轴向加载时腰椎间隙高度变化对腰椎负荷分布的影响

Axial load distribution of lumbar spine response to intervertebral space height alteration

目的探讨椎间隙高度变化对腰椎负荷分布影响的规律。方法取7具急性脑死亡青壮年腰3～腰5节段新鲜标本，切除腰4／5椎间盘，将椎体间压力传感器和刚性金属垫片置入椎间隙，将关节突关节压力传感器置入左侧关节突关节内，分6种状态（高度5、高度4、高度3、高度2、高度1和高度0）进行加载（轴向1000N及2000N），测量经过椎间隙及关节突关节内的压力负荷。用SPSS10．0统计软件包进行统计分析。结果经过椎间隙内的压力随椎间隙高度下降而减少，经过关节突关节内的压力随椎间隙高度下降而增高，且这种变化在高度下降的初始阶段最明显。结论腰椎负荷分布变化与腰椎高度变化呈非线形关系，只有将椎间隙高度恢复正常才能避免腰椎负荷的异常分布。

Objective To explore the relationship between the load distribution of lumbar spine and the intervertebral space height. Methods Seven lumbar spine segments （L3-L5） from young people who died from accidents were used to test in vitro. In order to get the pressures in intervertebral space and facet joint of L4/5, one transducer was placed in the intervertebral space and the other was in the left facet joint of the same segment. Five rigid washers （the height of each washer was 1.4 mm） were placed on the transducer in intervertebral space to control and regulate the intervertebral space height. The pressure forces were measured during different axial loading （1000N and 2000N）. One washer was remored each time until no washer to alter the interverebral space height and each time the pressure forces were measured at same way. The data were analyzed by SPSS for windows 10.0. Results Following with the interverebral space height decreasing at each loading condition, pressures decreased in intervertebral space and increased in facet joints. But the tendency of pressure decreasing was slowed down during the height descending. Comparing with which at initial height, there was a statistical significance pressure changing in intervertebral spaces or facet joints when one washer was moved away in each loading condition （P〈0.05）. Conclusion The axial load distribution of lumbar spine changes in a non-linearity manner response to intervertebral space height alteration. Only restoration and maintaining the intervertebral space at normal height can avoid abnormal load distribution.