| Fetal sacrum is made up of five vertebrae(S1～5) through the intervertebral disc and cartilage and connected into a forward concave and back convex triangle bone block.Because the sacral vertebral pedicle, transverse process have a unique three-dimensional anatomical structure,the internal fixation of screw have different embedded direction.On the other hand,because of the sacrum bone relative porosity, physiological curvature in the lumbosacral transitional, carrying larger load and the local shear stress and other factors,So the sacral fixation screw implant without relatively stable fastness.Combined with important organs, blood vessels, nerves and anatomical variations in front of lumbar, sacral vertebral body,Higher incidence of screw loosening, hernia, lead to the research of screw nail into point and angle of the nail becomes more urgent.Many scholars both in china and abroad use a variety of methods including spine anatomy, X-ray, SCT and MRI to research sacral pedicle and lateral mass previously.Research focuses on the distribution of cancellous and cortex of bone..But for adult 5 piece of sacrum and accessories have been merged into one, so the research conclusion is not applicable to fetal sacrum.Fetal sacrum vertebral pedicle, transverse process and lamina by cartilage and fiber ingredients together.Between vertebral pedicle and cartilage(neural arch central epiphyseal) to endow them with bipolar continuous growth and development potential.And neighboring the cartilage for transverse process between vertebral body growth and lateral mass formation is also crucial.Fetal sacrum cartilage exist between the different parts, so that it can be have its special anatomical characteristics.Improper operation and fixation implants to the destruction of the epiphyseal cartilage and interference are blocking the sacrum which result in the adverse consequences of artificial birth defects.So the related research and clinical application of the fetal sacrum becomes more pressing.ObjectiveThis topic through fetal sacral l 、 2 pedicle SCT scan+ 3D reconstruction technology, getting imaging data, and to measure simulation into the screw angle, direction and depth.In specimens simulated screw implants, after repeating imaging to confirm correct implanted, anatomy and measure fetal sacral 1、2, vertebral body, pedicle, transverse process, anatomical form and law of lamina, concluded that fetal sacrum 1、2, pedicle screws implanted each index of data and methods.For clinical and surgical operation to provide the anatomical basis for the establishment of operation scheme.Materials and Methods1 specimen collectionCollected 19 cases without spinal malformation fetus from October 2014 to March 2016 in our hospital. fetal age 26 weeks ～ 38 weeks, 8 cases of male, female in 11 cases, an average of 32 ± 5 weeks gestational age.Fetal specimens is divided into two groups, groupⅠ(gestational age < 32 weeks) 12 cases;groupⅡ(gestational age > 32 weeks) in 7 cases.2 SCT scan、measurementScan two groups of fetal spine with 16 layers spiral CT,3 d reconstruct locate on(S1～S5) segmental.Repeat scanning, taking completion and clear imaging.4 cases of each group underwent spinal area gross anatomy.measure the imaging of S1、2 through Dicom3.0 software on computer.Measuring parameters include: The diameter of vertebral bodies,neural arch central epiphyseal, angle pedicle,s angle of S1、2.For anatomic and radiographic parameters by SPSS17.0 statistical analysis software for chi-square, and paired t test in the group, a scatter diagram analysis, inspection level for α = 0.05.Select group Ⅱgestational age larger specimen anatomic study, and simulation in vertebral arch screws, SCT scan test into effect finally.Result1 Vertebral body pedicle of S 1、 2Three-dimensional reconstruction of spine SCT + visible display samples S1, 2 vertebral body bone ossification is not complete, more cartilage components, far below the normal bone bone CT values.Stuffed with gestational age 32 w ～ 38(w) vertebral transverse section of vertebral bone ratio between 50% ～ 85%.About diameter and diameter ratio before and after the S1 vertebral bodies about 1 to 1. 75, after fanterior diameter S2 about 1:3. 33.S2 vertebral sagittal axial horizontal Angle with growth increases gradually, the Angle increases faster than S1(P<0.05).S1 vertebral body axial Angle is about 18.90±2.34o(15.27 ～ 15.27 o), S2 vertebral body axial Angle is about 28.54±2.33o(24.35 ～ 32.83 o).2 Pedicle of S 1、 2S1, 2 pedicle abducent angles increase gradually, and S1 pedicle abducent angles increase rate of the S2 is big(P<0.05), ratio of 1 to 1.3:1.S1 pedicle abducent angles along with the growth of the left in the 44.39±2.39o(30.40o～61.05o), the right side in the 44.56±2.26o(30.21o～57.69o),without statistical differences(P>0.05).S2 pedicle abducent angles along with the growth of the left in the 49.12±1.99o(35.89o～62.68o), the right side in the 49.76±2.05o(36.01o～64.35o),without statistical differences(P>0.05).3 Neural arch central epiphyseal of S 1、 2S1, 2 neural arch central epiphyseal replication and sagittal Angle decreases, and S1 pedicle abducent angles decrease rate than S2,(4 ～ 5 to 1)(P<0.05).S1 neural arch central epiphyseal replication Angle along with the growth left in 31.56±2.33o(15.50o～36.35o), the right side in the 31.77±2.38o(15.60o～36.62o),without statistical differences(P>0.05).S2 neural arch central epiphyseal replication Angle along with the growth left in 13.83±0.56o(9.78o～15.63o), the right side in the 13.80±0.57o(9.46o～15.74o),without statistical differences(P>0.05).S1, 2 neural arch central epiphyseal replication thickness thinning, its growth rate gradually decreased, vertebral body and pedicle bone ingredients.Vertebral body and pedicle diameter increase gradually, gradually reduce cartilage ingredients, bone instead of cartilage element is a gradual process of evolution.Conclusion1.The diameter of vertebral body pedicle bone composition, neural arch central epiphyseal replication Angle, bilateral pedicle axial Angle of Fetal sacrum1、2 hange gradually along with the gradual increase of the gestational age.2.And its evolution is a process.Its gradual evolution process have certain rules to follow, namely the vertebral transverse section of vertebral bone ratio increased gradually;. |
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