11.2.6\ Vertebrectomy

11.2.6.1\ Discussion

Vertebrectomy is sometimes necessary to treat extensive spine, tumors, infections, or fracturedislocations. Part (partial vertebrectomy) or all (total vertebrectomy) of a vertebra can be removed. In particular, corpectomy is a specific type of partial vertebrectomy in which the vertebral body is partially or completely resected. Extensive vertebrectomy operations are often performed in stages. For example, en bloc bone resection can be performed using a diamond threadwire saw (T-saw), osteotome, and/ or Gigli saw. The threadwire is sometimes left in the surgical bed for staged operations, such that the device may sometimes be encountered on interval imaging (Fig. 11.15). Subsequently, the vertebra can be reconstructed using iliac crest, tibia, and fibula strut grafts or various types of synthetic cages. Interbody cages, such as the Harms cage, are interposed vertically between vertebral bodies after vertebral body resection in order to promote fusion and provide

a

mechanical support­ (Fig. 11.16). Expandable cage designs that can be adjusted to fit the length of the surgical defect are also available (Fig. 11.17). Morselized bone graft material is often packed inside the cage. The Harms cage is often used in combination with anterior or posterior fusion hardware, which yields fusion rates of over 90%. Carbon fiber cage systems can also be used for anterior column reconstruction following corpectomy, mainly in the setting of spine tumor and trauma surgery. Carbon fiber is a biocompatible material that can be used to make stackable cage systems. Except for the central metallic rod, on radiographs and CT, the carbon fiber components are radiolucent, while on MRI, the carbon fiber components are of low signal intensity on T1 and T2 sequences (Fig. 11.18). The role of imaging, particularly with CT, is to assess the progression of fusion and to evaluate for complications, such as graft or instrument displacement (Figs. 11.19 and 11.20). High-resolution CT with 3D renderings is particularly useful for assessing the position and integrity of the hardware.

b

Fig. 11.15  Staged total vertebrectomy using threadwire saw and fibular bone graft reconstruction. Axial (a) and sagittal (b) CT images and the frontal radiograph (c) show the wire encircling a diseased vertebral body following

laminectomy and posterior fusion. The follow-up sagittal CT image (d) shows interval corpectomy with fibular grafting and removal of the wire

Fig. 11.16  Harms cage. Sagittal (a) CT image shows a cage filled with bone graft (arrow). There is also anterior fusion hardware. 3D CT image (b) in a different case

shows a cylindrical metal mesh cage and adjacent posterior fusion hardware

Fig. 11.18  Corpectomy with stackable carbon fiber reconstruction. Frontal (a) radiograph shows corpectomy and fusion with stackable carbon fiber-reinforced cages constrained by a central metallic rod (arrow). The cages are otherwise radiolucent except for tiny metallic markers.

Axial CT image (b) shows the low attenuation rectangular stackable cages and constraining metallic rod. Axial T2-weighted MRI (c) shows the low signal intensity rectangular carbon fiber cage

Fig. 11.20  Dislocated bone grafts. Frontal radiograph (a) and coronal CT image (b) show lateral displacement of the bilateral fibular grafts out of the corpectomy defect

such that the inferior end of the right graft and the superior end of the left graft no longer contact the adjacent endplates