Malignant bone tumors occur in adolescents and are most likely to invade the fast-growing epiphysis, and lesions 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 was not high. In the past three decades, bone tumor surgeons all over the world have adopted various methods to try to preserve limbs and prolong the survival of patients, but all of them are not ideal. The methods used in the past include: amputation of the tumor segment with large allograft bone graft, boiling in vitro, alcohol soaking or cobalt 60 irradiation and then implantation back into the body. These methods not only have a very high recurrence rate, but also cannot complete the crawling replacement of the tubercle bone, which directly leads to multiple pathological fractures and re-amputation after surgery. The author has followed up numerous cases of large allograft bone replacement of the lower femur and proximal tibia, and all the allograft bones became tofu crumbs and could not be weight-bearing. Among them, the osteotomy of the tumor segment and artificial joint replacement: since most of the malignant bone tumors are in adolescent patients, the complications after the replacement, such as unequal limb length and loosening of the prosthesis, are much more than those in the elderly, and more importantly, the osteotomy and artificial joint replacement can easily lead to local contamination of the tumor and recurrence soon after the operation. Many studies have shown that high temperature can kill tumor cells and the limit of temperature 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 contamination by tumor cells to ensure a safe surgical boundary for tumor surgery. The antenna of microwave therapy machine with specific frequency and rated maximum output power is evenly inserted into the tumor segment bone in an array 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. Then the microwave inactivated tumor tissue and surface crusts are scraped away to reconstruct bone structure and strong internal fixation. According to our experience, the insertional microwave antenna array induced high temperature in situ inactivation technology for malignant bone tumors has the incomparable superiority of traditional treatment methods such as “tumor segment amputation plus reconstruction” and “artificial joint”: only in situ separation of the tumor ( 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 joint, thus preserving the stability and continuity of the bone and joint structures. Thus, the function of the limb and joint can be preserved to the maximum extent, and the disadvantages of the existing limb preservation surgery of bone amputation and destruction of joint structure are abandoned; 6-12 microwave antennas are evenly inserted into the tumor segment bone and extra-osseous mass to form an antenna array to protect normal tissues with reliable circulatory cooling measures. So that the high temperature generated by the microwave antenna array radiation can not only 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 will be done to expand the range of thermal inactivation to ensure that a sufficient surgical safety boundary can be obtained. The reconstruction of bone defects left by tumor necrosis after scraping microwave inactivation is performed by using allogeneic decalcified bone matrix bone cement material with good plasticity, which can effectively reinforce the bone tissue eroded by tumor, and provide good anchorage after recanalization and new bone production, and can provide stronger biomechanical support for the repaired bone tissue. The material is a composite of allogeneic decalcified bone matrix particles. Due to the use of bone defect repair materials and prophylactic internal fixation, the repaired area forms a mechanically unified whole. It is also quite critical that the localized bone defect is repaired with 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, which is also confirmed by postoperative ECT (isotope scan) follow-up examination of some patients. The combination of pre- and post-operative herbal medicine – Yi Qi and Dispersing Stasis and neoadjuvant chemotherapy – also makes limb preservation even better. In conclusion, the limb preservation technique for malignant bone tumors should firstly ensure to get local control of tumor, and local control of tumor should ensure to get surgical safety limit, which is directly related to the patient’s survival quality and limb function status. 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 “high temperature + Chinese medicine + chemotherapy” will become the mainstream of limb preservation surgery for malignant bone tumors and will be improved day by day. At the same time, the requirements for the operator are very high: he or she must have experience in tumor-free operation of bone tumors, good microsurgery technique and repair and reconstruction ability, and not just a surgeon who can cut tumors in the past.