Charcot Neuroarthropathy, Part I:  Causes, Signs, and Symptoms

By Asma Khan, DPM

            One of the complications of diabetes mellitus is Charcot neuroarthropathy, however, few diabetics hear about this condition prior to developing its signs and symptoms.  The insidious, and often, confusing onset of symptoms are often overlooked for a long period of time, and presentation to a physician’s office typically occurs when significant damage has already been done.

 

            Charcot neuroarthropathy, or Charcot joint, is a derangement of the weightbearing joints of the lower extremities of the body that is characterized by complete loss of the integrity of the joints, such that they collapse under the weight of the person.  The bones become soft and the joints dislocate.  As the joints dislocate, the bones of the foot and ankle collapse.  This causes pressure against the vulnerable soft tissues and skin.  The sharp pressure of the bones against the tissues causes ulcerations, which can become infected, and lead to severe, limb-threatening infections.

 

            The signs and symptoms of Charcot joint are redness and swelling.  Surprisingly, pain is typically absent, despite the impressive bone and tissue destruction and dislocation that is present.  Rarely, patients may describe some “pain” or “achiness” that is still very minimal given the amount of physical changes.  This surprising finding is a direct result of the underlying causes that result in Charcot joint.

 

            Charcot joint is most commonly seen in patients who are neuropathic due to diabetes mellitus, or more rarely, due to alcohol-related neuropathy.  This means that the nerves to the feet and legs are not working properly.  As a result, multiple systems in these areas of the body fail.  For example, the patient may not feel trauma occurring to the feet and legs because of a compromised ability to feel things due to poor sensation.  In addition to the malfunction of sensory nerves, peripheral diabetic neuropathy also causes malfunction of the nerves that control blood flow to the structures of the feet and legs.  This leads to unchecked blood flow to the bones and joints.  The extra blood flow is theorized to play a role in “washing out” of calcium from the bones, leading to softening and loss of structural integrity.  The nerves that provide feedback to our brains about the position of our joints are equally at risk for malfunction.  It is theorized that this feedback about joint position is also lost in diabetic neuropathy, leading to the rapid joint dislocation seen in Charcot joint.

 

            As the foot and ankle begin to collapse due to Charcot joint, changes that are readily noticeable include a flatter arch, a more swollen foot or leg, and redness and warmth.  However, many patients do not want to “overreact” since they do not feel sick and believe that this may be due to aging or some small sprain or injury.  In the meantime, the collapsed bones of the foot continue to create pressure, which leads to calluses and wounds.  Because these wounds do not heal without removing the underlying pressure that is causing them, they fester and proceed to become infected, if not treated quickly.  Infections at these sites can easily track to the bones and joints that are already easy targets for bacteria due to the damage caused by the Charcot process.  Once bone infection, or osteomyelitis, is confirmed in a Charcot joint, the risk of limb amputation is very high.

 

Figure One:  Ulceration, caused by increased pressure due to collapsed arch in Charcot joint.

 

Figure Two:  X-ray of the ankle, showing the destruction of the bone and joints due to Charcot neuroarthropathy.

 

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