椎间融合器植入颈椎即刻稳定性的生物力学评价

Biomechanical evaluation on primary stability of cervical spine instrumented with interbody fusion cage

目的 :①探讨不同直径螺纹状椎间融合器对颈椎强度、刚度和稳定性的影响。②椎间融合器植入法改进 ,最佳融合器直径的选择 ,为临床手术提供理论依据。方法 :成人新鲜颈椎标本 12具 ,实验应力分析 ,对颈椎的稳定性与不同程度切除终板、植入不同直径融合器后的生物力学关系进行系统分析和比较。结果 :①椎间融合器植入后 ,颈椎强度增加 2 2 % ,椎体应变下降 15 % ,而刚度增加 43 % ,位移减小 2 0 % ,与植入前颈椎具有非常显著性差异 (P <0 0 1) ,颈椎稳定性得到增强。②在改进植入法中 ,选用直径 11～ 12mm融合器 ,其覆盖椎体终板超过 3 0 %以上 ,接触面积达 65 %以上 ,颈椎最稳定 ,其椎体应变、融合器位移及沉降率最小。结论 :颈椎前路螺纹状椎间融合器植入是一种有效的初始稳定手段 ;改进植入法应选用直径 11～ 12mm之椎间融合器。

Objective:1.To explore the influence on strength,stiffness and stability of cervical spine instrumented with different diameter thread interbody fusion cage.2.To provide rationale of modified surgical technique with thread interbody fusion cage and select the best diameter cage.Method:Twelve fresh human cervical spine specimens were used in this study.Cervical spines were instrumented with different diameter cages after different volume of endplate being removed.Experimental stress analysis was applied to analyze and compare the stability and biomechanical relation of the cervical spines.Result:1.The strength of instrumented cervical spine increased 22%,the flexibility decreased 15%,the stiffness increased 43%,and the migration decreased 20%.It showed a significant difference compared with the noninstrumented ( P<0.01 ).2.Modified insertion approach using 11～12mm diameter cage attained the best stability and the least subsidence rate because the cage covered more than 30% of hard endplate and more than 65% contact area between cage and grafting bed.Conclusion:1.The cervical spine instrumented with interbody fusion cage can get primary stability.2.Eleven to twelve mm diameter cage is suggested to use in modified approach of the cervical interbody fusion.