| Objective:Adjacent segment degeneration is one of the major complications of lumbar vertebral fusion operation, also its biomechanisms still not explicit. This study is to evaluate the primary effect of simi-rigid fixation on adjacent segment degeneration by biomechanical and clinical techniques, expect to explore a method to resolve it.Methods:6 whole fresh lumbar spinal specimens (L2-S2) obtained from adult cadaverswere were used to assume the biomechanical measurements. The specimens were divided into integrity group, BioFlex group and rigid fixation fusion group, include L4-L5 segments were fixed by BioFlex semi-rigid and conventional rigid fixation system.The range of movement (ROM) and the inner pressures of vertebral disc of the L3-L4 segment were measured under the load of neutrality and pure moments of axial, anterior flexion, extension, lateral bending and rotation. The datas were analysised by CHISS 2005. According to prospective randomized control study method,60 patients who were suffered from lumbar degenerative disease from February 2009 to September 2010 were randomly divided into two groups. One group treated with BioFlex system, the other treated with traditional rigid fixation and vertebral fusion surgery. The clinical effects were evaluated through the score of ODI and VAS. X-ray and MRI were used to evaluated the ROM and the degenerative degree of the upper adjacent segment.Results:The biomechanics study indicated that though the ROM and the inner pressure in L3/4 segment of BioFlex fixation groups are increased, there have no obviously differences compared with integrity groups. compared to intact condition, althrough the ROM and the stress was. The traditional regid fixation groups show increase and statistic significant of the ROM and the disc inner pressure in L3/4 segment compared to intact condition and BioFlex groups. The clinical study indicated that ODI and VAS scores were much higher at any follow-up in two different surgical operations than those at preoperation, but no difference between BioFlex and rigid fixation groups. Though the BioFlex fixed group's ROM of upper adjacent segment show a little more increased than preoperation, there have no differences in statistics between 6 months post operation and the last follow-up. At the same time, the rigid fixed group's ROM of upper adjacent segment also show a gently increase than preoperation. There have no differences in statistics at 6 months after operation but significance statistics at the last follow-up. Compared with BioFlex group, there were 5 new adjacent segment degenerative discs revealed by MRI in the rigid fixation group, but none in BioFlex fixed groups.Conclusions:The biomechanical and clinical study shows that the BioFlex semi-rigid fixation system has good effect on the treatment of lumbar disc degeneration disease. Though under all kinds of physiological loading, the BioFlex system increased the ROM and the disc inner pressure in adjacent segment, it is still closed to normal range. This device offers a design to limit the abnormal range of motion and to enhance load sharing. It can resume the mechanism of normal stress conduction, therefore can avoid or reduce the degree of adjacent segment disc degeneration. The BioFlex system may also have a role to reverse the disc degeneration of adjacent segment that has happend preoperation, but the protect effect is limited. It can't adjust the direction of adjacent segment degeneration and can just offering a proper mechanical condition. By the way, We suggest that the patient has no obvious symptoms of adjacent segment disc degeneration can treated with preventive surgery by using semi-rigid fixation system,also this suggestion has yet to be improved by further study.
|
PDF Full Text Request