Cracked heels also known as heel fissures are cracks that occur in the back of the heel, usually on both heels.
For some people this can be a chronic problem, which is more annoying than dangerous. However, for some people such as diabetics, people with poor circulation and people with immunosuppressant diseases this problem can have major consequences. At times, the cracks can be very painful.
Most people with heel fissures will start out with dry skin on the heels known as xerosis. Causes include disruption in the barrier or protective function of the skin, leading to increased water loss from the epidermis (outer skin layer), low humidity as seen in winter, genetics, diuretic use, decreased sweat gland activity, dyskeratosis which is the formation of an abnormal keratin layer and aging. Medical conditions which can lead to dry skin and thus heel fissures include venous stasis dermatitis, diabetes, hypothyroidism, Down syndrome, kidney disease, malnutrition and lymphoma.
This condition can be more prevalent in heavier people and those that wear backless shoes. Regular shoes that have a back to them keep the heel 'cupped,' in other words the skin and fat of the heel area is pushed together. When you wear a backless shoe all the body fat and skin is displaced laterally and it tends to become callused and since callused skin is not healthy skin, it will begin to crack and the heel fissure will form.
Obviously, the heavier you are the more the heel fat and skin is displaced laterally even if you wear shoes with a back to them.