Finite Element Biomechanical Analysis And Early Clinical Observation Of Treatment For Lumbar Spinal Stenosis With Full Endoscopic Fenestration Decompression

Background and objective At present,full endoscopic fenestration decompression has been used in the treatment of lumbar spinal stenosis(LSS),but there are few studies on the precise scope of full endoscopic fenestration,which may obviously lag behind the clinical application.the purpose of this study is to simulate treatment of lumbar spinal stenosis by finite element analysis.To evaluate and analyze the effects of different decompression ranges of fenestration on lumbar of segmental stability and stress distribution in full endoscopic fenestration decompression,and to provide biomechanical and theoretical basis for the clinical application of full endoscopic fenestration decompression in minimally invasive treatment of LSS,combined with the retrospective analysis of the early clinical effect of full endoscopic fenestration decompression.PartⅠFinite Element Simulation and Biomechanical Analysis of Treatment for Lumbar Spinal Stenosis with Full Endoscopic Fenestration DecompressionObjective To explore the biomechanical influence of precise decompression with different laminectomy zones on lumbar mobility and stress distribution using the entire degenerative lumbar finite element model.Methods A patient with LSS was randomly selected.Based on CT data,the lumbar 4-5segment finite element model(M1)was established using relevant biomechanical software,with which the validity was verified.After that,the finite element simulation of fully endoscopic precisely laminectomy decompression operation was performed.Combined with LSS pathological classification,personalized laminectomy decompression aiming at different L4-5 segment stenosis(disc and above plane stenosis,disc and below plane stenosis,unilateral multilevel stenosis,total canal stenosis)was established.Specifically include: L4 lamina margin and partial facet joint resection model(M2),L5 lamina margin and partial facet joint resection model(M3),L4/5 lamina margin and partial facet joint resection model(M4),M4 + “Over-the-Top” contralateral partial facet joint resection model(M5),and L4/5 lamina margin and over 50% facet jointresection model(M6).The same boundary loading was applied to the various finite element models.The range of motion(ROM)and equivalent stress of intervertebral discs were compared under six conditions including flexion,extension,left and right flexion,leftand right rotation.Results Compared with ROM of the entire M1 model,those of M2,M3,M4 and M5 model were similar under various conditions,but ROM of M6 model was significantly increased to 151%-264% scope,especially in the extension and rotational conditions.In terms of the equivalent stress of disc,the M2,M3,M4 and M5 models showed no obvious increasing trend at the anterior,left and right regionsunder various working conditions.The largest increase of the equivalent stress at posterior and middle disc regionswas 53%maximally,but with no significant stress concentration.However,the equivalent stress in total disc regions showed a significant increasing trend in M6 model,,especially in flexion condition with the maximum three times of M1 model.Conclusion Extensive laminectomy can significantly affect the stability of the lumbar spine,with the intervertebral disc stress increase at the corresponding segment which is more likely to accelerate segmental degeneration.Minimally invasive endoscopic decompression is precise and controllable.The personalized decompression schemes can be adopted for different types of LSS.Under the premise of effectively preserving the weight-bearing structure of facet joints,unilateral laminectomy decompression(Endol OVE)and unilateral laminectomy bilateral decompression(Endo-ULBD)can effectively maintain the biomechanical properties of surgical segments without additional internal fixation.Full endoscopic surgery has a high cost-effective treatment,can effectively reduce iatrogenic segmental instability and delay further degeneration of lumbar.PartⅡ Early Clinical Observation of Treatment for Lumbar Spinal Stenosis with Full Endoscopic Fenestration DecompressionObjective To observe and evaluate the early clinical efficacy of full endoscopic fenestration and decompression in the treatment of lumbar spinal stenosis and to explore its clinical practicability.Methods From December 2018 to January 2020,the clinical data of 45 cases of LSS who underwent full endoscopic fenestration decompression in our center were analyzed retrospectively.All the cases were selected as lumbar 4-5 segments.According to the level and degree of stenosis,different levels of fenestration decompression were performed,including intervertebral space and below decompression group(group A),intervertebral space multi-level decompression group(group B),and Multislice intervertebral space + contralateral stealth decompression group(group C).There were 15 cases in group A(7 males and 8 females,age 54-78(63.80±8.04)years,BMI 24.73±3.54 kg / m2,follow-up time 18.93±3.65 months).There were 15 patients in group B(8 males and 7 females,age 56-76(65.27±6.03)years,BMI 23.13±2.50 kg/m2,follow-up 18.80±3.59 months),and 15 patients in group C(7 males,8 females,age 56-80(68.67±6.31)years,BMI 23.40± 2.80 kg/m2,follow-up 18.93±3.47 months).The general baseline data,operation time and hospital stay of the patients in the above three groups were recorded and observed.the Visual Analogue Score(VAS)of low back and leg pain,Oswestry Disability Index(ODI)and Japanese orthopaedic association low back pain score(JOA)were recorded and analyzed before and 6 months after the operation,12 months after the operation and the last follow-up,and the Mac Nab criteria were used to analyze and evaluate the early clinical effect.Results There was no significant difference in general data and perioperative data among the three groups.There was no significant difference in VAS,ODI and JOA evaluation among the three groups before and after operation.The VAS,ODI and JOA evaluation decreased significantly at 6 months,12 months and the last follow-up in the three groups,and the difference was statistically significant(P < 0.05).In the last follow-up evaluation of the three groups,the excellent and good rates were 93.3%,86.7% and 86.7% respectively,and there was no statistical difference among the three groups(P > 0.05).Conclusion Full endoscopic fenestration decompression is effective in the early treatment of LSS.The advantages of endoscopic minimally invasive surgery visualization and intraoperative imaging real-time monitoring can ensure accurate and controllable decompression range.Full endoscopic fenestration decompression can achieve personalized accurate decompression for different types of stenosis LSS,which has a broad application prospect.