Treating a wound on a Charcot foot can be a challenge. Our expert panelists discuss the diagnosis of acute Charcot, the management of Charcot and Charcot-related wounds, indications for exostectomy and keys to facilitating a return to weightbearing.
Q: How do you diagnose an acute Charcot foot? Do you use any ancillary testing?
A: Most of the time, Geoffrey Habershaw, DPM, diagnoses acute Charcot by combining the patient’s history and physical with simple tests.
Dr. Habershaw, Lawrence Lavery, DPM, and David G. Armstrong, DPM, PhD, cite swelling and temperature changes as signs of Charcot. Dr. Habershaw says crepitus, deformity, swelling and warmth “pretty much clinch” the diagnosis of Charcot. He adds that plain X-rays with the aforementioned physical findings will confirm Charcot. Dr. Habershaw says a triphasic bone scan will confirm micro-fracture and ligamentous damage. In this clinical scenario, he rarely uses magnetic resonance imaging (MRI).
For Dr. Lavery, the diagnosis starts with a high index of suspicion. He notes that Charcot patients have unilateral edema along with trauma that is mild, incidental or unknown. Such patients will have numbness, tingling and formication, according to Dr. Lavery. He says these patients feel their feet are thick as if they have a sock or mud stuck to the bottom of their foot. He says a thorough sensory examination with monofilaments will reveal diminished pressure sensation and an abnormal vibration perception threshold. Dr. Lavery notes that temperature assessment will usually reveal the affected foot has an increase in temperature of 4 to 10º F in comparison to the other foot. He advises checking radiographs to ensure the patient does not have a fracture or dislocation.
Dr. Armstrong notes that Charcot’s arthropathy of the foot is a diagnosis of exclusion.
“A profoundly and globally red, hot, swollen foot in a neuropathic patient in the absence of other causes should be considered Charcot arthropathy until suggested otherwise,” maintains Dr. Armstrong.
Likewise, Lawrence Karlock, DPM, says when a patient presents with a warm, red, swollen diabetic neuropathic foot with a closed soft tissue envelope, one should consider it a Charcot foot until proven otherwise. He says one must rule out other differential diagnoses of cellulitis and gout.
In a patient with neuropathy, new, unilateral pedal edema will rule out Charcot in the differential diagnosis, according to Dr. Habershaw.
Q: What wounds do you commonly see in the Charcot foot or ankle?
A: Dr. Habershaw says classic midfoot Charcot and Charcot in the Lisfranc joint may lead to ulceration either below the first metatarsocuneiform joint or below the cuboid. When there is rearfoot Charcot or Charcot in the Chopart joint, Dr.
Habershaw says the wound will be proximal to the cuboid. In Dr. Lavery’s experience, the most common wound site with Charcot is over the cuboid.
Dr. Karlock agrees. He says it is common to see a midfoot Charcot foot present with a plantar first MPJ ulcer medially or with a subcuboid ulcer laterally. He notes the Charcot ankle will present with a varus deformity and a lateral malleolus ulcer.
In regard to subtalar or ankle Charcot, Dr. Habershaw says one will see ulcerations either medial or lateral on the foot and ankle depending on which way the foot drifts. With a medial foot drift, one will see a lateral ulceration whereas a lateral foot drift may lead to medial ulceration, according to Dr. Habershaw.
Dr. Armstrong notes that approximately 40 percent of people with Charcot arthropathy will present with a concomitant wound. He adds that about 80 percent of those wounds associated with Charcot arthropathy are in the midfoot.
Q: How do you manage the acute and chronic Charcot deformity, and its wounds?
A: Dr. Lavery manages Charcot wounds as he manages other neuropathic ulcers and fractures. He first uses compression to reduce edema and emphasizes non-weightbearing if realistic. He then uses a total contact cast (TCC) to immobilize the foot and protect the ulcer from the forces of weightbearing. Dr. Habershaw says non-weightbearing is “the keystone” in Charcot treatment, particularly for patients with ulcers.
For acute Charcot, Dr. Karlock uses complete non-weightbearing, a below-knee fiberglass cast with close monitoring. He will also use a CROW Walker.
Dr. Habershaw emphasizes optimal wound care by ensuring adequate arterial flow, control of the infection, offloading and frequent and aggressive ulcer debridement. He also suggests appropriate consults in order to facilitate metabolic control and monitoring of cardiac function, renal disease and nutrition.
In the short term, he says nonsteroidal antiinflammatory drugs (NSAIDs) may be effective while bisphosphonates may be helpful in the long term. Dr. Lavery works closely with endocrinologists who institute bisphosphonates. Dr. Lavery adds that he will employ bone stimulators when patients meet the Centers for Medicare and Medicaid Services (CMS) criteria. Dr. Karlock likewise uses external bone stimulation.
Q: What approach do you take in the surgical treatment of these wounds/deformity? Is there any role for skin substitutes?
A: Dr. Armstrong stresses that Charcot arthropathy is “first and foremost a medical disease.” He notes that only 25 percent of people with the arthropathy need any form of surgery and two-thirds of those patients generally need exostectomies. At the Center for Lower Extremity Ambulatory Research (CLEAR), Dr. Armstrong says the group is interested in the possibilities for treatment on the medical side of the equation as well as the surgical. He says it may be useful to address the RANK-L OPG pathway with modalities like intranasal calcitonin (200 IU/day in alternating nostrils), and perhaps even TNF alpha inhibition.
