Vertebral Column Resection

Andrew H. Milby

Dheera Ananthakrishnan

Illustrative Case

The patient is a 48-year-old male s/p motor vehicle accident at age 18, L1 fracture treated with a posterior fusion in situ. He underwent an L4-S1 anterior-posterior spinal fusion for stenosis and spondylolisthesis as an adult, and most recently thoracic myelopathy requiring T10-L1 decompression and fusion, presenting now with worsening back pain, kyphosis, and recurrent myelopathy after a fall (Figure 17-1).

Figure 17-1 ▪ A, Lateral 36-in standing radiograph. B, Anteroposterior 36-in standing radiograph. C, CT scan sagittal reconstruction thoracic spine showing severe spondylosis T9-10 above the level of fusion. D, CT scan sagittal reconstruction lumbar spine showing old fractures at L1 and L2. Robust fusion from T10-sacrum.

Figure 17-1 ▪ (continued)

Indications for Vertebral Column Resection

A fixed, severe deformity in the sagittal and/or coronal planes
This can be due to old trauma, congenital kyphosis or scoliosis, iatrogenic deformity, idiopathic deformity with autoankylosis, tumor, or infection.
Ideally the vertebral column resection (VCR) should be performed at the apex of the deformity; in this manner the correction can be performed most efficiently. Obviously in the case of a tumor or an infection, the resection should be at the diseased level.

Radiologic Assessment

Every case requires 36-in radiographs, MRI, and CT. Flexibility can be assessed with a combination of bending films, supine/prone films, or bolster films as needed. The scout images of the CT scan can be very helpful because they are essentially plain supine films. The pelvic incidence can be measured on the lateral CT scout image.
Carefully assess preoperative imaging to determine apex of deformity, presence of fusion mass, and degrees of correction and translation desired in each plane to determine type and extent of resection required.
Measure approximate lengths and sizes of planned instrumentation.
Review preoperative plain films carefully to establish vertebral level nomenclature for intraoperative localization.

Special Equipment

Motor evoked potential (MEP) and somatosensory evoked potential (SSEP) monitoring, including triggered electromyogram for screw stimulation
C-arm fluoroscopy
Consider use of intraoperative navigation or CT to assist in cases where anatomic landmarks may be altered because of prior resection or fusion.
Consider a 3-D printed model of the spine that can be sterilized and referred to intraoperatively to assist with instrumentation placement. These models can be printed in advance by the medical device companies using CT scans.

Positioning

May position prone with Mayfield head holder if crossing cervicothoracic junction, or on the prone Jackson table for thoracolumbar exposure.
A hinged table can be helpful during the correction portion of the procedure. Alternatively, the hips/legs can be placed in a flexed position at the start of the case, then elevated with blankets or foam pads to facilitate correction after the resection.
- Ensure posterior iliac crest is prepped and draped if harvesting autograft.
Consider use of balanced cervical traction in Gardner-Wells tongs for cases in which long anticipated duration may place patient at risk for facial edema or skin breakdown (Figure 17-2).

Figure 17-2 ▪ Gardner-Wells tongs placed to assist in positioning the severely kyphotic patient.
Consider use of bilateral kidney support pads in addition to typical prone support pads to facilitate rolling of table to either side for visualization (Figure 17-3).
Consider elevating the patient’s chest with excess padding to accommodate the kyphotic deformity and to avoid hyperlordosis of the cervical spine (Figure 17-3).

Figure 17-3 ▪ Jackson table setup for positioning the severely kyphotic patient with elevated chest pad and kidney support pads.

Anesthesia/Neuromonitoring Concerns

MAP goal >80 mm Hg in the setting of myelopathy or during planned deformity correction. Be careful when attempting a deformity correction that also needs a decompression, as the risk of neurologic deficit will be higher because of the preexisting neural compromise. If this is the case, consider staging the decompression and the correction by some number of weeks to allow for recovery of neurology.
Total intravenous anesthesia in the setting of MEP monitoring. Be sure to discuss the monitoring strategy with the neurophysiology technicians and the anesthesia team preoperatively. If the deformity is rigid and there is no underlying neurologic compromise, consider obtaining signals after positioning, followed by the administration of a low dose of paralytic to assist with blood loss minimization during exposure. This paralytic should be able to be reversed if need be, but usually it should be metabolized naturally so that MEP signals return once the instrumentation is ready to be placed.
Intraoperative management of blood loss should be discussed with the anesthesia service preoperatively, including the use of high-dose tranexamic acid if there is no contraindication (refer to chapter on posterior correction of scoliosis).
Discuss the sequence of the case with the anesthesia team and the neurophysiology team, as well as the scrub tech and the circulating nurse. Ensure that all members of the operating team understand the magnitude of the case, and that blood products, fluids, and medications should be at the ready during the case. Although as the surgeon you are likely to be focused on the surgery, it is imperative that you check in with the team periodically to adjust the intraoperative plan if necessary.
Keep in mind that there is usually a great deal of prep to be done before the VCR is started. This means that often the most complex part of the case will be started in the afternoon, when the surgical team is somewhat fatigued, and the patient has been under anesthesia for some time and has lost a fair amount of blood. Consider electively staging these cases, with the first stage being instrumentation removal and placement, decompression, and prepping for the VCR, then coming back on a second day 2 to 3 days later to perform the VCR when the patient and the team are fresh. Of note is that this strategy may pose other problems (post-op ileus/obstruction, medical issues that preclude a return to the OR), so each case should be carefully strategized rather than employing a one-size-fits-all plan.

Localization of Incision

See Chapter 13. Patients will often have a prior incision that should be utilized and extended as needed. As these cases are usually revisions, anatomic landmarks can be altered. Prior instrumentation can help with localization of levels. Careful preoperative planning is necessary, as is having multiple methods of radiographic confirmation.

Approach

See Chapter 13. Preoperatively note any areas of open canal, retained instrumentation, pseudoarthroses. Care should be taken to raise full-thickness flaps rather than leaving a significant amount of tissue on the posterior elements; not only is this faster, but it leads to less dead space and a more robust soft-tissue envelope in what is likely an already compromised tissue bed. Take care in the areas of open canal when dissecting with the electrocautery; Sharp Cobb elevators may be preferred to elevate the tissue flaps, although it is possible to injure dura and neural tissue with Cobb elevators as well.

Instrumentation Techniques

See Chapter 13 for screw and hook placement techniques. Instrumentation issues that are particular to rigid deformity cases include alignment of screw heads and use of fixed/monoaxial screws to allow for controlled correction across the vertebrectomy, difficulty with the identification of pedicles, use of fusion mass screws, use of satellite rods across the vertebrectomy site to increase rigidity and decrease pseudoarthrosis rates. Prior instrumentation may or may not need to be removed. With Harrington rods in particular, we try not to remove the rod because it is usually encased in bone; removal can result in extra blood loss as well as loss of the fusion mass cortex (often needed to dock screw heads). In addition, we lean toward leaving hooks and sublaminar wires in place if possible, given the risk of injury to the dura and neural elements, particularly with the latter.

Vertebrectomy Techniques