The pathogenesis is unknown, but it is thought that the synovial membrane is formed by reactive hyperplasia after trauma or inflammatory stimulation. The chondrocytes formed by synovial cell metamorphosis are deposited in the synovial membrane, and more blood vessels grow into the center of the ossification, which grows continuously in the form of polyps with long tips attached to the synovial membrane, and then increase in size and fall off to form free bodies in the joint cavity. After the loss of blood supply, the peripheral cartilage is like an envelope, which can continue to grow and form larger and more numerous tumors depending on bone fluid. This disease can cause joint pain and swelling and lead to dysfunction due to the invasion of joints, so it should be diagnosed and treated by surgery at an early stage. At this time, because of the small trauma and less bleeding, there is less adhesion and scarring. It is conducive to the recovery of joint function and disappearance of pain symptoms after surgery. During the operation, strict aseptic operation should be carried out, blood should be closely applied to avoid re-injury to the surrounding tissues, and free bodies and focal tissues in the joint should be completely removed to prevent recurrence. Infection, postoperative adhesions and dislocations can affect functional recovery. Pathological changes: Synovial congestion, thickening, proliferation of villi, nodules of different sizes, ranging from small ones like corn grains to large ones of more than 1 cm in diameter. The nodules are hard, white or translucent, or occasionally lavender; they are attached to the synovial membrane by a broad base or narrow tip, or they may be dislodged into the joint cavity, or located in the synovial bursa and the tendon sheath near the joint, becoming free bodies. The shape varies, mostly round or oval. The cartilage is cartilaginous in section and may be calcified or ossified within, and there may be lipid marrow in its central part. Microscopically, vascular proliferation, lymphocyte aggregation, proliferation of synovial surface cells and fibrous tissue can be seen, and sometimes patches of fibroblasts can become chondrocytes, forming chondrocytes and calcifying and ossifying in different stages. Transitional synovial lesions combined with synovial osteochondroma and free bodies; ③ Termination of osteochondral lesions: normalization of synovial membrane or only mild inflammation and formation of multiple free bodies. The clinical manifestations are the same as those of chronic arthritis and intra-articular free bodies. However, the course of the disease is slow. Most patients may be asymptomatic in the early stage, but after months, years or even decades, the affected joints gradually become painful, swollen and functionally restricted. Preferred population and location From the above cases, it can be seen that this case mostly occurs in adults, mostly women. Almost all of them are large joints, including 65% of knee joints and 28% of hip joints, and shoulder joints are also affected. The typical imaging presentation x-ray D changes are multiple round or ovoid opaque shadows in the joint area, which can be homogeneous and dense, or high density in the periphery. The center may be translucent. The joint space and joint surface generally remain normal. In advanced patients, degenerative changes of osteophytes at the edges of the joint surface are seen. 1/3 of patients have no calcification or ossification changes on radiographs, and multiple negative shadows can be seen on inflatable imaging. CT – The performance is generally similar to that seen on plain film, except that the free body is clearly demarcated from the constituent bone of the joint as seen on cross-section, and the constituent bone of the joint is mostly undamaged. MRI-MRT1WI, T2WI and FSEIR are consistent with the signal of the central yellow marrow tissue of the femur, and the dotted T1 low signal and FSEIR high signal visible in the center of the lesion should be considered as unossified cartilage tissue. The pain was eliminated after treatment with acupuncture.