Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
Spine J. 2010 Dec;10(12):1118-27. doi: 10.1016/j.spinee.2010.09.020.
Minimally invasive procedures for the treatment of vertebral compression fractures (VCFs) have been in use since the mid-1980s. A mixture of liquid monomer and powder is introduced through a needle into one or both pedicles, and it polymerizes within the vertebral body in an exothermic chemical reaction. The interaction between cement and the fractured vertebral body determines whether and how the cement stabilizes the fragments, alters morphology, and extravasates. The cement is intended to remain within the vertebral body. However, some studies have reported cement leakage in more than 80% of the procedures. Although cement leakage can have no or minimal clinical consequences, adverse events, such as paraplegia, spinal cord and nerve root compression, cement pulmonary embolisms, or death, can occur. The details of how the cement infiltrates a vertebral body or extravasates out of the body are poorly understood and may help to identify strategies to reduce complications and improve clinical efficacy.
Apply novel techniques to demonstrate the cement spread inside vertebrae as well as the points and pattern of cement extravastation.
Ex vivo assessment of vertebral augmentation procedures.
Vertebrae from six fresh whole human cadaver spines were used to create 24 specimens of three vertebrae each. The specimens were placed in a pneumatic testing system, designed to create controlled anterior wedge compression fractures. Unipedicular augmentation was performed on the central vertebra of 24 specimens using polymethylmethacrylate/barium sulfate Vertebroplastic cements (DePuy Spine, Raynham, MA, USA). The volume of cement injected into each vertebra was recorded. Fine-cut computed tomography (CT) scans of all segments were obtained (Brilliance 64; Philips Medical Imaging, Amsterdam, The Netherlands). Using multiplanar reconstructions and volume compositing three-dimensional imaging (Osirix, www.osirix-viewer.com), each specimen was carefully assessed for cement extravasation. Specimens were then immersed in a 50% sodium hypochlorite solution until all overlying soft tissues were removed, leaving the bone and cement intact. The specimens were dried and visually examined and photographed to assess cement extravasation and fracture patterns. Specimens were cut in the axial or sagittal plains to assess the gross morphology of cement infiltration and extravasation. Finally, 25-mm block sections were removed from selected specimens and imaged at 14-μm resolution using a GE Locus-SP micro-CT system (GE Healthcare, London, Ontario, Canada).
Infiltration was characterized by an intimate capture of trabecular bone within the cement, forming an irregular border at the perimeter of the cement that is determined by the morphology of the trabeculae and marrow spaces. Extravasation of the cement was assessed as "any" if any small or large amount of extravastation was detected and was also assessed as severe if a large amount of extravasation was found. Out of the 23 levels studied, some extravasation was visibly apparent in all levels. A wide spectrum of filling patterns, leakage points, and interdigitation of the cement was observed and appeared to be determined by the interaction of the cement with the trabecular morphology. The results support the fact that the cement generally advances through the vertebrae with relatively regular and easily identifiable borders.
Using a cadaver VCF model, this study demonstrated the exact filling and extravastation patterns of bone cement inside and out of fractured vertebrae. These data enhance our understanding of the vertebral augmentation and extravastation mechanics.
自 20 世纪 80 年代中期以来，微创治疗椎体压缩性骨折（VCF）的方法已经在使用。将液体单体和粉末混合物通过一根针注入一个或两个椎弓根，然后在放热化学反应中在椎体内部聚合。水泥与骨折椎体的相互作用决定了水泥是否以及如何稳定碎片、改变形态和外渗。水泥的目的是留在椎体内部。然而，一些研究报告称，80%以上的手术都存在水泥渗漏。虽然水泥渗漏可能没有或只有轻微的临床后果，但可能会发生诸如截瘫、脊髓和神经根受压、水泥肺栓塞或死亡等不良事件。水泥渗透到椎体或从体内渗出的细节了解甚少，这可能有助于确定减少并发症和提高临床疗效的策略。
应用新技术来展示椎体增强过程中水泥的扩散以及水泥外渗的点和模式。
椎体增强术的离体评估。
使用 6 具新鲜全人尸体脊柱的椎体制作了 24 个标本，每个标本有 3 个椎体。将标本放置在气动测试系统中，设计用于创建受控的前楔形压缩骨折。对 24 个标本的中央椎体进行单侧增强，使用聚甲基丙烯酸甲酯/硫酸钡骨水泥（DePuy Spine，雷纳姆，马萨诸塞州，美国）。记录每个椎体注射的水泥量。对所有节段进行精细切割计算机断层扫描（CT）扫描（Brilliance 64；飞利浦医疗成像，阿姆斯特丹，荷兰）。使用多平面重建和体积复合三维成像（Osirix，www.osirix-viewer.com），仔细评估每个标本的水泥外渗情况。然后将标本浸入 50%次氯酸钠溶液中，直到去除所有覆盖的软组织，使骨骼和水泥保持完整。将标本干燥并进行肉眼检查和拍照，以评估水泥外渗和骨折模式。将标本在轴向或矢状面切割，以评估水泥渗透和外渗的大体形态。最后，从选定的标本中取出 25mm 块段，使用 GE Locus-SP 微 CT 系统（GE Healthcare，安大略省伦敦，加拿大）以 14-μm 分辨率成像。
渗透的特征是水泥紧密捕获小梁骨，在水泥的周边形成不规则边界，该边界由小梁和骨髓空间的形态决定。如果检测到任何小或大量的外渗，则将水泥外渗评估为“任何”，如果发现大量外渗，则将其评估为严重。在所研究的 23 个水平中，所有水平都明显存在一些外渗。观察到各种填充模式、渗漏点和水泥的交织，这似乎是由水泥与小梁形态的相互作用决定的。结果支持这样一个事实，即水泥通常以相对规则和容易识别的边界通过椎体推进。
使用尸体 VCF 模型，本研究展示了骨折椎体内部和外部骨水泥的确切填充和外渗模式。这些数据增强了我们对椎体增强和外渗力学的理解。
