Objective To evaluate the effect of type Ⅱ odontoid fracture,type Ⅰ Hangman fracture,C2-C3 disc injury on stability of C1-C2 and C2-C3 segments and investigate the clinical significance.Methods Ten fresh-frozen cadaveric cervical specimens (5 men and 5 women; 25-45 years of age,mean 35.7 years) were selected to test the stability of C1-C2 and C2-C3 segments in the settings of intact condition (control group),type Ⅰ Hangman fracture,type Ⅱ odontoid fracture,type Ⅰ Hangman fracture + type Ⅱ odontoid fracture,type Ⅰ Hangman fracture + type Ⅱ odontoid fracture + C2-C3 disc injury.Range of motion (ROM) and neutral zone (NZ) of those segments were measured.Results Compared with the intact condition,type Ⅰ Hangman fracture produced no significant variations in C1-C2 ROM in all loading modes and C2-C3 ROM during left and right lateral bending; type Ⅱ odontoid fracture produced no significant variations in C2-C3 ROM in all loading modes and C1-C2 ROM during left and right rotation; type Ⅰ Hangman fracture + type Ⅱ odontoid fracture revealed no significant variations in C1-C2 ROM during left and right rotation and C2-C3 ROM during extention; type Ⅰ Hangman fracture + type Ⅱ odontoid fracture + C2-C3 disc injury produced no significant variations in C1-C2 ROM during left and right lateral bending and extension-flextion and C2-C3 ROM in all loading modes (P ＜ 0.05).Conclusions Type Ⅰ Hangman fracture can reserve C1-C2 segmental left and right rotation and extension-flextion; type Ⅱ odontoid fracture can reserve C1-C2 segmental left and right lateral bending and extension-flextion; type Ⅰ Hangman fracture + type Ⅱ odontoid fracture + C2-C3 disc injury can reverse atlantoaxial rotationary stability and C1-C3 segmental stability in all directions.This study provides the biomechanical basis for clinical treatments and the related researches of internal fixation.

The evaluation systems for chronic venous insufficiency of lower extremities play a very important role in standardizing the diagnosis and evaluating the curative effect in patients with the disease. This paper gives an introduction to the CEAP classification system, VSS evaluation system and chronic venous insufficiency questionnaire.

Objective To explore an ideal screw insertion point and optimal trajectory for anterior axis pedicle screw (AAPS) so as to provide an anatomical basis for AAPS placement.Methods CT scan of the cervical spine was performed for 40 healthy Chinese adults.Then,the CT data were imported into the Mimics software to reconstruct the three-dimensional images of the axes.The data were divided into two groups according to the gender.The following data were measured:pedicle centerline minimal diameter on both left and right sides,pedicle axial length,the distance between entrance point and upper endplate,the distance between entrance point and median sagittal plane,the distance between entrance point and peak of crista lambdoidalis of C2 vertebral body,extraversion angle and sagittal angle.The screw fixation parameters for AAPS were measured using the Mimics software.Results There was no statistical difference between the left and right sides as well as between the genders (P ＞ 0.05).The entrance point for insertion of AAPS was recommended to be on (4.39 ± 0.67) mm from the upper endplate,and on (3.95 ± 0.44) mm from the median sagittal plane.The ideal pedicle axial length was (34.15 ± 2.93) mm,and the pedicle centerline minimal diameter was (7.04 ± 0.87) mm.The distance between the entrance point and the peak of crista lambdoidalis of C2 vertebral body was (1.45 ± 0.19) mm.The ideal extraversion angle was (30.80 ± 2.79) °,and the ideal sagittal angle was (36.35 ± 3.26) ° . Conclusion The ideal insertion pathway of AAPS placement can avoid spinal canal,foramen intervertebrale and other important anatomical structure,which is feasible in regard of anatomy.The insertion point can refer to the peak of crista lambdoidalis of C2 vertebral body.However,AAPS placement should be individualized in term of its anatomy variability.

Objective To investigate the clinical outcomes of pedicle screw fixation assisted with the 3D printing positioning guide template for treatment of unstable atlas fractures.Methods A retrospective case series review was made on 10 patients with unstable atlas fractures undergone direct posterior C1 pedicle screw fixation assisted with the 3D printing drill guide template from September 2012 to May 2015.There were 7 males and 3 females,with a mean age of 52.6 years (range,23-75 years).All patients complained of neck pain,stiffness and decreased range of motion without neurologic deficit.Preoperative skull traction was used routinely.After the three-dimension reconstruction of cervical vertebrae,ideal trajectory for C1 pedicle screws was designed with a complementary basal template for posterior surface of atlas corresponding anatomical structure.Then the drill guide template was materialized in a rapid prototyping machine and used during operation.Start point and direction of the ideal and actual trajectories were measured after matching the position of the pre-and post-operative patients' cervical spine.Safety of pedicle screw fixation was assessed in the transverse and sagittal planes of CT scan.Operation time and blood loss were recorded.Visual Analogue Scale (VAS) of neck pain was recorded before operation and 3 months after operation.Clinical efficacy,fracture reduction,stability and surgical complications were reviewed at the follow-up.Results A total of 20 screws were inserted safely.No significant differences existed in deviation of entry point and direction between ideal and actual trajectories (P ＞0.05).Operation time was 60-90 min (mean,75 min) and intraoperative blood loss was 110-300 ml (mean,160 ml).No spinal cord or vertebral artery injury was noted during operation.All patients were followed up for 12-36 months (mean,20.5 months).VAS was improved from preoperative 7.3 (6.3-9.5) points to 1.4 (0.3-2.5) points 3 months after operation (P ＜ 0.05).All patients had normal range of motion of the cervical spine 3 months after operation.Bony fusion was achieved 6 months after operation.At the follow-up,good cervical alignment was maintained with no instrument failure and C1.2 instability.Conclusion For treatment of unstable atlas fractures,direct posterior C1 pedicle screw fixation assisted with the 3D printing drill guide template can improve the precision of screw placement,reduce complications,and preserve the function of the occipital-atlantoaxial junction.

