Objective:To investigate the clinical significance of a new classification system for atlas fractures based on pre- and post-treatment CT features, with a focus on diagnosis and treatment.Methods:A retrospective analysis was conducted on 75 cases of cervical vertebra fractures treated at the Sixth Hospital of Ningbo City between January 2015 and December 2020. The study included 44 males and 31 females, with an average age of 53.3±13.0 years (range: 27-81 years). The fractures were classified according to the Landells classification, resulting in 12 cases of type I, 13 cases of type II, 33 cases of type III, 9 cases that were difficult to classify due to fracture lines located at anatomical junctions, and 8 cases that could not be classified using the Landells classification due to diverse injury mechanisms. To establish a new preliminary classification for cervical vertebra fractures, the researchers considered whether the fracture line in the CT images involved the facet joint surface of the atlas, the impact on bilateral half-rings, and the displacement distance of the fracture ends. Five spinal surgeons were randomly selected to classify the CT images of the 75 patients using the new classification method. After one month, the imaging data of the 75 cases of cervical vertebra fractures were randomized and reclassified to assess the reliability and repeatability of the classification.Results:The new cervical vertebra fracture classification method comprised three types based on whether the fracture line involved the facet joint surface of the atlas: type A (no involvement of the facet joint surface of the atlas), type B (involvement of one side of the facet joint surface with intact contralateral half-ring), and type C (involvement of one side of the facet joint surface with fractured contralateral half-ring). Additionally, based on the maximum displacement distance between the fracture ends (>4 mm), six subtypes were identified: subtype 1 (≤4 mm displacement) and subtype 2 (>4 mm displacement). Consequently, the subtypes were classified as A1, A2, B1, B2, C1, and C2. According to the new classification method, the 75 patients included 17 cases of A1, 12 cases of A2, 7 cases of B1, 13 cases of B2, 12 cases of C1, and 14 cases of C2. The classification demonstrated excellent consistency, as assessed by the five doctors, with Kappa values of 0.85 and 0.91 for reliability and repeatability, respectively. At the final follow-up, all conservatively treated patients achieved bone healing, while four surgically treated patients experienced non-union of the fracture ends but exhibited good fusion between the atlas and axis. The remaining surgically treated patients achieved bony union without complications such as loosening or fracture of internal fixation.Conclusion:The new cervical vertebra fracture classification method, based on CT imaging features, comprehensively covers common clinical cases of cervical vertebra fractures and demonstrates excellent consistency. It provides valuable clinical guidance for the diagnosis and treatment of cervical vertebra fractures.

Objective:To compare the consistency of tomographic infrared spectrum analysis with conventional infrared spectrum analysis for the composition analysis of large-volume of urinary stones in vitro.Methods:Postoperative urinary stone specimens collected from 105 patients admitted to Beijing Tsinghua Changgung Hospital from January 2019 to June 2021 were analyzed, including 81 (77.14%) kidney stones, 16 (15.24%) ureteral stones, and 8 (7.62%) bladder stones. All stones measured ≥0.8 cm in maximum diameter on preoperative imaging. Eighty-four specimens, which were mainly stone fragments, were collected from percutaneous nephrolithotomy and ureteroscopic lithotripsy. These 84 specimens were analyzed and retested for stone composition using conventional infrared spectrum analysis by random multiple sampling. Other 21 renal stone specimens were obtained by laparoscopic lithotomy or standard percutaneous nephrolithotomy after November 1, 2020. These 21 specimens had a maximum diameter of ≥0.8 cm measured postoperatively. Based on intraoperative observation, stone specimens with typical layered structures were chosed. Then, all 21 samples were analyzed and retested by conventional infrared spectrum analysis and tomographic infrared spectrum analysis, respectively. When using tomographic infrared spectrum analysis, we need to take two maximum cross sections with a vertical spacing of these sections >2 mm, then perform multiple points sampling according to the morphological stratification of the first section. If the section's structure was homogeneous, we equidistantly took 2 to 3 samples from the center to the periphery. Otherwise, every layer needed to take a stone sample according to the stratification. Putting all the results of one section together, we obtained complete tomographic infrared spectrum analysis data. Take another coaxial cross-section of the same specimen for retesting. We recorded the characteristics of the three-dimensional distribution of stone composition