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Authors of section


Ronald Lehman, Daniel Riew, Klaus Schnake

General Editor

Luiz Vialle

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Direct osteosynthesis of the isthmus

1. Introduction

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

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

direct osteosynthesis of the isthmus

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. Approach and positioning

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

anterior fixation

4. Fixation

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

direct osteosynthesis of the isthmus

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).

c2 pedicle screw insertion


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

c2 pedicle screw insertion

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.

c2 pedicle screw insertion

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.

c2 pedicle screw insertion

5. Aftercare

Patients are made to sit up in the bed on the evening following the operation.

A collar is commonly used following surgical stabilization to moderate patient activity.

The purpose of a collar is to prevent ranges of motion outside of limits deemed unfavorable for fracture healing. Collar is optional.

Patients with intact neurological status are made to stand and walk on the first day after surgery. Patients can be discharged when medically stable or sent to a rehabilitation center if further care is necessary. This depends on the comfort levels and presence of other associated injuries.

Patients are generally followed with periodical x-rays at 6 weeks, 3 months, 6 months, and 1 year.