The Acute Effect Of Spinal Cord Shortening On Function And Blood Flow In Rabbit Undergoing The Lumbar Body Posterior Vertebrectomy

Objective:To establish the animal model of spine cord shortening by the 4th lumber body vertebrectomy,and study the acute effects of spine shortening on the spinal function and blood flow.To make contribution to the security of spine osteotomy by researching the safe limits of spine shortening in different spine segments.Methods:25 male rabbits were randomly divided into five groups,the mean weights were 2.0±0.40kg and the mean lengths were 35.0±5.0cm.After general anesthesia and local anesthesia,Gorup A was the control group, which undergoing the 4th lumber body circumspinal vertebrectomy without docking.Group B,C,D,E were experimental groups,with samely the 4th lumber body circumspinal vertebrectomy.Then the two ends of osteotomy were docked different distance.it is grouped by docking 25%,50%,75%,100% percent of the 4th lumber body length. After total vertebrectomy of L4,we performed spinal column shortening and meaused the diameter and length of spinal cord,the angle of the spinal shift point. The animals were executed after 6 hours'observation. Blood vessels casting preferred to the harvesting of spinal cord samples.The micropictures of the spinal slides were gained to obtain the data of average vessel area of each group, which is calculated via a picture analying system.Then studied the H-E slides in pathology. Results:1,Two animals were excluded in group A and E respectively because of the accident of operation.2,Self control in every group:after 6 hours'observation,there were no statistic significance(P>0.05) among the Jacobs grade and Reuter score in group A,B,C,and existed statistic significance(P<0.05) in group D,E.3,Group control:the diameter of spinal cord between group A and B, the angle of the spinal shift point among group A,B,C,the SCBF between group A and B did not exist statistic significance(P>0.05),others had statistic significance(P<0.05).4,Correlations:the diameter, the angle of the spinal shift point and SCBF were statistically correlated between two of the three(r=0.895,P< 0.01;r=0.918,P<0.01;r=0.981,P<0.01).The Reuters scores was negtive correlated with the diameter,the angle of the spinal shift point and SCBF (r=-0.908,P<0.01;r=-0.994,P<0.01;r=-0.979,P<0.01)5,The manifestation of histopathology was swelling neurons shrinking nucleus,irregularly nervous fibers.The longer dictance of the spinal is docked the larger area of the neurons swell.Conclusions:1,There was no distinct influence in spinal function by circumspinal vertebrectomy, the spinal shortening can lead to the change of spinal function and blood flow in our models.2,With the spinal shortening the distance increased, decreased local spinal cord blood flow, increased spinal cord motor and sensory dysfunction, there were correlations among them.3,The nerve was injured when the circumspinal vertebrectomy regularly was to exceed 50% in our models.