Calluses and corns are forms of callosities which occur as a part of a natural physiological response towards prolonged excessive pressure or friction on the skin called hyperkeratosis.

There are multiple causative factors for callosities including poorly fitting shoes, abnormal pressure in areas where there is a foot deformity present, or it could even be an inherited condition when they are found in areas that have not been succumbed to irritation.

Hyperkeratosis also occurs as a defense mechanism towards chronic inflammation, infection and irritation from chemicals or UV rays.

Callosities develop when the skin overlying bony prominences of the foot (eg. Bases of the metatarsal heads and protruding joints) experience constant pressure during walking or friction from a tight shoe.

As a natural response, the body attempts to protect that area of skin by thickening the outer layer of the skin. Callosities may be advantageous to the skin in preventing blisters, but it can be a vicious continuous cycle as their development can cause further pain and discomfort when it takes up space in shoes or creates a further focal area of pressure.

Callosities can be painful, and the symptoms can progress into a stage where an individual’s gait, choice of footwear, as well as activities can be compromised. Regular sharp debridement or consistent use of emollients can help manage the symptoms, but the underlying mechanical issue should also be addressed to ensure longer-lasting relief, or complete recovery.

There are two main types of callosities: corns and calluses.

Corns (heloma) are characterized as having a distinguished circular border of hyperkeratosis and a visible translucent core. This centralized core causes pain and inflammation as it presses deep into the dermal layers of the skin¹. There are two types of corns commonly observed: the hard corn and soft corn.

• Hard corns (heloma durum) are a dry horny shaped mass which are commonly found on the top of the interphalangeal joints of your lesser toes. It is commonly called a digital corn.
• Soft corns (heloma molle) are commonly called interdigital corns. Even though they are termed “soft”, they are usually the more painful corn. Interdigital corns are corns which have increased moisture (from sweating or not drying between the toes properly); leading to maceration and is most commonly a precursor for bacterial or fungal infections.

Calluses don’t have a clear circular demarcation. They are significantly larger than corns and is characterized by a larger spread of hyperkeratosis. Calluses may or may not be painful as it does not have a core like a corn. In common cases, a wart (verruca) or corn can exist beneath a callus.

There are multiple risk-factors for the development of callosities and can either be self-managed or requires external intervention. Poor footwear (tight shoes, irregularities in the shoe) and level of activity are manageable risk factors.

A simple solution would be to obtain shoes which have a wide enough toe box. Athletes with high levels of activity tend to develop callosities due to the repeated high pressure contact points on their feet. This is also partially why individuals suffering from obesity also tend to develop calluses.

Other risk factors would be foot deformities which alter or accentuate bony prominences. Most commonly this includes toe deformities such as the claw, hammer or mallet toes, hallux rigidus or even a high arched (pes cavus) foot where pressure is concentrated around the heel and first metatarsal head. Faulty foot mechanics can also be a factor.

When pressure is unevenly distributed across the feet, callosities form in the areas of higher pressure. This could come in the form of a transfer lesion where more weight is taken by a metatarsal (other than the first) due to discrepancies in length (too short or too long), or even in structures which no longer have the required range of motion (eg. Hallux rigidus or malunion of a fracture).

As a podiatrist, our first course of treatment is to assess the root mechanical cause of the callosity. At present during the consultation, podiatrists would perform debridement to remove the calluses and/or enucleate the corns. If the root cause is due to foot mechanics, we would either aim to improve the range of motion of your various joints through stretches, strengthening or mobilization techniques. The main aim is to redistribute the pressure under the foot and by having a podiatrist recommend footwear suitable to your foot type, the formation of callosities can be prevented. In cases of foot deformities, in-shoe devices and orthotics can be formed to help offload areas of high pressure.

Easy at home remedies to practice to help prevent the development of callosities include wearing properly fitting shoes, wear footwear even in the home (especially when the floor is hardwood or tiled), moisturize your feel daily and have regular checks to identify hyperkeratosis and monitor them.

If you or someone you know may need help managing their foot health, get in touch with our Podiatry team today.