| Objective: Vertebroplasty is an effective surgical method for the treatment of osteoporotic vertebral compression fractures,which can quickly relieve pain and partially repair the height of fractures of the vertebral body.However,there are some postoperative complications of vertebroplasty,such as bone cement leakage,bone cement embolism,pulmonary embolism,hematoma,spinal cord compression,radiculopathy,infection and adjacent vertebral fracture and so on.At present,whether vertebroplasty the increased risk of adjacent vertebral fractures,domestic and foreign scholars have been controversial.Some reports indicate that vertebralplasty for the recovery of vertebral stiffness and bardness changes the biomechanics of spinal motion segment,so that the adjacent vertebral body in a disadvantageous position,more prone to fracture;some scholars believe that postoperative fracture Is the natural process of osteoporosis,has nothing to do with vertebroplasty.The aim of this study was to investigate whether vertebroplasty induced adjacent vertebral fractures by analyzing biomechanical experiments using preservative specimens and analyzing their causes.Methods: Four the same age,race,the average age of 60 years of male's embalmed specimens are selected,each body to take T9-L5 vertebral body,all vertebrae were positive lateral X-ray film to exclude congenital malformations,fractures,tumors.Thoracic and lumbar vertebrae specimens were divided into three groups: T9-T11,T12-L2 and L3-L5.The soft tissue of the muscles on both sides was excised,and the intervertebral disc and ligament were dissected at the two ends.12 spine segments were divided into two groups of A and B groups.A group of 6 spinal segments(T9-T11,T12-L2,L3-L5 2),group B 6 spinal segments(the same as group A)In A group,experimental vertebral compression fractures were created at middlevertebraes(some cortical bone and cancellous bone were chiseled away through the anterior vertebral body,which account for half of vertebral body depth and a third of the vertebral body height.Then compression bending was applied to create the wedge fracture),and the all the fractures of the vertebral body was injected the same amout(3ml)of bone cement which was offered by the same manufacturer;Group B did not do any treatment.After the injection of bone cement in group A,the individual spinal segments of group A and B were placed in molds respectively.The vertical loading was carried out at a loading rate of 5 mm / min using a biomechanical testing machine.When the vertical load reached the maximum Start loading down to stop loading,record the maximum vertical load at the moment of the spinal segment,and derive the stiffness of the vertebral segment by the displacement-stress curve peak.The maximum vertical load,stiffness,the location of the vertebral body adjacent to the fracture and the circumstance of bone cement intervertebral disc leakage in A group were recorded and compared with the statistical analysis.Results: The maximum vertical load of group A was(3048 ± 403)N,and the maximum vertical load of group B was(3586 ± 418)N,the difference between the two groups was statistically significant(t =-2.267 P=0.047).After injection of bone cement,the maximum vertical load of group A was about 15% lower than that of group B,which suggested that the maximal vertical load of group A was decreased after vertebroplasty,and vertebroplasty increased the risk of adjacent vertebral fractures.The stiffness of group A was(514 ± 51)N / mm,and the average stiffness of group B was(528 ± 38)N / mm.There was no significant difference between the two groups(t=-0.542 P=0.60).In the A group,new fractures following VP occurred at T9 in 2 specimens,T12 in 2,and L3 in2.All new fractures occurred in the superior vertebrae in the A group.In the B group,it occurred at T9 in 1 specimen,T10 in 1,T12 in 1,L1 in 1,and L3 in 2.Only one bone cement leakage of intervertebral disc was found in group A,which located between T10 and T11.Conclusions: Our results show that the maximum vertical load of the spine segment in the cement group is lower than that of the untreated group,and the site of the recurrent fracture is mainly occurred in the upper adjacent vertebral body.Therefore,we believe that the failure strength of spinal segments can be decreased by vertebroplasty,which will increase the risk of adjacent vertebral body fracture,especially the superior vertebrae... |
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