What is Charcot foot?
Charcot foot is a rare but serious complication that can affect persons with peripheral neuropathy, especially those with diabetes mellitus. Charcot affects the bones, joints, and soft tissues of the foot or ankle. The bones become weak and can break and the joints in the foot or ankle can dislocate. If not caught in its earliest stage, the joints in the foot collapse and the foot eventually becomes deformed. A deformed foot can cause pressure sores to develop in the foot or ankle. An open wound with foot deformity can lead to an infection and even amputation.
Who gets Charcot foot?
Charcot foot develops in persons who have peripheral neuropathy. This is a condition in which the nerves in the lower legs and feet have been damaged. The damage causes a loss of sensation in the feet.
Symptoms and Causes
What are the signs of Charcot foot?
In the early stages, the foot is red, feels warm to the touch, and there is significant swelling of the extremity.
What causes Charcot foot?
Researchers have not found one, single cause for Charcot foot. But there are certain known events that create the right conditions for it to develop. One common known event is an unrecognized sprain or injury. Because the individual has peripheral neuropathy, they cannot feel pain or other sensations and the injury can go unnoticed. If a broken bone in the foot or ankle is not correctly treated, the deformity can worsen, lead to foot sores and infection. Charcot foot has also been seen as a complication following organ transplantation in patients with diabetes. (This is due to the use of drugs to prevent organ rejection, which also have the side effect of causing bone loss and fractures.)
When the midfoot is involved in Charcot foot, the arch collapses, which rounds the bottom of the foot. This is called a rocker-bottom foot deformity. Depending on the location of the bone break, the toes can start to curve under like claws or the ankle can become deformed and unstable.
Diagnosis and Tests
How is Charcot foot diagnosed?
In its early stages, Charcot foot is difficult to diagnose. X-rays are often normal. If X-rays and laboratory tests are normal, Charcot foot is diagnosed by knowing the signs of the condition. Charcot foot is suspected in persons who have diabetes and peripheral neuropathy and the following signs: a red, hot, swollen foot (without a foot ulcer) and an increased skin temperature in the affected foot (compared with the other foot).
Management and Treatment
How is Charcot foot treated?
Early diagnosis and treatment can prevent more damage and avoid deformity and other complications. Treatment has three goals: take the weight off the foot, treat bone disease (usually with cast; bisphosphonates and other supplements are sometimes used), and prevent new foot fractures.
The first and most important treatment is rest or to take the weight off of the affected foot (also called “offloading”). In the early stage of Charcot foot, offloading helps prevent inflammation and stops the condition from getting worse and prevents deformity. Protected weight-bearing (walking in a walking boot) in later stages can prevent complications from the existing deformity and avoid new deformities.
Offloading may involve putting the foot into a cast, which protects it and keeps it from moving. The patient usually wears a series of casts or a removable cast walker over a total of 8 to 12 weeks. Crutches, knee walker, or a wheelchair are used to avoid putting any weight on the affected foot. The cast is changed several times as the swelling in the foot goes down. A cast stays on the foot until the redness, swelling, and heat are resolved.
After the cast is removed, the patient is given a prescription for footwear. Prescription orthopaedic footwear properly fits the foot and relieves pressure points to prevent a repeat injury and ulcers. A common device used is a Charcot Restraint Orthotic Walker (CROW). The doctor may also recommend changes in the patient’s activity to avoid further trauma to the feet.
Surgery is recommended for those patients who have severe ankle and foot deformities that are unstable and at high risk of developing a foot ulcer. In addition, if the deformity makes braces and orthotics difficult to use, surgery may be indicated. After surgery, the patient will have to avoid putting full weight on the Charcot foot for an extended period of time.
All people with Charcot foot must be dedicated to wearing protective footwear and taking extra care of their feet for the rest of their lives. Education of the patient and family members about preventive foot care and signs to watch for is an important part of preventing future problems.
What are the complications of Charcot foot?
Deformity in any part of the foot or ankle can cause skin ulcers from the bone pressing against the shoe or the ground. When Charcot foot affects the ankle, the joint may become unstable or “floppy” because tissue has replaced the bone in the joint. This so-called “floppy foot” also can cause ulcers.
Ulcers are often difficult to heal due to complications of diabetes, poor circulation in the feet, being on your feet for long periods of time, and the development of infections. An infected ulcer that does not heal can be limb-threatening and even result in amputation of the foot or even the leg.
Outlook / Prognosis
What is the prognosis (outlook) for people with Charcot foot?
All persons with diabetes who have been treated for Charcot foot should have regular foot care with a foot and ankle specialist or a specialist in diabetic foot problems. These specialists will watch for new changes related to Charcot and other diabetic foot complications. Patients who have Charcot foot from other causes also should have regular follow up as recommended by the doctor.