Experimental Research On The Acute Effect Of Spinal Cord Shortening On Function And Blood Flow In Rabbit Undergoing The Posterior Osteotomy Of Thoracolumbar Vertebra

Objective:To establish a circumspinal vertebrectomy animal model of spinal cord shortening by the 1st lumber body vertebrectomy, and investigate the acute effects of spine shortening on the spinal morphous, function and blood flow.To make contribution to the security of vertebral osteotomy by researching the safe limits of spine column shortening.Methods:25 male rabbits were randomly divided into five groups, the mean weights were 2±0.4kg and the mean lengths were 35±5cm.After general anesthesia and local anesthesia, Group A was the control group, which undergoing the 1st lumber body circumspinal vertebrectomy without docking. Group B,C,D,E were experimental groups, with the 1st lumber body circumspinal vertebrectomy. Then the two ends of osteotomy were docked different percent of lumber body length.It is grouped by docking 25%,50%,75%,100% percent of the 1st lumber body length.Target:After total vertebral osteotomy of L1,we performed spinal column shortening and measured the diameter and length of spinal cord,the angle of the spinal sagittal circuity in different percent of shortening. Jacbos grade and Reuters score were recorded 6 hours after surgery. Then the animals were executed. Blood vessels casting preferred to the harvesting of spinal cord samples. The micropictures of the spinal slides were acquired with the aid of picture collecting system. Then it was ready 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:Three animals were excluded in group A, D and E respectively because of the accident of operation.1.Self control in every group:diameter of spinal cord and sagittal circuity existed statistic significance in group C,D and E(P<0.01),after 6 hours' observation, there were no statistic significance in the Jacobs grade between group A and B(P> 0.05),and existed statistic significance in group C,D,E(P<0.05).There were statistic significance in Reuters scores in group B, C, D, E.2.Group control:the diameter and the sagittal circuity of spinal cord, Jacobs grade, Reuters scores and SCBF between group A and B did not exist statistic significance(P>0.05),others had statistic significance(P<0.05).3.Correlations:the diameter, sagittal circuity and SCBF were all statistically correlated with Reuters scores(r=0.955,P<0.001;r=0.848,P<0.001; r=-0.869,P< 0.001).The diameter and sagittal circuity were correlated with SCBF(r=-0.946,P< 0.001;r=-0.997,P<0.001)4.The manifestation of histopathology was swelling neurons, shrinking nucleus, irregularly nervous fibers. The longer distance of the spinal is docked the larger area of the neurons swell.Conclusion:1.Animal model of spinal shortening is successful with posterior total osteotomy of vertebra and internal fixation. It is feasible and reasonable.2. Shortening of spine will damage the function and blood flow of spinal cord3.The damage of spinal cord function has positive correlation with shortening of spine, and has negative correlation with SCBF4.SCBF has negative correlation with shortening of spine5.The safe limit of spine shortening in L1 is about 50% of its total height.