in 21 stone specimens. Meanwhile, we compared the consistency of the results of conventional infrared spectrum analysis and tomographic infrared spectrum analysis for the same sample.Results:The consistency rate of the conventional infrared spectrum analysis was 56.19% (59/105), and that of tomographic infrared spectrum analysis was 80.95% (17/21). The difference in consistency between two methods was statistically significant ( χ2=4.447, P=0.035). Among 21 specimens, the consistency rate of conventional infrared spectrum analysis was 38.10% (8/21), which was significantly lower than that of tomographic infrared spectrum analysis ( χ2=7.814, P=0.005). Regarding the characteristics of the three-dimensional distribution of the components, the color and crystal morphology of five common types of stone components were different, and layered structure in the cross-section of the stones were observed. When the calculi were of the same composition, they were displayed in different morphology. We observed a trending change in the composition ratio between sublayers from the center to the edge in some compound-composition stones. Conclusions:For the composition analysis of larger-volume urinary stones, tomographic infrared spectrum analysis showed a higher consistency of retesting than conventional infrared spectrum analysis, and the three-dimensional distribution of stone composition had some characteristic features.

Objective:To explore the effect and mechanism of lncRNA SBF2-AS1 on glioma cell proliferation, apoptosis and radiosensitivity.Methods:Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the mRNA expression levels of SBF2-AS1, miR-1287-5p and FSCN1 in normal human brain glial cell HEB and glioma cell lines, including LN18, SW1088, Hs683, and western blot method was used to detect the expression level of FSCN1 protein in cells. Glioma cells including LN18 and SW1088 were taken as the research object. After SBF2-AS1 small interfering RNA, miR-1287-5p mimics, FSCN1 small interfering RNA were transfected into LN18 cells, CCK-8 was used to detect cell proliferation, flow cytometry was used to detect cell apoptosis, clone formation experiment was used to detect cell radiosensitivity, Western blot was used to detect the protein expressions of cyclin D1, cleaved-caspase 3 and phosphorylated histone 2A variant phosphorylated histone (γ-H2AX). Dual luciferase reporter gene experiments verified the regulatory relationship between SBF2-AS1 and miR-1287-5p, as well as miR-1287-5p and FSCN1.Results:Compared with HEB cells, the expression level of SBF2-AS1 and the expression levels of FSCN1 mRNA and protein in glioma cell line LN18, SW1088 and Hs683 were significantly increased ( P<0.05), and the expression level of miR-1287-5p was significantly reduced ( P<0.05). After down-regulating SBF2-AS1, up-regulating miR-1287-5p or down-regulating FSCN1 expression, LN18 and SW1088 cells activity and cyclin D1 protein expression were significantly reduced ( P<0.05), the apoptosis rate and cleared-caspase-3 protein expression were significantly increased ( P<0.05), the survival score was significantly reduced ( P<0.05), and the expression ofγ-H2AX protein was significantly increased ( P<0.05). The results of dual luciferase reporter gene assay showed that the luciferase activity of LN18 and SW1088 cells co-transfected with miR-1287-5p mimics and SBF2-AS1-WT or FSCN1-WT was lower than that of co-transfected miR-NC and SBF2-AS1-WT or FSCN1-WT in LN18 and SW1088 cells ( P<0.001), while the luciferase activity of LN18 and SW1088 cells co-transfected with miR-1287-5p mimics and SBF2-AS1-MUT or FSCN1-MUT was not significantly different from that of miR-NC transfected with SBF2-AS1-MUT or FSCN1-MUT ( P>0.05). The expression level of miR-1287-5p in LN18 and SW1088 cells in si-SBF2-AS1 group was higher than that in si-NC group ( P<0.05), and the expression level of miR-1287-5p in LN18 and SW1088 cells in pcDNA-SBF2-AS1 group was higher than that in si-NC group ( P<0.05), but lower than that of pcDNA-NC group ( P<0.05). The protein expression level of FSCN1 in LN18 and SW1088 cells in the miR-1287-5p group was significantly lower than that in the miR-NC group ( P<0.05), and the protein expression level of FSCN1 in LN18 and SW1088 cells in the anti-miR-1287-5p group was significantly higher than that in the anti-miR-NC group ( P<0.05). When miR-1287-5p and SBF2-AS1 were down-regulated simultaneously or FSCN1 was up-regulated while SBF2-AS1 was down-regulated simultaneously, the proliferation and cyclin D1 protein expression of LN18 and SW1088cells were significantly increased ( P<0.001), the apoptosis rate and cleared-caspase-3 protein expression were significantly reduced ( P<0.001), the survival score was significantly increased ( P<0.001), and the expression of γ-H2AX protein was significantly reduced ( P<0.001). Conclusion:SBF2-AS1 highly expresses in glioma cells, down-regulation of SBF2-AS1 expression can inhibit the proliferation of glioma cells, promote apoptosis, and enhance cell radiosensitivity by regulating the miR-1287-5p/FSCN1 axis.

