Dorsal corns, meaning top, can be particularly sore because they are formed on areas where there is little fatty protection- mainly on the tops of toes.
Just like any corn formation, the dorsal corns are there because something is putting pressure on the tops of those toes. But it doesn't have to be the tops of toes to enjoy these corns. Boney prominences where there is outgrowth of bone can be an area of corn formation. People who have large boney areas on top of their 1st toe (from a prolonged condition called Hallux Limitus) can be prone to dorsal corn formation (as the picture below shoes the boney area)
Dorsal corns are formed when a piece of footwear is too shallow for the foot. Now did you notice that I said footwear rather than shoes. It is a common mistake to say that shoes are the cause, another, less well known cause is the slipper. Slippers have the reputation of being soft, fluffy and warm. But just like shoes they are very inelastic and can be too tight for the foot- especially if a patient has foot swelling. This causes rubbing- patients then think that the corn is caused by their shoes so they wear their slippers even more, which makes the matter worse.
Apart from too shallow a piece of footwear. Seams can be another factor in dorsal foot corn development. We saw one patient who had the top of their big toe dressed daily for 6 months- yes 6 months. We went in, saw that the patients slippers had a lovely seam running directly over the lesion- we cut a hole in the slipper. Out protruded the top of the toe. Within 3 weeks that same toe had healed.
That is the main problem with all corns- the possibility of breakdown. Because corns are an upside down pyramid the point sticks into the tissues. With added pressure from above the corn presses down on the tissues even more. Sometimes the pressure becomes too great that the blood vessels break and blood seeps into the corn causing a red line or streak within the corn. Noted in the picture below:
If that happens you know that blood is being pressed away from the area. If blood can not get to the tissues then they starve of oxygen and then tissue break down occurs and then you will get an ulceration under the corn.
In severe cases where the dorsal foot corn is there for a very long period of time, coupled with a patient with reduced circulation, the broken down products from the above situation can not go anywhere, so they go through the path of least resistance which is usually down. In this instance it is not too uncommon to remove the corn and find that it has tracked down to bone, in this case weekly redressings and a possible course of antibiotics is needed. Dorsal corns are notorious for this because of the little in the way of "fat and meat" that separates the skin and bone on the toes.
Now I am not trying to scare you into anything, I am just stating what a small corn can do. So don't leave it, get something done about it.
There are many methods for removal and prevention of the dorsal foot corn. Some have their pros and some have their cons.
1- Prevention is much better than cure, so finding out where the corn comes from in the first place is the best start. If its cause is from shallow shoes or slippers change them. Going to the Cobbler and having them stretched is a good initial method of relief but we found that just getting new deeper shoes is the best alternative. If it is from slippers, cut a hole out of them where the toe hits the top of the slipper. If you don't want to go down that route, get deeper slippers. If it is a seam in the slipper or shoe then get a better pair.
Go out about 2-3 o'clock when your foot is bigger and then find a new pair of shoes or slippers. Remember sneakers are a really good alternative. But if you have got extra boney growths or your foot is wider then most high street shops will only really sell to the majority rather than the minority foot types, so you may have to try specialty stores that cater for the wider and deeper foot.
2- Enucleation. This is where a Chiropodist/ Podiatrist removes the corn from your toe. It is one of the best treatment methods for corn removal around. It should be painless, quick and the relief is found as soon as it is removed. Once you have a corn, any rubbing is going to keep it there. So once it is enucleated you can then start prevention methods. There is a downside to this treatment and that is the Chiropodist themselves. If they are no good or they don't follow up the treatment with a preventative measure then you will be going back for a while, and that can be costly, quickly painful and pointless.
3- Corn plasters/ corn paste/ silver nitrate. Stay away from these devices. The problem comes in the fact that they contain an acid which is supposed to remove the corn. However as many times the manufacturers put a warning on them not to be touched by blood insufficient and neurologically reduced patients, they invariably do and the consequences are a big problem. Because it is an acid, it will wipe out the corn but it will wipe out the surrounding healthy tissue and will only stop when it becomes painful (you taking the treatment off your toe) or when it becomes neutralised by blood. If you are neurologically compromised then you will not feel the effects of the acid and will leave it on until you get an ulcer. If you are vascular compromised then you will have a tough time healing and repairing the damage left behind.
4- Dosal shields- temporary. These are "u" shaped felt crescents which act by deflecting the pressure away from the dorsal foot corn. These work very well. You can get them from over the counter and they are little donut rings, but usually a Chiropodist can make you one. The "over the counter" rings aren't beveled and are not custom made to your toe so they usually fall off easily. The felt custom ones are better.
Again the problem can be with the Chiropodist if they are no good at making these things. Another is that you really don't want something sticky being attached to your foot all the time. Sticky tape makes the skin dry and worse for wear especially if the device is left on for ages. Some patients wash the felt and re-stick onto their foot and it looks, and is, awful. Another problem is the application of the device. If you do it yourself then you might place it in the wrong area. This would then add to the pressure and make the dorsal foot corn worse.
5- Dorsal Shields- permanent. A better version of the temporary shield. The permanent version which is made out of Silicone lasts much longer (up to a couple of years), is washable and works very well. In our clinic we usually make the temporary version, then bring the patient back 6 weeks later and then find out how they did with the felt device. If they liked the toe feeling much better, without pain, they always go for the silicone device.
There are problems though. They are only made by the Chiropodist, but if that Chiropodist doesn't make them that well or doesn't like to- then you will get a poor device. Secondly, if you insert the device wrongly onto your toe it will become ineffective. The device is a preventative measure- if you have a dorsal foot corn then apply a silicone device it will not work because the corn is there. It prevents the corn from coming back- so it needs to be worn all the time (apart from bed and baths/showers). Some patients just do not like something "different" on their foot so they resist the device and remove it.
Those are the main treatment methods. They are the most effective. A dorsal foot corn can be treated with ease by preventative measures- by removing the problem in the first place will illicit relief. If you have a corn get it removed by a Chiropodist and then you will notice the difference.
Places where you could have a corn.