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What is Intractable Plantar Keratosis?

Ouch…there seems to be a small stone in my shoe! You take off your shoe and there is nothing. Maybe you’ve experienced this before.

An Intractable Plantar Keratoma
An Intractable Plantar Keratoma

On inspection there is a “hard spot” in the same location. Prior to this you may have had the “hard spot” or callus, and although you knew it was there, it did not really bother you. Now, however, the area really hurts. It hurts more if you walk barefooted on a hard floor, but feels better on a carpeted floor. It will hurt if you are wearing a thin soled, or high heel shoe; it will feel somewhat better if you are in sneakers. You may have even tried to trim it away or put a pad on it to make it feel somewhat better, but ultimately, it just hurts. So what is it?

The most common cause for this scenario is what is known as an intractable plantar keratoma, commonly referred to as an IPK. This is a benign condition that develops as a result of excessive pressure under one or more of the balls of the toes, but can occur anywhere under the feet. It feels like a splinter stuck on the bottom of the foot. The pressure itself will initially cause a callus to form. The callus itself may or may not be a painful condition; some require treatment, many do not.

This type of callus is caused not by shoes or external sources, but from internal pressure. IPKs are usually tender with direct pressure rather than squeezing, and can be diminished with topical treatments, but when internal pressure from bone spurs or weight bearing knuckles are the root cause, topical treatments and trimming alone won’t make them go away forever. Unfortunately, with calluses, unless you modify the internal pressure, we’re talking surgery at this point or they are likely continue to come back.

Some contributory factors

 – Shape of the metatarsal head – Along this line of thought is the idea that the shape of a given metatarsal head may also precipitate the formation of an IPK. The underside of each metatarsal head consists of two condyles, which are rounded protrusions of bone. In some individuals, the lateral condyle (the one on the outside), will be excessively large and this can contribute to the formation of a keratoma.

– Hammertoes – Also to be considered are the effects of these, particularly what are known as rigid hammertoes. As the name implies, these are toes that stay bent or crooked during weight bearing and non-weight bearing. The excessively bent toe puts a retrograde or downward pressure on the metatarsal head just behind it, thus creating more pressure against the ground. This can contribute to the formation of an IPK.

– Lack of fat on ball of foot – Other anatomical considerations include the amount of fat that an individual has under the ball of their foot. The one part of the body where we do need to have fat is the bottom of the foot; unfortunately, that’s one part of the body where we lose fat as we age. Without the added cushioning, some people will be more prone to IPK formation. I should also mention that conditions like rheumatoid arthritis will also exacerbate the formation of an IPK.

Common conditions that may mimic an IPK is a plantar wart and a porokeratosis. If you go to your doctor complaining of a painful growth on the bottom of the foot, more often than not, you will get a diagnosis of wart. In all fairness, warts can “grow” in callused areas of the foot, but the majority of these lesions are IPKs.

Treatment

Conservative care

Avoid heelsShoe selection – In many instances changing the type of shoe that you wear will actually eliminate the problem. For example, the higher the heel that you wear, the more pressure you put on the ball of the foot. Wear lower heels. Very thin soled shoes will aggravate the condition; try wearing thicker soled shoes with a more cushioned bottom.

– Pads and cushions – Many people will resort to buying different types of pads to cushion the arPads help reduce the discomfort of IPKea; and yes, that can help. A few words of caution. If you are using adhesive pads, they should be changed daily. If not, you run the risk of developing an infection under the pad. Be careful when removing the pads, you do not want to tear the skin, otherwise the foot will hurt more. Avoid using medicated pads, especially if you are diabetic or have poor circulation. Medicated pads contain an acid.

– Professional medical care – Visit a podiatrist periodically, who will trim the callus and curette (carve out) the IPK. This is generally not a permanent cure and has to be repeated periodically, but having said that, it can gradually disappear or reduce in size due to nothing more than regular professional care.

Orthotics will help with IPK– Orthotics – When the IPK is due to a biomechanical problem such as an elongated metatarsal bone, or excessively hypermobile first metatarsal bone, an orthotic can be very helpful. Depending on the underlying cause, a custom orthotic can be built to take pressure off the IPK. With padding, what generally happens is either the growth disappears over time, or the time it takes for the growth to come back is dramatically increased.

Surgery

There are surgical approaches for the treatment of IPK in those individuals where nothing else gives satisfactory relief. The problem here is that the success rate is not necessarily as high as it is for other foot procedures.

Your podiatrist will have maintenance options for you though, so if you’re not wild about operating rooms, there is still hope for those feet. The bottom line is, before you start using over-the-counter topical irritants like corn or wart removers, see your podiatrist to determine what your problem spot really is.

 Your feet mirror your general health . . . cherish them!

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