Can The Foot Have A Fever?

An increasing body of research is finding that raised temperatures can be predictive of diabetic foot ulcers (DFUs) or recurrent ulcers.

A study in press in the Journal of the American Podiatric Medical Association focused on 37 patients with diabetes: nine with diabetic neuropathy and a history of DFUs, 14 with diabetic neuropathy, and 14 without neuropathy.¹ My coauthors and I measured resting barefoot plantar temperatures with an infrared thermal camera. The study notes the mean temperature readings in each foot region were higher than 30°C in those with DFUs and neuropathy in comparison to those without neuropathy (below 30°C).

This study raises a couple of important points. We have known for quite some time that a wound will heat up before it breaks down. Our group and others have proven if one compares one foot to another and a difference of 4°F or more appears to be a key number that is associated with a higher risk of ulceration or re-ulceration. It also appears to be important vis-a-vis assessment of patients with Charcot.

This study asks the question: can the foot have a fever? It is pretty compelling because certain types of patients and certain types of diabetic feet may have warmer resting temperatures than others. There are previous studies that indicate that increased skin temperatures just by themselves, over a certain very high temperature like 35°C, might actually put a foot at higher risk for skin breakdown. If that’s true, then we may want to be monitoring the absolute foot temperature in addition to select areas of the foot.

The simplest and most inexpensive thing we use is a temperature monitor from Amazon, costing about $12. We have our nursing staff come in and measure both feet. They circle an area that might have high temperatures. We tell the patient to do that at home. Many other devices are much fancier and companies like Podimetrics and Siren are coming out with other diagnostic technologies that are equipped to monitor the foot. If physicians really want to be at the cutting edge, I would definitely recommend looking at thermometry and measuring inflammation.

Reference
1. Yavuz M, Ersen A, Hartos J, et al. Temperature as a causative factor in diabetic foot ulceration: a call to revisit ulcer pathomechanics. J Am Podiatr Med Assoc. 2019; epub Nov. 18, 2018.