A callus, also known as hyperkeratosis, is an area of hard, thickened skin that can occur across the ball of the foot, on the heel, or on the outer side of the big toe. Although many consider them a skin problem, they are indicative of a problem with the bone.
Calluses form from repeated friction and pressure, as the shoe (or ground) rubs against a bony prominence (bone spur) on the toe or foot. The skin thickens in response to this pressure. Small amounts of friction or pressure over long periods of time cause a corn or callus. A great deal of friction or pressure over shorter periods of time can cause blisters or open sores. Calluses typically develop under a metatarsal head (the long bone that forms the ball of the foot). Calluses have painful nerves and bursal sacs (fluid-filled balloons that act as shock absorbers) beneath them, causing symptoms ranging from sharp, shooting pain to dull, aching soreness.
Calluses can be treated with over-the-counter callus removers, which use strong acids to peel this excess skin away after repeated application. Be careful using these products as they can cause chemical burns when misapplied or used in excess. Alternatively, treat calluses as follows: Begin by soaking the foot or feet in warm soapy water and gently rubbing away any dead skin that loosens. Next, use a pumice stone or emery board to file away the thickened skin. Apply a good moisturizer to the hardened areas to keep them softer and relieve pain. Nonmedicated corn pads or moleskin (a thin fuzzy sheet of fabric with an adhesive back) are available in stores and can relieve pain caused by calluses. However, use caution removing pads or moleskins to avoid tearing the skin.
If you need assistance relieving calluses, please contact our office. We can trim and apply comfortable padding to the painful areas. In more severe cases, we may prescribe medication to relieve inflammation, or inject cortisone into the underlying bursal sac to rapidly reduce pain and swelling.
A plantar callus forms on the bottom of the heel over time where one metatarsal bone is longer or lower than the others. This structure causes the one metatarsal to hit the ground first and with more force than it is equipped to handle. As a result, the skin under this bone thickens. In most cases, plantar calluses can be treated without surgery. In some recurring cases, however, a surgical procedure, called an osteotomy, is performed to relieve the pressure on the bone.
A condition called Intractable Plantar Keratosis (IPK) is a deep callus directly under the ball of the foot. IPK is caused by a "dropped metatarsal," which happens when the metatarsal head drops to a lower level than the surrounding metatarsals and protrudes from the bottom of the foot. This results in more pressure being applied in this area and causes a thick callus to form. A dropped metatarsal can either be a congenital abnormality, a result of a metatarsal fracture, or a structural change that may have occurred over time.
You can prevent calluses by:
- Switching to better-fitting shoes or using an orthotic device to correct an underlying cause.
- Buying socks with double-thick toes and heels or nylon hose with woven cotton soles on the bottom of the foot.