Objective:To evaluate the accuracy of the domestic "Skywalker" surgical robot in implementing personalized lower limb alignment reconstruction scheme in total knee arthroplasty (TKA) and the short-term clinical outcome of robotic assisted TKA.Methods:From September 2020 to January 2021, the data of patients who received surgical robot assisted TKA in 5 clinical centers in China (Shanghai Ninth People's Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Southwest Hospital affiliated to Third Military Medical University, The Affiliated Hospital of Qingdao University, The First Affiliated Hospital of Chongqing Medical University and Yantai Yuhuangding Hospital, and Shanghai Ninth People's Hospital affiliated to Shanghai Jiao Tong University School of Medicine was the group leader) were prospectively collected and retrospectively analyzed. There were 24 males and 82 females with an average age of 67.6±7.3 years, (range 45-80 years); Average body mass index 26.42±4.31 kg/m 2, all the operation were performed by "Skywalker" surgical robot system according to preoperative design based on CT. The operation time, intraoperative blood loss, hospitalization days and postoperative complications were recorded, and the imaging indexes including hip-knee-ankle (HKA), lateral distal angle of femur (LDFA) and medial proximal angle of tibia (MPTA) measured before and after the operation, implant model indexes (preoperative planning implant model and postoperative implant model) and short-term clinical efficacy indexes [Western Ontario and McMaster Universities (WOMAC) osteoarthritis index] pain score, stiffness score, joint function score, total score and SF-12 score before and 3 months after the operation) were compared. Results:The average follow-up period was 109.60±9.80 d, (range 95-143 d). The average operation time of 106 patients was 105.30±23.22 min; The average intraoperative blood loss was 141.70±58.33 ml; The average length of hospitalization was 5.82±2.80 d. One patient had ischemic stroke after operation, and one patient had abnormal liver function after operation. According to the judgment of the investigator, all of them were not related to the operation. The actual angle error is the difference between the preoperative planning angle and the postoperative measurement angle. The absolute error of 99.1% (105/106) of the HKA angle was within 3°, 90.8% (69/76) of LDFA, 98.7% (75/76) of the MPTA. In 45 patients in one center where data were available, the actual implant models used in all patients were consistent with the preoperative planning size, and there were only differences in version selection such as Asian condyle. WOMAC pain score, joint function score, total score was improved from 7.34±2.85, 25.10±9.85, 34.75±13.02 to 3.34±2.66, 14.68±9.64, 18.66±13.49 before and after operation, respectively, which were statistically significant ( P<0.001) and SF-12 physiological score and psychological score were improved form 27.24±6.42, 30.68±8.26 to 38.83±5.74, 39.36±7.85 before and after operation, respectively, which were statistically significant ( t=7.33, P<0.001; t=4.53, P=0.043). Conclusion:Domestic surgical robot system "Skywalker" can assist the surgeon to achieve accurate and personalized reconstruction of lower limb alignment and achieve satisfactory short-term clinical outcomes. The long-term clinical outcomes of personalized reconstruction and survival rate of implant still need to be further studied.

Objective Based on the principle of uncemented stem design, the femoral anteversion in different CT planes before total hip arthroplasty (THA) and stem anteversion after THA was compared, so as to find out the preoperative measurement to estimate stem anteversion in patients with developmental dysplasia of the hip(DDH) after THA. Methods Twenty-one primary THA patients (28 hips) who were diagnosed with DDH between September 2007 and May 2013 in Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine were selected. Preoperative and postoperative CT scans were performed on all patients. The femoral anteversion angle was defined as the angle between the midcortical line between the anterior and posterior cortical line in five CT slices and the posterior condylar axis. The slice levels for the 4 femoral sites were selected，including the area just distal to the femoral head, the center of the lesser trochanter，1 cm height above center of the lesser trochanter, 2 cm height above center of the lesser trochanter (marked as femoral anteversion 1-4). Femoral anteversion 5 was defined as the midcortical line of the anterior cortical line in the slice of 2 cm height above center of the lesser trochanter and the posterior cortical line in the slice of 50% of the distance from the top of greater trochanter to the center of the lesser trochanter above the center of the lesser trochanter. The stem anteversion angle was defined as the angle formed by the stem neck major axis and the posterior aspect of the femoral condylar line. The cup version and stem alignment were also calculated. The difference value and correlation coefficients of femoral anteversion 1-5 and stem anteversion were compared. Results Femoral anteversion 1-5 was 17.70°±10.54°, 35.59°±7.21°, 31.09°±7.98°, 24.71°±9.11°, 21.94°±10.10°, respectively。Stem anteversion was 20.52°±10.90°. The difference value between stem anteversion and femoral anteversion 1-5 was 2.82°±6.27°, -15.08°±7.99°, -13.80°±15.68°, -4.19°±5.69°, -1.42°±4.07°, respectively. Cup anteversion was 25.60°±11.65°, and combined antevertion was 46.11°±13.28°，sagittal stem tilt was 1.13°±1.53°. There were statistically significant differences between femoral anteversion 1-4 and stem anteversion (P＜0.05), and no statistical difference was found between femoral anteversion 5 and stem anteversion. The correlation coefficients of femoral anteversion 1-5 and stem anteversion were 0.829, 0.681, 0.689, 0.853, 0.928, respectively. Conclusions Femoral anteversion 5 had a highly positive correlation with stem anteversion, which was an effective a substitute of stem anteversion before THA.