Charcot foot: the early signs people miss
Charcot foot (also called neuropathic arthropathy) is damage to the bones and joints of a foot that has lost protective sensation. It usually begins without a wound and often without much pain, which is exactly why it is missed. Caught early it can often be managed by offloading the foot; caught late it can leave permanent deformity.
What the early stage looks like
- A warm foot. One foot feels noticeably hotter than the other, especially across the middle and the top of the foot.
- Swelling. The foot or ankle looks puffy and shoes feel tight, often on one side only.
- Redness. Colour change that may fade when the leg is raised for a few minutes.
- Little or no pain. Many people carry on walking, which is what drives the joint damage.
- No wound. Unlike an ulcer or infection there is often nothing to see on the skin.
Why temperature matters here
Because the visible signs are subtle, clinicians commonly compare the temperature of the same point on each foot. A difference of about 2.2°C (4°F) between one foot and the matching spot on the other foot is the figure most often used as a warning threshold. The 2023 IWGDF guidance describes this as a widely used rule while being clear that its diagnostic accuracy has not been established — temperature alone can neither confirm nor rule out active Charcot.
Two practical limits are worth knowing. If both feet are affected, the left-right comparison loses its value. And there is no separately validated threshold for the top of the foot, even though that is a common site for early Charcot change. We set out the sources behind this on our clinical evidence page.
What to do if you notice a hot, swollen foot
- Contact your podiatry clinic, GP or diabetes team the same day.
- Stay off the foot as much as you can until you have been seen.
- Keep recording daily temperatures so the clinic can see the pattern.
- Seek urgent care if you also have fever, pus, spreading redness, or a break in the skin — that may be infection rather than Charcot.
How PodiaScan fits in
PodiaScan records seven zones on each foot — six on the sole and one on the top of the foot, added specifically because dorsal warmth can be an early Charcot clue. The app compares each zone with the matching zone on the other foot and flags a hot spot. If the same zone stays hot on three days in a row, your linked clinic is notified automatically.