Objective To measure the vertebral rotational centers in sagittal and transverse plane. These data may be quite valuable for the design of artificial disc. Methods Ten healthy volunteers of 40-60 years old were recruited under IRB approval and informed consent. Three-dimension lumbar spine models of L_2, L_3 and L_4 were reconstructed from MR scans. Spine motions were then reproduced using combined dual fluoroscopic imaging system (DFIS) and MR scan technique during flexion-extension and left-right twisting of the body. Based on the geometrical features of the vertebrae, ranges of motion (ROM) of 3 representative lo-cations were measured from anterior to posterior, the vertebral body center, the spinal cord canal center and the spinous process tip. Rotational centers of the vertebral segments were then located by calculating the point of zero ROM. Results Motion patterns: The ROMs of L_2 with respect to L_3 (L_(2,3)) and L_(3,4) increased pro-portionally from anterior to posterior locations. During flexion-extension motion, the vertebral body center moved within a range of 0.6 mm, while the spinous process tip moved within 7.5 mm in the sagittal plane. During left-right twisting, the vertebral body center moved within 1.0 mm, while the tip moved within 1.6 mm in the transverse plane. No statistical differences were found in the ROMs between L_(2,3) and L_(3,4). Rotational centers: the rotational centers of flexion-extension in sagittal plane for both L_(2,3) and L_(3,4) segments were located at posterior one-third of the vertebral body. The rotational centers of both L_(2,3) and L_(3,4) segments were located approximately 30 mm anterior to the front edge of the vertebral body. Conclusion The anterior portion of the vertebrae was found to have smaller ROM than the posterior portion. The vertebra rotates with the center of rotation located at approximately the posterior one-third of the vertebral body in sagittal plane. However, the vertebra rotates in transverse plane with respect to a point about 30 mm in front of the vertebra. The data indicated that the different portions of the vertebra have distinct motion characters during different motions.

Objective To measure the range of motion (ROM) of the lumbar pedicle screw entrance point (LPSEP) in vivo during unrestricted motion under physiological weight bearing.Methods Eleven healthy volunteers aged 45-60 years underwent MRI scans in a supine position.Three-dimensional (3D) models of L2-5 were constructed.Next,each volunteer was asked to stand and was positioned in the following sequence:standing,45° flexion,maximal extension,maximal left-right twisting,while two orthogonal fluoroscopic images were taken simultaneously at each position.The MRI models were matched to the osseous outlines of the images from the two orthogonal views to determine the position of the vertebrae in 3D at each position.Coordinate systems were established to study the ROM of the LPSEP.Results The predominant translations were along anteroposterior and craniocaudal axis from supine to standing position (average,2.44mm and 2.35 mm).Rotation of the LPSEP occurred mainly around the mediolateral axis(average,3.91 °).During flexion-extension movements of the trunk,the predominant translation were along anteroposterior and craniocaudal axis and rotation were around mediolateral axis.During lateral bending and twisting,ROM of LPSEP did not rotate or translate in one dominant direction.Instead,the resulting motion represented a combination of rotation and translation in different directions.There was no significantly difference in translation and rotation between the three axis in L4,5segment (P＞0.05).Conclusion The kinematic behaviors of the LPSEP of the upper lumbar spine (L2,3 and L3,4) are similar which are different from that of the lower lumbar spine (L4,5).