Objective To determine the treatment options for teardrop fracture of the axis and discuss the treatment efficacy.Methods Nineteen patients with teardrop fracture of the axis treated from March 2003 to June 2013 were retrospectively reviewed.Teardrop fracture of the axis accounted for 3.9％ of the cervical injuries and 11.4％ of the axis fractures over the same period.There were 15 males and 4 females,at age range of 21-56 years (mean,37.8 years).Injury was caused by traffic accidents in 12 patients,falls in 6,and hit from heavy objects in 1.Cervical imaging examinations (X-ray,CT and MRI) were performed on admission.Thirteen patients were immobilized for 3 to 6 months with the Halovest device,and six patients underwent anterior cervical surgery.No patients had neurologic deficit [American Spinal Injury Association (ASIA) grade E].Visual analogue scale (VAS),implant failure and bone fusion were recorded after operation.Results All patients were followed up for 12-18 months (mean,15.6 months).At the final follow-up,no implant loosening or breakage happened and 18 patients achieved bone union.Neck mobility returned to normal,which showed VAS improved from (7.5 ± 1.2) points to (3.1 ± 1.5) points.ASIA grade E remained in 18 patients,and one patient were progressed to grade D.Conclusions Teardrop fracture of the axis is rare cervical injury,and can be treated conservatively in most cases.However,surgery is often necessary when imaging findings suggest the existence of instability.

AIM:To observe the structural basis of ocular motility abnormalities in patients with congenital fibrosis of the extraocular muscles type Ⅰ ( CFEOM Ⅰ) due to missense mutations in the developmental kinesin KIF21A using high - resolution magnetic resonance imaging ( MRI) .
METHODS: Totally 11 affected individuals reported KIF21A mutations were correlated with MRI studies demonstrating extraocular muscles ( EOMs ) size, location, contractility, and innervation. EOMs and the motor nerve in the orbits were imaged with T1 weighted in a triplanar scan using a dual-phased coils with 2. 0mm thick. Motor nerves were imaged at the brainstem using head coils and 3D-FIESTA with 0. 6-mm thick.
RESULTS: Patients with CFEOM Ⅰ exhibited different degrees of hypoplasia of oculomotor nerve, the abducens nerve and the trochlear nerve were also affected, of which 8 cases of orbital section could see the signal of abnormal nerve dominated by oculomotor nerve to lateral rectus. The both sides of six EOMS in all patients exhibited variable atrophy and abnormal bright internal signal on T1 imaging, particularly severe for the superior rectus and levator muscles.
CONCLUSION: High - resolution MRI can directly demonstrate pathology of motor nerves,affected EOMs, and ‘Pulley' hypoplasia caused by CFEOM Ⅰ due to mutations in KIF21A,and these findings suggest that the neuronal hypoplasia is the etiological factor of CFEOM.

Objective To compare the clinical efficacy and fusion rate of unilateral and bilateral C1 and C2 pedicle screw fixation of unstable Jefferson fractures.Methods This retrospective casecontrol study enrolled 22 patients with unstable Jefferson fractures admitted between April 2012 and May 2015.There were 18 males and four females,with the mean age of 52.9 years (range,35-67 years).Mean preoperative visual analogue scale (VAS) was 6.09 points (range,4-8 points).According to the American spinal injury association (ASIA) classification,two patients were rated grade D and one patient grade C.Mean Japanese orthopedic association (JOA) score was 12.3 points.Bilateral C1 and C2 pedicle screw fixation was performed for 15 patients (bilateral group).Advantage side unilateral C1 and C2 pedicle screw fixation was performed for seven patients with extremely unstable fracture or narrow pedicle (unilateral group).Operation time,blood loss and surgical complications were recorded.VAS was used to evaluate the improvement of neck pain after operation.ASIA classification and JOA score were used to assess nerve function recovery.Atlanto-dental interval (ADI),srew position and bone fusion were evaluated after operation.Results All patients successfully completed the operation.Operation time was (119.5 ±21.2)min,and blood loss was (280.1 ±83.1)ml.A total of 74 screws were placed and CT scan showed satisfactory position of the screws.No complications were noted either during the operation or after surgery.All patients were followed up for mean 20.7 months (range,13-33 months).VAS was improved in both groups after operation (P ＜ 0.01),and there was no significant difference between the two groups (P ＞ 0.05).Two patients with ASIA grade D in bilateral group were improved to ASIA grade E after operation.One patient with ASIA grade C in unilateral group was improved to ASIA grade D after operation.JOA score increased to mean 15.7 points at last follow-up.ADI were decreased in both groups after operation(P ＜0.05),but there was no significant difference between the two groups (P ＞ 0.05).All patients had bony fusion 6 months after operation,with similar fusion rate between the two groups (P ＞ 0.05).Conclusion Advantage side unilateral screw fixation can be used for the patients with bilateral C1 and C2 pedicle screw fixation failure,for the technique can improve cervical pain and provide relatively high stability and fusion rate.

