General Editor: Luiz Vialle

Authors: Ronald Lehman, Daniel Riew, Klaus Schnake

Occipitocervical trauma - Traumatic spondylolisthesis, Levine IIa Direct osteosynthesis of the isthmus

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Authors: Ronald Lehman, Daniel Riew, Klaus Schnake

1 Introduction top

A careful evaluation of the fracture pattern is essential for this procedure. IF the fracture does not run through the inter-articular portion of the C2 the screw trajectory will need to be modified.

2 Reduction top


Reduction is performed under image intensifier. Extension or flexion is applied depending on the position of the fragments. Reduction should not include traction maneuvers.

A short K-wire may be inserted bilaterally to temporarily hold the reduction. Great care has to be taken during this insertion not to damage the surrounding structure. The K-wire will typically not need to be inserted further than 1 cm.

3 Appraoch and positioning top


This procedure is performed through the anterior approach with the patient placed in the  supine position.

4 Fixation top


The typical osteosynthesis is performed according to the technique of C2 pedicle screws, however they are inserted as lag screws.


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).



Burr a starting-hole 2 mm lateral to the intersection of line 1 and line 2.


Remove one K-wire and use either a pedicle probe or a handheld drill in an oscillating mode 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.


Screw insertion

Tap, measure the length, and place a 3.5 mm cortex screw or lag screw. Screw length is typically between 25 and 35 mm.

The procedure is then repeated on the contralateral side.

v1.0 2016.12.01