The Biomechanical Influence Of Middle Segment After Cross Section Of Thoracic And Lumbar Vertebral Reinforcement

Background: vertebroplasty, which is the percutaneous injection of bone cement intovertebral bodies has recently been used to treat painful osteoporotic compressionfractures. Early clinical results have been encouraging,but longer-term studies havesuggested a possible accelerated failure rate in the adjacent,non-augmented level.Objective: This study aimed to investigate the biomechanical influenee of cross-sectionof thoracic and lumbar vertebral vertebroplasty on the middle non-augmented vertebralbody and its cranial and caudal disc.It through the different amounts of PMMA bonecement inter-segment thoracic and lumbar spine reinforcement in vitro we can bemeasured the augumentation segment, the middle vertebral body, and its upper andlower disc mechanical changes of Pre-and post-PVP.Methods:Six old human specimens (with T8-L4) were soaked in the formalin, All ofthe specimens should be X~rayed to exclude congenital deformit,fractures,tumors andother abnormalities. the bone mineral density (BMD) determined on each vertebrauseing dual-energy X-ray absorptiometry (DEXA) and exclude non-osteoporoticvertebral bodies. Osteoporosis was defined according to the World Health Organisation(WHO) as a BMD of more than2.5standard deviations below the mean of a younghealthy reference population of the same gender (‘T-score’). All of the specimens isdivided into three segments according to A: T8~T10, B: T11~L1, C: L2~L4, a totalof18function spine unit (FSUs), including Attached three vertebral bodies and twodiscs, and keep the integrity of posterior vertebral ligament structure.A components A1,A2; B components B1, B2; C components C1, C2. Each FSU were injected withPMMA bone cement in cranial and caudal vertebral bodies with the middle vertebralbody untreatment. The material were filled3ml,4ml,5ml in low dose group and5ml,6ml,7ml in medium dose group. All of the FSUs were conducted biomechanical testBefore and after PVP. Data processing:The Spss17.0paired t test analysis. Results:1. No significant difference in the whole stiffness of FSUs and the stiffness ofmiddle Vertebral body were found pre–and post augmentation in low dose group(p>0.05). the strain of the cranial and caudal vertebral disc of the middle vertebral bodypre–and post augmentation showed no significant difference in low dose group.2. No significant difference in the whole stiffness of FSUs and the middle vertebralwere found pre–and post augmentation in medium dose group (p>0.05), The strainupper and lower vertebral disc before and after PVP were significantly different(p<0.01).Conclusions:1.When the cranial and caudal vertebral bodies of all FSUs were bothaugmented with small dose of PMMA bone cement，the stiffness of the whole FSU andthe stiffness of middle Vertebral body were not affeeted, The strain of upper and lowervertebral disc were not affeeted also.2. When the cranial and caudal vertebral bodies of all FSUs were both augmented withmoderate dose of PMMA bone cement，the stiffness of the whole FSUs and thestiffness of middle vertebral body were not affeeted, But the strain of upper and lowervertebral disc were significant influence. it can speed up the adjacent discdegeneration.3. Results suggest that clinical use of bone cement with low dose and the middleVertebral body does not prophylactic vertebroplasty.