Baisc Study Of Vertebroplasty Injection Of Autosetting Calcium Phosphate Cement

Part one Comparison of effects of vetebroplasty between injection of different volumes of autosetting calcium phosphate cementObjective: To compare effects of vetebroplasty between different volumes of autosetting calcium phosphate cement (ACPC) during vertebroplasty. Methods: Flexional compression fractures were experimentally created in 24 thoracolumbar vertebral bodies (T10-L2) obtained from 8 spines harvested from fresh cadavers. After initial strength and stiffness were determined, vertebral bodies were stabilized by bipedicular injection of 2, 4, 6, or 8ml ACPC and recompressed ibidem. Then the aforementioned values were measured again. Results: Strength increased significantly and stiffness restored effectively in all groups. But there was no significant difference between four groups. Conclusions: Vertebroplasty injection of 2 to 4ml ACPC can restore vertebral mechanical property and bring about little leakage. Such volume is comparably fit for vertebroplasty assisted with ACPC in thoracolumbar region.Part two Biomechanical evaluation of vertebroplasty injection of different cements and through different approachesObjective: To compare effects of vertebroplasty between injection of ACPC and of PMMA, effects between unipedicular and bipedicular vertebroplasty, and to evaluate effect of vertebroplasty on mechanical property of adjacent intervertebral disc by means of biomechanical study of ex vivo three-level osteoporotic spine. Methods: Fifteen specimens consisting of continuous three thoracolumbar vertebae were obtained from 7 spines of fresh cadavers. Initial stress, strain and axial stiffness of middle vertebrae and cranial adjacent intervertebral discs were determined respectively during flexion, extension, left lateral bending and right lateral bending ofspecimens under nondestructive load. Stiffness of middle vertebrae during torsion of specimens under nondestructive load was also measured. After flexional compression fractures were experimentally created in the middle vertebrae and utmost strength and stiffness of middle vertebrae were measured, specimens were divided into three groups randomly. The middle vertebral bodies were then stabilized by unipedicular injection of 3ml PMMA, unipedicular injection of 3ml ACPC and bipedicular injection of 3ml ACPC (1.5ml per pedicle) respectively. All the specimens were tested ibidem and aforementioned values were determined. Result: Compared with the initial, in three groups postoperative stress and axial stiffness of middle vertebra had no significant increase during flexion, extension, left lateral bending or left lateral bending of specimens under nondestructive load. Additionally there was no obvious difference between different cements and different approaches. But torsion stiffness in all groups declined. Strength significantly increased in all groups while there were no significant differences between them. Stiffness in unipedicular injection of PMMA and bipedicular injection of ACPC groups increased no more than the initial, while that in unipedicular injection of ACPC group couldn't restored. In PMMA group stress of cranial adjacent intervertebral disc increased by 21% and axial stiffness decreased by 14%, while they had no significant change after injection of ACPC. Conclusion: Vertebroplasty assisted with both cements and through both approaches can restore vertebral mechanical property of vertebra. But unipedicular injection of PMMA and bipedicular injection of ACPC have a little superiority in respect of restoration of torsion stiffness and utmost stiffness. High stress of adjacent intervertebral disc after vertebroplsty assisted with PMMA indicated that there was abnormity in load shift which might results in new fractures of adjacent vertebrae. And injection of ACPC might reduce such efficacy and avoid the occurrence of new fractures of adjacent vertebrae.Part three Change of cardiopulmonary function after vertebroplastyinjection of ACPCObjective: To investigate whether change of hemodynamics and blood gas, and pulmonary fat embolism of dogs would take place after vertebroplasty assisted with ACPC or PMMA. Methods: Fifteen healthy adult dogs were divided into three...