I. General data The group of 16 cases, 13 male and 3 female, aged 21-45 years old, average 31.5 years old. There were 3 cases of car accident injury and 13 cases of fall from height injury. According to AO/ASIF typing: C27 cases, C39 cases; among them, 4 cases were fixed with tibial simple tension screw, 4 cases were fixed with fibular plate screw, 8 cases were fixed with internal fixation of tibial support plate and bone graft; the first two types of surgery were fixed with short leg plaster until clinical healing, and the postoperative follow-up was 8 months~3 years, with an average of 15 months. 1. Preoperative preparation: Heel traction was performed for 7-10 days after admission to the hospital. One day before surgery, front and lateral radiographs of bilateral ankle joints and middle and lower tibia were taken, and the approximate shape of the affected fracture block was depicted with transparent film and pieced together against the healthy side radiographs. 2, the specific steps of surgery: generally take a longitudinal incision of the anterior medial tibia first, that is, from the lateral 5 mm of the parietal tibial crest curved to the medial tibia to the tip of the medial ankle, revealing the anterior ankle joint and the medial ankle, depending on the fracture, take a longitudinal incision of the posterior lateral fibula, which can reveal the lower tibiofibular joint and the posterior ankle, clean up first, then put together, put together the complete joint surface of the distal tibia, the bone fragments involving the joint surface can be fixed temporarily with a kerf pin first, using the heel bone and If there is a cortical bone defect on the lateral and posterior side of the tibia, the fibular plate screw should be used for fixation; if there is a cortical bone defect on the anterior or medial side of the tibia, the supporting plate should be used for internal fixation. The number of tension screws does not exceed 5, and the fibular plate is a 4- to 6-hole semi-tubular plate; while the shape and position of the supporting plate are based on the fracture pattern and the site of the bone defect. Bone grafting includes cancellous bone and cortical bone, with the cancellous bone filling the medullary cavity and the cortical bone being trimmed into a wedge shape and embedded in the defect site. The degree of reliability of internal fixation determines whether external fixation is necessary. 3. Postoperative treatment: intravenous antibiotics were given for 5-7 days, plaster cast was removed after 4-6 weeks for those with external fixation, partial weight-bearing from 2 months after surgery, and full weight-bearing from 3 months after surgery; for those without plaster cast, CPM exercises were given for 2 weeks after surgery, and then active functional exercises were changed, and the weight-bearing time was the same as the former. Results 1. Efficacy assessment criteria: Content/efficacy Excellent Good Poor Complaint: 1 Pain Painless Painless Pain when standing for a long time Pain when standing 2 Swelling No swelling Slight swelling Pain with swelling when walking Swelling is obvious 3 Painless Walking 》1000m 》500m Ankle mobility 》90% 》75% 》50% 》50% Compared with the healthy side Return to work or daily life Return to original work Return to work but not return to work Daily life is not Self-care of daily life Labor intensity is reduced Daily life can be self-care Can be self-care 2. It was first described by Destot in 1911 and is often associated with insertion of the articular surface and bone loss, making it difficult to treat. The literature reports only 43%-55% excellent rate of conservative treatment David and beals reported 80 cases of surgical treatment of Pilon fracture and 65% poor results, while Teeny and Wiss reported 60 cases of surgery and 75% poor results. The reason for the wide variation in outcomes is the inconsistency in surgical indications, surgical principles, and surgical methods. By 1973, Rvedi and Allgowen proposed four principles of surgical treatment: 1) restoration of fibular length; 2) anatomical reconstruction of the distal tibial articular surface; 3) implantation of the tibial epiphysis; 4) internal fixation of the tibial support plate. In practice, we have achieved good results in the surgical treatment of heavy closed Pilon fractures by flexibly applying the above principles. There are many preoperative typing methods for Pilon fractures, and the common ones are Rüedi-Alg?wen typing and AO typing. 16 cases in this group, for example, were classified as type C according to the former classification, while the latter was more carefully classified as type C2C3. In the retrospective analysis, we found that support plates were used for type C3, while no case of type C2 was fixed with support plates and bone graft. Thus, although both types of typing can provide information on the indication of surgery for Pilon fractures, the AO typing is clearly more advantageous, as it not only has a reference value as an indication for surgery, but will also provide guidance for the subsequent operation. Therefore, we believe that AO staging is worth using in Pilon fractures, especially for heavy Pilon fractures. The importance of preoperative preparation It seems that the details of preoperative depiction of the fracture block with film have never been mentioned in previous similar joint surgeries, and the operation is based only on the radiographs and intraoperative views at the time of injury. From the viewpoint of shortening the operation time and improving the success rate, we think it is necessary to make adequate preoperative preparation. There is no uniform opinion on the surgical incision for Pilon’s fracture. The appropriate incision should meet the following three requirements: 1. facilitate visualization of the fracture; 2. be suitable for the placement of internal fixation; 3. avoid important blood vessels and nerve tissue. In this group of cases, we found that it is more appropriate to adopt a longitudinal incision in the anterior medial tibia, while the incision in the fibula is best made after determining what internal fixation method to adopt, and it is required that the skin bridge between the two incisions should not be less than 7.5 cm, and the incision goes straight to the deep fascia, forming a wide enough tip and a thick enough fascial flap, which is the guarantee that the distal end of the incision will not have poor blood supply. V. Selection of internal fixation and bone grafting Reliable fixation and oligodisturbance of blood supply are two basic requirements for the selection of internal fixation. the Rüedi-Allg?wen principle proposed to support plate application for all surgical Pilon fractures is overly focused on the toughness of internal fixation and ignores the severity of its disturbance of blood supply. Therefore, we propose to choose the internal fixation method that interferes as little as possible with the blood supply as long as the internal fixation can maintain the fracture status. In this group of cases, three different internal fixation methods were designed and used according to the bone defect, and all of them achieved good results. Clinically, we used standardized AO operation techniques and imported plates or cortical bone screws (Synthese.Tren.Smith-Nephew products) as internal fixation, compared to domestic plate screws which are slightly inferior. We attach great importance to bone grafting, the amount of bone grafting should be sufficient, and the cancellous bone and cortical bone should be implanted, the cancellous bone is used to fill the medullary cavity, and the cortical bone is trimmed and embedded in a wedge shape according to the shape of the bone defect. For the fracture, good repositioning is required to restore the flatness of the joint surface and the relationship of the weight-bearing plane. Preoperative traction with the aid of heel traction or intraoperative traction with the aid of an extra tibial talar brace can be used for traction, and excessive traction helps to restore the structure of the articular surface. In conclusion, through this group of cases, our preliminary understanding is that the Rüedi-Allg?wen principle is indeed worth following for the surgical treatment of C2C3 Pilon fractures, but it should vary from person to person and from place to place, and one similar pattern should not be forced. For the surgical operation, we emphasize that: 1. the preoperative preparation must be adequate; 2. the surgical incision is preferable to an anterior medial tibial longitudinal incision or a combined incision with a lateral fibular longitudinal incision; 3. depending on the bone defect, the method of internal fixation is chosen, and in the absence of an obvious cortical bone defect, a simple method with less interference with the blood supply to the fracture end is chosen as much as possible; 4. bone grafting must be performed in the presence of a bone defect and in sufficient quantity, with both implant cancellous bone and cortical bone.