Ex Vivo Study Of Balloon Kyphoplasty In The Treatment Of Osteoporotic Thoracolumbar Burst Fractures And Nonpathologic Thoracolumbar Compression Fractures

Part1: Objective To discuss the possibility of transpedicular balloon kyphoplasty for aged osteoporotic thoracolumbar burst fractures. Methods Simulated osteoporotic thoracolumbar burst fractures were created in 13 vertebral bodies. The burst fractures without obvious canal occupation were confirmed by spiral CT before the procedure. This operation involved the percutaneous insertion of two inflatable bone tamps into a fractured vertebral body transpedicularly under fluoroscopic guidance or spiral CT scan. Inflation of the bone tamp would elevate the endplates, restoring the vertebral body height, while creating a cavity to be filled with bone cement. Preoperative and postoperative heights were measured, preoperative and postoperative Sagittal diameter of vertebral canals were measured and the repaired vertebral bodies were compressed to determine strength and stiffness values .The cement distribution and extravasation was evaluated by spiral CT after the procedure. Results (1) The transpedicular balloon kyphoplasty resulted in significant restoration of the vertebral body height, the mean vertebral body heights was 22.12 ± 1.85mm preoperatively and 23.73 ± 1.87mm postoperatively (P<0.01 )(2) Preoperative and postoperative sagittal diameter of vertebral canals were similar (P>0.05) (3) The cement distribution is regular ,extravasation into spinal cannula was found in 1 case. The preoperative strength was significally greater than postoperative strength, whereas the postoperative stiflhess was less than preoperativestiffness (P<0.05).Conclusion Transpedicular balloon kyphoplasty was a effective way to treat aged osteoporotic thoracolumbar burst fractures without obvious canal occupations and neurologic deficit , the procedure can incease strength and restore height of aged osteoporotic thoracolumbar burst fractures, cement distribution and vertebral canal stenosis can be avoided, spiral CT is the first choice in device of radiology, although further in vivo animal and clinical studies should be done. Part2: Objective To discuss the efficacy of transpedicular balloon kyphoplasty for nonpathologic thoracolumbar compression fractures. Methods 12 thoracolumbar vertebral bodies(VBs) were harvested from 6 calves , the nonpathologic thoracolumbar vertebral bodies were confirmed by X-ray. All VBs were compressed in a materials testing machine to determine initial strength and stiffness. Simulated nonpathologic thoracolumbar compression fractures were created in 12 vertebral bodies by materials testing machine. This operation involved the percutaneous insertion of two inflatable bone tamps into a fractured vertebral body transpedicularly under fluoroscopic guidance . Inflation of the bone tamp would elevate the endplates, restoring the vertebral body back toward its original height, while creating a cavity to be filled with bone cement. Preoperative and postoperative heights were measured , and the repaired vertebral bodies were recompressed to determine strength and stiffness values .The cement distribution and extravasation was evaluated by CT after the procedure. Results (1) The transpedicular balloon kyphoplasty resulted in significant restoration of the vertebral body height, the mean vertebral body heights were 20.83 ± 0.89 mm preoperatively and 23.30 ±1.54mmpostoperatively (P<0.01) ,cement extravasation into spinal cannula were foundin 3 cases.balloon burst in 3 cases .the postoperative strength was significally greater than preoperative strength, whereas the postoperative stiffness was less than preoperative stiffness (P<0.05) . Conclusion Transpedicular balloon kyphoplasty was a effective way to treat nonpathologic thoracolumbar compression fractures , the procedure can increase strength and restore height of the fractures, whereas the stiffness can not be restored. The resistance of percutaneous insertion is increased. There were high incidence of balloon burst, the design of balloon should be suitable for operation, and properties of cement should be changed to abide by biomechanical principles.