Charcot Joint - HOW WILL A DOCTOR DIAGNOSE IT
It is accepted among medical professionals that Charcot Joint initial appearance is a warm , swollen and erythematous (red). The warmth is as it is compared to the patients other leg. We usually go by a rule of 2 degrees Celsius or higher of a difference as an indicator of the acute phase of charcot. The doctor would need a complete history of the problem (we always recommend a patient keep a prewritten history of the entire event and bring that to the doctors office including hospitalization, doctors seen, any history of infection and the bacteria and antibiotics given etc.). As far as pain, because of the neuropathy many patient do not feel any pain during the charcot process although depending on the level of the nerve damage some of our patients do feel pain.
Charcot Joint is often misdiagnosed since there are a number of other conditions that appear the same way initially. Some of these are skin infection, bone infection (osteomyelitis), gout, blood clot (DVT), sprain, and other joint disorders associated with inflammatory conditions. Since overall charcot joint is a rare condition it is often misdiagnosed. Some medical journal articles have shown that the misdiagnosis rate can be as high as 80%.
At this point an X-ray will be taken of the affected joint to see the amount of damage to the joints.
Before we see the X-rays it is important to understand the reason for the X-ray results. It is accepted today in medicine that there are 3 phases of charcot joint (Eichenholtz written in 1966). Some do accept that there is a stage 0 (Shibata 1990), which is the state of the charcot joint before any actual bone damage is seen so we can explain all of these phases.
Stage 0 - (prodromal phase) this phase is characterized by swelling, redness and warmth of the limb. There are no bone or joint issues visible on X-ray. This is almost kind of pre-charcot condition.
Stage 1 - (development phase) in this phase the patient continues to have the same clinical symptoms of swelling , warmth and redness but may also exhibit closeness of the joints . It is not well understood why the joints suffer from ‘ligamentous laxity’ or a weakening of the structures that hold the joints together. On an X-ray we may see weakening of the bones, dislocations of the joints, and fractures of the bones near the joints as well as joint collapse. This phase may last for weeks or months, there is no set accepted timeline.
Stage 2 - (coalescence phase) here the warmth, swelling and redness of the limb starts to decrease. On the X-ray we may see the larger fragment of bones broken during stage 1 start to heal to each other. This is almost healing phase of charcot where the body makes its best attempts at correcting the damaged joint. It is very hard to know clinically when the other stages stop and this stage begins so it can also be considered that these charcot stages are academic to some degree.
Stage 3 - (reconstruction phase) here the patients body continues with its own healing just as it would for any broken bone smoothing out any sharp surfaces slowly and continuing to heal fragment of broken joints together to at least stabilize the joint.
There are other classification systems that doctors use for this but the Eichenholtz is the most well known and accepted worldwide.
Now back to the X-rays of our patient - the doctor will take between 3 and 4 different X-ray angles of a joint, this is in order to see the different patterns of the effected joints. On some occasions X-rays do not need to be taken since they may not provide necessary information to the doctor. In many cases all the doctor will need is the patients history and the X-ray, no further imaging (mri,cat scan, etc.) may be needed to confirm the diagnosis. X-rays are used also to monitor the patients charcot progression and are taken serially, sometimes every 1 to 2 weeks as needed at the doctors discretion.
Below are some staged x-rays of charcot joint. The most important result of the charcot process is if there is a part of the affected leg that became deformed. what we assess from the X-ray is the “degree of deformity”. It is possible that the charcot deformity begins in the stage 1 of the process, sometimes it appears in any of the latter stages, 2 or 3. This really depends on the patients treatment as well as the joints effected by the charcot process. What happens is that as the those weakened joints start to collapse as the bones break up. Since the normal architecture is destroyed the structures holding the joint in their normal anatomical positions can then fail. It should be mentioned that charcot can affect multiple joints or just one joint; this then can dictate what kind of deformity the patient can end up with.
Why do i keep mentioning the importance of “degree of Deformity” ????
Because - as the bones and joints break down and collapse, prominent areas appear. As the charcot process comes to an end the neuropathy persists and the prominent areas are danger zones for rubbing in shoes and against the floor during walking and standing. These ‘danger zones’ can develop wounds ( click on wounds to read more about wound care). These wounds then may go undetected for some time and infections can occur, sometime theses skin infections go deeper to become bone infections (osteomyelitis). These can become limb and life threatening infections and this is why diabetic neuropathy and wounds and the leading cause of amputations of the feet today. Also this is why it is so important that neuropathic patients check their feet (top, bottom and sides) every day and contact their foot specialist immediately when they notice anything unusual - no matter how trivial it may be!!
Lets get back to the X-ray results :
When you research charcot on the internet you may come across the phrase “rocker-bottom foot”. This is one of those examples of dangerous prominences. This foot shape is considered a classic charcot deformity. Actually it issue to a specific charcot process of the mid foot joints, if you have charcot of the ankle joint you will not develop a rocker bottom foot but you may develop other deformities common to the ankle charcot. Ill discuss the most common deformities we see later and their consequences. However, it is possible to have more than one joint affected by charcot, in other words, someone can have a charcot of the foot and of the ankle in the same leg. The examples below show charcot ankle deformities where the foot is rolling inward, this is called a virus ankle deformity and these are very difficult to treat with bracing since you can see the outside of the ankle will push up against the brace and cause the ulcer you see in the center photograph.
The xray allows the doctor to formulate a treatment plan taking the stages of charcot into consideration. In some occasions more advanced imaging may need to be performed. An MRI (magnetic resonance imaging) uses magnetic fields and sound waves (no radiation) to create an image that very well shows the joints and even inside the bones. It can be useful in detecting very early signs of charcot even before any changes are seen on an xray. when MRI is most helpful is in helping the doctor differentiate between charcot and osteomyelitis (bone infection).
There are also CT scans (cat scan) that can show bones and joints but it will gives information to the doctor as opposed to an MRI. Occasionally your treating specialist will order one to see the overall structure of the joints when they are difficult to see on xray. This is really a surgeon preference. there are also a few other tests, the bone scan which is a nuclear medicine test. In these a dye is placed by IV into the patients artery and specialized xrays taken to assess bone conditions. These test offer little information. A Ceretec WBC (also called 99m Tc HMPAO or 111Indium) labelled bone scan thought is used to rule out bone infection. This is also a nuclear medicine test where patients blood is drawn, then a radioactive marker mixed with the blood that attaches to the white blood cells; then that blood sample is placed back into he patient and those specialized scan X-rays are taken. What happens is those marked white blood cells will automatically travel to areas of infection to fight the bacteria there. we will be able to see those cells grouping around areas of infection and be able to assess the infection overall. Again this test is very specific for its need and is not commonly used. Recently there has been more use of the PET scan in charcot and osteomyelitis cases but it is still considered investigational.
As far as in cases of acute infection these must be treated emergently (as infections would be treated quickly anyway). Bone infection may need to be investigated further, the bone biopsy is considered the gold standard in diagnosing bone infection and identifying the bacteria responsible to guide antibiotic treatment. These biopsies can be done in office setting or in a hospital and are a relatively simple procedure. a special needle is used to obtain a small piece of bone that is then cultured in a laboratory and examined under a microscope by a pathologist.
With the information above a doctor should be able to make the diagnosis as well as formulate a treatment plan which may be surgical or nonsurgical and usually depends on the surgeons own training and experience.