Biomechanical Study Of Vertebral Body In Different PMMA Infusion Reference To The Balloon Volume In Percutaneous Kyphoplasty(PKP)

Objective: The isolated porcine thoracolumbar vertebrae were decalcified with EDTA-Na2 to prepare osteoporosis model, using universal material testing machine to prepare vertebral compression fracture model. Biomechanical testing of vertebral compression will be conducted again after percutaneous kyphoplasty(PKP).Analysis the change of vertebral biomechanical parameters after PMMA proportion reference to the balloon volume, searching for optimal bone cement perfusion.Search for optimal bone cement perfusion,to provide reference data for clinical treatment.Methods: Selecting five fresh adult swine spine, five thoracic lumbar segment were chosen,a total of 25 vertebral body, Immersed in formaldehyde mixtured with distilled water( formaldehyde with distilled water to 1 : 1 mix), soaking for 24 hours.Along the lower edge of each right vertebral superior articular process punch Kirschner of 2.5mm to the central region of the vertebral body, decalcified with EDTA-Na2 for 14 days,vertebral model is randomly divided into 5(A, B, C, D, E)experimental groups( each group were five vertebrae).To 5mm / min loading rate with a universal testing machine vertical loading, until 25% of vertebral compression model.Recording the maximum compressive strength and compressive stiffness and postoperative vertebral height were recorded before and after test.After Each group performed with kyphoplasty(PKP),PMMA is infused referring to the balloon volume in different proportions,Each group(A, B, C, D, E) infusion dose of bone cement and balloon volume were successively ratio 0.6 : 1; 0.8 : 1; 1 : 1; 1.5 : 1; 2 : 1Dilatation balloon volume and postoperative vertebral height were recorded, so is the number of vertebrae leakaging PMMA.Then redup loading test under the same experimental conditions, recording the maximum compressive strength and compression stiffness of the vertebral body.Results: The vertebral compression strength and compression stiffness of five groups before PKP is not statistically significant( P>0.05).The comparison of maximum compressive strength and compressive stiffness intragroup before and after the PKP is statistically significant(P <0.01). The comparison of maximum compressive strength and compressive stiffness between B group and C group is not statistically significant( P>0.05),while the consequence is opposite comparing with A、D、E group(P <0.01).The postoperative vertebral height of each group before and after PKP present no difference(P >0.05). A, B,C group bone cement leakage rate was 0, D, E bone cement leakage rate were20.0%, 40.0%.Conclusion:1 According to to the balloon volume in PKP, infusing 0.8-1 timesPMMA can effectively restorethe biomechanical properties of thecompressed vertebral body, effectively reducing the risk of cementleakage;2 The recovery of postoperative vertebral height is no significantassociation with the perfusion of PMMA.3 The balloon expansion volume can be used as areference index of the perfusion of PMMA.