Objective:To explore the effect and mechanism of lncRNA SBF2-AS1 on glioma cell proliferation, apoptosis and radiosensitivity.Methods:Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the mRNA expression levels of SBF2-AS1, miR-1287-5p and FSCN1 in normal human brain glial cell HEB and glioma cell lines, including LN18, SW1088, Hs683, and western blot method was used to detect the expression level of FSCN1 protein in cells. Glioma cells including LN18 and SW1088 were taken as the research object. After SBF2-AS1 small interfering RNA, miR-1287-5p mimics, FSCN1 small interfering RNA were transfected into LN18 cells, CCK-8 was used to detect cell proliferation, flow cytometry was used to detect cell apoptosis, clone formation experiment was used to detect cell radiosensitivity, Western blot was used to detect the protein expressions of cyclin D1, cleaved-caspase 3 and phosphorylated histone 2A variant phosphorylated histone (γ-H2AX). Dual luciferase reporter gene experiments verified the regulatory relationship between SBF2-AS1 and miR-1287-5p, as well as miR-1287-5p and FSCN1.Results:Compared with HEB cells, the expression level of SBF2-AS1 and the expression levels of FSCN1 mRNA and protein in glioma cell line LN18, SW1088 and Hs683 were significantly increased ( P<0.05), and the expression level of miR-1287-5p was significantly reduced ( P<0.05). After down-regulating SBF2-AS1, up-regulating miR-1287-5p or down-regulating FSCN1 expression, LN18 and SW1088 cells activity and cyclin D1 protein expression were significantly reduced ( P<0.05), the apoptosis rate and cleared-caspase-3 protein expression were significantly increased ( P<0.05), the survival score was significantly reduced ( P<0.05), and the expression ofγ-H2AX protein was significantly increased ( P<0.05). The results of dual luciferase reporter gene assay showed that the luciferase activity of LN18 and SW1088 cells co-transfected with miR-1287-5p mimics and SBF2-AS1-WT or FSCN1-WT was lower than that of co-transfected miR-NC and SBF2-AS1-WT or FSCN1-WT in LN18 and SW1088 cells ( P<0.001), while the luciferase activity of LN18 and SW1088 cells co-transfected with miR-1287-5p mimics and SBF2-AS1-MUT or FSCN1-MUT was not significantly different from that of miR-NC transfected with SBF2-AS1-MUT or FSCN1-MUT ( P>0.05). The expression level of miR-1287-5p in LN18 and SW1088 cells in si-SBF2-AS1 group was higher than that in si-NC group ( P<0.05), and the expression level of miR-1287-5p in LN18 and SW1088 cells in pcDNA-SBF2-AS1 group was higher than that in si-NC group ( P<0.05), but lower than that of pcDNA-NC group ( P<0.05). The protein expression level of FSCN1 in LN18 and SW1088 cells in the miR-1287-5p group was significantly lower than that in the miR-NC group ( P<0.05), and the protein expression level of FSCN1 in LN18 and SW1088 cells in the anti-miR-1287-5p group was significantly higher than that in the anti-miR-NC group ( P<0.05). When miR-1287-5p and SBF2-AS1 were down-regulated simultaneously or FSCN1 was up-regulated while SBF2-AS1 was down-regulated simultaneously, the proliferation and cyclin D1 protein expression of LN18 and SW1088cells were significantly increased ( P<0.001), the apoptosis rate and cleared-caspase-3 protein expression were significantly reduced ( P<0.001), the survival score was significantly increased ( P<0.001), and the expression of γ-H2AX protein was significantly reduced ( P<0.001). Conclusion:SBF2-AS1 highly expresses in glioma cells, down-regulation of SBF2-AS1 expression can inhibit the proliferation of glioma cells, promote apoptosis, and enhance cell radiosensitivity by regulating the miR-1287-5p/FSCN1 axis.

