This is a type of crystal disease with deposition of calcium pyrophosphate dihydrate crystals within the joint and joint cartilage.

The term pseudogout arises from the similarity in presentation to the well-known common condition of gout. Patients present with an acute episodic inflammatory arthritis, much like that seen in gout. However, the crystals involved are different, hence the treatment is also different. 

In pseudogout, CPPD crystals are deposited in the joint cartilage at the joint surfaces. It is a joint disease that manifests with intermittent attacks of acute joint inflammation. Degenerative arthritic changes can be severe but are often asymptomatic.  

CAUSES 

While the causes of pseudogout are unknown, there’s a striking association with age, and the condition is rare under 50 years. It is often associated with other conditions like trauma, surgery, hyperparathyroidism, gout, and haemochromatosis. Thus, it seems that the deposits of the CPPD crystals follow degenerative or metabolic changes in cartilage. 

SYMPTOMS 

There are two common presentations of pseudogout. The first is that of acute inflammation in a single joint (monarthritis), mimicking the classic acute attack of gout. The commonest presentation is sudden onset of severe pain, stiffness, and swelling developing over 6-24 hours. The knee is usually the site of involvement, followed by the wrist, shoulder, ankle, and elbow. The joint is acutely inflamed, red, and swollen and the patient, especially the elderly, may have a fever and be generally unwell and even confused. The acute attack usually clears within 1-3 weeks but may recur in another joint. Between attacks symptoms may be completely absent, or there may be low-grade symptoms like those of rheumatoid arthritis. These patterns can persist for life. 

A more chronic form of this condition resembles rheumatoid arthritis in the elderly. Presentation is with chronic pain, stiffness, and limitation of mobility in the knees, wrists, shoulders, elbows, hips, and midfoot. Acute attacks may be superimposed on this chronic background of pain and inflammation. 

Pseudogout may coexist with and aggravate osteoarthritis. Joint swelling and local heat and thickening of the joint lining (the synovium) occur. 

TREATMENT 

The aims of treatments are to reduce symptoms, identify and treat triggering illnesses and rapidly mobilise the patient once inflammation has settled. Elderly patients often have other coexisting conditions and local therapies are often the best. Low dose oral colchicine may be quite effective. If the joint is swollen from inflammation, it should be drained and injected with cortisone. Symptomatic therapy is also possible using anti-inflammatories (NSAIDs), or newer safer anti-inflammatory drugs known as COXIBs. 

Patients with progressive large joint involvement such as the knee may benefit from joint replacement.