可调式中空钛合金人工椎体的生物力学评价

Biomechanical evaluation of adjustable hollow titanium artificial vertebral body

目的 测试并评价可调式中空钛合金人工椎体的生物力学性能。方法 2 7具小牛胸腰椎标本随机分为对照组 (IS)、髂骨植骨组 (IBG)及人工椎体组 (AVB) 3组 ,测试屈曲、伸展、侧屈及扭转状态下的载荷 应变、载荷 位移关系变化以及最大载荷时的应力强度及刚度。IBG组、AVB组分别附加前路钢板及后路椎弓根螺钉进行第 2次、第 3次测试 ,各组间进行比较 ,并进行统计学处理。结果 髂骨植骨组不同状态下应变及位移均大于原始标本 ,人工椎体组小于原始标本 ,且差异具显著性 (P <0 .0 5 ) ;附加内固定后应变及位移均较不附加内固定者减小 (P <0 .0 5 ) ,且人工椎体组附加内固定后分别小于髂骨植骨组 (P <0 .0 5 )。人工椎体附加或不附加内固定时的应力强度及轴向刚度均大于或接近原始标本 ,而单纯髂骨植骨组伸展及侧屈状态下 ,以及附加前路或后路固定后的侧屈状态下的应力强度低于原始标本 ;轴向压缩刚度亦小于原始标本 ,附加前路钢板后有所提高 ,但只有附加后路椎弓根螺钉后才与原始标本相当。人工椎体组的扭转强度大于髂骨组 ,扭转刚度与原始标本接近。而髂骨植骨组即使附加内固定后的扭转刚度亦远小于原始标本。结论 单纯人工椎体替代基本可满足生物力学性能要求 ,附加前路或后路固定后 ,可满足包括扭转性?

Objective To evaluate the biomechanics of adjustable hollow titanium artificial vertebral body.Methods Twenty-seven thorathic-lumbar spine specimens were randomly divided into three groups: control group (intact specimen,IS),iliac bone graft group (IBG) and artificial vertebral body group (AVB).The load-strain,load-displacement,strength and stiffness in flexion,extension,lateral bending and torsion were tested respectively.After the first measurement,the IBG group and AVB group were supplemented with anterior plate and pedicle screw fixation respectively and measured for the second and third times.The results were compared statistically among groups.Results The strain and displacement of IBG group was more than control group,but was less in AVB group than in control group ( P <0.05).The strain and displacement was decreased after supplemented with anterior plate or pedicle screw fixation ( P <0.05).Strength and stiffness in AVB group with or without additional fixation was more than that in IBG group,while in IBG group,the strength and stiffness in extension was less than in control group.In lateral bending,although supplemented with AP or PS,the strengh and stiffness was less than control group.The torsion stiffness in AVB group was more than that in IBG group,but similar to that in the control group.But in IBG group the torsion stiffness was far less than that in control group although supplemented with anterior plate or pedicle screw fixation.Conclusion AVB replacement can provide basic biomechanical stability of spine.After supplemented with fixation,it can provide all the stability including torsion stiffness.But biomechanical stability in IBG group cannot be obtained; the supplemented fixation is essential,even though the torsion stiffness can't obtained satisfactorily.