Biomechanical Study Of The Effect Of Lumbar-iliac Fixation On Cranial Adjacent Segments

Objective: We construct there simulation model of lumbar and pelvis to explore the biomechanical mechanism, including control group, unilateral Lumbar-iliac fixation group, double side Lumbar-iliac fixation group.1.The range of movement(ROM) of the L4-5segment were measured under the load of pure moments of anterior flexion, extension, lateral bending.The data were analysised by SPSS16.0to compare the difference in there groups.2. The anterior height of intervertebral disc of the L4-5segment were also measured under the load of pure moments of anterior flexion, extension, lateral bending.The datas were analysised by SPSS16.0to compare the difference in there groups.Methods:l.The simulation model of lumbar and pelvis were casted in parallel on the L1and Ischial tuberosity with self curing dental base acrylic resin powder.The position of the model were the same as human body pelvis position.the L4-5segment were drilled and fixed with2.0kirschner wire(lenth3.0)in the front of the Vertebral body.2.The simulation model of lumbar and pelvis were placed in the CSS-44100, measuring the range of movement(ROM) of the L4-5segment by anterior flexion, extension, lateral bending.One universal pedicle screw was fixed in L5vertebral body according to the standard method, at the same time, one schanze needle was fixed in posterior superior iliac spine, bending the connecting rod and connecting the screw and schanz needle, measuring the the range of movement(ROM) of the L4-5segment by the preparation of unilateral lumbar-iliac fixation model. Also,the bilateral lumbar-iliac fixation model was performed to measure the range of movement(ROM) of the L4-5segment.The data was analyzed by statistics.3.The front height of intervertebral disc was measured in the control group under the movement of anterior flexion, extension, lateral bending, The other groups of unilateral lumbar-iliac fixation model and bilateral lumbar-iliac fixation model were measured by the same way. The data was analyzed by statistics.Results:l.The three groups of control model、 unilateral lumbar-iliac fixation model and bilateral lumbar-iliac fixation model were compared together.Compared to the control group, the range of movement of the L4-5segment in unilateral lumbar-iliac fixation model increased obviously under movement of anterior flexion, extension, lateral bending.The difference in statistics was significant(p<0.05). Compared to the control group, the range of movement of the L4-5segment in bilateral lumbar-iliac fixation model also increased obviously under movement of anterior flexion, extension, lateral bending.The difference in statistics was significant, too(p<0.05).The range of movement of the L4-5segment in bilateral lumbar-iliac fixation model increased a little than the unilateral lumbar-iliac fixation model, but no difference between the two groups(p>0.05).2. Compared to the control group, The front height of intervertebral disc of the L4-5segment in unilateral lumbar-iliac fixation model increased obviously under movement of extension, and decreased obviously under movement of anterior flexion.The difference in statistics was significant(p<0.05). Compared to the control group, The front height of intervertebral disc of the L4-5segment in bilateral lumbar-iliac fixation model also increased obviously under movement of extension, and decreased obviously under movement of anterior flexion.The difference in statistics was significant, too(p<0.05).There was no difference between the two groups(p>0.05).Conclusion:1. The groups of unilateral lumbar-iliac fixation model and bilateral lumbar-iliac fixation model could increase the range of movement of cranial adjacent segment bothly, but the two groups of unilateral lumbar-iliac fixation model and bilateral lumbar-iliac fixation model have no differences in statistics.2. The groups of unilateral lumbar-iliac fixation model and bilateral lumbar-iliac fixation model could increase the front height of intervertebral disc of cranial adjacent segment bothly, but the two groups of unilateral lumbar-iliac fixation model and bilateral lumbar-iliac fixation model have no differences in statistics.