Experimental Research And Clinic Application Of Vertebroplasty

Percutaneous vertebroplasty (PVP), originally developed for the treatment of metastatic lesions and haemangiomas, is now being used extensively as a keyhole treatment for vertebral compression fractures. Short-term clinical outcomes appear favorable in 70-80% patients. Polymethylmethacrylate (PMMA) does not adhere to bone nor induce bone formation. It may contribute to periprosthetic osteolysis. Calcium phosphate cement (CPC) is new bioactive cement that posses degraded, osteoconductive, biocompaible, injectable and so on. In spite of not inducing bone formation, solidified CPC take on a lot of micropore structure that is propitious to new bone formation. CPC is all right carrier of bone morphogenetic protein (BMP). The composite materials of calcium phosphate cement combined with bone morphogenetic protein (CPC/BMP) and PMMA were implanted goat vertebral body in vertebroplasty, in order to observe vertebral bone defects reconstruction and degradation ability of CPC/ BMP and the biomechanical changes of PMMA and CPC/BMP in different stages. To compare the biomechanical properties of isolated and leakage of CPC, fractured osteoporotic thoracolumar vertebral bodies were treated with tamp vertebroplasty or injection vertebroplasty with CPCIn clinical studies, CPC has long been in the stabilization and reconstruction of traumatic and pathological fracture of the vertebral body. Vertebroplasty withinjectable self-setting CPC was used as an addition to the posterior short-segment transpedicular fixation in preventing failure of short-segment fixation for thoracolumbar burst fractures 14 cases. PVP was performed in osteoporotic compression fractures 8 cases and symptomatic vertebral hema- xgiomas 3 cases. All the above patients had successful procedures.Section oneExperimental Research of VertebroplastyObjectivel.To probe ability of composite material of CPC and BMP in the vertebral bone defects reconstruction. In order to evaluate feasibility to use this material to repair the vertebral bone defect in vertebraplasty as perfusion material, the ability of CPC was compared with CPC/BMP by animal experiments.2.To compare the differences of the biomechanical changes of CPC/BMP and PMMA in implanting goat vertebral body in different stages in vertebroplasty by animal experiments.3.To compare the biomechanical properties of isolated and leakage of CPC, fractured osteoporotic thoracolumar vertebral bodies treated by tamp vertebroplasty or injection vertebroplasty. Methodsl.The bone defect of lcmxlcmxlcm in vertebral body was made by vertebraplasty in 16 goats. CPC/BMP and CPC were implanted into the lumbar vertebral body respectively. The specimens were harvested separately at the end of 3 and 6 months after operation. The new bone formation and the biological degradation of materials were evaluated by taking X-ray, histological examination and scanningelectron microscope (SEM). The results of CPC /BMP groups and CPC groups were compared on the same condition.2.CPC/BMP and PMMA were implanted into goat vertebral bodies. The vertebral bodies implanted with CPC/BMP and PMMA were tested with axial compressive and torsional testing at different stages, in order to observe the biomechanical changes of PMMA and CPC/BMP.3.Compression fractures were experimentally created in 16 vertebral bodies of 4 osteoporotic thoracolumar vertebral bodies (T11-L4) assigned to either tamp or injection vertebroplasty group. The tamp treatment was consisted of inserting stick into compressed vertebral body, raising the endplate and filling the void with CPC. The vertebroplasty treatment was injected with CPC into the compressed vertebral body. The repaired vertebral bodies were recompressed to determine post treatment strength and stiffness values. The leakages of CPC were observed both kinds of vertebroplasty. Results1.A11 the animals survived after operation, and no reaction of toxicity were found. New bone formation was observed to be increasing significantly in CPC/BMP group with the time of implantation. At 3 months, a lot of chondrocytes and wove bone were found, Remodeling of new lamellar bone and absorption of the composite material were observed, the material was combined to new bone in CPC/BMP group. After 6 months, a lot of lamellar bone was found, the material was melted and big micropore appeared in CPC/BMP group. The defect was nearly repaired. During the repaired process of bone defect, the material degraded while new bone formed, the speed of degradation and new bone formation of CPC/BMP was evidently higher than that of the CPC groups. On electron microscope scanning, CPC/BMP and host cancellous bone were interdigitating. The conjugation between CPC/BMP and thevertebral body was biomechanical connection.2.At implanting, PMMA groups were stronger than normal vertebral bodies as well as CPC/BMP groups in compressive testing, significant difference was observed among three groups in the strength of vertebral bodies (/?=0.000) . CPC/BMP groups was weaker than PMMA groups and normal vertebral bodies in stiffness, significant difference was observed among normal vertebral bodies, PMMA and CPC/BMP groups in torsional angle of vertebral body in torsional testing (/?=0.000) .After 3 months, the strength of PMMA group came down, while the strength of CPC/BMP group rose. Significant difference was observed among three groups in the strength of vertebral body. Stiffness of PMMA group went down, while stiffness of CPC/BMP group ascended. Significant difference was observed among three groups in torsional angle of vertebral bodies in torsional testing (/?