CPPD – the Lesser-Known Crystal Arthritis

CPPD – the Lesser-Known Crystal Arthritis

Calcium pyrophosphate deposition disease (CPPD), commonly called pseudogout due to the symptomatic similarity to gout, is one of the many forms of arthritis. Both conditions result from crystal deposits within a joint, although the type of crystal differs. Gout results from deposition of urate crystals while CPPD results from deposition of calcium pyrophosphate crystals.

Joint problems caused by calcium pyrophosphate crystals may be one of the most misunderstood forms of arthritis. Proper diagnosis (detection) is important for correct treatment that will help to avoid joint damage and reduce the severity of symptoms.

Diagnosis

Diagnosis of CPPD is began by ruling out other possible diseases. These include gout, rheumatoid arthritis, and joint infection.  Imaging of the joint, including ultrasound, X-ray, CT, or MRI may help detect whether calcium-containing deposits are present in the cartilage. Diagnosis is confirmed by using a microscope to see small calcium pyrophosphate crystals in samples of joint fluid.

Symptoms

The joint most commonly afflicted by CPPD is the knee. Less frequently these crystals can form in wrists, elbows, shoulders, hands, ankles and other joints. Rarely does it affect the neck but when it does it can cause neck, shoulder pains, headaches and in some cases fevers. This occurs when the calcium crystals deposit around the dens part of the second cervical vertebra. The condition is then called crowned dens syndrome. Quite often many people are unaware that their joints contain these crystals but during a pseudogout attack the affected joint will become swollen, warm and severely painful. The pain is caused by crystals of the mineral calcium rubbing against soft tissue. Over time, these joints may degenerate, or break down, resulting in long-term disability. Some treatment options for the arthritis pain do exist, but these do not treat the underlying crystal deposits.

Causes

It has not yet been determined exactly why these crystals form, but as you age there is greater probability of having these crystals present in your joints. At 60, around 3% of the population will have crystals present but from 85 years onwards, nearly half the population will have them. However, not everyone who has them will go on to develop pseudogout and the accompanying symptoms, in fact most will not. The release of the calcium pyrophosphate crystals into the joint fluid can attract white blood cells, leading to a painful attack. Attacks of acute (short-lasting) arthritis can occur after injury to the joint, after surgery, or without a clear reason. So, what causes one person to develop pseudogout over another person? There are a number of factors that have been linked to an increased likelihood of developing pseudogout.

Risk Factors

As previously mentioned, the risk increases with age. If you have joint trauma due to serious injury or a surgical procedure you are more likely to develop pseudogout. In cases in which pseudogout is seen in younger patients there tends to be more than one family member with the condition so it is likely that it has a hereditary element.

A number of other medical conditions can also make you more prone to developing pseudogout. These include a thyroid condition (hypothyroidism), kidney failure, parathyroid disease (hyperparathyroidism), mineral imbalances in which a patient has excessive calcium (hypercalcemia) or iron (hemochromatosis) or too little magnesium (hypomagnesemia). Other forms of arthritis can increase the likelihood of developing CPPD, osteoarthritis patients are 2-3 times more likely to have CPPD. This relationship appears to be bidirectional with repeated pseudogout attacks leading to joint damage and osteoarthritis.

Treatment

Experts do not know how to prevent these crystals and there is currently no means or medication by which the crystals can be dissolved. If CPPD is due to some other medical problem, treatment of that condition may sometimes prevent CPPD from getting worse.

During an acute attack a patient may be prescribed NSAIDs. NSAIDs treat pain and swelling during severe attacks. If patients are unable to tolerate NSAIDs (due to factors such as stomach ulcers or poor kidney function), it may help to drain the joint fluid and inject a corticosteroid into the affected joint. In an attempt to reduce the number and intensity of future attacks low doses of colchicine (usually used to treat gout) may be prescribed. Standard autoimmune drugs such as hydroxychloroquine (Plaquenil), methotrexate or one of the biologics may also be considered during severe attacks. In extremely severe cases, surgery may be required to repair joint damage.

Those who believe they may be suffering from CPPD should consult with a rheumatologist to develop an individual treatment plan.

ANRF
Article Author
Arthritis National Research Foundation
arthritisresearch@curearthritis.org

The Arthritis National Research Foundation's mission is to provide initial research funding to brilliant, investigative scientists with new ideas to cure arthritis and related autoimmune diseases. Writing articles about the patients affected and the science being done to find a cure shows why we need to come together to #CureArthritis!

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