These are referred as fissures and are caused by dry skin.

• It does not look nice and the skin feels very hard when touched and at times it can be painful.
• Heel fissures form at the junction between the hairless skin (on the bottom of the foot) and the hairy skin on the side of the foot.
• They are essentially tears in the epidermis.
• For most persons, cracked heels are nothing more than a cosmetic problem
• The condition is characterised by calluses and fissures in the heel area, and the skin often appears darker and, occasionally, has a yellowish tinge.
• In more advanced cases, however, the cracks can become painful, especially during weight-bearing, particularly if they penetrate into the deeper layers of the skin (ie, the dermis).
• In the most severe cases the fissures can bleed and become infected, leading to complications such as cellulitis.
• Heel fissures occur predominantly as a result of dry skin (xerosis), which can have many contributing factors.
• During walking the heels support the entire body weight. To absorb shock and soften the load, a fatty pad (corpus adiposum) exists under the heel bone (calcaneus).
• Normal skin is flexible but skin that is dry and hardened is less so.
• Walking places stress on the fat pad — especially if the skin is dry — increasing the likelihood of cracking.
• Persons tend to experience cracked heels more in the summer months.
• However, the problem can also occur when the skin is exposed to drying environments, such as air-conditioning or excessive heat, particularly if the person is bare footed.

Cause

• Drying environments, such as air-conditioning or excessive heat, particularly if the person is bare footed.
• Excessively wet skin has lower tensile strength (so can easily crack), heel fissures can also develop in people who suffer from excessive sweating or who spend a lot of time in water.
• Overweight
• Foot conditions i.e flat feet, heel spurs
• Poor posture – putting pressure on certain areas of foot
• Diabetes (especially nerve damage in the feet caused by diabetes- numbing and burning sensation)
• Atopic dermatitis
• Psoriasis
• Juvenile plantar dermatosis
• Moccasin-type athlete’s foot (which produces a dry scaling over the entire sole and heels)
• Hypothyroidism (the lower metabolic rate also reduces the degree of sweat produced, giving rise to dry skin- xerosis ‘winter itch’.
• Peripheral vascular disease

The Pharmaceutical Journal, PJ, June 2010;()::DOI:10.1211/PJ.2021.1.81121