=0.010) .After 6 months, the strength of PMMA group continued dropping, while the strength of CPC/BMP group went on rising. No significant difference was observed among normal vertebral bodies, PMMA groups and CPC/BMP groups in the strength of vertebral bodies (/>=0.536) . Stiffness of PMMA group kept on descending. Stiffness of CPC/BMP group maintained to increase. PMMA groups were stronger than normal vertebral bodies and CPC/BMP groups in torsional angle of vertebral body. Significant difference was observed among three groups in torsional testing(/?=0.028).The strength and stiffness of vertebral body of PMMA group were observed to descend significantly in different stages. There was significant difference in different stages in the strength and stiffness of vertebral body of PMMA group. The strength and stiffness of vertebral body of CPC/BMP group were observed to move up significantly in different stages. There was significant difference in different stages in the strength and stiffness of vertebral body of CPC/BMP group.3.There was no significant difference of BMD in tamp and injection groups. Theaverage strength of vertebral body was 2032.7N and 2090.5N after tamping and injecting treatment respectively. Both treatments resulted in significantly stronger vertebral bodies relative to their initial state (p<0.05). The injecting group could enhance vertebral body stiffness significantly (p<0.05), while tamping treatment group restored vertebral body stiffness to initial values (p>0.05) . There was no significant difference with tamp and injection vertebroplasty in strength and stiffness of vertebral body. There were 2 cases with paravertebral leakage in injecting vertebroplasty while paravertebral leakage was observed in tamp vertebroplasty. Conclusions1. CPC is all right carrier of BMP. CPC/BMP is believed to be an ideal material during vertebroplasty. Vertebroplasty with CPC/BMP offer an opportunity of permanent augmentation and reestablishment at vertebrae with gradual replacement of CPC/BMP by host bone. The CPC/BMP has great potential in vertebral bone defects repairing and could be used as perfusion material in vertebraplasty.2.As far as biomechanic properties are concerned, CPC/BMP is believed to be an ideal material in vertebroplasty. Vertebroplasty with CPC/BMP offer an opportunity of permanent augmentation and reestablishment of vertebrae with gradual replacement of CPC/BMP by host bone.3.Tamp treatment resulted in significantly greater strength stiffness restoration of vertebral body as percutaneous vertebroplasty. Tamp treatment can reduce extrusion of cement which is safe, effecting, economical treatment mothed.Section twoClinic application of VertebroplastyObjectivel.To explore the method and effect of short segment pedicle instrument combined with CPC vertebroplasty on thoracolumbar blow-out fracture.2.To investigate the initial clinical results of percutaneous vertebroplasty in the treatment of painful osteoporotic vertebral compression fractures.3.To assess the outcome of percutaneous vertebroplasty for symptomatic vertebral hemangiomas. Methods1.After reduction and fixation with short segment pedicle instrumentation were performed transpedicular vertebroplasty of the fractured vertebrae with injectable self-setting calcium phosphate cement was carried out under fluoroscopic guidance on 14 patients of thoracolumbar fractures.2.Percutaneous vertebroplasty procedures were performed in 8 patients suffering from painful osteoporotic vertebral compression fractures under DSA guidance using polymetylmethacrylate (PMMA). Unipedicular vertebroplasty was performed in all patients. After intervention, all patients were checked with spiral CT scan, X-ray and were followed-up for 2-8months.AU patients were observed the change of pain, and the incidence of complications.3.Three cases with 4 symptomatic vertebral hemangiomas were treated with percutaneous vertebroplasty. All Patients were observed by clinical manifestations and X-ray plain film CT or MRI before and after vertebroplasty . Results1 .The average height of anterior and posterior column of injured vertebral bodies and angle of Cobb were 49.4%, 83.1% and 22.8° respectively before operation. The average height of anterior and posterior column of injured vertebral bodies, angle of Cobb and the rat of spinal stenosis were 92.5%, 95.7% and 3.6° respectively after operation. All patients obtained successful surgery without neurologicalcomplications. There are little extrusion of cement in vertebral canal and intervertebral foramen. They were followed up for 5-16 months (average 9.5 months). Except 1 patient with the spinal cord function for Grade A, other the patients had average improvement of Degree 1 to 2 on the spinal core function. All patients were perfectly recovered without noble correction loss or implant failure during following-up.2.A11 patients were treated successfully without neurological complications, 7 patients had marked or basis pain relief, only 1 patient was middling pain relief after vertebroplasty. 1 case with intra-disc leakage had no clinic symptoms. No other complications occur at follow-up for 3-8 months.3.Procedures of all patients were successful without complications. The clinic symptoms of all patients resolved within 24 hours after vertebraplasty. Neurological deficits and symptoms of all patients were free and no vertebral collapse, nor reentrance of hemangiomas showed on Imaging in following up 6-36 months. Conclusion1.Fixation of short segment pedicle instrument and vertebroplasty with injectable self-setting calcium phosphate cement is a safe and effective method for thoraclumbar blow-out fracture.2.Percutaneous vertebroplasty provided effective pain relief with painful vertebral compression fractures, and complications were infrequent. Percutaneous vertebroplasty is a promising less invasive intervention for painful compression vertebral fractures.3.With long-term follow-up and quick elimination of symptoms, precutaneous vertebroplasty is proved to be a safe and effective treatment for symptomatic vertebral hemangiomas.