OBJECTIVE: To explore the genetic variation of a Chinese family affected with congenital insensitivity to pain with anhidrosis and albinism. METHODS: Whole exome sequencing (WES) was carried out to screen potential variants within genomic DNA extracted from the proband and his parents. Whole genome sequencing (WGS) was applied when variants were not found completely. Suspected variants were validated by Sanger sequencing. RESULTS: WES has identified a heterozygous c.1729G>C (p.G577R) variant of NTRK1 gene and two heterozygous variants of OCA2 gene, namely c.1363A>G (p.R455G) and c.1182+1G>A. WGS has identified two additional heterozygous variants c.(851-798C>T; 851-794C>G) in deep intronic regions of the NTRK1 gene. CONCLUSION The compound heterozygous variants of the NTRK1 gene probably underlay the congenital insensitivity to pain with anhidrosis. And the compound heterozygous variants of the OCA2 gene probably underlay the albinism in the proband. In the case where no variant is detected by WES in the coding region, WGS should be considered to screen potential variants in the whole genome.
Albinism ; Child ; DNA Mutational Analysis ; Hereditary Sensory and Autonomic Neuropathies/genetics* ; Heterozygote ; Humans ; Membrane Transport Proteins ; Mutation ; Pedigree

Objective:To investigate the anatomical safety and feasibility ofposterior occipitocervical fixation with atlan-tooccipital-clivus screw.Methods:Data of 60 patients who treated in the spinal department of our hospital with upper cervical computed tomographic scans from February 2017 to November 2019 were retrospectively collected. Occipitocervical infection, injury, tumor and deformity were excluded. The Mimics software was used to reconstruct the occiput, atlas and measure the anatomical parameters, including the height and width of the anterior edge of the clivus, the height and width of the middle part of the clivus, the thinnest distance of the soft tissue in front of the clivus, the anteroposterior diameter, transverse diameter, the angle of inside tilting in coronary plane of the occipital condyle, the distance from the hypoglossal canal to the atlantooccipital articular surface, the anteroposterior diameter and transverse diameter of the superior joint of atlas, the height of the lateral mass, and the height and transverse diameter of the inferior articular process of the superior atlas joint. The three-dimensional digital modeling was performed and the screw diameter of 3.5mm was simulated. 3-Matic software were used to measure the screw placement parameters, including the inside tilting angle in coronary plane of screw, and the angle of upper tilting in sagittal plane and length of screw. The atlanto-occipital junction was exposed at the rear of 8 cadavers. According to the above parameters, the titanium alloy screws with a diameter of 3.5 mm were transferred from the inferior articular process and posterior arch of the atlas to the clivus through the atlantooccipital. Finally, the screw path was cut along the nail path with a pendulum saw, and the track of the screw was observed to confirm the safety and effectiveness of the screw.Results:The leading edge height and width of male clivus was 16.8±2.5 mm and 20.1±3.1 mm. The middle part of the clivus was 9.7±2.3 mm and 22.4±3.7 mm. The thinnest soft tissue in front of the clivus was 5.8±1.48 mm. The anteroposterior diameter of the occipital condyle was 19.1±1.9 mm, the transverse diameter was 12.6±2.0 mm, the inside tilting angle was 33.7°±4.5°, and the vertical distance from the lowest point of the neural tube to the articular surface of the occipital condyle was 9.6±1.1 mm. The height of the lateral mass of atlas was 12.9±2.4 mm, the anteroposterior diameter of the upper joint of atlas was 21.7±1.9 mm, and the transverse diameter was 11.7±1.4 mm. The width of the inferior facet was 14.9±1.4 mm and the height of the inferior facet was 5.7±0.85 mm. The distance from the screw entry point to the vertical line of the lateral mass migration midpoint was 2.5±0.6 mm; The distance from the screw entry point to the horizontal line of the midpoint was 2.3±0.7 mm.The inside titling angle of screw was 18.4°±1.6°, the upper tilting angle was 55.6°±3.1°, the length of the screw track was 53.0±2.8 mm, the adjustment range of upper tilting angle was 15.0±2.8 mm, the adjustment range of inside tilting angle was 10.4±2.4 mm. The anatomical parameters of females were slightly smaller than those of males, and the difference was statistically significant, but there was no significant difference between left and right parameters. The screws of 8 specimens could be inserted safely and effectively.Conclusion:Atlan-tooccipital-clivus screw can be implanted without damaging the nerve and vascular structure, and it can be used as a choice for occipitocervical fixation.

