BACKGROUND:At present,the surgical treatment of atlantoaxial dislocation mainly adopts the posterior atlantoaxial screw-rod internal fixation system for lifting and reduction.During the operation,the curvature of the connecting rod is often increased to increase the drop between the atlantoaxial vertebrae to improve the reduction effect,but it increases the difficulty and risk of surgery.The axis pivot screw directly increases the reduction drop between the atlantoaxial vertebrae,but the extent to which it increases the reduction capacity is unclear.OBJECTIVE:To test the reduction ability of axis pivot screw and compare it with ordinary screw.METHODS:Six fresh human craniocervical specimens were used in study.The joint capsules of two lateral mass joints and atlanto-odontoid joint and transverse ligament were removed to make an atlantoaxial instability model.Three kinds of internal fixation were performed successively on both sides of the axis of each specimen:uniaxial axis pivot screws(group A),multi-axial axis pivot screws(group B)and ordinary screws(group C).Flexible ultra-thin film pressure sensors were placed in the anterior atlanto-odontoid space.Two connecting rods with the same curvature were placed to simulate the lifting and reduction,and the pressure of the anterior atlanto-odontoid space was obtained.Comparative analysis was conducted among the three groups.RESULTS AND CONCLUSION:(1)The anterior atlanto-odontoid space pressure of groups A-C was(97.59±8.58),(60.43±5.09),and(22.74±0.81)N,respectively.There were significant differences among the three groups(F=251.603,P=0.000).The pairwise comparison among the three groups showed significant differences(P=0.000).(2)The axis pivot screw applied to the posterior atlantoaxial screw-rod internal fixation system can improve the reduction capacity compared with the common cervical posterior screw,and the uniaxial axis pivot screw has more reduction capacity than the multi-axis uniaxial axis pivot screw to improve the posterior atlantoaxial screw-rod internal fixation system.

BACKGROUND:At present,the surgical treatment of atlantoaxial dislocation mainly adopts the posterior atlantoaxial screw-rod internal fixation system for lifting and reduction.During the operation,the curvature of the connecting rod is often increased to increase the drop between the atlantoaxial vertebrae to improve the reduction effect,but it increases the difficulty and risk of surgery.The axis pivot screw directly increases the reduction drop between the atlantoaxial vertebrae,but the extent to which it increases the reduction capacity is unclear.OBJECTIVE:To test the reduction ability of axis pivot screw and compare it with ordinary screw.METHODS:Six fresh human craniocervical specimens were used in study.The joint capsules of two lateral mass joints and atlanto-odontoid joint and transverse ligament were removed to make an atlantoaxial instability model.Three kinds of internal fixation were performed successively on both sides of the axis of each specimen:uniaxial axis pivot screws(group A),multi-axial axis pivot screws(group B)and ordinary screws(group C).Flexible ultra-thin film pressure sensors were placed in the anterior atlanto-odontoid space.Two connecting rods with the same curvature were placed to simulate the lifting and reduction,and the pressure of the anterior atlanto-odontoid space was obtained.Comparative analysis was conducted among the three groups.RESULTS AND CONCLUSION:(1)The anterior atlanto-odontoid space pressure of groups A-C was(97.59±8.58),(60.43±5.09),and(22.74±0.81)N,respectively.There were significant differences among the three groups(F=251.603,P=0.000).The pairwise comparison among the three groups showed significant differences(P=0.000).(2)The axis pivot screw applied to the posterior atlantoaxial screw-rod internal fixation system can improve the reduction capacity compared with the common cervical posterior screw,and the uniaxial axis pivot screw has more reduction capacity than the multi-axis uniaxial axis pivot screw to improve the posterior atlantoaxial screw-rod internal fixation system.

Objective To detect the expressions of Lingo-1 and myelin associated protein in the white matter and hippocampus of ovariectomized rats after short-term estrogen replacement therapy in order to explore the possible mechanisms for the effects of estrogen on the brain myelin sheaths and cognitive function.Methods 24 middleaged (9-12 months) female Sprague-Dawley (SD) rats were bilaterally ovariectomized (OVX) and randomly divided into vehicle replacement (OVX+Veh) group and estrogen replacement (OVX+E) group.After one month ERT,The spatial learning and memory ability of all rats were assessed with Morris water maze.Then,10 rats were randomly selected from each group.The ultrastucture of myelin sheaths in the cerebral white matter and hippocampus were observed,and the protein expression of MBP and Lingo-1 were investigated with Western blot and immunohistochemical staining.Results The escape latencies of OVX+E rats in navigation test were significantly shorter than that of OVX+Veh rats(P＜0.05).The myelin sheaths in the white matter and hippocampus of OVX+Veh rats showed obviously degeneration.In the OVX+E group,the expression of MBP in the white matter and hippocampus was significantly higher than that of OVX+Veh group(P＜0.05),however,the expression of Lingo-1 was significantly lower than that of OVX +Veh group (P＜ 0.05).Conclusions One-month ERT has significant beneficial effects on the spatial learning capacity and myelin sheaths in the white matter and hippocampus.The protective effects may be related to estrogen-induced downregulation of the Lingo-1 expression in the white matter and hippocampus of rats.

Chondrosarcoma ; diagnosis ; Female ; Humans ; Magnetic Resonance Imaging ; Middle Aged ; Positron-Emission Tomography ; Pulmonary Artery ; pathology

To understand the local hemodynamics of modified TF-AHCB carotid bifurcation model, using particle image velocimetry technique to measure the instantaneous velocity distribution of the model attatched to a circuit. The velocity was controlled by regulating the height of the reservoir. The working fluid consists of glycerine and water mixture with viscosity of 3.75 mPa.s similar to human blood. Instantaneous velocity fields were obtained by PIV and the shear stresses were calculated according to the velocity. The results showed that inside the model, there were a large flow separation and an anticlockwise rotating vortex on the lateral wall of ICA, The location and distance of the vortex changed with the flow velocity. The higher the flow velocity, the smaller the vortex distance, and the farther the location. The shear stresses on the lateral wall were significantly lower in all work condition. And there a low shear stress kernel when the velocity was lower than 0.839 m/s. The location of the low shear stress was just the position of atherosclerosis. The flow pattern inside the model consists of large flow separation and vortex zones. And there are low shear stress zones at the lateral wall of ICA, Where are thought to be associated with the genesis of atherosclerosis.
Blood Flow Velocity ; Carotid Arteries ; physiology ; Models, Cardiovascular ; Pulsatile Flow ; Regional Blood Flow ; physiology ; Rheology ; methods ; Stress, Mechanical