The heel is at risk for three different kinds of wound, and each one suggests a different reason a wound there might stall.
Pressure. Heels are among the places pressure sores tend to form. The rule is that they form where skin covers bony areas with less tissue under the skin to pad the area. A heel resting on a bed takes the full weight of a leg on very little padding, and it is out of sight under bedding.
Blood supply. People at risk of ischemic ulcers should check the tops and bottoms of the feet, ankles, heels, and between the toes every day, looking for changes in color and red or sore areas. Most of those wounds occur on the feet and legs.
Diabetes. Heels should be inspected in the daily foot check. Redness, warmth, or tenderness are often absent because of nerve damage.
There is one thing specific to heels worth knowing, because it looks like neglect and is not. Debridement (removing dead tissue) may not be appropriate for dry and intact eschars with no clinical evidence of underlying infection. That includes an unstageable pressure ulcer with an intact eschar at the sacrum, buttock, or heel, because the intact eschar serves as a natural covering over the skin defect underneath. A hard dark area on a heel may be deliberately left alone.
A sore covered in dead skin cannot be staged at all, because the dead skin makes it hard to tell how deep the sore is.
The general reasons apply here too: infection, diabetes, poor circulation, nerve damage, bone infection, immobility, a weak immune system, poor nutrition, excess alcohol use, smoking, and a foreign body. And the numbers: a wound that has not started to heal in 2 weeks, or not completely healed in 6, is called non-healing.
Pressure relief is the part that can change today. Reposition about every 2 hours in bed, and use pillows, foam cushions, booties or mattress pads chosen with a provider. Avoid donut-shaped or ring-shaped cushions, which reduce blood flow to the area and may cause sores.