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Calluses: Friend or Foe?

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Put A Spring in Your Step without Winding up Wounded

Spring has sprung! And there are many new activities that you’ll want to join in, this spring. So how can you be sure that you’re putting your best foot forward? We have recently been focusing our series on pressure ulcers that occur because of immobility. Now we will focus on a common skin condition caused by too much mobility: calluses. Are they friend or foe?

All of us have probably had the experience of doing a new activity or something we haven’t done in a while, like raking leaves or playing guitar or walking in a new pair of shoes and experienced some blisters or calluses on the thin-skinned areas of our feet or hands. Conventional thought says that we should just keep doing this and our skin will toughen up. IF you have normal sensation and circulation, calluses can just be thickened layers of skin that come with repetitive activity. They initially protect the skin from breakdown.

But what about the “high risk” foot? What about those who have peripheral neuropathy, loss of protective sensation in the foot? What about those with peripheral arterial disease or decreased blood supply to the foot? Are calluses safe for these feet? First, let’s take a few steps back.

What is a callus?
Callus is defined as a “common, usually painless thickening of the stratum corneum at locations of repeated, external pressure or friction” (AAWC Wound Glossary).

There are 2 types of pressure on feet:
Direct pressure: standing, weight bearing pressure
Friction: resistance between two surfaces rubbing together.

If the callus gets too thick and goes unattended, then the callus itself that starts out protecting one’s skin can become the problem itself, many times causing a wound. Remember: pressure wounds are caused by tissue usually stuck between a rock and a hard place – the bone and the callus. No oxygen can get to the tissue and so it erodes and can cause a wound.

Callus can actually be a pre-ulcerative lesion. Many times there are speckles of bruising or blood in the callus and it is actually hiding a wound beneath it. One study by Sage found that 82% of diabetic foot ulcers are preceded by calluses.*

Take a look to the left at what is lurking beneath this callus:


What is going on inside the skin?

Take a look at these next photos: this first one shows a problem occurring in the most common area for calluses.
This woman came in with a large diabetic foot ulcer over the ball of her foot. Over the last ths (the 4th and 5th metatarsal heads), she has calluses. She could not feel her feet due to neuropathy. Her open wound itself was clean, non-infected, and pretty superficial.

Now take a look at these next two close-ups: they are the same picture, a side view of a callus seen from the inside out. The callus is white because it is moist. Look at the thickness of those built up layers! It’s just like having a built in rock in her shoe.

Left unattended, that callus would have bore a hole through the outer layers of the skin and cause more wounding. When this woman came in, we removed the layers of callus (by debridement) and gave her good pressure relief.

Here is the good news! This photo was taken just 2 weeks later: her wound has closed and her calluses are much less!

So how do you prevent callus formation?

Prevention is the key – as with any pressure problem. Calluses form where there is FOCUSED pressure and friction and there are 26 bones in the foot! Calluses are reduced when pressure is redistributed on softer, more pressure tolerant areas of the feet with the right inserts and shoes.

We all come in different shapes and sizes. See a foot specialist to evaluate your feet and to get properly fitted inserts and shoes to give your foot the right support (from a podiatrist or a pedorthist). In general, you want the “Goldilocks” version of footwear: Not too small to where it will create pressure, Not too big that it will slide and create friction, but …

Just the right size!

It has been said: “Pain is a gift that nobody wants”. If you cannot feel your feet, they will not alert you to a problem. This is the crux of neuropathy and the development of wounds. Protect your feet by inspecting, cleaning, and moisturizing them daily (or having someone look at them for you if you cannot see them) to catch any problems early. See diabetes.org for a complete list of foot care and prevention tips.

With a good team, proper pressure relief footwear, and regular attention to your feet, you will make big strides toward good health.
So Spring into action toward happier feet!

*Sage, Ronald. “Journal of the American Podiatric Medical Association.” Outpatient Care and Morbidity Reduction in Diabetic Foot Ulcers Associated with Chronic Pressure Callus. JAPMA, 1 June 2001. Web. 20 July 2013.

This blog post was written by Robin Carlson, PT CWS
What is PT CWS? Physical Therapist and Certified Wound Specialist

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