The so-called synovial osteochondromatosis, also known as synovial chondroplasia, is a rare benign joint lesion. At present, its etiology is not very clear, mainly characterized by the formation of cartilage nodules on the synovial membrane, cartilage bodies are mostly gravelly, and can reach dozens of times, which can grow with tips and protrude into the joint cavity, and some of them can easily be detached to the joint cavity and form free bodies, which are nourished by the synovial fluid and gradually increase in size. In the later stage, the cartilage nodules may be calcified or ossified, so it is called synovial osteochondromatosis. This disease mainly occurs in the joints, especially in the knee, hip, elbow and shoulder joints.