| Part Ⅰ Study on Manufacture and Mechanics Experiments of Three Dimensional Bone Grafting DeviceBackground:In the operation of thoracolumbar burst fracture,satisfactory open reduction of the fractured vertebra by the Pedicle screw system can result in significant bony deficiency which need to be filled.Existing vertebral bone graft tools can’t accurately fill the bone graft material to the vertebral bone defect area;Besides that,the central and posterior collapse area of the end plate could not be restored by traditional methods too.Seeing that extent and intensity of bone healing depends on the degree of bone graft and bone volume,a more reliable solution should be proposed.In this study we designed and made a Three Dimensional Bone Grafting Device which can free pass the pedicle to the vertebral body;meanwhile with the similar structure and working principle of the Manual screw jack,this device can provide sufficient thrust from different directions.Objective:To outline a new device for vertebral bone graft and to analyze mechanism properties(anti-extrusion capacity,ability to resist stretch),and to provide the theoretical basis for its clinical application.Methods:Select 10 samples for extrusion test recording the data and curves of the pressure change with stroke,and then continue to increase the load value to the Maximum Loading.As to the study on tensile failure test,using the static tension and pressure tester to analyze the ability to resist stretch of the important part of grafting device:thread rod and the thread sleeve,obtain the maximum tensile force before article being broken and find dangerous cross sectionResults:In the Extrusion and failure test,ION and 25N were taken as pre-tightening force,respectively.The pressure-displacement data of every sample were measured and the Trend of pressure displacement curve showed no significant difference among each sample.Under certain pre-tightening force,the pressure of device rises rapidly at the beginning of the filling phase(initial two circle);then the pressure changes slowly and tends to be stable.The average Maximum extrusion force of the devices was 121.5±6N(range,113-128N)and the Maximum load resistance was 150±3N(range,142-165N).In the Tensile failure test,the tensile displacement curve showed the same trend.The maximum stretch resistance was 1.75+0.09KN(range,1.73-1.82KN).Fracture parts distributed two ends of the screw rod while all the thread sleeves were still intact,which means the dangerous cross section is not in the set surface position between thread sleeve and thread rodConclusion:Three Dimensional Bone Grafting Device can generate sufficient thrust,withstand considerable resistance,not easy to be broken by The manual maximum torque and have excellent process stability.Meanwhile the precise design tool facilitates surgeons to reduce vertebral fracture well and make effective bone graftsPart Ⅱ Imaging and clinical analysis of the application of three-dimensional bone graft for reconstruction of thoracolumbar burst fracture vertebral heightBackground:Pedicle screw fixation combined with transpedicular intracorporeal grafting is common in the treatment of thoracolumbar vertebral burst fractures.The amount and extent of intracorporeal grafting determines the extent and intensity of healing.Bone defect in the fractured vertebra will be made after reduction,Existing Bone graft is prone to formation of cavities,as the "eggshell like" vertebral body.The bad reduction of the endplate is easy to accelerate the degeneration of the intervertebral disc,causing chronic low back pain.Therefore,it is necessary to improve the reduction of the endplate and intracorporeal grafting,to improve the curative effect of thoracolumbar vertebral burst fracture.Objective:To evaluate the early imaging effect of transpedicular bone grafting by three-dimensional bone grafting instrument in the treatment of thoracolumbar fracturesMethods:Fifty-two patients suffering from Denis type B thoracolumbar burst fractures from 2010 to 2014 were divided randomly into two groups,group A and group B,according to different method of bone grafting.Patients in group A were treated with transpedicular bone grafting by three-dimensional bone grafting instrument,while by bone grafting funnel in group B.X-ray and CT were taken a week after operation.Radiographic measurement included anterior height of injured vertebra,anterior height of normal vertebra,middle height between endplates of injured vertebra and middle height between endplates of normal vertebra on X-ray and CT.AHVR(ratio between anterior height of injured vertebra and normal vertebra),MHER(ratio between middle height between endplates of injured vertebra and normal vertebra)and volume of vertebra bone defect was also calculated.Results:Preoperative anterior height of injured vertebra of group A and group B was 1.59±0.20cm and 1.61±0.18cm respectively,while postoperative anterior height of injured vertebra of group A and group B was 2.81±0.19cm and 2.77±0.17cm.Anterior height of normal vertebra of group A and group B was 2.96±0.32cm and 2.91±0.36cm respectively.Postoperative middle height between endplates of injured vertebra of group A and group B was 2.34±0.22cm and 1.85±0.26cm respectively,while middle height between endplates of normal vertebra was 2.42±0.18cm and 2.48±0.23cm respectively(P>0.05).AHVR was(95.3±3.6)%in group