Objective: To explore and evaluate the biomechanic relationships between different depth of pedicle screw penetration with the sagittal plane reconstruction in thoracolumbar fracture. Methods:Six fresh cadaveric specimens of lumbar spine from L_1 to L_3 were used to make the model of thoracolumbar fracture. The system of universal spine system( USS )pedicle screw was adopted with the 6 mm diameter of screw. Each of two Schanz screws was implanted into the pedicles of L_1 and L_3 A canulated screw was fixed into the former of vertebral body in L_1 and L_3, and the distance of the two canulated screws was taken as the normal height. The axial loads were given while the pedicle screws were implanted at the depth of D1, D2 and D3, and the distance of the two canulated screw was measured as well as the distance was reduced to the normal height by axial load. The index measured included of the depth of pedicle screw penetration, the height of fractured vertebral body and afterload. Results: Along with the increasing of afterload, the height of injured vertebral body was increased accordingly, but the extent was different at three depth of pedicle screw penetration (D1, D2, and D3). While the injured vertebral body was reduced totally (reduced distance 0.00 mm), there was (2 630±13) g of afterload needed in Dl depth, and (2 339±61) g and(2 221± 164) g of afterload in D2 and D3 depth respectively. There was significant difference in distance between D1, D2 and D3 (P< 0.01), however, no significant difference between D2 and D3 (P> 0.05). Conclusion: There is a relationship in the depth of pedicle screw penetration, the capacity of reduction and sagittal plane reconstruction. The depth of pedicle screw had a significant effect on the capacity of reduction for the injured vertebral body, which would be the best option in biomechanics when the pedicle screw was implanted more than 1/2 pedicle or all of it.

Objective:To explore the preventive value of "integrated prevention strategy" for nipple and areola ischemia after single-port endoscopic subcutaneous mastectomy.Methods:The clinical data of 72 patients with breast cancer who received single-port endoscopic subcutaneous mastectomy in Beijing Friendship Hospital, Capital Medical University from July 2019 to July 2021 were retrospectively analyzed, they were all female. The follow-up period was up to July 2022. According to the perioperative treatment methods, the patients were divided into observation group ( n=40) and control group ( n=32). The patients in the observation group who adopted the "integrated prevention strategy" scheme, and patients in the control group who adopted the conventional treatment scheme. The incidence of postoperative nipple and areola ischemic was compared between the two groups, and the postoperative cosmetic effect, quality of life and satisfaction of patients were evaluated. Measurement data were expressed as mean ± standard deviation ( ± s), and t-test was used for comparison between groups; the Chi-square test was used to compare the data groups. Results:The postoperative drainage volume in the observation group was significantly lower than that in the control group [(632.40±226.37) mL vs (774.91±239.85) mL], and the difference was statistically significant ( P=0.013). Two weeks after operation, there was 1 case of nipple and areola ischemia in the observation group, and 7 cases in the control group, the difference was statistically significant between the two groups ( P=0.019). Twelve months after operation, the score of breast satisfaction (83.93±11.64 vs 67.28±11.52), chest satisfaction (89.63±8.06 vs 83.03±9.49) and psychosocial well-being (89.43±12.42 vs 78.88±10.40) in the observation group were better than those in the control group, the differences were statistically significant ( P<0.05). Conclusion:"Integrated prevention strategy" can effectively prevent the occurrence of nipple and areola ischemic after single-port endoscopic subcutaneous mastectomy and improve patient satisfaction, which has certain promotion value.