Objective: To investigate the limb-preserving treatment of osteogenic sarcoma of the tibia. Methods: Seventy-five cases of tibial osteogenic sarcoma admitted from 1992 to 2001 were treated with insertional microwave antenna arrays to induce high-temperature in situ inactivation, supplemented with preoperative and postoperative chemotherapy and postoperative immunotherapy, and evaluated for limb joint function according to the Enneking criteria. Conclusion: Insertional microwave antenna array induced high-temperature in situ inactivation of tibial osteogenic sarcoma, supplemented with chemotherapy and immunotherapy, is safe and effective, and can be popularized. Malignant bone tumors are most likely to occur in adolescents aged 10 to 20 years, most likely to invade the rapidly growing epiphysis, and lesions occurring around the knee joint (distal femur and proximal tibia) account for 50-70% of all patients. In addition to the primary foci, there are many microscopic lesions in the body that cannot be detected by modern examination instruments. The treatment of malignant bone tumors is a worldwide problem, and in the past, amputation was the main treatment, but the five-year survival rate is still less than 5% (old textbook). In the past three decades, bone tumor surgeons around the world have adopted various methods to try to preserve limbs and prolong the survival of patients, but they are not ideal. This method not only has a very high recurrence rate, but also cannot complete the crawling replacement of the tumor bone, which directly leads to multiple pathological fractures and amputation again after surgery. The second method is osteotomy of the tumor segment and large allograft bone grafting, which was popular for a while, but in addition to the aforementioned high recurrence rate, it is even more difficult to replace the crawling. The third type of method is osteotomy of tumor segment and artificial joint replacement. Since most of the malignant bone tumors are in adolescent patients, the complications after replacement, such as unequal limb length and loosening of prosthesis, are much more than those in elderly people. Many studies have shown that high temperature can kill tumor cells, and the temperature limit that tumor cells can tolerate is 43℃. At this temperature level, tumor cells can be selectively killed without damaging normal tissues. Based on the above facts, insertion of microwave antenna array to induce high temperature in situ inactivation of bone tumors is the best method for limb preservation. Using the good thermal conductivity of bone, the surface temperature of the tumor segment bone can reach more than 50℃ after receiving microwave radiation, while the central temperature can reach more than 108℃, while the temperature limit that tumor cells can tolerate is 43℃, thus ensuring that all tumor cells are killed, while the surrounding normal tissues, especially blood vessels and nerves, are protected from high temperature damage due to protective measures such as local heat insulation and cooling. Most importantly, in vivo inactivation has no effect on the cruciate ligament and meniscus in the knee joint, so the postoperative knee function is unmatched by any other methods. During the operation, the integrity of a thin layer of normal tissue on the bone surface of the tumor segment is preserved, and the operation is strictly tumor-free: normal tissue is protected from tumor blood contamination to ensure the safe surgical boundary of tumor surgery. The antenna array of the microwave therapy machine with a frequency of 2450 MHz and a rated maximum output power of 800 W was inserted evenly into the tumor segment bone for high temperature inactivation, with a tumor surface temperature of 50-60°C and a central temperature of up to 108-120°C for 30-40 minutes. The microwave-inactivated tumor tissue and surface crust are scraped away, and the bone structure and strong internal fixation are reconstructed. According to our experience, the insertional microwave antenna array induced high-temperature in situ inactivation treatment for malignant bone tumors has the incomparable superiority of the traditional “tumor segment amputation plus reconstruction” treatment method: only the in situ separation of the tumor (including important blood vessels, nerve bundles and uninvolved muscles) is done, without destroying the internal and external structures of the bone and joints. The stability and continuity of the bone and joint structures are preserved intact. Thus, the function of the limb and joint is preserved to the maximum extent, and the disadvantages of the existing limb preservation surgery of osteotomy and destruction of joint structure are abandoned; 6-12 microwave antennas are evenly inserted into the tumor segment bone and extra-osseous masses to form an antenna array to protect normal tissues with reliable circulatory cooling measures. The high temperature generated by the microwave antenna array can kill the tumor cells locally through the thermal effect of microwave high temperature, but also adjust the range of microwave antenna insertion, using the high temperature heat conduction effect of microwave, the tumor area to do an expanded range of thermal inactivation to ensure that sufficient surgical safety boundary can be obtained; scraping the reconstruction of bone defects left by tumor necrosis tissue after microwave inactivation, the use of good plasticity, can effectively strengthen the tumor eroded by the bone tissue, re-use of plasticity, can be effective. For the reconstruction of bone defects left by tumor necrosis after microwave inactivation, allogeneic decalcified bone matrix bone particles with good plasticity, effective reinforcement of tumor eroded bone tissue, good “anchoring” after revascularization and new bone production, and strong biomechanical support for the repaired bone tissue were used. The application of the bone defect repair material and prophylactic internal fixation results in a mechanically unified local area. It is also quite critical that the localized bone defect repair must have the ability to repair with bone regeneration. Studies on microwave high-temperature inactivated bone revascularization and other studies have shown that: microwave high-temperature inactivated bone can be revascularized in situ and become viable, and the revascularization of inactivated bone is nearly complete within 6 to 12 months. Once the signs of bone repair and regeneration appear, the original inactivated dead bone becomes a permanent regenerative autologous living bone scaffold. ECT (isotope scan) follow-up examinations of some patients also confirmed this view. In conclusion, the technique of limb preservation for malignant bone tumors should first ensure the local control of tumor, and the local control of tumor should ensure the acquisition of surgical safety limits, which is directly related to the quality of survival and functional status of the patient’s limbs. Under the premise of orderly and meticulous surgical operation, the application of inserted microwave antenna array induced high-temperature in situ inactivation treatment technology, combined with the imaging data and surgical observation; the scope of microwave antenna array insertion can be adjusted, using the high-temperature heat conduction effect of microwave radiation, the tumor area can be in situ and expanded thermal inactivation, which can ensure that sufficient surgical safety boundary can be obtained. Therefore, we believe that the treatment system of “hyperthermia plus immunotherapy and chemotherapy” may become the mainstream of limb preservation surgery for malignant bone tumors and will be improved day by day.