The skin or epidermis is the external protective layer of the integumentary system. Skin provides protection against injury from the external environment. Direct pressure and friction forces can create thickening of the skin eventually leading to the development of a callous. Callous is a protective response of the skin to prevent injury.  Thickening of the callous over time can lead to the development of pain. The excess callous on the foot can cause pain related to an increase in pressure on the underlying sensory nerves of the skin.

Callous on the foot can occur on the weight bearing and non weight bearing surfaces of the foot. The weight bearing surface of the foot would be generally considered the bottom of the foot with the non weight bearing surfaces the top of the foot. Callous on the weight bearing surface of the foot occurs related to pressure and friction forces that develop between the bottom surface of the foot and the ground while callous on the non weight bearing surface of the foot generally occurs related to friction pressures between the skin and the shoe surface.

 Callous on the bottom of the foot is generally seen at the heel or the ball of the foot. Pressure and friction forces are experienced through the three phases of walking including heel contact, midstance and propulsion. Pressure and friction forces are different through all three phases of the walking cycle. Generally, callous occurs more frequently at the heel and the ball of the foot with very little callous occurring in the arch region.  Callous at the heel region generally occurs in the periphery of the heel related to friction forces that occur between the motion of the fatty tissue on the sides of the heel and the ground. Callous to the ball of the foot can occur at each of the five metatarsal contact points. Each of the five metatarsal can take up different pressures and friction forces during walking with callous occurring at the metatarsal that experiences the greatest direct weight bearing and friction forces.  

Callous formation on the bottom of the foot can be diffuse or localized. Diffuse callous like the development of callous in the palm of your hand typically does not cause pain. Localized callous or keratoma can be quite painful related to the direct pressure placed on the underlying sensory nerves. These keratomas can occur within sweat glands on the bottom of the foot called porokeratosis.  Porokeratosis and keratoma are often misdiagnosed as plantar’s warts because of their localized appearance. The pain associated with callous can be relieved by reducing pressure at the callous site by either thinning the callous or by placing more pressure around the callous. Reducing the thickness of the callous can be performed by thinning the callous with the use of over the counter debridement agents like pumice stones as well as the medically guided use of topical corn or callous remover agents. Pain relief by increasing pressure around the callous can be accomplished with the use of an arch support that displaces pressure off of the callous region and the appropriate selection of a shoe.

Pressure reduction is the main treatment to reduce the pain as well as recurrence of callous on the bottom of the foot.  Store purchased or custom orthotics with an appropriately cushioned shoe can be used to reduce the pressure at the callous site. By reducing the pressure with an orthotic pain as well as the callous build up will resolve. Orthotics not only reduce direct pressure on the callous region but also decreases the friction forces that occur during the various phases of the gait cycle. Additional padding on the store purchased or custom orthotics additionally reduce pressure to help relieve pain.

Callous occurring on the non weight bearing portion of the foot generally occur related to contact friction that occurs between the skin and the surface of the shoe. The tops of the toes often develop callous or “corns” related to friction forces. These corns often occur related to preexisting deformity of the feet including at toes with flexion contractures called hammertoes.

Shoe selection is critical in the reduction of pressure to all areas of the foot. Callous or corns that occur on the toes are generally improved with the selection of a shoe that provides adequate room in the toe box area of the front of the shoe.  Women’s as well as men's slip on shoes including flats and loafers tend to be narrower in the ball of the foot as compared to the heel region. The narrower fit in the ball of the foot can increase friction forces on the toes which can secondarily build up painful corns. Reducing the friction forces at the toes with the use of a shoe that is wider in the ball of the foot can help over time reduce the thickness of corns. The medically guided use of corn or callous remover agents along with the use of pumice stones can also help in pain reduction. If deformities including hammertoes are present surgical correction may be indicated if adequate shoe changes have not provided pain relief from the corn.

The surgical correction of a hammertoe relieves pain by removing the underlying prominent bone which will secondarily reduce the friction forces occurring between the skin and the shoe surface.

The location of the callous helps direct the type of care needed. Callous occurring on the bottom of the foot can often times be treated by pressure reduction with the use of an orthotic device as well as reducing the thickness of the callous tissue. Callous occurring on the tope of the foot and the toes is generally treated with pressure reduction with the use of a well accommodating shoe which will reduce the friction forces occurring on the toes or elsewhere on the foot.