Recently, our joint surgery department successfully managed a patient with synovial chondromatosis. The patient, Chen**, female, 58 years old, of Gaoming nationality, was admitted to the hospital with recurrent swelling of the knee joint with frequent locking for 6 months. After admission, we followed up the medical history in detail, and the patient had no clear history of trauma. The patient’s symptoms were typical and the diagnosis was clear, so we recommended surgery, but the patient’s family held different opinions on whether to operate or not, thinking that they could take medicine or do physical therapy to relieve the symptoms. The patient was very satisfied with the surgery and was discharged from the hospital on the second day after the surgery. Synovial chondrosarcoma is also known as primary synovial chondrosarcoma. It is statistically reported to account for 6.7%-22.6% of synovial tumors or aneurysmal lesions, with an age of onset from childhood to 80 years of age and a male to female ratio of 2:1. It often involves one joint. It occurs in about 2/3 of the knee joints, followed by the hip, elbow and shoulder joints, and is rare in other joints. Most people consider synovial osteochondroma to be a synovial reactive degenerative lesion of unknown etiology. Once diagnosed, synovial osteochondromatosis should generally be treated with early and aggressive surgery to avoid irreversible mechanical damage to the articular cartilage caused by the free body (in this patient, the damage to the articular cartilage was not age-appropriate due to long-term locking). Classical interlocking is a condition in which the knee joint is stuck before it is fully extended and cannot be fully straightened. Most patients can “unlock” the joint themselves. The causes of locking are complex: true locking usually includes meniscus, free body, or ligament stump compression, while pseudo locking is commonly caused by some reactive joint inflammation.