The Biomechanical Influence Of Vertebroplasty On The Adjacent Vertebral Body And Intervertebral Disc

Objective:To investigate the biomechanical influence of vertebroplasty on the adjacent vertebral body and intervertebral disc.Samples:Specimens were collected from eight cadavers with T10-L1 function spine unit (FSU),thereinto 6 male and 2 female,including 32 vertebrals and 24 discs.The age range from 65-79 years,70.6 average.The X-ray show that the specimens have no congenital abnormality and surgery before death.Methods:Eight cadaver specimens were applied to make 8 T10-L1 function spine unit (FSU).All the FSU were underwent flexion-axial loading to result in T11 and L1 vertebral body fracture.Following reduction,the fractured vertebral body were strengthened by the method of vertetroplasty,with using Polymethylmethacrylate (PMMA).And with the increase of PMMA's quantity,all the FSU were conducted biomechanical test before fracture and after vertebroplasty.Results:1.When the stiffness of T11 vertebral body was enhanced by 19%,without any affection on the stiffness and strength of the whole FSU,the stiffness of upper vertebral body was decreased by 6.7%(P＞0.05),the height of upper disc was decreased evidently(P＜0.01). 2.Even when the stiffness of T11 vertebral body was 5 to 6 times augmented,the stiffness and strength of the whole FSU were still not affected(P＞0.05),the stiffness of upper vertebral body was decreased by 24.4%(P＜0.01),the height of upper disc was decreased very evidently(P＜0.01).3.When the stiffness of T11 and L1 vertebral bodies were both augmented,the stiffness and strength of the whole FSU were still not affected(P＞0.05),the stiffness of T10 vertebral body was decreased by 24.4%(P＜0.01),and the stiffness of T12 vertebral body was decreased by 32.2%(P＜0.01),the height of upper disc was decreased very evidently(P＜0.01).Conclusions:Following vertebroplasty,the enhanced vertebral body don't result in great stress concentration in the adjacent vertebral body,it means that vertebroplasty technique is safe in the respect of biomechanics.While some extend of stress concentration are present in the adjacent dise,which will possibly accelerate disc degeneration process.