Objective:To investigate the safety of posterior atlantoaxial transarticular screw combined with atlas pedicle screw fixation in Chinese.Methods:CT data of upper cervical spine in 48 patients were collected from Ningbo No.6 Hospital, including 26 males and 22 females aged 26-58 years [(37.3±13.5)years]. All CT data was transformed into 3D dimensional model and inserted with virtual screws by Mimics 19.0. Firstly, the vertical plane P 1 and the horizontal plane P 2 of the atlas were built in those atlantoaxial models, secondly the atlantoaxial transarticular screw S 0 was inserted by Margel method, and it's insertion point was located at 3 mm lateral and 2 mm cephalad in the C 2 inferior articular process. Finally, four atlas pedicle screws were inserted at the midline of atlas lateral mass. The four screws are inserted as follows. S 1: the screw was tangent to the lateral side of the S 0 or the medial of the atlas pedicle. S 2: the screw was tangent to the lateral wall of the atlas pedicle. S 3: the screw was tangent to the upper wall of the atlas pedicle. S 4: the screw was tangent to the inferior wall of the atlas pedicle. The angles between S 1, S 2 and P 1 as the camber angle, and the angle between S 3, S 4 and P 2 as the gantry angle were measured. Then the safety range of camber angle and gantry angle were calculated, and the screw length of S 1, S 2, S 3 and S 4 was measured. In all models, the camber angle and gantry angle of the screws were adjusted an interval of 2°, the number of successful cases was calculated and the success rate of insertion was calculated. Results:All 3D models were inserted successfully. The minimum value, maximum value and safety range of the camber angle of atlas pedicle screws were (-6.7±5.2)°, (10.4± 4.3)°, (17.1±3.7)°, respectively; and of the gantry angle were (-0.5±3.5)°, (11.0±5.8)°, (11.5±4.9)°, respectively. The length of screw placement was S 1: (31.1±2.4)mm, S 2: (28.3±2.5)mm, S 3: (29.2±3.8)mm, S 4: (29.6±3.0)mm, respectively ( P<0.05). When the camber angle was from -1°to 5°, the success rate of screw placement was 87.5%; when inserting with 2° camber angle, the success rate was 100%; when the gantry angle was 5°, the success rate was 93.8%. Conclusion:The posterior atlantoaxial transarticular screw combined with atlas pedicle screw can achieve satisfy insertion length and success rate.