However, when a patient has a profoundly deformed foot and/or ankle that will not fit in a shoe, this is an indication for reconstruction, according to Dr. Armstrong. In such cases, Dr. Armstrong has found hybrid external ring fixation “highly useful” at CLEAR.
If the patient has osteomyelitis, Dr. Habershaw opts for surgery early. He says one can efficiently diagnose osteomyelitis by combining a probe to bone test with an X-ray. He says the specificity and positive predictive value approaches 90 percent with this technique. While MRI is more sensitive and specific, Dr. Habershaw cautions that there are more false positives and the test is expensive.
When it comes to Charcot wounds, Dr. Lavery says one may consider bioengineered tissue such as Dermagraft (Advanced Biohealing), VAC therapy (KCI) and collagen matrix materials like Unite (Pegasus). He says one can use these products with offloading in a prefabricated boot such as the Aircast boot.
Q: What is your indication for exostectomy?
A: Before considering surgical reconstruction, Dr. Lavery waits until the acute phase of the process ends. As he says, the goal of therapy is to get a functional plantargrade foot via the least invasive means.
“If we catch these injuries early enough, often a simple exostectomy is all that is required,” he says. “If there is a more severe deformity, the surgical plan obviously becomes more involved.”
In most cases of a chronic, stable Charcot midfoot deformity, Dr. Karlock says one can use a simple exostectomy along with Achilles tendon percutaneous lengthening. Otherwise, he says Charcot reconstruction may be indicated.
Stable Charcot with a non-healing ulcer will respond to an exostectomy adjacent to the ulcer, according to Dr. Habershaw. He says one would saucerize the exostosis and leave in a drain before closure. Dr. Habershaw advises leaving the wound open if sepsis is present. He recommends performing open reduction with internal fixation (ORIF) for a patient with ulceration, no osteomyelitis and unstable Charcot. Dr. Habershaw says the surgeon should attempt to restore the arch with plantar plates in midfoot Charcot or reposition the foot under the leg with nails or large compression screws in the case of subtalar or ankle Charcot.
Dr. Habershaw does not use external fixation frames in these cases. If the patient needs a frame, Dr. Habershaw says it is because the surgeon waited too long before considering exostectomy or ORIF.
Q: What are your preferred off-loading devices in these cases?
A: For Dr. Habershaw, offloading devices include crutches, walkers, wheelchairs or, in an agile patient, a Roll-About. He says canes do not qualify as offloading. While Dr. Karlock says a wheelchair is the “most prudent” offloading device when indicated, he notes that most patients refuse to use one.
Dr. Habershaw places acute Charcot patients who cannot be totally non-weightbearing in a padded cast brace and molded plastazote orthotic, which they use for three months or more. For exostosis patients who have a history of ulcers and have undergone primary closure, Dr. Habershaw says they should be non-weightbearing for four to five weeks. He subsequently transitions them to padded cast braces. Those who have undergone ORIF are non-weightbearing for three months before wearing cast braces, according to Dr. Habershaw.
Dr. Armstrong will use a TCC or instant total contact cast (iTCC) until the foot cools down.
Dr. Karlock ideally prefers to use a true or modified TCC in compliant patients and he notes that the CROW Walker has an obvious advantage of daily wound inspection.
Immobilization is often inadequate or used for too short a time period, says Dr. Lavery. For 15 years, he has assessed temperature using a handheld infrared thermometer (TempTouch, Xilas Medical) to help in the evaluation process. He uses the opposite foot to compare temperatures. Once the temperatures are about the same on the Charcot extremity, Dr. Lavery says the patient is ready to advance to the next level of “offloading.”
With such a patient population, Dr. Lavery does note a catch-22.
“They need to be active to combat obesity and heart disease and diabetes, but they need to rest and immobilize a limb that usually takes two to three times longer to ‘heal’ than a traditional fracture in a non-diabetic,” he says.
Accordingly, Dr. Lavery will normally begin with a TCC and then transition the patient to a prefabricated fracture boot like the AirCast boot or the Ossur diabetic boot. While patients are in a removable boot, he says the pedorthist can begin making shoes and insoles. Often custom shoes and insoles are required because of the severe deformity, according to Dr. Lavery.
Dr. Armstrong is a Professor of Surgery, Chair of Research and Assistant Dean at the William M. Scholl College of Podiatric Medicine at the Rosalind Franklin University of Medicine in Chicago. He is the founder and director of CLEAR, and is the co-Founder of the International Diabetic Foot Conference (DFCon), which is held annually in Los Angeles.
Dr. Habershaw is an Assistant Professor of Surgery at Boston University School of Medicine, and Chief of Podiatry at Boston Medical Center.
Dr. Lavery is a Professor in the Department of Surgery at Texas A&M Health Science Center College of Medicine.
Dr. Karlock (shown at the left) is a Fellow of the American College of Foot and Ankle Surgeons, and practices in Austintown, Ohio. He is the Clinical Instructor of the Western Reserve Podiatric Residency Program in Youngstown, Ohio. Dr. Karlock is a member of the Editorial Advisory Board for WOUNDS, a Compendium of Clinical Research and Practice.