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Canadian Medical Alliance for the Preservation of the Lower Extremity
On our debridement page, we discussed the importance of removing the callus and dead tissue surrounding a wound in order to fully assess the ulcer. This is because it's difficult to assess what you cannot see.
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As a real-life example, we asked you to look at the six calluses below.
Can you tell which two of these photos represents a routine callus with normal skin (no ulcer, no infection) underneath? Click here to find out.
Which callus covers an ulcer extending through the skin to the soft tissue (but not bone)? Click here to find out.
Which covers an uninfected ulcer that extends down to bone? Click here to find out.
Which covers a soft tissue infection? Click here to find out.
And which covers a bone infection? Click here to find out.
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The simple calluses proved to be #3 and #5.
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Given the black discoloration associated with the callus, one might imagine that there was an ulcer beneath the callus here, with the black representing bleeding beneath the skin.
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But debridement proved it to be a simple, routine callus.
This callus looks quite large, but upon debridement, we can see it's not deep, and not an ulcer.
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Click here to go back to the top.
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The callus covering an ulcer that extended through the skin and into the soft tissues below is #1.
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It's a small, superficial ulcer.
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Click here to go back to the top.
Which covers an uninfected ulcer that extends down to bone? It's #2.
This patient had an ulcer treated for over a year, and she was told it was closed, and the dead skin was "just a callus."
But calluses aren't normal, and need to be debrided to assess the foot. In this case, the crust was simply pulled back, to reveal an ulcer down to bone (see blue arrow) in the photo to the right (tilted to keep the foot orientation straight) and its x-ray
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The ulcer never became infected and was treated with local wound care and sugar control. To see the effects of hyperglycemia (high sugar) on a wound, visit our page on diabetes and its effect on foot ulcers.
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Click here to go back to the top.
Which callus covers a soft tissue infection? It's #4.
This patient had an infected 2nd toe. It was treated with oral antibiotics, 6 weeks of IV antibiotics. The patient had a vascular consult, an infectious disease consult, several x-rays, a CT, an MRI and a bone scan.
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Imagine the cost of this work up.
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The problem was a simple corn (a callus on a toe). It needed debridement (removal of the corn) in order to drain the pus from the ulcer, and offloading (removal of body weight), achieved with a custom moldable support (above photo).
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It was healed at two weeks. The patient kept the ulcer away by using the support long term. The toe could have been surgically corrected to achieve offloading, but she was not a good surgical candidate.
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This is something any podiatrist would recognize and know how to treat instantly. She wasn't referred, however, because most podiatric services are not covered by most provincial health plans.
Click here to go back to the top.
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And which covers a bone infection? It's #6.
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The callus (far left) didn't look like much.
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Even after debridement, (near left), it didn't look like much.
But if you look closely, you can see a small hole on the outside edge of the callus (blue arrow, near left).
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This, too, doesn't look like much. But the ulcer extended to bone, and the bone was infected (osteomyelitis).
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The infection was resolved with antibiotics delivered through IV (a line inserted into a vein).
However, the recurrent nature of the wound prompted a decision to remodel the bone to surgically offload the weight, with the hope of permanently resolving the ulcer.
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Unfortunately, the post-operative biomechanics of the foot was not fully considered, and the metatarsal head was removed. (It's previous location is marked with an O.)
This resolved the ulcer, it is true, as there is no bone left to press down causing the callus that leads to an ulcer.
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But with the 5th metatarsal head now gone, something else must bear weight.
In this case, it is the base of the 5th metatarsal, where the callus has developed.
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More often, it would be the adjacent 4th metatarsal head (marked with an X).
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In this case, a new ulcer has developed underneath the new callus.
Conservative options are offloading through an orthotic or a custom shoe.
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Surgical options to remodel or remove bone at this ulcer site are available. But this removing the bone involved with the callus would leave a new location to bear weight. And as tendons attach to this site, removing the bone would tend to cause the foot to invert (roll onto the outside, causing additional problems.
As you can see, your surgeon needs to have a very good grasp of biomechanics, or surgery can lead to unintended results. This is a specialty of podiatric surgeons.
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How did you with your assessments? Could you tell what was going on with the wounds by looking at the calluses?
Even experienced clinicians would have difficulty making a proper assessment without debriding the calluses.
So debridement is a basic and necessary treatment for calluses in the diabetic and neuropathic foot.
As we tell our patients, if you see a "callus," "call us." The diagnosis (callus) literally tells you what to do (call us) when you see it.
Click here to go back to the top of the page.
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To learn more about biomechanics of the foot and what this means for foot ulcers, click here.
To learn more about surgical offloading, click here.
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Click here to go back to our page on debridement.
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This page written by Dr. S A Schumacher
Podiatric Surgeon
Surrey, British Columbia Canada
All clinical photographs are owned and provided
by Dr. S A Schumacher. They may be reproduced
for educational purposes with attribution to:
Dr. S A Schumacher, Surrey, BC Canada
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