Calcium pyrophosphate deposition (CPPD) is due to calcium crystals depositing within joints. CPPD can lead to different forms of arthritis including an acute form (commonly known as pseudogout), where people experience acute episodes of joint pain and swelling, or a chronic form, where symptoms can last for a longer period. People with osteoarthritis can also develop CPPD. Not all people with calcium crystals in their joints experience symptoms.

Although CPPD is common, there has been very little research into this condition. Currently, there is no universally accepted way of reporting outcomes in studies of this condition.