颈前路蝶型钢板系统的生物力学评价

Cervical spine butterfly plate for unstable cervical spine: A biomechanical evaluation in vitro

目的 :对颈前路蝶型钢板 (CSBP)进行生物力学评价。方法 :14具颈椎标本随机分为A、B两组 ,测量两组正常颈椎在 2 0Nm载荷下的运动范围 (ROM ) ;将两组颈椎制作成三柱不稳定模型 ,分别以CSBP和Orion钢板固定 ,测量两组颈椎的ROM。将CSBP固定于椎体模型上 ,施加 10 0N循环压缩载荷 (1Hz) ,观察CSBP松动、断裂情况。对疲劳测试条件下钢板的受力情况进行有限元分析。结果 :CSBP和Orion钢板均能显著降低颈椎各方向上的ROM (P <0 0 5 ) ,在前屈、后伸方向最大。应用CSBP钢板 ,前屈、后伸ROM较正常颈椎分别降低 6 6 %、6 0 % ;应用Orion钢板分别降低 72 %、71% ;两种钢板在重建颈椎稳定程度上无明显差异 (P >0 0 5 )。CSBP抵抗载荷次数达10 5次 ,于钢板钉孔外侧缘出现裂缝并断裂。有限元分析提示钢板钉孔周围是应力集中处。结论 :CSBP的生物力学稳定作用较好 。

Objective:〖WTBZ〗To evaluate the biomechanical stability of a cervical spine butterfly plate(CSBP) for unstable cervical spine.〖WTHZ〗Method:〖WTBZ〗Fourteen cervical spine specimens (C3～T1) were divided into two groups:A and B. All intact specimens were subjected to nondestructive testing in 6 loading modalities on a universal testing machine.A cadaveric model of complete C5～C6 instability was produced in both groups.Specimens in group A were stabilized with CSBPs,and group B with Orion plates.The nondestructive testing was repeated to determine structural stability.The 2 models were fatigued with 106 cycles(1Hz) of compression bending(100N) testing at a rate of loading 10.The location of fissure or rupture was observed.Stress in plate was analyzed by finite element method (FEM).〖WTHZ〗Result:〖WTBZ〗The injured spines stabilized with implants in both groups were significantly more stable than the intact specimens in all modes of testing 05).Stability of injured spines was increased most in flexionextension,66% in flexion and 60% in extension by CSBP while 72% in flexion and 71% in extension by Orion plate.The two constructs provided similar stability in 6 loading modalities 005).Both of the two tested CSBPs appeared fissures external to screw holes successively and ruptured at the level of screw hole before testing completed.It seemed that more stress was at the location circumferential to screw holes in the view of FEM.〖WTHZ〗Conclusion:〖WTBZ〗This study shows that CSBP provides biomechanical stability for unstable cervical spine.The area circumferential to screw holes in CSBP is weak with more stress.〖WTHZ〗Author′s address Medical Biomechanics Laboratory of PLA,The First Military Medical University,Guangzhou,Guangdong,510515