| Objective:According to the determination of the lumbosacral anatomy and imaging data develope L5/S1transpedicular screw-plate internal fixation system in anterior approach, and to evaluate its biomechanical properties.Methods:(1)Determine50sets of dry specimens of normal adult L5and S1height、width、arc of vertebral body, bone-screw channel length, the width of pedicle、the height of pedicle, pedicle and sagittal plane and horizontal plane Angle, lumbosacral joint Angle, height of L5/S1intervertebral disc scope of relevant data.(2)Select50cases (including eight L5/S1segment bony wet specimens) of normal adult lumbar positive lateral X ray film and CT slice (age18-55years old, average40.6years) measurement and adult dry specimens of the same indicators.(3)According to the design idea and anatomy、imaging data design L5/S1transpedicular screw-plate internal fixation system in anterior approach, the system consists of two pieces of length, width, height, arc the same rectangle plate and four eccentric hole%pedicle screw pressure.(4) L5/S1transpedicular screw-plate internal fixation system in anterior approach are installed on eight normal adult L5/S1segment bony wet specimens respectively,and carry on specimens of X-ray and CT scan.(5) The biomechanics test:eight specimens have internal fixation (experimental group) are installed in the universal mechanical testing machine and bending, compression, torsion, pull out of line respectively, and will it and safety of L5/S1anterior plate internal fixation group (PACH group), and L5/S1complete spinal biomechanical comparison group.Results:(1) The L5pedicle height is12.68±1.45mm, pedicle width is15.33±1.56mm, bone-screw channel length is50.15±2.46mm, fanterior radian is134.56±12.67°, pedicle and sagittal Angle is26.8± 2.0°, pedicle and horizontal Angle is7.3±0.8°. S1pedicle height is17.78±0.78mm, pedicle width is12.67±1.95mm, bone--screw channel length is44.69±3.77mm, pedicle and the horizontal plane Angle is10.3±1.02°, pedicle and sagittal Angle is27.8±1.6°. L5/S1intervertebral disc thickness is18.23±2.21mm, lumbosacral joint Angle2.21±5.9°. L5vertebral screws into the nail edge of point for L5vertebral level up to12±2mm, vertebral body near the central vertical line intersection point on5-7.5mm, S1vertebral bodies into the top pin point for S1vertebral body horizontal line12±2mm down, near the center line perpendicular intersection point open6-7.5mm, L5and S1into the needle Angle value with pedicle, pedicle and sagittal plane and horizontal plane Angle.(2) L5/S1anterior plate long is56.23±2.21mm, width is10mm, height is4mm, sagittal curve is138.6±5.9°and screw hole center distance is44.23±2.21mm, the eccentric hole Angle same as L5and S1into the needle Angle value. L5screw long is45mm, S1screw long is40mm, screw are all5mm in diameter, screw pitch is0.5mm.(3) Experimental group after forward bends, stretch, lateral bending, compression stiffness value is99.034N/mm,111.452N/mm,89.385N/mm,93.655N/mm, L5/S1anterior security steel plate fixation group is92.657N/mm,100.200N/mm,85.288N/mm,77.625N/mm,the experimental group before bending, resistant to compression ability is better than that of L5/S1road safety steel plate fixation group, with statistical difference (P<0.05). Experimental maximum axial pull output was712.34±245.31, L5/S1anterior security steel plate fixation group was420.51±149.43, the experimental group’s ability to resist pull out safer than L5/S1anterior plate fixation group, difference has statistical significance (P<0.001). Experimental torque and torsional rigidity is11.112N·m、2.222N-mm/°respectively, L5/S1anterior security steel plate fixation group is10.964N·m、2.193N-mm/°, two groups of torque and torsional rigidity is not statistically difference (P>0.05).Conclusion:According to the determination of L5/S1section anatomy and imaging data design and develope L5/S1transpedicular screw-plate internal fixation system in anterior approach conform to the requirements of the anatomy of the region, and has a good biomechanical stability. |
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