Charcot neuroarthropathy is a progressive degenerative condition that affects the joints in the feet. It was first described in patients plagued with leprosy and alcoholism. Any condition causing sensory or autonomic neuropathy can lead to a Charcot deformity. The French neurologist, Jean-Martin Charcot further characterized the pathology that now the condition is named after. It is often associated with nerve damage related to diabetic neuropathy that decreases the ability to sense stimuli, including pain, and decreases muscular reflexes that control movement. As a result, the joints in the feet are subjected to repeat trauma and injury, referred to as the “neurotraumatic effect,” causing progressive damage to the ligaments, cartilage, and bones. Charcot foot commonly affects the metatarsal, tarsometatarsal, and tarsal joints, which are located in the forefoot and midfoot. Furthermore, the neurovascular theory relates to the increase in peripheral blood flow that is responsible for the weakening and the osteopenia found in the Charcot foot, causes bone resorption and demineralization. This increased perfusion is due to the loss of vascular sympathetic tone associated with the autonomic neuropathy.
Charcot foot occurs most often in people with diabetes mellitus but may also be attributed to other systemic conditions. Diabetes mellitus involves elevated blood sugar and the majority of foot problems arise from two serious complications of the disease: nerve damage and abnormal arterial circulation. Charcot neuroarthropathy is one of the more critical complications as a result, which can deform the shape of the foot and lead to disability.
Incidence and Prevalence
According to the American Diabetes Association, over 25 million people in the United States have Diabetes, roughly 8% of the population, with many also undiagnosed. 60-70% of people with diabetes develop peripheral nerve damage and up to 29% of these patients may develop Charcot. In most cases, onset occurs later in life and generally after the patient has had diabetes for an extended amount of time.
Nerve damage, or neuropathy, is a well-known complication of diabetes, as well as other conditions, leading to a loss of sensation in the feet. Patients can no longer feel when something has irritated or even punctured the skin, which in turn, commonly creates a wound as small as a blister and can progress to a serious infection in a matter of days. Nerve damage causes muscle weakness and increasing mobility in ligaments, which result in joint instability and subsequent subluxation and/or dislocation. Subluxation initiates the process of degenerative joint disease (arthropathy). The ends of misaligned bones ultimately may grind against each other and fragments of bone and cartilage enter joints and often produce a coarse grating sound (audible crepitus) upon movement. As mentioned, diabetes affects the peripheral circulation, weakening bone and causing disintegration and fractures within the foot and ankle. When a person with diabetes fractures a bone in the foot or ankle, he or she may not realize it because of the aforementioned nerve damage. Continuing to walk on the injured foot results in more severe fractures and joint dislocations, with sharp edges of broken bone increasing the risk of chronic foot sores from the abnormal pressure created. If there is any doubt as to this phenomenon taking place, you should see a Weil foot and ankle physician immediately.
Risk Factors and Causes
Diabetes mellitus and peripheral neuropathy are the primary risk factors for Charcot neuroarthropathy in the foot and ankle. Chronically high levels of glucose in the blood (hyperglycemia) are associated with preceding events of bone disintegration and trauma. Proper systemic medication is critical in controlling a person’s blood sugar, as well as exercise and proper dieting. Closely monitoring high-risk patients and recognizing early signs of Charcot arthropathy in persons with diabetes involves careful, daily inspection of the feet and overall health stabilization.
Signs and Symptoms
The progression of Charcot foot can occur in a matter of weeks or months. Minor trauma, such as twisting the foot, generally can initiate the process and the loss of pain perception and the sense of foot position can result in repeated joint injuries. The patient will commonly not experience much pain, if any.
Symptoms of Charcot foot include the following:
- Swelling, particularly significant amounts, which can occur without an obvious injury, due to joint fluid leaking out of the bones and joints.
- Redness, particularly so in the early stages.
- Increased warmth, particularly so in the early stages.
- Chronically open ulcerations through the skin.
- Instability with x-ray changes pertaining to misalignment, either from fracture and/or dislocations. Often times, these bones collapse, resulting in an outward bowing of the arch, referred to as “rocker bottom,” and will lead to calluses and ulcerations due to the chronic irritation of the skin. This phenomenon may also be confused for a bone infection or possibly a combination of both in certain situations.