寰枢椎失稳不同缆材内固定系统的生物力学比较研究

Biomechanical performance of different wires and cable fixation devices in posterior instrumentation for atlantoaxial instability

目的比较寰枢椎后路固定技术中几种不同线型固定材料的生物力学性能;测定不同锁紧力量和操作方法对固定效果的影响。方法 6例新鲜寰枢椎复合体标本(CO-C3)。在改良WD-5力学试验机上,分别测量正常寰枢椎复合体(N组)、寰枢椎不稳(M组)以及不稳时行寰枢椎Brooks法双向钛缆固定(A组)、Atlas钛缆固定(B组)、Songer钛缆固定(C组)、钢丝固定(D组)的寰枢椎复合体在屈、伸、侧屈、旋转等情况下的应变、位移、强度、刚度、扭矩、扭角等的大小。结果双向锁定式钛缆A组在相同锁紧拉力条件下固定强度为最高,应变、载荷位移最小,同各内固定组与正常组(N组)相比有显著性差异(P<0.05)。双侧同时锁定的效果好于单侧轮流锁定(P<0.05),经休息后再次固定的效果好于单纯双侧同时锁定的效果(P<0.05)。结论对于钛缆内固定系统来讲,随着锁紧力量的加大,钛缆锁定的效果也更加理想。双向锁定钛缆因为锁紧方式的改变相同锁紧力量达到了比钢丝和进口钛缆更好的固定效果。Brooks法钛缆固定时,双侧同时锁定后经休息再次锁定的效果最好。

Objective To compare the biomechanical performances of different wires and cable fixation devices in posterior instrumentation for atlantoaxial instability, and test the effect of different fixation strengths and fixation approaches on the surgical outcomes. Methods Six specimens of the atlantoaxial complex （C0-C3） were used to establish models of the normal complex, unstable complex （type II odontoid fracture） and fixed complex. On the wd-5 mechanical testing machine, the parameters including the strength and rigidity of anti-rotation, change and strength of stress, and stability were measured for the normal complex, atlantoaxial instability complex, the new type titanium cable fixation system, Atlas titanium cable, Songer titanium cable, and stainless wire. Results The strength and rigidity of anti-rotation, change and strength of stress, stability of flexion, extension and lateral bending of the unstable atlantoaxial complex fixed by the new double locking titanium cable fixation system were superior to those of the Songer or Atlas titanium cable （P0.05） and medical stainless wire （P0.05）. Simultaneous cable fastening on both sides resulted in better fixation effect than successive cable fastening （P0.05）. Better fixation effect was achieved by fastening the specimen following a rest （P0.05）. Conclusions The fixation effects can be enhanced by increased fastening strengths. The new type double locking titanium cable fixation system has better biomechanical performance than the conventional Songer and Atlas titanium cables. Fastening the unstable specimens after a rest following simultaneous fastening of the specimen on both sides produces better fixation effect.