| Objective: Nowadays the osteoporotic vertebral compression fractures(OVCF)has become more and more often,which mobility has risen higher than before with the coming of aging society.The reasons of OVCF are calcium losing,bone trabecula sparse,more fragile of the bone,less biomechanics with the age increasing.So,falling down or even coughing can make it happen.As we known,the most common place is thoracolumbar vertebra,to conque this,the traditional conservative therapy is lying on the bed,physical therapy and analgesia,but as an old people,the calcium lose faster than growing,so,3 months is just an conservative time,the accurative date is according to the X-ray test and patient' s feeling.This is an attack to fragile old peoples,it's easy to lead the calcium lose faster and muscles atrophy,and there more can lead to pulmonary infection and phlebothrombos,counting this,operation is the best therapy to OVCF.But,just like one coin has two sides,the two proven operations(PKP,PVP)also have relative merits.The PKP operation has an easy way to inject more cement which can lead other vertebral(especially the neighbouring ones)fracture,and the PVP operation can produce too much power in the vertebra during the time of injection.For this reason,we brought a new operation on the base of two proven technique :Percutaneous Vertebroplasty(PVP)and Percutaneous Kyphoplasty(PKP)which name is Percutaneous Vertebroplasty with Microballoon Cement Augumentation.This experiment is to evaluate the biomech-anical properties of microballoon cements using in vertebroplasty in calf osteoporotic vertebral compression fracture model.And to offer academic support for its clinical use.Methods: 1 Material chosen and group: Thirty vertebral bodies(T9-L4)were chose from fresh calf spines.The bone were examined by X-ray to avoid some disease such as obvious osteroprosis;congentinal malformation;bone fracture;cancer and some other disesses.The bone had been divided into single centrum,and all the ligament and soft tissue had been rejected without ruinning the intergrity of the bone.Sort the centrum from one to thirty.Then thirty vertebral bodies were divided randomly into PKP group,PVP group,and PMA group,and each group has 10 cases.Three groups' mineral density were measured with dual-energy radiographic absorption.2 Establishing the calf osteroprosis compression vertebral fracture(decalcification)2.1 Establishing the calf osteroprosis vertebra: all the bilateral pedicle of vertebral arch of centrum had been made bil-tunnel by screw tap(standered 5 mm diameter),the depth of the tunnel is one third of the vertebral body.Each centrum's bil-tunnel were filling-in 3% concentration diluted hydrochloric acid by a micro-speed injection macine on a stead speed which is 40ml/h,after 24 hours later,the osteroprosis vertebral model were accomplished.after these steps,cleaning the bone especially the tunnel with normal saline to wash out the residual concentration diluted hydrochloric acid.And using the dual-energy radiographic absorption to measure three groups' mineral density again.Compare the new BMD with the first reasult.2.2 Establishing the calf compressional fracture model:After the osteroprosis model accomplished,measure the height of the vertebral body'anterior edge with vernier caliper,and record the data,after that,put all of the vertebral bodies onto the biomechanical testing machine(TYPE CSCC-44020)compress the anterior edge of vertebral body in 5 mm/min speed.The axis of the force onto the centrum is 5mm of the anterior edge,untill one quarter of the vertebral body'anterior edge was compressed did stop to accomplish the osteoprosis compression fracture model.Lying on the vertebral bodies' compressed anterior height and the displacement,got the graph of the force-displacement,and according to the graph we can got the initial strength and stiffness through the spinodal and slope.2.3 Injecting cement: All of the osteoprosis compression fracture centrum of three groups had been injected same cement which is PMMA,but in different operation types.One is PVP,the other is PKP,the third one is PMA.Afer this step,put the vertebral bodies onto the same biomechanical testing machine again,also the speed of compressing is 5mm/min,get the post-operation graph,examine the post-operation strength and stiffness of 3 groups.Results: Thirty calf vertebral bodies' initial BMD is(1.59)g/cm2,after decalcification,the post-decalcification BMD is(0.90)g/cm2,the latter was siginificantly lower than the former.Three groups of cement injection volume were similar,between PVP(4.13±0.73)ml,PKP(4.02±0.49)ml,and PMA(4.13±0.60)ml,there is no significant difference of BMD between three groups(P>0.05).Three groups' vertebral body's compressional height were(9.47±0.30)mm,(9.50±0.58)mm,(9.75±0.62)mm,and there is no siginificantly difference between three groups.(P>0.05);The height of vertebral bodies' after operation is(29.45±0.89)mm,(29.62±1.16)mm,(29.00±0.98)mm(P>0.05)which means that there is no statistic difference between 3groups;The PKP group's initial stiffness is(2406.00±731.92)N/mm,the after-operation stiffness is(518.42±173.95)N/mm,the result after using the paired t-test to compare the inter-groups of PKP is(P <0.05),there is statistical difference between the initial and after-operation stiffness,and the former is bigger than the latter one.The PVP group's initial stiffness is(2399.23±630.57)N/mm,the after-operation stiffness is(664.27 ±61.66)N/mm,the result after using the paired t-test to compare the intergroups of PVP is(P<0.05),there is statistical difference between the initial and after-operation stiffness,and the former is bigger than the latter one.The PMA group's initial stiffness is(1807.38±625.23)N/mm,the after-operation stiffness is(711.51±109.13)N/mm,the result after using the paired t-test to compare the inter-groups of PMA is(P<0.05),there is statistical difference between the initial and after-operation stiffness,and the former data is bigger than the latter one.The PKP group's initial strength is(5128.15±815.68)N,the after-operation strength is(9003.54±784.44)N,the result after using the paired t-test to compare the inter-groups of PKP is(P<0.05),which means that there is statistical difference between the initial and after-operation strength of PKP,the postoperational strength was bigger than the initial strength;the PVP group's initial strength is(5700.13±964.99)N,the postoperation strength is(8985.74±827.15)N,the result after using the paired t-test to compare the inter-groups of PVP is(P<0.05),which means that there is statistical difference between the initial and after-operation strength of PVP,the postoperational strength was bigger than the initial strength;The PMA group's initial strength is(5660.72±881.56)N,the after-operation strength is(9020.87±637.04)N,the result after using the paired t-test to compare the inter-groups of PMA is(P<0.05),which means that there is statistical difference between the initial and after-operation strength of PMA,the postoperational strength was bigger than the initial strength.The intra-groups comparisons of initial strength of 3 groups is that there is no significant difference between 3 groups(P>0.05),and the comparison of after-operation strength is(P>0.05)which means that there is no siginificant differences between 3 groups.The inter-groups comparisons of initial stiffness of 3 groups is(P>0.05),which means that there is no significant differences between 3 groups.The inter-groups comparis-ons of after-operation stiffness of 3 groups is(P<0.05),combined with the data which tested by the biomechanical machine,they were lower than the initial vertebral stiffness obviously,but the stiffness of PMA is better than the group of PKP,and similar to PVP group.Conclusions: The operation of PMA is available to be used on the osteoprosis compression fracture.On the recovering of vertebral bodys' compressional height,there is no siginifcantly differences between 3 groups,and about recovering the stiffness of vertebral body,the PMA is better than the PKP group,but similar to the PVP groups;and about the recovering the biomechanical proprities of strength,the PMA group was similar to the other two groups,.Generally,the PMA is available to be used on the healing of osteoprosis compression fracture,also,this experiment test provides theoretic support for its clinical use. |
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