| Objective: Osteoporotic vertebral compressive fractures(OVCFs)is the main indication of percutaneous kyphoplasty.But the percutaneous kyphoplasty operation is possible increase the risk of adjacent vertebra fractures,this is possible attributed to the natural course of vertebral osteoporosis or the stress concentration between the strenghten vertebra and its adjacent vertebrae.Clinical examination of bone mineral density is usually use the dual energy bone density detector,measuring the bone mineral density value of lumbar two to four.But the majority of OVCFs is happen to the thoracolumbar segment,and the bone mineral density values of lumbar two to four is hardly to represent the bone mineral values of the strenghten vertebra and its adjacent vertebra.This research assumed to predict the the relationship of the stress matches between the injured vertebra and adjacent vertebrae,and then predict the fracture risk of adjacent vertebra.The advanced intervention strategies could be done if the fracture risk is too high,the extensive orthosis protection or preventive bone cement infusion to decrease “stress gap”,and then prevent the adjacent vertebra fractures.Methods: Collect all of the cases who was performed with percutaneous kyphoplasty after osteoporotic vertebral compressive fractures and hospitalized in the spinal surgery department of the Second Affiliated Hospital of Dalian Medical University from Jun.1st,2004 to Dec.31 st,2015.167 cases was found in total.Eliminate the thirty-eight cases who was followed up less than half a year,the rest of 129 cases can be divided into 22 males and 107 females,20 cases was found with fracture of other vertebrae,incidence rate of fracture is 10.2%.Eliminate the three cases for injured adjacent vertebra fracture and jumping vertebra fracture,the remaining 17 cases can be divided into 4 male cases and 13 female cases,minimal age is 54 years old,maximal age is 91 years old,mean age is 76.94±9.93 years old.Retrospective study the the X-ray and computed tomography(CT)of postoperative reexamination of the 17 patients,measuring the vertebral height and mean CT value of operated vertebra and its adjacent vertebra in the X-ray and CT via PACS system.And measuring the cross-sectional area of vertebra in the “narrowest” section via picture analysis software.We called the product of the vertebral height and cross-sectional area with effective load bearing volume,and we called the product of the product of the mean CT value and effective load bearing volume with total CT value.This research use CT1,CT2 and CT3 represent the mean CT value of operated vertebra,the adjacent fractured vertebra and the adjacent vertebra which is not fractured.We use the total CT1,total CT2 and total CT3 represent the total CT value of operated vertebra,the adjacent fractured vertebra and the adjacent vertebra which is not fractured.Compare and research the abosolute value and relative value(CT1/CT2,CT1/CT3,total CT1/total CT2,total CT1/total CT3)of the mean CT value and total CT value of the operated vertebra,the adjacent fractured vertebra and the adjacent vertebra which is not fractured.We analysis the data with the method of T-test of paired sample mean if their D-value is satisfied with normality,and with the method of Wilcoxon signal rank sum test if their D-value is unsatisfied with normality.Analysis the four group of data and compare its diversity.Results: All of the seventeen patients are followed up at least half a year,the shortest,longest and average time of followed up is 6.5,24.0 and 15.03±5.77 months respectively.1.Compare the mean CT value of fractured vertebra(CT2)with that of which is not fractured(CT3).analyzed the data with paired samples T-test,statistics t=-2.644,v=16,p=0.018,according to the statistical criterion ?=0.05,so,the difference between the two groups of data is makes a lot of statistical sense.2.Compare the mean CT value ratio of operated vertebra and adjacent fractured vertebra(CT1/CT2)with that of operated vertebra and adjacent vertebra which is not fractured(CT1/CT3).Analyzed the data with the Wilcoxon signed rank test,statistics Z=-1.681,P=0.093,according to the statistical criterion ?=0.05,so,the differencebetween the two groups of data is makes no statistical sense.3.Compare the total CT value of fractured vertebra(total CT2)with that of which is not fractured(total CT3).Analyzed the data with the Wilcoxon signed rank test,statistics Z=-3.385,P=0.001,according to the statistical criterion ?=0.05,the difference between the two groups of data is makes a lot of statistical sense.4.Compare the total CT value ratio of operated vertebra and adjacent fractured vertebra(total CT1/total CT2)with that of operated vertebra and adjacent vertebra which is not fractured(total CT1/total CT3).Analyzed the data with paired samples T-test,statistics t=4.497,v=16,p<0.001,according to the statistical criterion ?=0.05,the difference between the two groups of data is makes a lot of statistical sense.Conclusion: The adjacent vertebra fracture rate is high after the PKP for OVCFs,the result of this research is about 10.2%.1.The risk of the adjacent vertebral fracture after PKP is predictable via the mean CT value and the total CT value of the operated vertebra,the adjacent fractured vertebra and the adjacent vertebra which is not fractured.2.The low mean CT value or total CT value of adjacent vertebra and the high total CT value ratio between the operated vertebra and the adjacent vertebra are the risk factors of adjacent vertebra susceptible to fracture after PKP operation.The limitation of this research include: sample capacity is not enough;retrospective study the single fractured segment and without prospective trials;lack of the infusion volume of bone cement of injured vertebra,and lack of the relationship of the infusion volume,CT value and the fracture risk of adjacent vertebra.We research the single fractured segment,and lack of multiple or jumping segment cases,and therefore,the study result could be constricted in the use of these cases.Furthermore,this research is not include the ages,gender,disc degeneration,intervertebral disc leakage,the type of bone cement distribution,life habits,working ways,local biomechanical environment which is possible influence the result. |
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