Despite the passing of 140 years since first being described, little is known about Charcot foot as a lower-extremity complication of diabetes. Charcot foot occurs in about 1% of patients with diabetes, the most common disease associated with Charcot foot. In January 2011, the American Diabetes Association and American Podiatric Medical Association called together an international group of 18 leading experts to develop a consensus on the definition, diagnosis, and medical and surgical treatments of the Charcot foot in diabetes. The consensus was subsequently published in the September 2011 issue of Diabetes Care.
Recognizing & Diagnosing Charcot Foot
Neuropathy is an essential element of Charcot foot. Also, nearly 50% of patients recall some type of trauma, which is many times trivial in nature and has caused no pain. Patients tend to walk on this non-painful, traumatized foot, which then becomes highly inflamed. This can lead to focal osteopenia, collapse of the arch, and bone fractures.
“Early diagnosis is the most important way to prevent complete destruction and amputation of the foot.”
When considering a Charcot foot diagnosis, clinicians should look for a red, hot, swollen foot. The Charcot foot can be so hot that physicians will observe a palpable difference between extremities as high as 10° F. A difference between feet greater than 4° F with a dermal thermometer is considered significant for inflammation.
Early diagnosis is the most important way to prevent complete destruction and amputation of the foot. If a foot is diagnosed by deformity, damage within the foot has already occurred, placing patients at risk for amputation. Imaging should support the clinical diagnosis. The first diagnostic test should be a plain x-ray, which in many cases is enough to make an accurate diagnosis. If osteomyelitis is thought to coexist with the Charcot foot, advanced imaging with an MRI or bone scan should be used.
Charcot Foot Treatment
Because patients with Charcot foot are often seen after deformity has set in, treatment is challenging. Such cases can require reconstructive surgery to give patients a more biomechanically stable foot. Surgical options range from lengthening the Achilles tendon to reconstruction of the entire foot and placing it inside an external fixator. If caught early, the Charcot foot is usually treated with offloading, using a total contact cast and an order to avoid weightbearing activities, which is often successful. Care must be taken to avoid trauma on the contralateral foot; the incidence of bilateral Charcot foot is 30%.
While antiresorptive therapy has been analyzed in a few studies in the Charcot foot, the sample sizes of these investigations are too small to support any general recommendations. Bone growth stimulation has not been shown to result in major improvements in patients with Charcot foot outside of use in surgery. It’s clear that more research is needed to establish the true value of antiresorptive therapy and bone growth stimulation.
Looking on the Horizon
Ongoing studies are currently looking at the use of blood tests to help diagnose Charcot foot based on genetic predisposition in patients with diabetes. It’s hoped that more information on this approach will emerge in the next decade. In the meantime, early recognition and referral to a Charcot foot specialist remain critical in avoiding deformity and subsequent surgery. The earlier Charcot foot is identified, the more likely we’ll be able to better manage patients through this difficult complication.
JonN