Objective To evaluate the accuracy and reliability of O-arm-based thoracolumbar pedicle screw installation.Methods A retrospective review was conducted on 75 patients who had undergone thoracolumbar pedicle screw fixation assisted with O-arm navigation (navigation group,n =32) and C-arm fluoroscopy (fluoroscopy group,n =43) from March to October 2014.All the patients were assessed with X-ray and CT images after operation.Accuracy of screw installation in both groups was compared.In navigation group,screw directions were measured on the sagittal and axial images of intraoperative navigation and post-operative CT scanning to evaluate the concordance.Results In fluoroscopy group,a total of 206 pedicle screws were placed with the one-time success rate of 93.2％ and accuracy of 90.8％ for screw placement,and one misplaced screw (grade llⅢ) led to L3 nerve root symptom.In navigation group,a total of 226 pedicle screws were placed with the one-time success rate of 100％ and accuracy of 96.9％ for screw placement,and no screw was grade Ⅲ.Further,there were no significant differences in screw directions on the sagittal and axial images between intraoperative navigation and postoperative CT scanning (P ＞ 0.05).Conclusion O-arm navigation that provides high-resolution images and high precision improves the accuracy of thoracolumbar pedicle screw installation,and possesses good reliability.

Objective: To understand physical activity status and its relation with cardiopulmonary endurance among Chinese children and adolescents, so as to provide reference for cardiopulmonary endurance improvement and intervention of Chinese children and adolescents. Methods: During September to November 2018, a stratified cluster sampling method was used to select 4 269 children and adolescents aged 7-18 years in six major regions of China, 20 m shuttle run test and physical activity were assessed. Results: Average duration for daily lowintensity physical activity among boys was (31.49±30.01) min, for moderate to vigorous physical activity (68.37±46.50) min. Average duration for low intensity physical activity among girls was (34.02±31.58) min, for moderate to vigorous physical activity was (63.02±44.91) min. The number of 20 m shuttle run test for boys reached ( 36.17 ±21.94) times, and the maximal oxygen uptake per minute was (44.51±5.05) mL/kg; the number of 20 m shuttle run test for girls reached (26.59±12.56) times, and the maximal oxygen uptake per minute was (41.99±5.29) mL/kg. There were statistically significant differences in the number of 20 m shuttle run test and maximal oxygen uptake across age groups in boys ( F= 589.37 , 152.79, P <0.01), as well as that in girls ( F=305.21, 1 032.46, P <0.01). The proportion of boys and girls who met moderate to vigorous physical activity standard was 49.24% and 42.92%, respectively. Linear regression analysis showed that there was a significant positive correlation between the duration of moderate to vigorous physical activity and maximal oxygen uptake ( β=0.11, P ＜ 0.01). Conclusion There is a significant correlation between moderate to vigorous physical activity with cardiorespiratory endurance among Chinese children and adolescents. Higher level of moderate to vigorous physical activity is important to help improve cardiopulmonary endurance among children and adolescents.

The impact of plateau environment on cerebral venous thrombosis (CVT) is more complex and diverse than in plain areas. This article reviews the epidemiological characteristics, affected sites, and especially the pathogenesis of CVT in plateau areas.