Early exercise training after limb surgery can significantly accelerate the recovery of limb function. With the prolongation of the survival period of malignant tumors of the extremities and the widespread development of limb-sparing surgery, the postoperative functional rehabilitation of the limbs of this part of the patient is of great significance for improving the quality of their survival. However, the motor function rehabilitation after limb preserving surgery for malignant tumors of the extremities has its own particularity. Due to the large number of tissues removed during surgery, reconstruction of bone, muscle, skin and even blood vessels and nerve tissues is often required. Therefore, there are some problems to be explored in the early exercise training of postoperative limbs, such as the time of starting exercise, the intensity of exercise, the speed of adding weight, etc. Since May 2000 – May 2005, our department has carried out functional rehabilitation training for 54 patients after limb preservation surgery for limb tumors and gained certain experience, which is summarized as follows: 1. General data: 54 cases in this group, 34 men and 20 women. Age 12-75 years old, average 43 years old. There were 13 cases of upper limb and 41 cases of lower limb. There were 21 cases of bone tumor and 33 cases of soft tissue tumor. 2, the way of limb preservation and reconstruction: 21 cases of bone reconstruction: 3 cases of artificial prosthesis replacement, 12 cases of tumor bone inactivation and replantation, 6 cases of cemented allograft bone filling; 16 cases of myodynamic reconstruction: 9 cases of synergistic muscle local transposition, 4 cases of antagonistic muscle local transposition, 3 cases of muscle transposition on the opposite side of the joints; 17 cases of reconstruction of skin and soft tissue defects: 2 cases of free skin grafting, 12 cases of vascularized insular flaps, 3 cases of free skin flaps, 3 cases of vascularized insular flaps. 3 cases. 3.Rehabilitation training methods: bone reconstruction: (1) joint activity time: reconstruction of strong people, in the postoperative period that is isometric contraction of the relevant muscles, 12 days after the removal of stitches to carry out passive flexion and extension of the joints, the range of activities in the patient does not feel pain within. Active joint movements were started 3 weeks after surgery. Later on, under the premise of not affecting the stability of the bones, active and passive movement of the joints will be carried out, and the range of motion will be gradually increased. For patients with multiple reconstruction of joint bones or ligamentous structures, passive joint movement should be started at 4 weeks after surgery. (2) The time to start weight-bearing or walking: for those with artificial prosthesis or bone cement filling, weight-bearing walking can be started after 3 weeks. Inactivated tumor bone or allograft bone reconstruction patients can walk without weight bearing after 3 weeks with crutches, and walk with partial weight bearing after half a year. Full weight-bearing ambulation is seen after the formation of a solid bone scab, usually between six months and two years. For myodynamic reconstruction, the limb is immobilized in the lax position of the transposed muscles for 3-4 weeks after surgery, and then passive movement of the joints associated with the transposed muscles is started, so that the patient can feel the pull on the transposed muscles. After another 1-2 weeks, active contraction of the transposition muscle, so that the patient feels the new function of the muscle, repeated training and strengthening, to establish the reflex. At the same time, gradually increase the muscle strength training. For people with skin soft tissue reconstruction: for people whose joint activities do not affect the blood supply and tension of the tissue flap, joint function training will be started at 1 week after surgery. For those who affected the blood supply and tension of the tissue flap, the training was started at 2 weeks after surgery. Results The joint mobility was checked at 3 months after surgery and compared with that of the corresponding joint on the contralateral side. Reconstruction method Bone and armament solid reconstruction group Bone and armament non-solid reconstruction group Myodynamic reconstruction group Skin and soft tissue reconstruction group Maximum joint mobility (compared with the contralateral side) %) 50%-60% 20%-50% 50%-100% 100% DISCUSSION With the application of neoadjuvant chemotherapy to bone and soft tissue tumors of the limbs, the five-year survival rate reaches between 60% and 80%. As a result, patients’ demand for quality of life has increased accordingly, and limb-sparing therapy has become a trend. In recent years, the research of orthopedic biomaterials has made great progress, and orthopedic surgical techniques have been improved, making limb-sparing surgery widely available. As with other limb surgeries, the mobility of the joints of the reconstructed limb is crucial to the function of the limb. However, the structure of the reconstructed limb is different from that of the normal limb, and there are special requirements for the rehabilitation of the limb’s motor function. Through the initial observation of the limb motor function rehabilitation of this group of patients, there are some preliminary experiences. (1) Rehabilitation training after bone reconstruction: reconstruction of bone integrity in bone tumor limb preservation surgery is different from reconstruction of bone integrity after general fracture. The reconstruction of bone after bone tumor surgery is either prosthesis, or allogeneic bone, or inactivated tumor bone, or even reconstruction of composite various materials. Therefore, the strength and stability of the reconstructed bone is poor, and it is undoubtedly inappropriate to carry out limb function rehabilitation training according to the time and strength after general internal fixation of fracture. Rehabilitation training should be carried out according to the following principles: ① isometric muscle contraction training can be carried out after the operation, which is conducive to eliminating swelling and removing bruises, and preventing intermuscular adhesion. The isotonic contraction of muscles for joint movement and weight bearing should be agreed upon by the surgeon and the rehabilitation trainer according to the specific surgical situation. If the internal fixation is strong and reliable, such as prosthesis replacement or large allograft bone grafting, early non-weight-bearing training is feasible, the same as the general fracture. If the bone reconstruction is not strong, the start of joint functional training is delayed until 4 weeks after surgery. (iii) About weight-bearing training after reconstruction. For allograft and autogenous bone reconstruction, due to the slow healing of bone, it usually takes 1-2 years for the bone to heal and become strong. It is best to start weight-bearing training from 6 months after the operation, and start full weight-bearing after obvious bone healing is observed on X-ray. This will prevent the resorption and collapse of the implant block and the fracture of the internal fixation material. (2) Rehabilitation training after myodynamic reconstruction: malignant tumors of the extremities, especially soft tissue sarcoma, require extensive resection, even of the intermuscular compartment, in order to achieve the goal of reducing the local recurrence rate. Therefore, after tumor resection, all of them require reconstruction of myodynamic deficit. Muscle transposition is commonly used to rebuild power and compensate for the function of the surgically resected muscle. The transposed muscle should be fixed with the corresponding tissue structure to perform the new function. Rehabilitation is important to adapt the transposed muscle to the new purpose and mode of activity. The start of exercise should be delayed until 3-4 weeks after surgery to prevent cracking of the muscle fixation attachments, which can lead to surgical failure. A training program should be developed for training. Firstly, passive movement of the muscle-reconstructed joints should be performed to restore normal mobility. Secondly, the patient is trained to actively contract the transposed muscle to feel the new joint mobility function and establish the conditioned reflex as well as to train it to work with other muscles in order to make the muscle perform the new function better. Finally, the contraction strength of the muscle is trained to achieve the purpose of compensating for the function of the resected muscle group. Experience has proved that this rehabilitation training is crucial for the recovery of limb function after surgery, and the muscles that are transposed by those who do not train only serve to cover the trauma. (3) Rehabilitation of patients with skin tissue flaps covering limb tissue defects: for those without motor tension sites, joint muscle training begins at 1 week after surgery. For those around the joints and those with tension during activities, the intensity of activities should be gradually increased at 2 weeks after surgery to prevent ischemic necrosis of the tissue flap or incision cracking. In conclusion, the functional rehabilitation of limbs after limb-sparing surgery for malignant tumors of the extremities has its own particularity. In this paper, only a little rough experience is summarized. The starting time, intensity, mode, and evaluation of the results of the rehabilitation should be further studied.