Objective: To compare the clinical efficacy of posterior atlantoaxial screw-rod fixation combined with spinous process muscle-vessel complex bone graft or iliac bone graft for atlantoaxial instability. Methods: A retrospective case-control study was conducted to analyze the clinical data of 56 patients with atlantoaxial instability admitted to the Sixth Hospital of Ningbo from September 2014 to October 2016. There were 35 males and 21 females, with the age range from 9 to 59 years [(50.3±3.2)years]. A total of 26 patients were treated with posterior atlantoaxial screw-rod fixation combined with spinous process muscle-vessel complex bone graft (complex group), while 30 patients were treated with iliac bone graft (ilium group). Patients showed different degrees of neck pain and limited neck activity preoperatively. X-ray films and three-dimensional CT examination of the cervical spine were taken before and after operation for evaluating the atlantoaxial reduction, bone graft fusion and internal fixation. The operation time, intraoperative bleeding, bone fusion time, visual analogue scale (VAS), Japanese Orthopaedic Association (JOA) score, atlantodental interval (ADI) and axial symptoms were compared between the two groups, and the complications were recorded. Results: Both groups were followed up for 24-30 months, with an average of 27.4 months. In the complex group and the ilium group, the operation time was (2.21±0.25)hours and (2.72±0.26)hours (P<0.01); the intraoperative blood loss was (227.3±45.4)ml and (277.7±43.4)ml, respectively (P<0.05); the bone fusion time was (6.9±0.5)months and (8.1±1.8)months (P>0.05), respectively. In the complex group, the VAS was (5.45±0.69)points before operation, (2.64±0.51)points at the follow-up one month after operation, (0.91±0.7)points at the follow-up 12 months after operation, and (0.45±0.16)points at the follow-up 24 months after operation; and in the ilium group, the VAS was (5.18±0.75)points, (2.45±0.52)points, (1.27±0.19)points and (0.41±0.18)points correspondingly. In terms of VAS, there were significant differences before and after operation within each group (P<0.01), while there were no significant differences between the two groups at different time points (P>0.05). In the complex group, the JOA score was (10.82±0.35)points before operation, (12.73±0.65)points at the follow-up one month after operation, (15.18±0.61)points at the follow-up 12 months after operation, and (15.64±0.15)points at the follow-up 24 months after operation; and in the ilium group, the JOA score was (10.73±1.19)points, (13.01±0.63)points, (14.73±0.91)points and (15.55±0.51)points correspondingly. In terms of JOA score, there were significant differences between before and after operation within each group (P<0.01), while there were no significant differences between the two groups at different time points (P>0.05). In the complex group, the ADI was (2.28±0.59)mm before operation, (1.83±0.56)mm at the follow-up one month after operation, (1.71±0.56)mm at the follow-up 12 months after operation, and (1.59±0.67)mm at the follow-up 24 months after operation; and in the ilium group, the ADI was (2.23±0.60)mm, (1.80±0.18)mm, (1.67±0.69)mm and (1.62±0.53)mm correspondingly. In terms of ADI, there were significant differences between before and after operation within each group (P<0.01), while there were no significant differences between the two groups at different time points (P>0.05). The axial symptom scores were graded as excellent in 23 patients and good in three patients of the complex group while excellent in 21 patients and good in nine patients in the ilium group (P>0.05). There were no patients with spinal nerve injury caused by pedicle screw placement after operation. One patient in the ilium group had incision errhysis and recovered after dressing change, and other patients had no incision infection. Conclusions For atlantoaxial instability, posterior atlantoaxial screw-rod fixation combined with spinous process muscle-vessel complex bone graft or autogenous iliac bone graft can both achieve satisfactory clinical results. The spinous process-muscle-vascellum complex graft has less operation time and intraoperative bleeding than the autogenous iliac bone graft, which can be a feasible alternative operation.

