OBJECTIVE: To summarize the efficacy of knee surface replacement in the treatment of valgus knee osteoarthritis. METHODS Retrospective analysis of 11 cases, 4 males and 7 females, with an average age of 68 years (59-78 years), who underwent knee surface replacement for the treatment of ectropic knee osteoarthritis from July 2004 to February 2012. The results were followed up for a mean of 10 months (1~15 months). Using the HSS Knee Percentage System [1] scoring criteria, the preoperative score was 38 (5-57) and the mean postoperative score was 88 (77-95). Conclusion Knee surface replacement is an effective treatment for valgus-type knee osteoarthritis. Osteoarthritis; knee; arthroplasty Knee surface replacement has become one of the most successful treatments for inversion-type knee osteoarthritis. Proper osteotomy and soft tissue balancing techniques are key factors in the success or failure of surgical treatment, and knee valgus deformity is one of the late manifestations of knee osteoarthritis. A review of 11 patients with knee valgus osteoarthritis who received follow-up and satisfactory knee treatment results is reported as follows: I. Clinical data (1) General data: From May 2004 to February 2012, 11 cases of knee osteoarthritis with knee inversion deformity were treated by total knee replacement, 4 joints in men and 7 joints in women; the average age was 68 years (59-78 years), and the weight-bearing position X-ray measurements were performed before and after surgery, respectively, 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. ZIMMER posterior stabilized prosthesis from the United States and Akcome posterior stabilized prosthesis from China were used for the prosthesis. Postoperative joint rehabilitation training 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. 2. Results Appointment for follow-up by filming. 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. 3. Discussion Knee inversion deformity is most common in patients with total knee replacement. The technique for proper placement of the prosthesis is complex in patients with severe internal knee valgus. Karachalios et al. reported an average 5.5-year follow-up rate of 84% after knee inversion and 92% without inversion. 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 for 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.