Digital Measurement Of Clinical Anatomy Of Minimally Invasive Lumbar Spine Surgery And Finite Element Analysis Of Different Sizes By ALDH Minimally Invasive L_4/5 Foraminoplasty In Adolescents Aged 12 To 21 Years

Objective : 1.To measure 11 bone structure indexes of normal lumbar spine in adolescents aged from 12 to 21,and to improve the anatomical data of adolescent lumbar spine,so as to provide anatomical parameters for minimally invasive surgical treatment of adolescent lumbar spine diseases.2.Finite Element Analysis(FEA)was used to analyze the biomechanical effects of intervertebral foraminoplasty with different proportions of articular processes under spinal endoscopy on the biomechanical effects of lumbar articular processes,so as to provide biomechanical reference for the improvement of surgical treatment of adolescent lumbar disc herniation.Methods :90 cases of normal spinal CT images of 12 ～ 21 years old adolescents were collected.The image data of CT continuous scan were imported into Mimics 16.0 in DICOM format for 3D reconstruction and measurement.Measurement indexes:Foraminal High,H、Sagittal diameter of foramen,S、Transverse process length,TPL、Transverse process wide,TPW、Spines high,SH、Spines length,SL、Distance between spinous process and foramina,DSF。 Results: 1.H increased firstly and then decreased with the sequence of vertebrae,and the height was the largest at l3/4 segment and the smallest at L5/S1 segment.There were statistically significant differences in H between segments(P < 0.05),and there were statistically significant differences in H between genders at 12-14 years old(P < 0.05).S was the smallest at L1/2,increased to l4/5 with the growth of the vertebral sequence,and decreased at L5/S1.There was statistically significant difference in S between different segments(P < 0.05),and there was statistically significant difference in S between genders at 12-14 years old(P < 0.05).Female was larger than male.There was statistically significant difference between genders at l3/4 segment of 19-21 years old age group(P < 0.05),and males were larger than females.In TPL,L3 segment was the longest,followed by L5 segment.There were statistically significant differences in length between L3 and L5(P < 0.05),and there were statistically significant differences between L5 and L1,L2 and L4(P < 0.05).Except L4 segment narrowed slightly compared with the upper segment,TPW gradually widened with the segment,L5 segment was the widest,and the width comparison between L5 and L1-4was statistically significant(P < 0.05).The transverse process width of each segment gradually narrowed from inside to outside.Except L2,the width of the lateral segment decreased by about 35% compared with the medial segment.There were statistically significant differences in width between root and outermost of transverse process in all segments(P < 0.01),and there were statistically significant differences in width between root and middle of transverse process in L5 segment(P < 0.05).The height of the interspinous process was the largest at L1/2 and the smallest at L4/5,and there was no significant difference between L1/2 and L2/3,l3/4 and L5/S1(P > 0.05).The length of the central spinous process was the largest at L3 and the smallest at L5.There was no significant difference in the length between L1,L2 and L4(P > 0.05),but there was significant difference between L3 and L5 and L1,L2 and L4(P <0.05).2.(1)The stress values of L5 in model M1 under postextension(3.47± 1.50mpa)and right-rotation(4.32± 1.12mpa)were significantly different from those in model M(4.50± 1.14mpa)and(3.44± 1.58mpa)(P < 0.05).(2)The stress value of L4 left superior articular process in model M2 under the loading condition of left flexion(4.81±0.97Mpa)was significantly different from that in model M(3.37±0.84Mpa)(P< 0.05).(3)In model M3,the left superior articular process of L4 was posteriorly extended(3.08±1.20Mpa)and rotated(1.64±0.50Mpa),while the left superior articular process of L5 was flexion(5.67±1.02Mpa),flexion(3.91±1.31Mpa)and rotation(3.10±1.51Mpa).Right superior articular process of L4 flexes(1.63±0.51Mpa)and rotates(2.58±0.73Mpa)on the right side,There were statistically significant differences between the stress values of L5 right superior articular process under postextension(2.50±1.93Mpa),left flexion(1.81±0.43Mpa)and left rotation(3.21±1.42Mpa)and the stress values of model M process(P < 0.05).Conclusion:1.(1)Foraminal height increases with age in adolescents,and the upper and lower Angle range of PELD puncture increases with age.(2)The height and sagittal diameter of lumbar intervertebral foramina were 13.87 ～ 19.29 mm and 6.37 ～13.49 mm,and routine working cannula with diameter of 6.3 ～ 7.5mm could be used in clinical YESS surgery.(3)The transverse process hook of adolescent lumbar spine and lumbar spine correction system should be improved based on the following parameters: the range of lateral diameter(5.42 ～ 6.37mm)and the range of medial diameter(8.35 ～ 13.77mm).(4)Attention should be paid to gender differences in the design of adolescent intertransverse process spreader.It is recommended that the length of male spreader should be 15.19 ～ 24.59 mm,and that of female spreader should be 16.52 ～ 22.76 mm.2.In adolescent foraminoplasty,the lumbar biomechanical stability is obviously damaged when the medial area of the superior facet of one side and one segment of the lumbar spine is removed.It is recommended to carefully remove the facet facet of more than half of the lumbar spine to avoid lumbar instability.