OBJECTIVE: To evaluate the feasibility of S₂ alar iliac screw insertion in Chinese children using computerized three-dimension reconstruction and simulated screw placement technique, and to optimize the measurement of screw parameters. METHODS: A total of 83 pelvic CT data of children who underwent pelvic CT scan December 2018 to December 2020 were retrospectively analyzed, excluding fractures, deformities, and tumors. There were 44 boys and 39 girls, with an average age of (10.66±3.52) years, and were divided into 4 groups based on age (group A:5 to 7 years old;group B:8 to 10 years old;group C:11-13 years old;group D:14 to 16 years old). The original CT data obtained were imported into Mimics software, and the bony structure of the pelvis was reconstructed, and the maximum and minimum cranial angles of the screws were simulated in the three-dimensional view with the placement of 6.5 mm diameter S2 alar iliac screws. Subsequently, the coronal angle, sagittal angle, transverse angle, total length of the screw, length of the screw in the sacrum, width of the iliac, and distance of the entry point from the skin were measured in 3-Matic software at the maximum and minimum head tilt angles, respectively. The differences among the screw parameters of S₂ alar iliac screws in children of different ages and the differences between gender and side were compared and analyzed. RESULTS: In all 83 children, 6.5 mm diameter S₂ iliac screws could be placed. There was no significant difference between the side of each screw placement parameter. The 5 to 7 years old children had a significantly smaller screw coronal angle than other age groups, but in the screw sagittal angle, the difference was more mixed. The 5 to 7 years old children could obtain a larger angle at the maximum head tilt angle of the screw, but at the minimum cranial angle, the larger angle was obtained in the age group of 11 to 13 years old. There were no significant differences among the age groups. The coronal angle and sagittal angle under maximum cephalic angle and minimum cranial angle of 5 to 7 years old male were (40.91±2.91)° and (51.85±3.75)° respectively, which were significantly greater than in female. The coronal angle under minimum cranial angle was significantly greater in girls aged 8-10 years old than in boys. For the remaining screw placement angle parameters, there were no significant differences between gender. The differences in the minimum iliac width, the screw length, and the length of the sacral screws showed an increasing trend with age in all age groups. The distance from the screw entry point to the skin in boys were significantly smaller than that of girls. The minimum width of the iliac in boys at 14 to 16 years of age were significantly wider than that in girls at the same stage. In contrast, in girls aged 5 to 7 years and 11 to 13 years, the screw length was significantly longer than that of boys at the same stage. CONCLUSION The pelvis of children aged 5 to 16 years can safely accommodate the placement of 6.5 mm diameter S₂ alar iliac screws, but the bony structures of the pelvis are developing and growing in children, precise assessment is needed to plan a reasonable screw trajectory and select the appropriate screw length.
Humans ; Male ; Female ; Child ; Adolescent ; Child, Preschool ; Ilium/surgery* ; Retrospective Studies ; Feasibility Studies ; Bone Screws ; Pelvis ; Sacrum/surgery* ; Spinal Fusion/methods*

Objective:To determine the effect of comprehensive measures at reducing mosquito density in residential parking lot， and to provide scientific evidence for exploring a new mosquito density control mode in parking lot. Methods:During April to October in 2018， a package of measures were implemented in the observation group， including designating a full-time staff， combination of property management and mosquito eradication work， continual clean-up of breeding ground， appropriate use of pesticide， education and training of pest control knowledge， and so on. No intervention was conducted in the control group. Then we observed the effect of the above measures in reducing mosquito density. Results:After the implementation of the comprehensive measures， the average adult mosquito density and infant positive rate of ponding mosquitoes in the residential parking lot in the observation group were significantly lower than those in the control group. The mosquito positive rate in rainwater well， sewage well， drainage ditch and intercepting ditch in the observation group was significantly lower than that in the control group. There were no statistically significant difference between the observation group and the control group in the adult mosquito density and the infant positive rate of ponding mosquito in April. Conclusion:Through a package of comprehensive prevention and control measures， mosquito density in the parking lot at residential areas can be effectively reduced. However， there are still some resistances in the implementation process of measures， which need to be constantly optimized to achieve better on-site prevention and control effect.