Biomechanical Evaluation Of Foraminoplasty In Different Range By Spinal Endoscopy

Objective: Through biomechanical experiments of calf lumbar cadaver specimens,to investigate and compare the biomechanical stability of lumbar foraminoplasty in different range by spinal endoscopy,which provided reference and biomechanical basis for clinic.Methods: 9 fresh calf lumbar specimens were collected.7 models were prepared according to the following groups: normal group(N group),foraminoplasty 8mm group(8mm group),foraminoplasty 9.5mm group(9.5mm group),foraminoplasty 10.5mm group(10.5mm group),foraminoplasty 8mm plus anulus fibrosus defect group(8mm+AF group),foraminoplasty 9.5mm plus anulus fibrosus defect group(9.5mm+AF group),foraminoplasty 10.5mm plus anulus fibrosus defect group(10.5mm +AF group).Except for the normal group,all the models of L4-5 specimens were right foraminoplasty.Nondestructive flexibility tests in six directions of flexion,extension,left / right lateral bending and left / right rotation were performed in sequence using the spine multi-degree of freedom biomechanical testing machine.Load of 7.5 Nm maximum were applied with a compressive preload of 200 N.In each loading direction,3 preconditioning cycles were applied to eliminate the creep effect.The electronic sensor automatically collects the L4–5 angular range of motion(ROM)during the third loading.Each group ROM were recorded and compared.Results: In this study,the normal,foraminoplasty 8mm,foraminoplasty 8mm,foraminoplasty 9.5mm,foraminoplasty 10.5mm,foraminoplasty 8mm plus anulus fibrosus defect,foraminoplasty 9.5mm plus anulus fibrosus defect,foraminoplasty 10.5mm plus anulus fibrosus defect models of calf lumbar cadaver specimens was successfully constructed in vitro,and compared the L4/5 motion segment ROM.For the simple foraminoplasty in different range,there was no significant difference in flexion movement,extension movement and left lateral bending movement among each groups(P > 0.05).Compared with the 8mm group,the ROM of the 9.5mm group increased by 38.9% during right lateral(P<0.05).Compared with the 8mm group and 9.5mm group,the ROM of the 10.5mm group increased by 109% and 78%,respectively(P<0.05),during the flexion,extension,right and left bending,respectively,during left rotation.Compared with the 8mm group and 9.5mm group,the ROM of the 10.5mm group increased by 82% and 82%,respectively(P<0.05),during right rotation.In the model of foraminoplasty plus fibrous ring defect,during flextion,compared with the N group and 8mm+AF group,9.5mm+AF group,the ROM of the 10.5mm +AF group increased by 21%,25%,20%,respectively(P<0.05).During extension,compared with the N group and 8mm+AF group,9.5mm+AF group,the ROM of the 10.5mm +AF group increased by 47%,73%,30%,respectively(P<0.05).During left lateral bending,compared with the N group and 8mm+AF group,9.5mm+AF group,the ROM of the 10.5mm +AF group increased by 43%,52%,28%,respectively(P<0.05).During left rotation,compared with the N group and 8mm+AF group,9.5mm+AF group,the ROM of the 10.5mm +AF group increased by 48%,48%,69%,respectively(P<0.05).During right rotation,compared with the N group and 8mm+AF group,9.5mm+AF group,the ROM of the 10.5mm +AF group increased by 85%,44%,42%,respectively(P<0.05).Conclusion 1.With the increase of the range of the foraminoplasty,the rotation movement of lumbar is greatly affected.2.In the model group with different range of foraminoplasty plus anulus fibrosus defect,the ROM increased significantly in multiple directions,which increased the risk of spinal instability.