Objective To characterize the spinal motion of 6 degrees of freedom (6DOF) under the fulcrum bending in Lenke type 1 adolescent idiopathic scoliosis (AIS) patients using 3D image volume fusion technique.Methods Ten volunteers with Lenke type 1 AIS were examined by the Gemstone Spectral Imaging to obtain their T1-S1 vertebral morphological data in the supine position and fulcrum bending position.With the computer software,images of 2 different positions were fused with the 3D image to obtain in vivo kinematics data of each vertebral body in the target area.Results In the apical vertebrae (AV) region,the main range of motion in the fulcrum bending position ranged from-2.57°± 0.95° to-1.37°± 0.65°,showing significant differences between segments (P ＜ 0.05);along the vertical axis the coupling rotation ranged from-2.71° ± 0.48° to-1.27° ± 0.49°;along the coronal axis,the coupling flexion and extension ranged from 0.19° ± 0.85° to 1.51° ± 0.42°.In the upper end vertebrae (UEV) area,the main ROM ranged from-2.20° ± 1.13° to-1.91° ± 0.76°,showing no significant differences between the 3 segments (P ＞ 0.05);along the vertical axis,coupling rotation ranged from 0.18°±0.47° to 1.35°±0.52°;along the coronal axis,coupling flexion and extension ranged from 1.62° ± 0.41° to 2.07° ± 0.37°.In the lower end vertebrae (LEV) region,the main movement ranged from-0.79°± 0.63° to 0.73°± 1.09°,showing significant differences between the 3 segments (P ＜ 0.05);along the vertical axis,the coupling rotation ranged from-1.62°± 1.05° to-0.60°± 0.60°;along the coronal axis,the coupling flexion extension ranged from -1.41° ± 0.87° to-0.75° ± 0.66°.Conclusionts In the fulcrum bending position,Lenke type 1 AIS shows a unique motion and coupling mechanism in the spine.The coupling rotational movement in the UEV region is at the same side as the lateral flexion movement.The coupling rotational motion in the AV and LEV regions is opposite the lateral flexion movement.

Objective To observe and compare in vivo segmental lumbar motion between symptomatic L4 isthmic spondy?lolisthesis (IS) patients and L4 degenerative spondylolisthesis (DS) patients during functional weight?bearing activities. Methods Fifteen symptomatic L4 IS patients and fifteen symptomatic L4 DS patients were recruited. Fifteen asymptomatic volunteers were en?rolled as the control group. The L4,5 vertebral segment motion of each subject was reconstructed using three?dimensional computed tomography and a solid modeling software. In vivo, lumbar vertebral motion during functional postures (flexion?extension, left?right twisting and left?right bending) was observed using a dual fluoroscopic imaging technique. The spinal function unit was divided in?to anterior and posterior segments by the isthmic cleft. Local coordinate systems were established at the vertebral body, to obtain the 6 degree?of?freedom (DOF) intervertebral range of motion (ROM) at L4,5 and the ROM between the anterior and the posterior segments of L4 IS. Results The motion of IS at L4,5 was found to be increased. The migrations along both sagittal and vertical axis were significantly larger than control group (P<0.05). During left?right twisting, the migration along sagittal axis was significantly larger than control group (P<0.05);the rotation along vertical axis was significantly larger than DS and control group (P<0.05). During left?right bending, the migration along frontal axis was significantly larger than DS and control group ( P<0.05). The inter?vertebral ROM at L4,5 showed no significant difference between DS and control group. The migration between anterior and posteri?or segments of IS L4 was larger in standing than supine (P<0.05). The relative migration along sagittal axis between anterior and posterior segments of IS L4 was significantly larger in flexion than standing (P<0.05). Conclusion A spondylolytic defect does lead to detectable instability or hypermobility in the lumbar spine compared with degenerative spondylolisthesis and normal group. From supine to standing posture, migration at isthmic cleft along sagittal and coronal axis are identified in IS spondylolithesis.

Objective: To evaluate the quality of Japanese Encephalitis (JE) case reports based on the establishment of surveillance on acute meningitis and encephalitis syndrome (AMES) in Baoji. Methods: A surveillance network on AMES cases was set up in Baoji city of Shaanxi province between July 2013 and December 2016. All the cases met the surveillance definition of AMES cases were conducted a questionnaire, collected serum and/or cerebrospinal fluid (CSF) specimens to test JE immunoglobulin M antibodies by using enzyme-linkedimmunosorbent assay methods.The information of the incidence of JE in Shaanxi and Baoji from 2009 to 2016 originated from the China information system for disease control and prevention. Chi square test was used to compare the difference in JE incidence in Baoji, Shaanxi before and after the implementation of AMES monitoring project. Results: 75 out of 855 collected cases were laboratory confirmed as JE, Including 42 suspected JE cases and 33 other suspected cases diagnosed after hospitalization. Except 1 case occurring in December, all the other cases occurred between July and October, especially in August with a peak of 55 cases (73.3%), and 6 cases (8.0%) in July, 11 cases (14.7%) in September, 2 cases (2.7%) in October. The proportion of patients aging 0-6, 7-14 and ≥15 years old were respectively 4.0% (3 cases), 8.0% (6 cases) and 88.0% (66 cases). The biochemical test showed the cerebrospinal fluid in 13 cases (17.3%) were slightly turbid, the white blood cell in 31 cases (41.3%) elevated, the glucose levels in 24 cases (32.0%) were abnormal, and the chloride level in 23 cases (30.7%) were abnormal. A total of 103 cases of JE were diagnosed in Baoji from 2009 to 2016, with an average annual incidence rate at 0.34/100 000. The average incidence of JE in 2009-2012 and 2013-2016 was 0.21/100 000 and 0.48/100 000 respectively. From 2013 to 2016, the proportion of JE cases in Baoji, Shaanxi was 19.3% (71/369), and it was 8.9% (32/362) between 2009 and 2012 (χ²=4.15, P=0.040). Conclusion The AMES surveillance project improved the quality of the JE case report in Baoji. Changes appeared in biochemistrical and epidemiological characteristics of cerebrospinal fluid. The incidence of JE was seriously underestimated in Shaanxi province and therefore the sensitivity of Japanese encephalitis surveillance cases should be further improved.