A and(91.8±4.2)%in group B.MHER was(93.6±5.8)%in group A and(72.5±6.4)%in group B(P<0.05)Volume of vertebra bone defect was 0.75±0.16cm3 and 2.51±0.33cm3 respectively(P<0.05)Conclusions:Transpedicular grafting with three-dimensional grafting device is effective to restore the collapsed endplate,achieve excellent grafting,reduce the volumn of defect area,which suggests three-dimensional grafting device as an outstanding instrument to treat throacolumbar burst fracturePart Ⅲ Clinical and imaging studies of the temporary retention one side of balloon kyphoplasty in the treatment of vertebral compression fracturesBackground:Percutaneous vertebroplasty(PVP)is a minimally invasive treatment for compression fracture of thoracolumbar vertebral body with osteoporosis percutaneous kyphoplasty(PKP)with expanded balloon could be used to restore the height of injured vertebral body and reduce the risk of bone cement(Methylmethacrylate)leakage.The normal process during balloon kyphoplasty is the expansion of balloon followed by the injection of the Methylmethacrylate,in which the height loss of compressed vertebral body will happen after the balloon removal and the operation efficiency will decreaseObjective:To observe the changes of the vertebral body height when Methylmethacrylate was injected into the compressed vertebral body in one side and the balloon was reserved in another side at the same time during balloon kyphoplasty We hope the reserved balloon can help to maintain the height of the injured vertebral body after initial distractionMethod:A total of 69 cases including compression fracture of vertebral body with osteoporosis were received vertebroplasty or balloon kyphoplasty randomly from January 2011 to December 2013.The puncture technique was modified during the operation,which enabled the tip of the needle close to the anterior 1/3 of vertebral body from lateral view and not exceed the inner wall of the pedicle from anteroposternor review under X-ray.The balloon was used to expand the vertebral body bilaterally and then to keep the balloon inside the injured vertebral body in one side.The height of vertebral body was measured at different time point during the whole operation and the adjacent vertebral mean height was measured as base control(H).The height of vertebral body after postural reduction(HO)and after balloon expand(Hl)was recorded as well as that after the temporary pressure release of the balloon(H2).When the balloon was kept in one side of vertebral body,the Methylmethacrylate was injected into the body through another side.After the solidification of Methylmethacrylate,the balloon was taken out followed by the Methylmethacrylate injection at the same side.The height of vertebral body after the whole operation(H3)was measured as well as the changes of Cobb angle,VAS(visual analogue score)and ODI(oswestry dability index)evaluation before and after operation.The height of injured vertebral body(H4)was measured again at 1 year after operationResults:The average operation time of each vertebral body,the bleeding volume,the balloon pressure,the expansion of the balloon and cement injection volume were(48.5±12.4)min,(23.1±8.5)ml,180±250psi,(3.6 ± 1.1)m,(8.2 ± 2.4)ml respectively.In 2 cases,the balloon burst occurred during the injection of Methylmethacrylate and the balloon was taken out completely (1)Height changes of the vertebral body The ratio of height of injured vertebral body at different stage to the adjacent vertebral body(H0/H,Hl/H,H2/H,H3/H)were(58.23±12.57)%,(85.14±9.36)%,(70.25±8.12)%and(82.46±10.59)%respectively.The ratio of H1/H was higher than that of HO/H and H2/H(p<0.05).The ratio of H3/H was higher than that of H0/H(p<0.05)and there was no significant difference between HO/H and H3/H.After 1 years of follow-up,the ratio of height of injured vertebral body to the adjacent vertebral body(H4/H)was(78.59±9.37)%,which was similar as that of H4/H(p>0.05).)(2)The changes of Cobb angle The Cobb angle after postural reduction,balloon expand,temporary pressure release of the balloon,whole operation and 1 year follow-up was(18.65±4.25)°,(6.84±2.57)°,(10.22±3.41)°,(6.93±2.69)° and(7.06±2.86)° respectively.The Cobb angle after balloon expand was lower than those after postural reduction and temporary pressure release of the balloon(p<0.05).There was no significant difference in Cobb angle between time points after whole operation and 1 year follow-up((p>0.05) (3)VAS and JDI evaluation The VAS before operation,2 days and 1 year after operation was 8.26±1.17,2.11±0.36 and 1.83±0.31 respectively.The ODI before operation,2 days and 1 year after operation was(88.35±8.26)%,(23.56±3.12)%and(19.68±2.81)%respectively The VAS and ODI before operation was higher than those at 2 days and 1 year after operation(VAS p<0.05;ODI p<0.01)respectively.There was no significant difference in VAS and ODI between 2 days and 1 year after operation(p>0.05).Conclusion:The novel method including balloon reservation in one side and injection of Methylmethacrylate in another side can effectively maintain the height of vertebral body after distraction by balloon during percutaneous kyphoplasty,which will help to correct kyphosis.This modified method is better than existing process of traditional vertebral kyphoplasty and will be benefit for patients long time after operation. |
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