OBJECTIVE: To summarize the efficacy of joint replacement in the treatment of inversion knee osteoarthritis. Methods Retrospective analysis of 31 complete cases, 14 males and 17 females, with a mean age of 68 years (55-92 years), obtained by knee replacement for osteoarthritis of the knee from May 2004 to January 2010. The results were followed up for a mean of 11 months (1 to 18 months). Using the HSS Knee Percentage System [1] scoring criteria, the preoperative score was 39 (5-58) and the mean postoperative score was 89 (77-95). Conclusion Artificial total knee replacement is an effective treatment for inversion-type knee osteoarthritis. Osteoarthritis; knee; arthroplasty. Artificial knee replacement has become one of the most successful treatments for severe knee osteoarthritis. Proper osteotomy and soft tissue balancing techniques are key factors in the success or failure of surgical treatment, and inversion deformity of the knee is one of the advanced manifestations of knee osteoarthritis. I. Clinical data 1. General data: From May 2004 to January 2010, 31 cases of knee osteoarthritis with inversion deformity were treated by total knee replacement, 14 joints in men and 17 joints in women; the average age was 68 years old (55-92 years old), respectively. Weight-bearing position X-ray measurements were performed before and after surgery to compare the force line and angle changes of the knee joint before and after surgery and to analyze the influence of intraoperative surgical methods. 2. Surgical method: The surgery was performed by the same group of surgeons, all using a midline longitudinal incision of the knee joint with a medial parapatellar approach. The following operations were performed sequentially after entering the joint: excision of the prepatellar fat pad, subperiosteal debridement of the medial collateral ligament and soft tissue of the tibial plateau to the medial edge of the tibial plateau, and excision of the tibia and peripatellar bone. After osteotomy of the femur and tibial plateau, the following areas were released: removal of the medial residual bones of the tibial plateau, release of the posterior joint capsule and removal of the seed bone and bones of the joint capsule, and recontouring of the tibial plateau. The “NoThumbTest” test was performed after the trial mold was installed, and some patients underwent release of the lateral patellar support band. The ZIMMER posterior stability prosthesis was used in all cases. Medial collateral ligament release was performed in all cases, and postoperative joint rehabilitation was performed. 3. Statistical methods SPSS10.0 statistical software was applied for analysis, and paired t-test was used for comparison between groups, and P value <0.05 was statistically significant. II. RESULTS 2.1 Appointment to come to the hospital for follow-up radiographs. The follow-up period was from 1 month to 18 months after surgery, with a mean follow-up of 11 months (1-18 months). The preoperative HSS score was 39 (5-58) and the follow-up HSS score was 89 (77-95), which was statistically different from the preoperative one (P<0.05). The preoperative knee inversion angle was 13.80+2.50 (50~300), and the total postoperative knee inversion angle was 0.80+1.50, which was statistically different from the preoperative one (P<0.05). Four cases of postoperative patellar popping occurred 3~14 months after surgery, and the symptoms were relieved after quadriceps exercise. 2 cases had translucent lines in the tibial prosthesis part on reexamination X-ray, and the patients had no obvious prosthesis loosening symptoms. The internal derangement of the knee is the most common in patients with total knee replacement. In patients with severe internal derangement of the knee, the technique for proper placement of the prosthesis is complex. Karachalios et al. reported an average 5.5-year follow-up rate of 84% after internal and external knee arthroplasty, and 92% without internal and external knee arthroplasty. Zhou Dengge et al. found that tibial structural inversion accounted for only 22.8% of the inversion angle, while 53.2% of the inversion angle was due to soft tissue imbalance. In a total knee replacement, release of the superficial medial collateral ligament is the key, and in severe valgus, subperiosteal cuff release of the superficial tibial collateral ligament stop (along with the deep medial collateral ligament and joint capsule) is often required, even in the case of a "goose foot" release. However, it is controversial whether this type of release will affect the stability of the joint due to the wide range of subperiosteal dissection, and it is not easy for the surgeon to control the accuracy of the release. We found that the most common imbalance of the medial space in the extension position was in the soft tissue balancing process in this group of patients. The anterior bundle of the superficial medial collateral ligament can be corrected. It is important to note that there are two important stabilizing structures in the posterior medial knee, the posterior oblique ligament and the semimembranous tendon. When performing selective release of the superficial medial collateral ligament of the knee, it is important not to damage these two stabilizing structures. We do not have experience with lateral collateral ligament tightening. During the intraoperative tibial osteotomy, we found that the proximal anatomy and force line changes in patients with internal knee valgus often lead to external rotation of the tibia, combined with a medial stress hyperplasia of the tibial plateau, which can easily cause visual displacement and internal rotation of the tibial plateau after the osteotomy, so we believe that adequate exposure of the medial tibial plateau and removal of the hyperplasia are particularly important. Since we use prostheses without posterior tilt, we generally control the proximal tibial osteotomy section at 3° to 5° intraoperatively. After total knee arthroplasty, patellofemoral joint complications have become an important cause of postoperative knee joint malfunction. Patellar popping. Our experience in the prevention of tibial prosthesis loosening is to keep the tibial osteotomy within 10 mm as much as possible, in order to preserve the hard subcortical bone and prevent postoperative tibial bone collapse from causing prosthesis loosening. Postoperative functional exercise is important, and we require it to be performed without pain, with routine application of pain medication in most patients, and following an early start and gradual progress, with the possibility of using a CPM machine to maximize the restoration of flexion and extension of the joint. In conclusion, through fine soft tissue release especially medial collateral ligament release and standardized osteotomy technique, good treatment results can be achieved for total knee replacement in inversion knee osteoarthritis.