LOS ANGELES – Practitioners treating Charcot foot have little evidence to guide them in selecting the right medicine, according to an international task force offering guidance on diagnosis and treatment of the condition.
Reporting on its January 2011 Paris meeting, task force cochair Lee C. Rogers, D.P.M., said the group of 18 experts from six countries took hours just to arrive at a definition of the syndrome. Ultimately, they decided that Charcot foot is an inflamed foot in a person with neuropathy.
The official report of the task force, convened by the American Diabetes Association (ADA) and the American Podiatric Medical Association, will be published in the journals of those organizations. Dr. Rogers of the amputation prevention center at Valley Presbyterian Hospital, Los Angeles, cautioned that he was offering only his personal observations on the proceedings.
"The major thing you’ll see in this task-force document is that there is very little evidence for any of the pharmacological treatments ... [But] that doesn’t mean we don’t use them in clinical practice," he said at the Diabetic Foot Global Conference, which was presented by Valley Presbyterian Hospital.
Although there are no good prevalence studies on Charcot foot, the task force estimated that 0.15%-1% of patients with diabetes suffer from the syndrome, said Dr. Rogers. There are 40,000 new cases a year in the United States. Patients with Charcot foot are more likely to suffer amputations, and may have a higher mortality rate, he said.
Having Charcot foot increases the risk of a foot ulcer 36 times, and 30% of patients with one Charcot foot have two Charcot feet. "It’s known that Charcot foot impacts the lifestyle of the individual, and often ... leads to permanent disability and premature retirement," Dr. Rogers said.
The syndrome appears to start with a traumatic event, which the patient may or may not remember. The trauma sparks inflammation. A patient with autonomic neuropathy may continue walking on the foot without feeling pain, leading to a cycle of fracture, subluxation, dislocation, and deformity.
"One of the things that is very important that came out of this meeting is that inflammation is the key to the pathogenesis of Charcot foot, and is also the key to diagnosis," said Dr. Rogers.
Charcot foot is often misdiagnosed, or diagnosed late. If clinicians can recognize the inflammation early on, they may be able to prevent the chain of events that leads to such conditions as rocker bottom foot later on.
The panel agreed that a Charcot foot should be classified as "active" if inflammation is continuing, or "inactive" if the inflammation has subsided. They thought this was more useful than the terms "acute" and "chronic," which only suggest how long the condition has been present.
The first step after suspecting Charcot foot is imaging, Dr. Rogers said. "What’s important when you’re trying to make a diagnosis based on imaging is that you have to incorporate a lot of the clinical findings to determine which type of imaging to perform: whether or not you suspect osteomyelitis, [or] whether there’s the presence of an ulcer."
He recommended starting with an x-ray to see whether there is bone destruction. MRI can’t be specific for Charcot foot vs. osteomyelitis unless you consider secondary signs, said Dr. Rogers, who noted the following:
• More than 90% of cases of osteomyelitis in diabetic foot are from contiguous spread, and the spread can be traced from an ulcer to the bone on MRI.
• Osteomyelitis primarily affects only one bone, whereas Charcot may affect multiple bones.
• Deformity is more common in Charcot foot than in osteomyelitis.
• Charcot foot is more often in the midfoot, whereas osteomyelitis is more common in the toes and forefoot.
Turning to medical treatments, Dr. Rogers said, "The most important thing you can do is offloading."
He recommended educating "other members of the team," such as emergency room physicians who may treat Charcot patients presenting with an injury and a swollen foot that has not yet been x-rayed. "Offloading and immobilization can avoid the later sequelae," said Dr. Rogers.
There is little research to compare a cast walker or a total contact cast, he said. Some on the panel recommend complete avoidance of weight bearing, he said. A Roll-A-Bout walker offers another alternative.
In one study, patients took a mean of 18.5 weeks of casting to quiescence (J. Am. Podiatr. Med. Assoc. 1997;6:272-8). "This is not something where you can tell the patient, ‘We’ll have you out of the cast and walking in 3 weeks,’ " said Dr. Rogers. "You have to explain to the patient [that] this is a long process."