The concept of limb-sparing surgery for primary tumors of bone has evolved and matured over the past 25 years. Prior to this time, all highly malignant bone tumors were treated with amputation above the affected bone joint. With the introduction of adriamycin- and methotrexate-based chemotherapy at Memorial Sloan-Kettering Cancer Center in the early 1970s, surgeons such as Ralph Marcove, Kenneth Francis, and Hugh Watts began to apply custom prostheses to reconstruct post-tumor resection bone defects for limb-preserving treatment. These tremendous developments in treatment relied on a combination of multidisciplinary developments, including a deeper understanding of tumor biology, effective chemotherapy (neoadjuvant chemotherapy), accurate preoperative imaging techniques, maturing surgical techniques, and advances in material science that have led to progressive improvements in artificial prostheses. Over the past two to three decades, bone tumor centers in the United States and Europe have used a variety of reconstructive techniques to reconstruct the limb after bone tumor resection. Long-term follow-up results are now becoming available. While defect reconstruction may be unnecessary when resecting bones that can be sacrificed, such as ribs, clavicle, iliac wing, and fibula, reconstruction should be performed for defects left after resection of tumors in bones that are structurally or functionally important. The ideal reconstruction is one that restores function and stability without increasing the recurrence rate and without increasing the incidence of infection, loosening, fatigue fracture, etc., and without interfering with subsequent treatment. However, none of the current reconstruction methods can meet all of these conditions. William Enneking was the first to try to carry out reconstruction techniques for bone defects in the field of bone tumors. At that time, the main focus was on joint fusion and prosthetic joints with loss of postoperative joint mobility, and these techniques are rarely used nowadays. In the 1980s, surgeons at Massachusetts General Hospital and other bone tumor centers made extensive use of allograft bone grafts with articulation for reconstruction. Metal internal fixation is used to restore bone continuity between the allograft and the patient’s bone, and the periarticular ligaments and tendons are then reconstructed onto the allograft. However, this method of reconstruction has many complications, including non-union of the bone, fracture of the allograft and a high rate of infection, sometimes requiring a second-stage amputation. Long-term follow-up has found that the 10-year survival rate for lower extremity allograft bone reconstruction is less than half, and reconstruction using allograft bone alone is now rare in many bone tumor treatment centers. Alternatively, allograft bone (for stem bone defect reconstruction) and metal prosthesis (for joint reconstruction) may be used in combination. The advantage of this approach is that the stops of the periarticular ligaments and tendons can be reconstructed on allograft bone, and the joint surfaces with higher stress are reconstructed by metal prosthesis, thus avoiding some of the complications that occur in allograft-only bone reconstruction. Autologous bone grafting to reconstruct bone defects after tumor resection is more commonly used in bone tumor treatment centers in Europe and Japan. The most commonly used is the fibula, which is removed along with the trophoblastic vessels so that it can be revascularized. Although this technique is commonly used in the lower extremity, the results are better when used in the upper extremity postoperatively. Recently, Tsuchiya reported the use of the Ilizarov bone lengthening method to reconstruct bone defects after tumor resection. The bone lengthening technique is now also successfully performed in our center, mainly for the treatment of bilateral lower limb inequality after pediatric limb preservation surgery. The advantages of metal prosthesis reconstruction include: durable internal fixation, immediate postoperative stability, better short-term and long-term functional prognosis, and good postoperative joint mobility. Most importantly, the incidence of infection and complications is lower than that of allograft reconstruction. Prosthetic reconstruction of the distal femur (where osteosarcoma is most prevalent), proximal tibia (where osteosarcoma, chondrosarcoma, and Ewing’s sarcoma are most prevalent), proximal humerus, and scapula is very reliable, while the more difficult areas for reconstruction are the proximal tibia and acetabulum. The 5-year survival rate of patients with periprosthetic reconstruction of the knee is now over 85%. The type of prosthesis (proximal femur, distal femur, and proximal tibia) is the main factor determining the survival rate of the prosthesis, with a 5-year survival rate of 88-93% for the distal femoral prosthesis70,95 and 58% for the proximal tibial prosthesis. In the scapular girdle, the mode of resection and soft tissue reconstruction may have a greater impact on prognosis than the type of prosthesis. Minimally invasive or noninvasive lengthenable prostheses are an ideal method to avoid lower extremity limb inequality in pediatric patients with lower extremity bone malignancies. Proximal femoral APC and proximal femoral prosthetic reconstruction provide reliable, stable hip reconstruction. malawer believes that reconstruction of the hip capsule is necessary to effectively prevent joint dislocation, as hip dislocation is the most common complication after reconstruction for this department. The distal femur has a better postoperative function, and the upper tibia has a better oncologic prognosis for patients because there is less soft tissue coverage and the tumor can