| Background and objectivesSpinal cord tumors are common tumors of the central nervous system,accounting for approximately 15% to 25% of primary nervous system tumors.The current main treatment of spinal cord tumors is the surgical resection through the posterior approach.Depending on the involvement involving the laminar and its attachments during surgery,the surgery was divided into full lamina surgery and minimal invasive surgery,which includes hemi-laminectomy and hemi-semi-laminectomy.One of the largest damage to the posterior column structure was laminectomy in full lamina surgery.Cervical spinal cord tumors account for approximately 26%–35% of the primary spinal cord tumors.Due to the wide range of motion of the cervical segments,the incidence of cervical instability was high.Due to the important function of the cervical spine,the postoperative cervical instability will have a serious impact on the patients’ quality of lives.Therefore,some clinical experts believe that synchronous fusion fixation should be needed for those patient who underwent laminectomy to prevent iatrogenic cervical instability.However,others disagree that although there is a certain incidence of cervical instability after surgery,preventive fixation will increase surgical trauma and cost,cause cervical spinal dysfunction,and increase the risk of adjacent vertebral disease,so it does not support the preventive fixation for all patients who plan to have cervical laminectomies.The above two views and their clinical practice are not yet unified.laminoplasty is a full lamina with the goal of restoring anatomical reconstruction after spinal surgery.However,there is insufficient evidence for whether the restored vertebrae have good bone healing and whether the restored reconstruction contributes to the maintenance of spine stability.Although with the development of medicine,as well as the improvement of technology and instruments,minimal invasive surgery is gradually promoted,it is still inevitable to cause certain damage to the biomechanical structure of the cervical spine,causing the risk of iatrogenic cervical instability.However,the differences between the effects of different types of minimal invasive surgery on cervical stability and their mechanisms have not been demonstrated.Therefore,it is of great significance to collect clinical data of patients who underwent cervical spinal cord tumor resections and to analyze evidence-based research.This study aims to accomplish the following objectives: firstly,to analyze the epidemiological characteristics and influencing factors of cervical spine stability after cervical spinal cord tumor resection,then to compare the different effects of laminectomy and laminoplasty on the stability,and focus on the healing status of restored lamina and its influence factors,finally,to compare the different effects of hemi-laminectomy and hemi-semi-laminectomy on postoperative cervical spinal stability,and to explore its biomechanical mechanism.Materials and methodsThis study retrospectively collected epidemiological information,images of cervical spine images,disease information and treatment,as well as follow-up information from 182 cervical spinal cord tumor surgery patients admitted to neurosurgery at the Second Affiliated Hospital of Zhejiang University Medical School referred to the Electronic Medical Record System(EMRS)and Picture Archiving and Communication System(PACS).First,logistic regression was used to screen out the risk factors for postoperative cervical instability and divided into different subgroups according to the surgical method to analyze risk factors of postoperative cervical instability or postoperative cervical kyphosis.Secondly,the effects of laminectomy and laminoplasty on cervical stability were compared by repeated ANOVA,and the effect of the healing status of restored lamina on postoperative cervical stability was explored;generalized estimation equation was used to analyze the influence factors of the lamina healing.Thirdly,we compared the effects of hemi-laminectomy and hemi-semi-laminectomy on postoperative cervical stability,and analyzed the correlation of surgical characteristic index and cervical curvature by linear regression,then analyzed the personalized finite element analysis of the data of the cervical spine,and analyzed the correlation between the stress and the size of surgical bone window as well as the surgical segments.ResultsThe first part of the study analyzed the epidemiological characteristics of 182 patients after cervical spinal cord tumors,and the total incidence of cervical instability was approximately 9.3%.Age,preoperative weakness,surgical method,and intraoperative blood loss varied significantly between the cervical unstable and cervical stable groups(both P values were below 0.05).The incidence of cervical instability after laminectomy,laminoplasty,hemi-laminectomy and hemi-semi-laminectomy were21.21%,10.11%,4.35% and 0%,respectively.The incidence of cervical instability was significantly higher after full lamina surgery compared with that after minimal invasive surgery(P=0.0130).After adjusting for potential confounders,it was found that the surgical method was a risk factor for postoperative cervical instability(P=0.023).A total of 122 patients were included in the full lamina subgroup,including 33 with laminectomy and 89 with laminoplasty.Significant differences were found in age,preoperative weakness,and intraoperative blood loss between cervical unstable and cervical stable groups(both P values were below 0.05).When divided into three subgroups aged under 20,20 to 50 years old and older than 50,the incidence of postoperative cervical instability was 56%,14% and 2%.Multivariate logistic regression analysis suggested that age below 20 and preoperative weakness were significantly associated with cervical instability following full lamina surgery(both P values were below 0.05).There were 60 cases in the cervical minimal invasive surgery subgroup,including 23 with hemi-laminectomy and 37 with hemi-semi-laminectomy.The surgical method varied significantly between cervical kyphosis and none cervical kyphosis groups(P=0.0108),and hemi-semi-laminectomy was a protective factor for postoperative cervical curvature(P=0.0431).The second part of the study analyzed the cervical stability of 122 patients after cervical spinal cord tumor resection.The data showed that the difference between the effects of full lamina surgery on cervical stability increased as follow-up time went by,and laminoplasty was protective against cervical stability(P=0.0001).The proportion of patients with all segments healing and more than half healing were significantly positively associated with follow-up time(both P value were below 0.05);the proportion of all segment healing patient in both patients with long segments(more than3 segments)and with short segments(less than 3 segments)were significantly positively correlated with follow-up time(both P value were below 0.05).Both healed segments of the restored lamina were better protected against the head and caudal segmental curvature than the laminectomy and unhealed segments(both P values were below 0.05).The number of segments in the bilateral healing showed significantly linearly negatively correlated with the posterior convex increment of surgical segments(both P values were below 0.05).The posterior increment in surgical segments varied significantly between the postoperative cervical instability and postoperative cervical stability groups(P=0.0187).Further analysis of the epidemiological features of 72 reset lamina joints found that men and gap width less than 1.5mm were protective for the healing(both P values were below 0.05).The above results suggested that laminoplasty has a gradually significant protective effect on postoperative cervical stability,and the healing status of restored laminina may be involved.While men and gap width less than1.5mm favor healing of the restored lamina.The third part of the study analyzed 23 hemi-laminectomy and 37hemi-semi-laminectomy patients and found that hemi-semi-laminectomy significantly favored cervical curvature at postoperative phase and at follow-up period(both P values were below 0.05)and significantly shortened surgical duration(P=0.0214).Individualized finite element analysis of cervical data from selected patients showed TISUM had the best match between the effect of each joint stress on the cervical curvature and the surgical method on cervical curvature,and a significant positive correlation with the posterior convex increment of cervical curvature(P=0.0123).The above results suggest that hemi-semi-laminectomy may achieve protection on postoperative cervical curvature by reducing TISUM.ConclusionThis study found a significantly higher incidence of cervical instability after full lamina surgery compared with that after minimal invasive surgery.Among them,laminoplasty,compared with laminectomy,had increasing protective effect on the cervical stability as time went by;the healing status of the restored lamina increased with time.Male and gap width less than 1.5mm were protective factors for healing of the restored lamina.The healing status of restored lamina was positively associated with the maintenance of surgical segment curvature,which was significantly associated with postoperative cervical spine stability.Hemi-semi-laminectomy protects postoperative cervical stability compared with hemi-laminectomy.Hemi-semi-laminectomy reduced postoperative TISUM,and postoperative TISUM was inversely associated with cervical stability after minimal invasive surgery. |
PDF Full Text Request