Basic calcium phosphate crystal deposition disease is a group of diseases in which crystals such as hydroxyapatite (apatite), octacalcium phosphate, and tricalcium phosphate are deposited in and around joints, often complicated by osteoarthritis and destructive joint lesions. The most common calcifications are deposited in the supraspinal ligament of the scapula, which is called calcific tendinitis; these substances can also be deposited next to the joints, especially the tendons, causing recurrent inflammation, so it is also called paratendon calcification, joint phosphate rheumatism, calcific paraarticular inflammation, etc. At present, this clinical syndrome is summarized as basic calcium phosphate crystal deposition disease.