Objective To observe the changes of force bearing area and pressures of the rabbit tibiofemoral contact area and the biomechanical reconstruction level of joint after meniscal allograft. Methods A total of 28 Japanese rabbits were involved, weighing 3.0-3.5 kg, male or female. Of 28 rabbits, 7 were selected as meniscus donors, the remaining 21 rabbits were randomized into group A (n=7), group B (n=7), and group C (n=7). Group A underwent single knee opening and suturing, group B underwent medial meniscus excision and suturing, and group C underwent medial meniscus allograft after medial meniscus excision and suturing. The rabbits were sacrified at 12 weeks after operation for biomechanical observation through biomechanical machine and color imaging system. The meniscus tissue specimens were harvested from groups A and C to perform histological and immunohistochemical staining. Results After operation, all rabbits in 3 groups survived to the end of experiment. There were significant differences in the force bearing area and pressures at 0-90° flexion between group B and groups A, C (P lt; 0.05) at 12 weeks, showing no significant difference between group A and group C (P gt; 0.05); and there were significant differences in the force bearing area and pressures at 120° flexion among 3 groups (P lt; 0.05). The histological observation showed that the number of cartilage cells and collagen fibers returned to normal in group C, and the immunohistochemical staining showed that transplanted meniscus of group C contained large amounts of collagen fibers consisting of collagen type I and collagen type II. After 12 weeks of operation, the collagen type I contents were 0.612 5 ± 0.059 8 in group A and 0.587 2 ± 0.063 9 in group C, showing no significant difference (t=0.765, P=0.465); the collagen type II contents were 0.772 4 ± 0.081 5 and 0.814 3 ± 0.051 7, respectively, showing no significant difference (t= —0.136, P=0.894). Conclusion The allograft of rabbit meniscus can significantly increase the force bearing area of the tibiofemoral contact area and reduce the average pressure. Therefore, biomechanically speaking, the meniscus allograft can protect the articular cartilage and reconstruct the biomechanical balance.
Objective To investigate the clinical effect of the DaVinci robot system and laparoscopic radical gastrectomy. Methods Propensity score matching and retrospective cohort study were adopted. Data of 446 patients who underwent robotic or laparoscopic radical gastrectomy in the Department of Gastrointestinal Surgery, Xijing Hospital, the First Affiliated Hospital of Air Force Military Medical University from January 2014 to April 2021 were collected. Among them, 174 cases underwent robotic and 272 cases underwent laparoscopic surgery. Using the method of propensity score matching, 133 cases were selected from robotic operation group and laparoscopic operation group respectively as the research object. The perioperative indexes of the two groups were compared. Kaplan-Meier survival analysis was used to draw the survival curve and calculate the survival rate. Cox regression model was used to analyze the risk factor of prognosis. Results There was no significant difference in baseline data between the robotic surgery group and the laparoscopic surgery group after propensity score matching (P>0.05). The operative time of the two groups [(236.47±50.32) min vs. (230.64±44.51) min, t=1.000, P=0.318], the number of lymph nodes dissected [(23.32±6.58) vs. (23.95±6.03), t=–0.826, P=0.410], the time of first anal exhaust [(3.46±0.77) days vs. (3.38±0.75) days, t=0.882, P=0.378], and the length of postoperative hospital stay [(6.98±2.84) days vs. (6.94±3.61) days, t=0.094, P=0.925] were similar, the differences were not statistically significant. Compared with the laparoscopic surgery group, the robotic surgery group had less intraoperative bleeding [(83.76±58.23) mL vs. (116.54±58.58) mL, t=–4.577, P<0.001], but the total hospitalization expenses was higher [(10.04±1.92) ten-thousand Yuan vs. (6.80±1.27) ten-thousand Yuan, t=16.211, P<0.001]. The incidence of postoperative complications between the two groups (χ2=0.057, P=0.812) and Clavien-Dindo classification of complications (Z=–0.440, P=0.965) were similar between the two groups, the differences were not statistically significant. The 3-year survival situation was similar between the two groups (P=0.356). Body mass index [RR=0.803, 95%CI (0.698, 0.924), P=0.002], TNM-staging [Ⅱ -stage vs.Ⅰ -stage, RR=4.152, 95%CI (1.121, 15.385), P=0.033; Ⅲ -stage vs.Ⅰ -stage, RR=5.476, 95%CI (1.458, 20.558), P=0.012] and postoperative complications [with vs. without, RR=3.262, 95%CI (1.283, 8.293), P=0.013] were prognostic factors for 3-year survival. Conclusion Compared with laparoscopic radical gastrectomy, robotic radical gastrectomy has the same short-term and long-term prognosis.