What type of fixation should be used after osteotomy for surgical correction of internal and external knee deformity? There are two methods of fixation: internal fixation: plate and intramedullary nail; external fixation: single arm external fixation and circumferential external fixation. How to choose? This is not only a question of surgical technique, but also of the surgeon’s preference, mastery of the instrument, and the specific circumstances of the disease. There is no one size fits all, and a good result can only be obtained by adapting to the local situation. Let’s start with external fixation. Originally, many surgeons looked down on external fixation frame, thinking it was something without technical content. Since Ilizarov technology has become a worldwide sensation, Chinese doctors have been paying more and more attention to external fixation technology. Because this technology can treat various difficult diseases in orthopedics. 1.Heavy deformity, one correction cannot be completed (especially knee valgus deformity, one correction is easy to damage common peroneal nerve); 2.Poor local soft tissue condition, high risk of plate placement; 3.Simultaneous existence of multiple deformities, compound deformity, such as angulation, rotation, shortening, etc. The original Ilizarov stent configuration is more complicated, and it is difficult for patients to adjust the stent. Single-arm external fixation stent, represented by Italian imported product ORTHOFIX, although it is single-plane fixation, but because of the designer’s clever design, it can also complete the correction of various deformities at the same time, and if the design is carefully evaluated before surgery, it can achieve the same result. Internal fixation technique has been used to correct deformities for a long time, and it also has certain indications: 1, the deformity is mild and can tolerate a one-time completion of the orthosis; 2, for elderly osteoarthritis, high tibial osteotomy, relieving knee pain by adjusting the force line; 3, better local soft tissue, no surgical scars on the skin; 4, no compound deformity, no need for simultaneous bone lengthening of patients. How to reduce the wearing time of external fixation brace has been the direction of doctors’ efforts in various countries. Dror Paley of the United States invented the technique of combining internal and external fixation to correct the deformity, which corrects the deformity by external fixation stent during the operation, and after the deformity is corrected satisfactorily, the intramedullary nail is inserted intraoperatively, so that there is no need to wear a stent at all after the operation, which greatly improves the patient’s comfort and restores the joint function faster. However, this technique also has certain indications: 1, not applicable to patients who are underage; 2, the deformity is mild and there is no shortening deformity; 3, the curvature of the bone cannot be too large, otherwise the intramedullary nail cannot be driven.