Design And Imaging Measurement Of One-sided Lumbosacral Axial Screw With Spiral Blade

Objective: A unilateral locking lumbosacral axial screw with a spiral blade was designed by imaging measurement of lumbosacral vertebrae in normal adults.Methods: the designed unilateral locking lumbosacral axial screw with a spiral blade consists of a main nail and a s1 pedicle locking nail,in which the main nail consists of three parts: a l5 vertebral spiral blade,a l5/s1 intervertebral space and the s1 vertebral cylinder.1.Imaging measurement of main nail: To establish axial fixation baseline and measure axial height s1 vertebral body,height of l 5/s 1 space and axial height of l5 vertebral body on the normal lumbar lateral slice,to provide reference for the length design of the main nail in each part.the transverse and sagittal diameters of the l5?s1 vertebrae were measured in the cross section of the normal lumbosacral CT to provide a reference for the diameter of the main nail in each part.2.Comparison of s1 safety of unilateral locking nails placed through the left and right s1 pedicle: A random selection of normal lumbosacral CT data,men and women were 40 cases,men were 41.5±8.1 years old,women were 40.1±9.3 years old.The height(wz)measured on the sagittal ct of the s1 pedicle isthmus and the width(xy)measured on the cross-sectional ct of the pedicle isthmus provide reference for the diameter design of the locking nail.The distance(ab)from the lateral cortex of the left pedicle to the contralateral front of the vertebral body and the straight distance(bc)from the key tissue around the c point of the anterior edge of the vertebral body were measured on the cross-sectional ct of the isthmus of the s1 pedicle(The same method was used to measure the insertion of locking pins through the right pedicle).To provide a reference for the length design of nail,and compare the safety of left and right nail placement.3.Imaging findings of main nail: Randomly selected normal lumbar lateral x,100 men and women,male group age 40.5±7.1 years old,female group age 42.1±6.3 years old.The angle between the end plate l5 the lower vertebral body and the end plate line of the s1 vertebral body was measured on the lateral plate of the lumbar vertebrae,which was the obliquity of the locking nail.Result:1.Anatomical data of each part of the nail: Length l5 axial height,s1 axial height of vertebral body,Male(26.76±3.94)mm?(29.12±2.18)mm,Women(22.91±2.91)mm ?(26.91±2.47)mm,There was significant statistical difference between men and women.l5/s1 space,l5 vertebral body,s1 vertebral body sagittal diameter,Male(12.62±1.90)mm ?(34.48±2.32)mm ?(35.65±4.28)mm,Women(11.92±1.78)mm ?(33.03±3.48)mm ?(33.53±3.26)mm,There was significant statistical difference between men and women.2.Imaging findings of unilateral locking nail of s1 pedicle: s1 the width(xy)and height(wz)of the isthmus of the pedicle,and the length(ab)of the distance from the lateral cortex of the pedicle to the anterior edge of the vertebral body,male 25.20±2.33 mm ? 16.29±2.07 mm ?80.92±5.11 mm,women 22.85±2.74mm?15.10±2.71mm?75.49±5.51.The line wz was smaller than the line xy.There was significant statistical difference between men and women.a left and right insertion s1 locking nail breaks through the shortest distance between the anterior edge of the vertebral body adjacent to the internal iliac vessels,Male(1.51±1.73)mm?(1.75±2.19)mm;female(1.99±2.45)mm?(2.69±2.92).There was no significant statistical difference between men and women.3.Imaging findings s1 the tilt angle of unilateral locking nail of pedicle: The angle between the s1 locking nail and the main nail was(12.05°±1.39°)for men and(11.25°±1.62°)for women.There was no significant statistical difference between men and women.Conclusion:1.The measured imaging results provide a reference for the design of lumbosacral axial screw with screw blade for unilateral locking.2.One-sided locking of lumbosacral axial screw with spiral blade l5 screw blade of vertebral body,difference of upper and lower diameter of intervertebral space part and locking nail of s1 vertebral body part can achieve better effect of anti-rotation and anti-axial compression in theory,and the operation procedure can be simplified theoretically by the design of tilt angle of locking nail.3.There was no difference in the safety of unilateral locking nail insertion through left and right sacral 1 pedicle.