The goal of this clinical trial is to learn the efficacy and safety of intra-arterial cisplatin plus anti-angiogenesis inhibitor rh-endostatin (Endostar) combined with systematic chemotherapy in osteosarcoma. The main questions it aims to answer are: * Is it safe when rh-endostatin and cisplatin are administered intra-arterially? * Does intra-arterial cisplatin plus rh-endostatin increase the rate of tumor necrosis compared with traditional treatment? Researchers will treat newly diagnosed osteosarcoma patients with systematic treatment and local treatment. For systematic treatment, regular high-dose methotrexate and adriamycin will be administered intravenously. For local treatment, rh-endostatin was administered intra-arterially with dosage of 150 mg for a 6-h continuous infusion; then cisplatin was administered intra-arterially at 120 mg/m2 as a 6-h continuous infusion. Local treatment is conducted by insertion of a catheter percutaneously using the Seldinger technique through the brachial or femoral artery under local anesthesia. Participants will: • Receive local combined with systematic treatment once every 2-3 weeks for 2-4 cycles before surgery.