be detected earlier, but because of the lack of soft tissue coverage and the importance of the extensor device for lower extremity function, the upper tibial prosthesis has more complications and mostly requires gastrocnemius medial cephalic muscle flap grafting. The main reconstruction modality of the distal tibia is allograft bone grafting, and when the bone defect is >15 cm, artificial prosthesis reconstruction can be considered for adults, but with more complications. Scaphoid replacement has now made great strides and has better postoperative function than scaphorectomy alone. Current follow-up results for all sites of prosthesis show that prosthetic reconstruction is a stable, durable method of reconstruction and that patients are functionally satisfied after surgery. Good soft tissue coverage reduces postoperative complications and plays an important role in postoperative limb function, and Ihara believes that functional muscle flap transfer is important for postoperative function after bone tumor preservation. Some experience has been gained in the revision of complications of tumor-based prostheses. Grime et al. performed second-stage revision of 34 infected tumor-based prostheses, and the infection control rate was 91% at 1 year and 74% at 5 years. There are many methods of surgical reconstruction for limb preservation, and the three main methods are autologous bone inactivation and replantation, allograft bone grafting and artificial prosthesis replacement, and other methods include autologous bone grafting with blood vessels, while soft tissue reconstruction is also very important. Various methods have their own advantages and disadvantages and corresponding indications. The decision should be based on the specific situation, the experience of the surgeon, the location of the tumor and the actual condition of the patient. Tumor resection with inactivation and replantation has been carried out in China for many years and its efficacy has been recognized by everyone. Its main advantage is that it is economical and simple. Allogeneic bone reconstruction can achieve similar results as tumor segment amputation with inactivation and replantation, but its promotion in clinical practice is somewhat limited due to the problems of price, source, matching and immune reaction. Modern materials and manufacturing processes allow for the production of individualized prostheses to replace bone from any part of the body. Assembled prostheses can be fitted to replace skeletal defects on a case-by-case basis. This type of modular prosthesis allows more flexibility in the extent of resection, especially in the event of wear and tear, fragmentation, etc., without having to replace the entire prosthesis. The porous long entry pads, rings, holes, and polymeric compressed sleeves are more conducive to soft tissue attachment. Cement-based and biologic prostheses are fixed to the host bone in different ways. Loosening of the prosthesis, wear of the polyethylene liner, and release of metal ions are all complications associated with reconstruction. Long-term outcomes of large segment prosthetic reconstruction have been reported in recent years. Artificial prosthesis replacement is currently the most widely used and most effective method of limb-preserving reconstruction. In recent years, tumor-based prostheses have become available and can be reconstructed with large segments of allograft bone. The lengthenable prosthesis used in pediatric patients was designed to address the problem of unequal limb lengths that occur in children during development. It was first used in 1976 and currently has the following types: ①Stanmore type prosthesis, which has now developed into the fourth generation. In order of development, they are: thread-driven (threaded screw adjustment), ball-bearing (tungsten carbide ball filled in the extension piston), C-ring tubular (“C” shaped cavity), and minimally invasive. Another KMFTR (Kotz Modular Femur and Tibia Resection System)/HMRS (Howmedica Modula Resection System) system prosthesis is also a modular prosthesis, which is equivalent to the minimally invasive Stanmore prosthesis. The non-invasive lengthenable prosthesis, which was invented by the French (Phenix prosthesis), has been improved several times since the 1990s, and now the trade name has been changed to Repiphysis. The self-adjusting lengthenable prosthesis, which is lengthened by the movement of the knee joint in flexion, driven by an isometric bevel gear through threaded screws. Cortical external bone grafting is used to allow bone or fibers to grow at the bone-prosthesis joint, thereby increasing the stability of the bone and prosthesis, protecting the bone cement, isolating debris from joint wear, and reducing distant aseptic loosening. The prosthetic stem is fixed with bone cement, the prosthesis is porous and surface bone grafted, relying on bone cement in the early stages and bone grafting in the later stages to induce new bone formation and provide scaffolding, producing bony wraps and obtaining biological fixation; the key to success is strong initial fixation with autologous bone grafting. Clinical and laboratory results confirm a significant reduction in the incidence of loosening, subsidence and fracture of the prosthesis. New studies have shown that the addition of bone morphogenetic protein (BMP), autologous bone marrow, or pluripotent stem cells derived from the placenta can significantly promote bone graft growth and remodeling if added to the bone graft. Artificial prosthesis replacement is an important method for limb-preserving reconstruction of bone tumors, and patients can resume functional limb activities early with very satisfactory near-term results and improving long-term results, but there is still a high level of complications.