Abstract: To investigate the clinical significance of MRI in limb salvage surgery on osteosarcoma around the knee joint. Methods43 patients with osteosarcoma were examined by Xray and MRI, and were staged by Enneking surgical staging system. Based on the tumor extent in the medullary cavity and the surrounding soft tissues, the operative plans were formulated and the custom artificial prostheses were made. After chemotherapy, tumors were removed and custommade prostheses were put on. Postoperatively the histopathological results were compared with the MR images. Followed up for 10 to 55 months (mean 38 months), the function of the involved knee joints was evaluated. Results Of the 43 cases, 10 were in stage Ⅱa and 33 in stage Ⅱb, all were successfully operated on. The functional recovery rate was 76.7%. MRI was of little diagnostic value in manifesting osteosarcoma, but was of great value in demonstrating intramedullary extension, skip metastasis, the relationship of bone tumor to vessel, nerve, muscle and adjacent joints, bleeding and necrosis in osteosarcoma. ConclusionMRI has great values in making operative plans and ensuring the operative outcome in limb salvage surgery on osteosarcoma.

Key words: MRI, Osteosarcoma, Surgical procedures,operative