Objective:To analyze the biomechanical characteristics of bilateral lumbo-iliac fixation by finite element analysis after digital optimization of a safe screw pathway.Methods:Firstly, a healthy adult male volunteer was recruited for this study who underwent CT scanning of the lumbus and pelvis, with a slice thickness of 0.625 mm.The original data were imported into Mimics 16.0 software for 3D lumbar and pelvic reconstruction.At the same time, a geometric screw pathway and a free screw pathway were generated in the pedicles of L4 and L5 and ilium.Secondly, all 3D models were imported into Ansys 12 software to assemble a finite element model.The displacements and von Misses stress distribution were measured in the conditions of forward bending, backward extending, lateral bending to the left and right, and left and right rotations in the models of 2 kinds of pathway after gravity axial load of 500 N was applied.Results:The models of 2 different pathways were similar in comprehensive displacement and stress in the conditions of forward bending, lateral bending and backward extending, and in the maximum stress of the screw in the conditions of forward bending and lateral bending.However, the comprehensive displacement and stress in the condition of rotation and the stress of the screw in the conditions of backward extending and rotating in the model of geometric screw pathway were obviously smaller than those in the model of free screw pathway.The maximum pelvic stress was on the screw surface between 190 and 260 MPa, concentrated on the bending area of the 2 screws connecting the sacrum and vertebral body.The lumbar-iliac fixation model showed high com-pressive stiffness.The maximum von Misses stress appeared in the L4-L5 pedicle screw on the longitudinal rod.Under rotational loading, the upper longitudinal rod connecting the L4-L5 pedicle screw and the iliac bone screw bore the maximum stress.Conclusions:Our finite element analysis shows that double verte-bral bodies and long screw fixation are effective ways of iliolumbar fixation.The geometric screw path optimized by digital analysis exhibits better fatigue resistance, rotation resistance and overall stability.Internal lum-bo-iliac fixation can effectively share the stress of vertebral bodies.

Objective:To evaluate the accuracy of an ultrasound-guided robot-assisted system for percutaneous facet joint puncture in an animal experiment by registration of ultrasound images and two-dimensional X-ray fluorescence images.Methods:Six specimens of fresh adult sheep lumbar spine were prepared and soaked in gelatin solution. The specimens contained a total of 48 facet joints with 24 ones respectively on the left and right sides. Half of the joints were assigned by the random number table method into a robot-assisted group which were subjected to percutaneous facet joint puncture assisted by the ultrasound-guided robot-assisted system while the contralateral ones into a freehand group which were subjected to percutaneous facet joint puncture by freehand. In the robot-assisted group, the left facet joints were 3 L 1, 3 L 2, 3 L 3 and 3 L 4 ones while the right facet joints were 2 L 1, 3 L 2, 5 L 3 and 2 L 4 ones. In this self-control animal experiment, both the robot-assisted punctures and the freehand punctures were carried out in the same specimen. The puncture success rate, puncture needle adjustment, positioning deviation, orientation deviation and operation time were recorded. Results:The positioning deviation and orientation deviation in the robot-assisted group [(2.21 ± 1.12) mm and 1.51° ± 0.47°] were significantly lower than those in the freehand group [(3.26 ± 1.44) mm and 2.24° ± 0.89°] ( P < 0.05). All the articular facet joint punctures were successfully accomplished for the first time in the robot-assisted group while those required multiple adjustments in the freehand group. In the robot-assisted group, the total operation time [(463.84 ± 34.93) s] was significantly longer than that in the freehand group [(298.40 ± 27.48) s], but the puncture time [(37.97 ± 6.87) s] was significantly shorter than that in the freehand group [(261.61 ± 33.15) s] ( P < 0.05). Conclusion:The ultrasound-guided robot-assisted system for percutaneous facet joint puncture can lead to accurate puncture with limited needle adjustments.

