The Three-Dimensional Finite Element Study On The Influence Of Cataplasia In The Adjacent Lumbar Segmenta After Different Lumbar Intervertebrae Fusion

[Objectives] To discuss the different influence of cataplasia in the adjacent lumbar segmenta and offer theoretical instruction for clinic,the research was carried out by observing the biomechanical influence in the adjacent segmenta after different lumbar intervertebrae been fused.[Methods] After the three-dimensional finite element model of backbone L1-S1 including the influence of surrouding ligament was set up,the condition that fusion accomplished in L3/4,L4/5, L5/S1 and L4/L5/S1 were imitated for the study. Then the model was loaded and made to flect,extend,lateral flect,ratate and the combination of lateral flect+rotate, lateral flect+extend, lateral flect+flect, rotate+flectjust like human's daily activities.The comprehensive stress in the intervertebral disc and joint of the adjacent segmenta after different lumbar intervertebrae fusion was accounted under various kinds of lumbus activities.[Results]1. When L3/4 was fused,the comprehensive stress of the intervertebral disc and joint in the upper adjacent segment respectively increased 6.7% and 5.8% in average,and it was 2.2% and 4.0% in the below.Dealt with statistics,the difference of comprehensive stress was notable before and after fusion(P<0.05),except in the below intervertebral disc.The comprehensive stress increased obviously in the upper adjacent segment.2. When L4/5 was fused,the comprehensive stress of the intervertebral disc and joint in the upper adjacent segment respectively increased 11.8% and 12.6% in average,and it was 9.24% and 3.8% in the below.Dealt with statistics,thedifference of comprehensive stress was notable before and after fusion(P<0.05),except in the below intervertebral joint.The comprehensive stress increased obviously in the upper adjacent segment.3. When L5/S1 was rused,the comprehensive stress of the intervertebral disc and joint in the upper adjacent segment respectively increased 17.6% and 16.4% in average.Dealt with statistics,the difference of comprehensive stress was very notable before and after fusion(P<0. 01).4. When L4/L5/S1 was double-segment fused,the comprehensive stress of the intervertebral disc and joint in the upper adjacent segment respectively increased 16.0% and 15.6% in average.Dealt with statistics,the difference of comprehensive stress was notable before and after fusion(P<0. 05).5. The biomechanical influence in the adjacent segment following different lumbar intervertebrae fusion,is biggest when fused in L5/Sl,even exceed in L4/L5/S1,secondly is in L4/5,and it is relatively small when fused in L3/4.[Conclusions]Lit would accelerate cataplasia in the adjacent segmenta after different lumbar intervertebrae been fused.lt was obviously in the upper adjacent segment.2. Fusing in lower intervertebral of lumbar would evoke much more cataplasia in the adjacent segment.lt hints that we should keep prudent for the fusion in lower lumbar segment. As for the cases that the adjacent segment have obvious cataplasia but without clinical symptom,it is considerable to fuse the adjacent cataplased intervertebral together,especially in lower lumbar segment.3. Simple-segment fusion in L5/S1 evoked much more cataplasia in the adjacent segment than double-segment fusion in L4/L5/S1.4.These conclisions were just the result of biomechanics study and need to be verified by clinic.