Since the 1970s, with advances in surgical techniques, imaging technology and chemotherapy, limb preservation has gradually become the treatment of choice for malignant bone tumors of the limb. Successful limb preservation surgery must rely on neoadjuvant chemotherapy and an accurate preoperative assessment of tumor extent, which should usually include both intraosseous medullary cavity extent and extraosseous soft tissue extent. Preoperative assessment of the extent of medullary invasion is particularly important and determines the plane of osteotomy during limb-sparing surgery. The main methods used for preoperative assessment of the extent of medullary invasion are radiographs, nuclear scans, CT and MRI, etc. The use of various tests plays an important role in the correct assessment of the extent of medullary lesions.