Objective To analyze plantar pressure features of patients in injured and healthy sides of the lower limbs under different walking conditions after the trimalleolar fracture surgery, and compare these characteristics with healthy subjects. Methods Twelve Trimalleolar fracture patients and twenty-three healthy subjects were recruited and their plantar pressure characteristics under different walking conditions were tested, including peak pressure, contact area and contact time percentage. Results Comparison between injured and healthy sides: during level walking, peak pressure of the 3rd-5th toe in the injured feet were smaller than those in the healthy sides; in inversion position, peak pressure and contact area of the 3rd-5th toe area in the injured feet were smaller than those in the healthy side; in eversion position, peak pressure, contact area and contact time of the 3rd-5th toe in the injured feet were smaller than those in the healthy sides, and peak pressures of the hindfoot area were larger than those in the healthy sides. Comparison between patients and healthy subjects: under three kinds of walking conditions, peak pressures of the 2nd and 3rd metatarsus bones, the 2nd toe, the 3rd-5th toe, contact area of the 1st-5th toe and contact time percentage of the 2nd toe, the 3rd-5th toe area were all smaller than those of healthy subjects, while contact time of the hindfoot and mid-foot area were all smaller than those of healthy subjects. Conclusions The plantar pressure characteristics of Trimalleolar fracture patients were asymmetrical. Compared with healthy subjects, the plantar pressure features of patients were abnormal during stance phase. Compared with healthy subjects, the motor control ability and stability of patients in eversion positions were decreased. The plantar pressure characteristics at ankle eversion can be used to evaluate ankle joint function.

Objective To investigate relative translations of the glenohumeral joint during abduction, scaption and forward flexion in normal Chinese, so as to provide references for diagnosis, treatment and follow-up of glenohumeral joint instability and subacromial impingement syndrome.Methods The biplanar fluoroscopy system combined with model-image registration technique were used to measure the humeral translation relative to the scapular in 13 healthy volunteers during abduction, scaption and forward flexion.Results The anterior-inferior glenohumeral translation during abduction, scaption and forward flexion was (4.0±1.3), (4.1±1.5),(4.8±1.9) mm, respectively. The superior-inferior glenohumeral translation was (3.0±1.0), (3.1±1.1), (3.3±1.5) mm, respectively. During the whole motion, there was a significant difference in superior-inferior translation at different arm elevation angles, while other significant differences were not found.Conclusions For normal Chinese, the humeral head was positioned posteriorly and superiorly on the glenoid. During forward flexion, the anterior-inferior and superior-inferior glenohumeral translation was the maxium. Therefore, in the process of clinical diagnosis, treatment and follow-up, patients performing the forward flexion may obtain a better evaluation effect.

A 61-year-old male patient with pyogenic spondylodiscitis and epidural and psoas abscesses underwent posterior decompression, debridement, and instrumented fusion, followed by anterior debridement and reconstruction. Sudden onset flank pain was diagnosed 7 weeks postoperatively and was determined to be a pseudoaneurysm located at the aorta inferior to the renal artery and superior to the aortic bifurcation area. An endovascular stent graft was applied to successfully treat the pseudoaneurysm. Postoperative recovery was uneventful and infection status was stabilized.
Aneurysm, False* ; Aorta ; Blood Vessel Prosthesis* ; Debridement ; Decompression ; Discitis ; Endovascular Procedures ; Flank Pain ; Humans ; Male ; Middle Aged ; Psoas Abscess ; Renal Artery ; Spondylitis* ; Stents*