跟随载荷对人颈椎的生物力学性能影响

Effects of follower load on biomechanical properties of human cervical spine

[目的]探索跟随载荷对多节段颈椎弯矩-转角参数及椎间盘内压的影响。[方法]用六轴机器人完成15具新鲜冷冻人颈椎标本(C_(3-7))的前屈、后伸运动,目标纯扭矩为2.0 Nm,分为无压缩载荷组和跟随载荷组。记录ROM与IDP,中性区参数由基于弯矩-转角曲线的双"S"拟合函数计算获得。[结果]跟随载荷的应用显著减少C_(3/7)的ROM,增加中性区的刚度,但对中性区的宽度和屈曲与后伸方向的弹性区刚度没有影响。标本在中立位加载跟随载荷时C_(3/4)与C_(6/7)椎间隙的IDP值均在应用跟随载荷后显著增加,且与跟随载荷值显著相关。跟随载荷显著增加前屈运动过程中C_(3/4)和C_(6/7)IDP的增加幅度,降低后伸运动过程中C_(3/4)IDP的增加幅度及C_(6/7)的IDP值。[结论]跟随载荷的应用能增加中性区的刚度,减少标本的ROM,增加颈椎的稳定性。

[Objective] To explore effect of follower load on multl-segment cervical spine moment-rotation parameters and intradiseal pressure. [Methods] Fifteen fresh-frozen human （C3-7） cervical specimens were biomechanieally tested in a 6-DOF system robot tbr a pure moment target of 2.0 Nm in flexion and extension, which were divided into two groups, the no compres- sion group and the follower load group. Range of motion and intradiscal pressure were recorded. Neutral zone parameters were calculated based on the moment-rotation eurve using a double sigmoidal fimction. [Results] Application of follower load signifi- cantly decreased C3-7 ROM, increased neutral zone stiffness, but resulted in no change in the neulral zone width or elastic zone stiffness. C3/4 and C6/7 IDP measured in the neutral position was significantly increased as follower load applied, with a correla- tion between them. The follower load increased the IDP change of C3/4 and C6, during flexion, whereas decreased the IDP change of C3/4 and C6/7, during extension. [Conclusion] Application of follower load significantly deereases ROM of the cervical speeimen, accompanied with increased neutral zone stiffness and increased the stability of specimen.