Pseudogout is a type of arthritis that causes pain, redness, heat, and swelling in many joints. The symptoms resemble those of gout. But pseudogout is caused by deposits of tiny crystals of calcium pyrophosphate rather than uric acid. Pseudogout may also be called calcium pyrophosphate deposition (CPDD) disease.

The knee is the joint that's most often affected. Over time, pseudogout may damage the cartilage of the joint. As this happens, the bones rub together and cause joint pain.

This type of arthritis usually affects people in their 60s. It is rare in people younger than 30.