files, pumice stones and synthetic pumice-like blocks

Careful technique is important for the safe and successful removal of corns and calluses, using the following procedure

 To soften the skin, soak the foot in mild soapy water for a few minutes or apply amoisturising or softening cream.

 Rub soap on to the appliance and gently rub the corn or callus for 5 minutes.

 Repeat the process nightly for 1 week, then review. There is no need to remove

the hard skin completely, just enough to relieve pain or irritation.

– Avoid ill-fitting shoes to help prevent recurrence.

Hydrocolloid and hydrogel plasters

Hydrocolloids and hydrogels are complex polymer formulations used in wound management
They swell in the presence of moisture absorbed from the skin. In corn and callus plasters the hydrocolloid or hydrogel forms a soft, protective gel-like cushion that rehydrates and softens the hardened tissue
 The plaster is left in place for about a week, and the corn or callused skin should come away when the plaster is removed

Salicylic acid

The function of salicylic acid in treating corns and calluses is to remove a thick layer of cornified skin cells, mainly through loosening the attachment of the hardened skin to the normal skin

The concentration in preparations ranges from about 11 to 50%.

Corn and callus caps and plasters contain high concentrations (usually 40%) in a semisolid base spread on to a suitable backing material, contained within a

ring that is either self-adhesive or attached to an adhesive plaster 

They should be changed every 1–2 days for about a week, after which the callosity should lift away easily

An ointment containing 50% salicylic acid is also available; it should be applied nightly for 4 nights

Paints and liquids contain 11–17% salicylic acid, often in a collodion-based vehicle. Collodions contain pyroxylin, a nitrocellulose derivative, dissolved in a volatile solvent such as ether, acetone or alcohol 
On application, the solvent evaporates, leaving on the skin an adherent, flexible, water-repellent film containing the medicament. This has the advantage of maintaining the salicylic acid at the site of application and also assists skin maceration by preventing moisture evaporation
 Liquid preparations are usually applied daily for several days until the corn or callus can be easily removed 
  As salicylic acid is caustic to normal skin, care should be taken  to prevent preparations from spreading beyond affected areas

Preparations containing high concentrations of salicylic acid should be avoided by people sensitive to aspirin