A corn is a rather funny name for a very un-funny problem. A corn is thick skin on a toe. Corns can appear on top, at the tip or on the side of a toe. Below you will eventually see a series of pictures of a variety of corns.
Corns are caused when a bone in one toe rubs against the ground, the shoe or another toe. The first two pictures on the left are a the same soft corn on a second toe. This one is called a soft corn because of its location between the toes. The area between the toes tends to be a little more moist than on the top of bottom of the toes. The moisture softens the callus skin thus creating a soft corn. Corns on the tip or top of any toe or the outside of the little toes are called hard corns. It is not incorrect to call the thick skin on a toe a callus, but by convention we refer to them just as corns. By reading this page you will soon know more about corn than anybody but a Nebraska farmer.
The photo above is another soft corn. This patient is a very active and lovely 50+ year old woman who finds it quite difficult to wear shoes. She is quite fashion conscious and chooses not to wear wide boat-like shoes. She usually visits me about 4 times a year to have me "trim" her corn. This usually gives her many weeks of relief. This time it got to painful for her to wait for her regular visit. She came to me with a significant pain in her toe. As you can see after I trimmed the lesion I found a tiny little break in the skin, called an ulcer, in the middle of the corn. The toe is quite red so it might be infected. I trimmed her corn (called debrided in foot lingo), put some anti-bacterial cream on it and gave her a slew of corn pads to wear. If she chooses to only wear wide shoes or always wear corn pads she may not need to do anything more for her corn. If she wants to live without pads and goofy shoes she should consider a surgical solution. I suggested to her that we remove a little bone under the corn with a burr introduced through a tine little hole. It can be done under local anesthesia with or without sedation. It can be closed with a single suture that can be removed in only a few days.
WHAT IS GOING ON HERE?
When a bone rubs against a hard object, like a shoe or other toe, the overlying skin protects itself by getting thicker. If the skin gets thick enough we refer to it as either a corn or a callus. It is natural and normal to have calluses on the balls of the feet, under your heels and on the inside of your right middle finger where your pen or pencil rubs. These normal calluses illustrate the important point that a callus, by itself, does not have to hurt. Calluses can be normal protective structures of the feet, hands and even the knees if you spend a lot of time kneeling.
If one little area of your toes rubs too much, however, the callus gets so big it can be felt as a discrete little bump. Again, this hard little bunch of skin does not have to hurt. But if it is big enough and hard enough and been there long enough it can hurt. And it can hurt so much that it is difficult to wear a shoe or sometimes even walk. This led one wag to say that "Hell hath no fury like a woman's corn." (Sorry!)
WHY DO THEY HURT?
Corns hurt for several reasons. The skin hurts because it is rubbed and irritated. The underlying structures of the bone or joint capsule can become inflamed causing the medical terms of periostitis or capsulitis.
The most unusual reason for a corn to hurt is, however, bursitis. A bursa is a little pillow of protection that your body has in the knees, shoulders, hips and other areas of high impact or frequent rubbing. Most of the bursae in the body are well known structures in well known locations. These are called anatomic bursae. When these bursae get inflamed the process is referred to as bursitis.
Now you astute students of anatomy might note that the anatomy text books never show the presence of a single bursa in the toes. Right you are, Mr. Gray's Anatomy. But the human body is endlessly clever. It has the capacity to grow a pseudo-bursa in areas where it forgot to put a real bursa. A bursa of this type is referred to as an adventitias bursa. The diagram below shows a typical hammertoe with an overlying corn and an inflamed adventitious bursa.
This amateurish drawing of mine shows a typical curled hammertoe. The green areas are the three typical possible locations for corns. It is common to have more than one corn on a toe but relatively rare to hit the triple corn toe. The red areas are the locations of the bursae and the black squiggly things on the bones are the areas where bone or joint capsule can be inflamed.
Corns can also hurt and get infected when they for an ulcer or break in the skin. Squeeze your finger and then let it go. Look at the area of skin where you had your finger. It is white for the briefest of seconds and then pinks up again. The time when it was white is the time that the skin was not getting any blood. If skin is left without blood for some period of time it will die. Big corns, like the ones in the pictures above, are at considerable risk for developing a break in the skin (ulcer). You can see that clearly if you double click on the first two pictures. Podiatrists do not get a lot of emergency calls. However, when I get a weekend call that a heretofore "just painful" corn is suddenly swollen, red and PAINFUL, I somehow know that it has gotten infected.
WHY DID I GET A CORN NOW?
The Master Designer is very clever. Very few, if any, bony prominences in our body are exactly next or opposite to each other. If you look at the back of your hand and gaze at the fingers you will note that very few finger knuckles are exactly next to another knuckle. They are offset just a little.
This another simple drawing to show how typical bones line up with the knob of one bone meeting the shaft of a neighboring bone. It is unusual to get two knobs to meet each other. But as we go through life and get "more mature" out toes start to curl or deviate just a little from each other. Slowly the knob/shaft relationship erodes. This second picture is attempting to show what happens when one toe starts to move in relationship to the other. The knobs of two bones now start to meet each other. In toes, there is skin trapped between these bones and the skin starts to develop a callus. If the process continues the callus gets larger, a periostitis, capsulitis and a bursitis develop. Thus develops a painful toe callus, or corn.
HOW DO YOU TREAT CORNS?
Corns are usually caused by a toe bone pushing skin up against the shoe. Treatment , then, is directed to the shoe, skin or bone.
1. Shoe modifications can help. This means getting wider shoes, shoes with taller toe boxes, softer shoes, no shoes, thicker socks or even moving to Hawaii and wearing no shoes. People who live in sandals get few or no corns.
2. Treat the skin by thinning the callus. On your own yo can do this with a callus brush, pumice stone or other device. Your pedicurist may be able to help or yo can have in done in a podiatry or dermatology office, although some family practice doctors are also shaving calluses lately. Instead of shaving the callus you can make it thinker with callus creams and lotions. Corn potions that contain acids should not be used by people with diabetes, poor circulation or no feeling in the toes.
3. Doing something about the bone. This usually implies a surgery for hammertoes. I will soon cover this in a section on hammertoe surgery but simply put a hammer toe surgery is done under local anesthesia and involves either shaving or removing a piece of bone from the toe. Recovery is rapid but does require some time in a flat surgical shoe.