The cracked skin that you may get around the edges the heels is often a painful condition if it is allowed to progress. This condition occurs when the skin around the backs of the heel is dryer and thicker than it should ordinarily be. As the callus builds up to make that dry thicker skin, it simply cracks because it is not too supple or adaptable. The split that develops in the hard skin, then attempts to tear or rip the good skin under it. In the most severe cases, this will become painful, might bleed and be an for an infection, so does need to be taken seriously. The explanation for these cracked heels isn't completely clear. Some individuals simply have a tendency to have a dryer skin and some people, because of the way which they walk tend to build up the callus around the periphery of the heel. Being overweight is another risk factor for cracked heels. Footwear which are open at the back are also thought to play a role in this problem.
The easiest method to manage the cracked heels is to get a skilled podiatrist to remove the thicker callused skin and then use an cream to soften the rest of the skin. You could try and remove that skin yourself with something such as a pumice stone or file, but that is a lot of effort and needs to be done often. The emollient lotion used after this ought to be applied on regularly to help keep the skin well hydrated and flexible. There quite a bit of opinion of what's the perfect cream or emollient to use is and the best answer is the one that matches your skin. A bit of trial and error may be required to find the best one. For cracked heels most podiatrists usually advocate starting with a urea based ointment.