Critical to obtain anteroposterior (AP) and lateral plain x-rays for counting levels, and preoperative computed tomography (CT) scan to evaluate pedicle anatomy

CT scans that include the entire thoracolumbar spine on a single sagittal image facilitate localization using the sacrum or the ribs intraoperatively

Patient is positioned prone on a radiolucent Jackson spine frame in the standard manner. Careful positioning is performed to assist with fracture reduction in trauma cases, or improve alignment in non-traumatic cases.

For percutaneous thoracic pedicle instrumentation, we use total intravenous anesthesia with somatosensory-evoked potentials and TcMEP monitoring, especially if this procedure is being performed for trauma, and a fracture reduction is planned as part of the operation.

We prefer the true AP targeting for percutaneous pedicle instrumentation.

Localization of incisions is done entirely fluoroscopically.

A true AP fluoroscopic image is obtained, with the center of the x-ray beam parallel to the superior endplate of the vertebra (Figure 14-2). This will produce a single endplate shadow as the anterior and posterior margins are superimposed on each other. Further, the pedicle shadows should be just inferior to the superior endplate shadow and the spinous process will be equidistant between pedicles. It is imperative to spend as much time as needed on getting a true AP image. This can be difficult in certain cases (DISH, deformity, obese patient) and may preclude using this technique.

Once a true AP image is obtained, the lateral border of the pedicle is marked with a K-wire on the skin. The skin incision is made 1 to 1.5 cm lateral to this point on the skin to account for the medial angulation of the pedicles. The deeper the vertebrae, either due to lordosis or body habitus, the more lateral the incision should be localized (Figure 14-3).

It is paramount to keep the vertebral body of interest in the center of the fluoroscopy image to prevent angulation errors.