颈椎前路融合术中植骨块的高度对邻近节段关节突压力及椎间位移的影响

目的　探讨颈椎前路融合术中植骨块的高度对邻近节段关节突压力及活动度的影响,为临床上选择适宜的植骨高度提供依据。 方法 采用8例新鲜成人尸体颈椎标本，对完整状态，C5/6节段椎间隙减压术后（100%M、120%M、140%M、160%M)5组，于BOSE机加载下行三维运动，并测量颈C4/5，C6/7关节突压力值及C4/5，C6/7三维运动范围；最后将结果行多重比较分析。 结果 中立位状态下，关节突压力值各组无显著差异，P>0.05；后伸状态下，关节突压力值增加最大，各组有显著差异，P<0.05，但植骨高度中以120%M时关节突压力值增加最小，左右侧屈及左右旋转时，各组植骨高度之间差异均有显著意义，P<0.05，但植高度为120%M时，关节突压力值增加最小。在前屈后伸、左右侧屈下：120%M与完整状态相比，上下临近节段活动度差异无显著差异，P>0.05；与其他各组差异均有显著差异，P<0.05；2）在左右旋转时各组差异无显著差异，P>0.05。 结论　下颈椎单间隙减压植骨，撑开植骨理想高度为平均高度的120%。

Impact of graft height on zygapophyseal joint pressure and range of motion adjacent to segment following cervical anterior fusion

Objective　To discuss impact of graft height on zygapophyseal joint pressure and range of motion of adjacent segments following the cervical anterior fusion and to guide the choice of optimal graft height in clinic.　Methods　Eight fresh-frozen human cadaveric cervical spines were used in this series, specimens were tested in five conditions, normal(specimens with intact discs)and different graft height(120％,140％,160％of mean height) after Smith-Robinson discectomy between the fifth and sixth cervical vertebrae.Each specimens were subjected to flexion-extension. Lateral bending and axial rotation in material test system(BOSE ELECTROFORCE) were adopted to measure zygapophyseal joint pressure and rotation of the fourth to fifth segments and the sixth to seventh segments. Finally, The data for each state was used to determine the statistical significance of differences.　Results　The height of bone graft had little effect on the zygapophysial joints pressure values in neutral position with no statistical significance noted among each groups(P>0.05); The zygapophysial joints pressure value was the highest increase in extension position,but 120%M increased minimum of zygapophysial joints pressure value, and statistical significance were noted among each groups（P<0.05); the zygapophysial joints pressure value increased in various degrees under flexion and rotation positions, and statistical significance were noted among each groups（P<0.05）; but 120%M increased minimum of zygapophysial joints pressure value.The range of motion at the upper and lower adjacent segments were not significantly changed between 120%M and complete condition (P>0.05), and statistical significance were noted in others groups（P<0.05）;The range of motion at the upper and lower adjacent segment were not significantly changed among each groups (P>0.05).　Conclusion　The appropriate graft height after single discectomy may be 120％mean height.