What is a corn?
There are 4 different types of corns:
- Hard corns (heloma durum): often seen in high pressure areas beneath the feet such as the metatarsal heads, or on the tops of the toes
- Soft corns (heloma mole): usually located between the toes. They can be more common in people who smoke
- Seed corns (heloma miliare): very small corns that can occur in conjunction with other dry skin conditions
- Neurovascular corns: often mistaken for warts, they contain tiny blood vessels and/or nerves. Again, they are more common in people who smoke.
What is a callus?
Callus is a build-up of hard dead skin or keratin, presenting as a hardened area with a grey or yellow tinge. Hyperkeratosis is the technical term for the build-up. Callus is the result of a large pressure area build up, whereas corns are smaller focal points of pressure. Callus often forms on the heels, the balls of the feet, the palms, and the knees. Calluses may feel hard, rough, dry or flaky.
The hardened layer of callused skin develops when the skin tries to protect itself against pressure and friction. If callus cracks, fissures develop and can come painful, particularly at the heels.
What causes corns and calluses?
Corns and calluses are the response to pressure and friction. The skin tries to protect itself from repetitive injury and thickens to prevent blistering.
Sources of pressure and friction include:
- Wearing ill-fitting shoes and socks:
- Shoes that are too tight in width or depth at the toes
- Shoes that are too loose, causing sliding
- Shoes with prominent internal seams
- Socks that fold or have prominent seams
- Wearing shoes without socks, causing increased pressure
- Repetitive trauma specific to an activity e.g., running
- Bony prominences, often exacerbated with aging and less fatty tissue under the feet
- Biomechanical abnormalities
Preventing corns and calluses
- Wear appropriately fitted shoes. Shoes with laces or Velcro will result in less friction than a slip-on shoe. An enclosed shoe will also prevent against callus compared to a thong
- Apply emollient: Foot creams that contain urea, salicylic acid or lactic acid are keratolytic and help soften hardened skin
- Do not smoke, as this restricts blood flow
- See a podiatrist for regular treatments
Corn pads should be used with extreme caution as they often cause burns or wounds. They should never be used by people with diabetes or the elderly, where circulation and ability to heal wounds is reduced.
How can a podiatrist help?
Podiatrists are trained to assist with the removal of corns and calluses with debridement and can determine the cause of their formation. They can also assist with modifying footwear, manufacturing pressure relieving insoles, spacing the toes with wedges, and assisting with biomechanical issues.
Article written by ATUNE Podiatrist, Kirby Read.
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