Objective: To investigate the accuracy and feasibility of individual 3D printing model for pedicle screw placement in treating patients with upper cervical spine fracture. Methods: A retrospective case control study was conducted to analyze the clinical data of 30 patients with upper cervical spine fracture admitted to Ningbo No.6 Hospital from August 2013 to December 2018. There were 19 males and 11 females, aged 45-67 years with an average age of 53.5 years. The 15 patients in the study group were treated with pedicle screw fixation and another 15 patients in the control group were treated with traditional freehand screw fixation. A total of 120 pedicle screws were implanted, with 60 screws in each group. The operation time, intraoperative blood loss, preoperative and postoperative visual analogue score (VAS), Japan Orthopedic Association (JOA) score were recorded. The position and grade of screws were evaluated according to Kawaguchi's evaluation method of screw grade after operation. The patients took monthly reexamination for the first three months after discharge. In the first two months after discharge, the patients took X-ray examination for observation of screw loosening or rupture of internal fixation. At the third month after operation, the patients took CT of cervical spine for observation of bone healing and fusion. Results: The mean follow-up duration was 17.8 months (range, 13-21 months). The study group had shorter operation time (99.13±3.04)minutes compared with the control group (107.00±6.92) minutes (P<0.01). There were no significant differences in intraoperative blood loss, preoperative VAS, JOA scores before operation and 1 year after operation between the two groups (P>0.05), but the VAS in study group was significantly lower than that in control group (P<0.05). In the study group, the VAS score 1 year after operation [(2.3±0.5)points] was lower than that before the operation [(7.7±0.7)points], and the JOA score [(16.8±0.4)points] was significantly higher than that before the operation [(15.9±0.7)points](P<0.01). In the control group, the VAS 1 year after operation [(2.5±0.5)points] was significantly lower than that before operation [(7.5±0.5)points] (P<0.01), and the JOA score [(16.5±0.5)points] was significantly higher than that before operation [(15.9±0.8)points] (P<0.05). In the study group, according to the CT results, there were 28 atlas pedicle screws of grade 0 (93.3%), two of grade 1 (6.7%), 0 of grade 2, 0 of grade 3, and there were 27 axial pedicle screws of grade 0 (90.0%), three of grade 1 (10.0%), 0 of grade 2, and 0 of grade 3. In the control group, there were 25 atlas pedicle screws of grade 0 (83.3%), four of grade 1 (13.3%), one of grade 2 (3.4%), 0 of grade 3, and there were 27 axial pedical screws of grade 0 (90.0%), three of grade 1 (10.0%), 0 of grade 2, and 0 of grade 3. There was no significant difference in the accuracy of pedicle screw placement between the two groups (P>0.05). No serious complications such as spinal cord or vertebral artery injury occurred. At 3 months after operation, CT showed that the fracture of cervical vertebra healed. Conclusion Individualized 3D printed cervical spine model can guide the pedicle screw placement for upper cervical spine fracture, which can shorten the operation time, reduce the postoperative pain of patients, improve the accuracy of screw placement, and reduce the risks related to operation.

Objective: To investigate the efficacy of microscope-assisted free-hand atlantal pedicle screw technique for unstable atlas burst fracture. Methods: A retrospective case control study was conducted to analyze the clinical data of 48 patients with unstable atlas burst fracture admitted to Ningbo No.6 hospital from January 2016 to June 2018. There were 32 males and 16 females, aged 24-72 years [(49.5±15.2 years)]. A total of 22 patients were treated with the technique of atlas screw placement by drill under microscope (Group A), including 14 males and eight females, aged 24-68 years. Twenty six patients (Group B) were treated with atlantal pedicle screw placement by hand, including 18 males and 8 females, aged 26-72 years [(50.7±15.4 years)]. The operation time, intraoperative blood loss and the times of intraoperative fluoroscopy were compared between the two groups. X-ray and CT were reexamined to evaluate the accuracy of screw placement within one week after operation. The visual analogue score (VAS) and cervical dysfunction index (NDI) were compared before operation and 1 year after operation. The intraoperative complications were recorded. One year after operation, X-ray and CT were reexamined to observe fracture healing, atlantoaxial fusion and failure of internal fixation. Results: Group A was followed up for 12-24 months [(18.4±6.8)months], and Group B for 12-24 months [(17.4±7.2)months]. The amount of intraoperative bleeding [(180.5±60.8) ml] and the times of intraoperative fluoroscopy [(1.3±0.8) times] in Group A were significantly lower than those in Group B [(280.1±80.2) ml, (2.2±0.8) times] (P<0.05), but there was no significant difference in the time of operation and the accuracy of screw placement (P>0.05). There were statistically significant differences in VAS and NDI before operation and one year after operation in both groups (P<0.05), but there was no significant difference between the two groups (P>0.05). No serious complications such as vertebral artery, nerve root and spinal cord injury occurred. One year follow-up CT showed healed fracture or continuous bone bridge passing through the atlantoaxial intervertebral space. Except for one patient in Group B with lost reduction, other patients had no loosening or fracture of internal fixation. Conclusion Compared with screw placement by hand, the pedicle screw placement by drill under the microscope can reduce the amount of bleeding and the times of fluoroscopy.