OBJECTIVETo study the clinical effectiveness of implanting miniscrew serving as anchorage instead of molars in treating maxillary dental arch crowding and protrusive patients mandibular molars complete missing.

METHODSEight adult patients aged from 22 to 38, whose maxillary dental arch were crowding and protrusion, with mandibular molars missing were chosed. At the missing side, a miniscrew was implanted on the buccal surface, 11-13 mm away from the distal end of the second premolar. After implanting, a self-made miniscrew traction cap was attached to its supergingival section by keyway retention. Premolars and anterior teeth were tracted in turn to distal end. Intermaxillary traction II was made necessarily on the traction cap.

RESULTSSuccessful results were acquired after treating together with normal overbite, overjet and right occlusion relation. It took 24 months in the longest course, 15 months in the shortest course and 20.8 months on average.

CONCLUSIONThe implanting miniscrew anchorages could be used in maxillary dental arch crowding and protrusive patients with single molars complete missing.

Adult ; Bicuspid ; Bone Screws ; Cephalometry ; Dental Arch ; Humans ; Molar ; Orthodontic Anchorage Procedures ; Overbite ; Tooth Movement Techniques

OBJECTIVETo evaluate the accuracy of four dominant methods of three-dimensional multisource data registration.

METHODSLaser-scanned dental model and maxillofacial cone-bean CT rebuilt model were collected for one orthodontic patient before treatment. Registration process was done based on locating spheres' center, anatomic landmarks, partial characteristic region and global data separately. The registration errors were detected by the function of Geomagic Studio 12.0 software. A comparison of the registration accuracy among these four methods was done by analyzing mean error and standard deviation.

RESULTSThe mean errors and standard deviations of methods of locating spheres' center, anatomic landmarks, partial characteristic region and global data were -(0.082 ± 0.221), -(0.104 ± 0.218), -(0.047 ± 0.138) and -(0.025 ± 0.129) mm respectively.

CONCLUSIONSICP registration methods had better reliability than landmark methods. The global registration was more accurate than partial characteristic region registration and the locating spheres' center method was better than anatomic landmarks method.

Computer-Aided Design ; Cone-Beam Computed Tomography ; methods ; Dental Models ; Humans ; Imaging, Three-Dimensional ; methods ; Malocclusion, Angle Class I ; diagnostic imaging

Abstract: Objective　To analyze the survival status of HIV/AIDS patients aged above 50 years receiving antiviral therapy (ART) in Shanxi Province from 2011 to 2019, and to provide evidence for further improvement of antiviral therapy. Methods　Basic information and follow-up information of HIV/AIDS patients aged above 50 years who first received HIV/AIDS antiviral therapy in Shanxi Province from 2011 to 2019 were collected. Excel database was established and SPSS23.0 software was used for analysis. Retrospective cohort study was conducted. Cox proportional risk regression model was used to analyze the factors influencing survival time. Results　A total of 1 183 subjects were included, of which 172 died, including 84(48.84%) from other causes, 74(43.02%) AIDS-related death and 14 (8.14%) from accidents, suicides and undetermined deaths. Setting AIDS-related deaths as an outcome event, life table analysis showed that the cumulative survival rates at 1, 3, 5, 7 and 9 years after receiving ART were 96.61%, 93.59%, 90.35%, 87.57% and 83.44%, respectively. Multivariate Cox proportional risk model analysis showed that the risk of death in patients aged 60-<70 years group and over 70 age group was 2.53 times (95%CI: 1.51-4.23) and 3.59 times (95%CI: 1.74-7.40) for patients aged the 50-<60 group , respectively. The risk of death in patients with baseline CD4+T lymphocyte (CD4) counts of ≥200/mm3, 50-<200 /mm3 was 0.22 times (95%CI: 0.12-0.41) and 0.37 times (95%CI: 0.21-0.67) for patients with CD4+T lymphocyte counts of <50/mm3. The risk of death in patients with opportunistic infections at baseline was 1.99 times (95%CI: 1.16-3.39) for patients without baseline opportunistic infections. Conclusions　The survival rate of HIV/AIDS patients aged above 50 who received antiviral therapy (ART) in Shanxi Province from 2011 to 2019 was relatively high. To further improve the quality of antiviral treatment in our province, the strategy of "early detection and early treatment" should be continued and improved in the future, and information collection of specific causes of non-AIDS-related deaths among this population should be further strengthened.