A foot is one of the hardest places on the body for a wound to heal, and there are three reasons why.
Sensation. Diabetes can damage the nerves and blood vessels in your feet, causing numbness and reduced feeling. That makes your feet more likely to get injured, and they may not heal well if they are injured. Diabetic ulcers are often painless, and redness, warmth, or tenderness are often absent because of nerve damage. The usual signals that something is wrong are missing.
Pressure. Foot ulcers are partly caused by too much pressure on one part of your foot — and that pressure continues every time the foot is used. Sometimes putting pressure on the healing ulcer for even a few minutes can reverse the healing that happened up to that point. A foot wound is one of the few that can be set back by ordinary walking.
Blood supply. Most ischemic ulcers occur on the feet and legs. Narrowed arteries prevent a healthy supply of blood from reaching them, so tissues don’t get enough nutrients and oxygen. For that kind of wound, blood flow to your legs needs to be restored.
All three can be present at once. People with poor blood flow often also have nerve damage or foot ulcers from diabetes.
Beyond those, here are the general reasons any wound fails to heal: infection, diabetes, poor blood flow, nerve damage, bone infection, being inactive or immobile, a weak immune system, poor nutrition, excess alcohol use, smoking, and a foreign body in the wound. Working out which apply is the job of a wound care team — to determine why it is not healing.
Here are the numbers that define the problem: a wound that has not started to heal in 2 weeks, or has not completely healed in 6 weeks, is called a non-healing wound. Foot ulcers are among the common types treated at a wound care center. Slow is not the same as failing — foot ulcers may take weeks or even several months to heal — but a wound that has not begun to change in two weeks is a different thing from a slow one.