Dry thickened skin (corn and callus) around the rim of the heel is the very first step towards cracking. Increased pressure on the fat pad under the heel causes it to expand sideways, leading to splitting or cracking of the callus. Some factors that contribute to cracking or splitting include:

• Excessive weight or obesity
• Prolonged standing, especially on hard floors
• Open-back shoes and sandals, as they provide no support to hold the fat pad under the foot