Pseudogout (SOO-doe-gout) is a form of arthritis characterized by sudden, painful swelling in one or more of your joints. These episodes can last for days or weeks. The most commonly affected joint is the knee.
Also called calcium pyrophosphate deposition disease, the common term "pseudogout" was coined for the condition's similarity to gout. Both conditions are caused by crystal deposits within a joint, although the type of crystal differs for each condition.
It isn't clear why crystals form in your joints and cause pseudogout, but the risk increases with age. Treatments can help relieve pain and reduce inflammation.