The Design Of Vertebral Rear Block Pressurizer And Experimental Studyies

Objective:To design Vertebral Rear Block Pressurizer (VRBP) avoiding complications caused by leakage of bone cement and resetting the spine bone chips in treating spinal burst fracture and vertebral rear defects.Methods:The VRBP is composed of beam rods, U-presser,screw and different sizes of gasket.12 fresh porcine spines were collected and divided into two groups:A(burst fractures)-. B(vertebral rear defects), and take the imaging to exclude bone diseases and removed all the muscle tissue specimens.The integrity of ligment and disc were reserved.According to Panjabi’s "free fall gradual impact method",group A were made into the burst fracture with posterior wall injury specimen.The models were deal with distraction and internal fixation of pedicle.The rate of spinal canal and the Height of vertebrae were measured by CT. The VRBP was installed to the models. Bone cement leakage and the integrity about vertebral rear was observed during surgical procedure and after surgical.The anterior, central, posterior heights of the compromised vertebral body,the spinal canal compromise were measured preoperatively and postoperatively.Date were analyzed in Spss 18.0Vertebral rear defects were created by drill which diameter is 10mm and the depth 10mm.X-ray and CT proved successful modeling.After the modles were deal with psdicle screws.Vertebral Rear Block Pressurizer (VRBP) were used together with PKP. Bone cement leakage and the integrity about vertebral rear was observed during surgical procedure and after surgical.Results:1.There is one case of bone cement leakage to the paraspinal.Cement leakage to the spinal canal was not found during the first experiment.2.The height of anterior vertebrae was restored from 63.5±10.6% preoperatively to 76.5±7.6% after distraction reset; to 77.2±7.6% after injection of bone cemmentThe height of middline vertebrae was restored from 60.1±9.8% preoperatively to 73.5±6.2% after distraction reset; to 74.4±6.7% arter injection of bone cemment.The height of posterior vertebrae was restored from 83.4±7.7% preoperatively to 94.5±7.0% after distraction reset; to 95.2±7.0% injection of bone cemment.The SOR changed from 34.4±5.2% preoperatively to 9.1±3.1% after distraction reset; to 3.0±0.8% injection of bone ceemment.After reset vertebral body distraction, the vertebral height and spinal canal ratio improved significantly compared with the preoperau’ve.After injection of bone cement, the Vertebral height and spinal canal ratio improved significantly compared with the preoperative.No significant difference was noted in maintenance of the height restoration between vertebroplasty and distraction reduction.Detective difference of SOR between vertebroplasty and distraction reduction.3.Cement leakage has not been found during the second experiment.Posterior vertebral body are intact after vertebroplasty.Conclusion:Vertebral Rear Block Pressurizer can resetting small bone chip and prevent cement leakage to the spinal canal for treating spinal burst fracture and posterior wall of the vertebral bone defect.