The Radiographic Measurement And Analysis Of Osteotomy Plane In Pedicle-lengthening Osteotomy

Objective: To determine the relevant date of pedicle osteotomy plane for Pedicle-lengthening Osteotomy.To provide data support for improving the pedicle osteotomy knife and for a safe implementation of Pedicle extension.Methods: Using Mimics software to reconstruct 100 patients with lumbar spinal stenosis using 3D model.Then,the pedicle extension was simulated and the data were analyzed.To reconstructing coordinate system for each pedicle according to the position of the navigation and the data were analyzed.The main measuring indexes were Transverse Screw Angle(TSA),Sagittal Screw Angle(SSA),pedicle screw path length(PL),Osteotomy plane Depth(OD),Longest Axis of Osteotomy plane(LOA),Least Axis of Osteotomy plane(LEA),and Osteotomy plane Inclination(OI).And the cortical thickness of the superior wall(CTS),the cortical thickness of the inferior wall(CTI),the cortical thickness of the medial wall,CTM),the cortical thickness of the lateral wall(CTL).Results: 1.The transverse screw angle of the Lumbar segmental L1-L5 pedicle is gradually increased,the male group increased from 9.5°to 25.7°,the female group increased from 9.6° to 25.6°.In the L1 and L2 segments,the pedicle sagittal screw angle is positive.In the L3-L5 segment,the sagittal screw angle is negative and the tail angle is gradually increased.The male group decreased from 1.6° to-10.7°,and the female group decreased from 1.5° to-10.7°.There was no statistically significant difference between the same segments(P> 0.05).2.As for pedicle screw path length,the L5 segment was the shortest.The longest was L1 segment in male group(50.27mm),however,in the female group,the L3 segment was the longest(47.13mm).In the L3-L5 segment,the pedicle screw path length showed a decreasing trend.The osteotomy plane depth showed a decreasing trend in the L1-L5 segment.The male group decreased from 18.43 mm to 13.92 mm.The female group decreased from 17.37 mm to 13.25 mm.There was significant difference between the male and female groups(P <0.05).3.The angle of osteotomy plane inclination was increasing in L1-L5 segment in male and female group,the angle of L1 segment was the smallest(male average 4.7 °,female average 4.1 °),L5 segment angle was the largest(male average 41.3 °,female average 40.0 °).There was significant difference between the male and female groups(P <0.05)in the L3 segment.4.In the L1-L3 segment,the longest axis showed a decreasing trend in the male and female groups,but showed an increasing trend in the L3-L5 segment-the L3 segment was the shortest and the L5 was the longest.In the measurement of the shortest axis,the male and female groups showed an increasing trend in the L1-L5 segment-the L1 segment was the shortest and the L5 segment was the longest.In the longest axis and the shortest axis measurement,the same segment of the male group was significantly larger than the female group,the difference was statistically significant(P <0.01).5.The thickness of the cortex in the edge of the pedicle of the pedicle was the smallest,the inner edge was the second,and the upper and lower marginal cortex was relatively thick.Conclusion:1.In the process of pedicle-lengthening osteotomy,the transverse screw angle was increased gradually from L1 to L5.In the L1 and L2 segments,the pedicle sagittal screw angle was approximately parallel to the endplate plane.In the L3-L5 segment,the sagittal screw angle is gradually increased.2.The changes of pedicle screw path length in the L1-L5 segment were not obvious.But the osteotomy plane depth showed a obvious decreasing trend from L1 to L5.Therefore,the ratio of the anterior and posterior sheath screw should be different in different lumbar segments.3.The longest axis and shortest axis of L5 segment were the longest,it suggests that this may need to design longer and stabler osteotomy knife.4.In the L1-L5 segment,the thickness of the upper and lower cortex was significantly larger than the thickness of the inner and outer cortex,suggesting that the cutting of the upper and lower cortex during the pedicle osteotomy is more difficult and takes longer.5.Mimics software can be used to establish a three-dimensional model of the lumbar spine,to reconstruct and obtain the corresponding section according to the requirements of the surgeon,can be more accurate measurement of the relevant anatomical parameters for the pedicle osteotomy knife design and safety implementation of pedicle extension surgery.