Study On The Stability Of Sheep's Rehabilitated Lumbar After Posterior Operation

Objective:To study the mechanical stability of the sheep's rehabilitated lumbar that after different type of posterior decompression on L4/5,by measuring vertebral segmental stiffness on six degrees of freedom.Methods:seventy eight 2-3 years old female physical maturity Small-Tailed Han sheep were randomly divided into thirteen groups.Each group have six sheep.The thirteen groups including one control group and twelve surgical groups.Three different style posterior decompression operation will be performed on the sheep's L4/5.Surgeryâ… :decompression laminectomy.Surgeryâ…¡:decompression laminectomy and left facet joint section.Surgeryâ…¢:decompression laminectomy and bilateral facet joint section.Each style surgery has four groups.The L4/5 lumbar will be harvested at six weeks,12 weeks,24 weeks,or 36 weeks after operation.All the lumbar samples will be tested and the data of each sample will be gotten.We will study the difference between the control group and the different surgery group which in the same time after surgery.The data will be learned by statistical analysis.All the sample's will be tested under the same physiological range of sheep's spinal motion. Corresponding changes of bending/torsional moment and angular displacement on 6 degrees of freedom were recorded by Instron8874 dynamic multidimensional biomechanical fatigue testing machine.Then the mean slope rate of curves of bending /torsional moment and angular displacement will be recorded and analyzed. SPSS 13.0 statistical package was used for a homogeneity of variance test and a single way analysis of variance(ANOVA)with a SNK test.The level of statistical significance was set to 0.05.Results:six weeks after the operation:surgeryâ… group,surgicalâ…¡group's flexion and extension stiffness increased;all operation group's left and right bending stiffness have no significant changes;surgeryâ…¢group's left and right axial torsion stiffness decreases.12 weeks after operation:all operation group's flexion and extension stiffness increased;all operation group's left bending stiffness has no significant changes;surgeryâ…¡group's right bending stiffness increased;all operation groups' left and right axial torsion stiffness have no significant changes.24 weeks after operation:all operation groups' flexion and extension stiffness increased;surgeryâ…¢group's left bending stiffness increase;surgeryâ…¡group and surgeryâ…¢group's right bending stiffness increased,all operation groups' left and right axial torsion stiffness have no significant changes.36 weeks after operation:all operation groups' flexion and extension stiffness increased,surgeryâ…¢group's left bending stiffness increased;surgeryâ…¡group and surgeryâ…¢group's right bending stiffness increased, the surgeryâ…¢group's stiffness increased significantly.All operation groups' left axial torsion stiffness increased.All operation groups' right axial torsion stiffness has no significant changes.Conclusion:The sheep's lumbar has good rehabilitation ability.The spinal stiffness after different type of posterior decompression surgery,can reached the normal level, even higher than the normal level.