Abstract: Objective:To study the effect of open surgery for treatment of primary synovial chondromatosis and to analysis the cause of the recurence.Methods:19 cases of primary synovial chondromatosis were retrospectively studied and followed up,which were performed with open surgery from May 1973 to March 1999.Results:All cases were confirmed by the pathological diagnosis.Only eight patients were followed up,from nine months to eight years and five months after operations（the average follow-up is four years and five months）.Three patients involved in knee joints,one in hip joint and one in ankle joint were demonstrated recurrence after the operations.But no canceration was followed up.Conclusion:1.Loose bodies should be removed completely and additional incisions were needed if necessarily;2.If loose bodies were calcified obviously and distributed everywhere in joints,X-ray examinations should monitor in operations;3.If no calcified loose bodies were observed from the routine X-ray films,CT or MRI should be recommended before operations.