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Authors (on behalf of the AOSpine Knowledge Forum Tumor)

Nicolas Dea, Jeremy Reynolds

General Editor

Luiz Vialle

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C2 pedicle screw insertion

1. Preoperative measurements

Pedicle vs pars

When only a C1–C2 arthrodesis is done, we prefer to use a C2 pedicle screw over a C2 pars screw. This is because the pars screw starting hole is more distal and therefore requires more muscle dissection. But, if a C2 pedicle screw is not possible, then we place a C2 pars screw.

C2 pedicle screw vs. pars screw

2. Preoperative evaluation

A preoperative CT image must be evaluated to determine if this screw is possible. Some patients have a pedicle that is too small to accept such a screw.

3. Screw entry point

The pedicle screw starts more cranially than the pars screw, and it is directed medially.

To find the starting point for the pedicle screw, draw a line along the cranial leading edge of the C2 lamina (1).

Then, draw a line along the midpoint of the pars mediolaterally (2) (see illustration).

Identifying entry point for C2 pedicle screw

4. Drilling

Burr a starting hole 2 mm lateral to this intersection.

56b X140 C2 pedicle screw insertion

Use either a pedicle probe or a handheld drill to drill the hole for the pedicle screw.

The direction of the drill is approximately 30°–45° medial and craniocaudally angled to the bottom half of the tubercle of C1.

Change the upper image as before

5. Screw insertion

Tap, measure the length, and place the screw. Typically a unicortical screw that is longer than 20 mm is adequate.

Placing a C2 pedicle screw
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