Indications
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Lumbar fusion for symptomatic isthmic, degenerative, or traumatic spondylolisthesis; intractable discogenic back pain; or correction of symptomatic degenerative scoliosis
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As an adjunct to direct lateral, transforaminal, posterior or anterior interbody fusion
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To supplement a posterolateral arthrodesis
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As a posterior adjunct to an anterior decompression or stabilization procedure for any of the following conditions:
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Trauma (e.g., burst fracture, Chance fracture)
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Neoplasms (resulting in instability)
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Infection (e.g., vertebral osteomyelitis, diskitis, spinal tuberculosis)
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Degenerative conditions (anterior lumbar interbody fusion [controversial])
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Planning and positioning
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The following equipment is needed:
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Fluoroscopy (needs to be draped in such a fashion as to allow anteroposterior and lateral imaging without risk of operative field contamination)
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Radiolucent table and frame
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Table that allows for free passage of the fluoroscopic C-arm gantry from anteroposterior to lateral position (i.e., Jackson table)
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Kirschner wire, Kirschner wire driver, and Jamshidi needle
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Cannulated instruments for pedicle screw placement (various systems from different manufacturers can be used)
Figure 84-1:
The patient is positioned prone on a radiolucent table and frame with adequate padding of all pressure points with the extremities placed outside the field of radiation.
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Procedure
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The spine is viewed on the fluoroscopic monitor in the same orientation as the patient is positioned on the table; this helps to prevent mental calculations when moving the pedicle targeting needle.
Figure 84-2:
The level is identified using a lateral fluoroscopic view and an 18-gauge spinal needle ( arrow ).
Figure 84-3:
A, The anteroposterior view can be used to identify the lateral aspect of the pedicle ( arrow ). B, The midline can be marked by palpation of the spinous processes or anteroposterior fluoroscopy using an overlying Kirschner wire.
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The fluoroscopic C-arm is positioned in the anteroposterior view to target the pedicles of the desired vertebral body. To enhance the image of the targeted vertebral level, one order of magnification is used, and the image is adjusted to achieve the maximum bone visualization using the collimator mode.
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The targeted vertebral body is placed in the center of the fluoroscopic monitor to prevent parallax distortion.
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The end plate of the targeted vertebral body is viewed as a single line composed of the posterior and anterior margins of the vertebral end plate. To achieve this, the fluoroscopic C-arm gantry is moved in the proper Ferguson view plane.
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The spinous process of the targeted vertebra is placed between the pedicles by moving the C-arm gantry in the lateral coronal projections.
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Lateral-Medial Targeting of Pedicle
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A Jamshidi needle is used to identify the lateral aspect of the pedicle on the ipsilateral side (i.e., the side on which the surgeon is standing).
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An incision is made in the skin, and the fascia is incised with monopolar cautery to facilitate passage of instruments. The incision extends from pedicle to pedicle being instrumented.
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A Jamshidi needle is passed through the muscle to dock onto the junction between the lateral aspect of the facet joint and transverse process of the desired level.
Figure 84-4:
Anteroposterior fluoroscopy is used to target the lateral superior edge of the pedicle of interest. This is the safest point of entry into the pedicle because the exiting nerve root travels in the medial inferior aspect of the pedicle, and the traversing nerve root travels on the medial aspect of the pedicle.
