Anterior odontoid screw

Biplanar radiographs should be used, with the second image intensifier positioned to obtain an open- mouth peg view.
The mouth is kept open with a radiolucent mouth- gag and the endotracheal tube positioned to one side to ensure an adequate view of the odontoid peg
After biplanar xray is positioned do not move it.

The skin incision is marked by projecting the intended screw trajectory on the surface using a lateral X- ray, this typically is at the C5/ 6 disc level.
Using a standard anterior cervical approach, the plane between the carotid sheath and the trachea and pharynx is developed down to the prevertebral space.
Use finger to blunt dissect cranially
Use II to slowly walk the guide cranially until the caudal edge of the C2.
Lateral self- retaining retractor blades are placed under the partially separated longus colli.
An angled retractor blade is then used to extend the approach cephalad up to the C2/3 disc space under lateral X- ray guidance, while remaining within the prevertebral space.

1) K-Wire Insertion

Drill divot at entry point
A K- wire is inserted into the inferior lip of the C2 vertebral body slightly incorporating the anterior annulus of C2/ 3, and advanced partly into the body of C2 using biplanar imaging.
Measure maximum K-Wire length beyond guard: 28-32 mm
Short drill bursts for K-Wire insertion
Feel for resistance at all times
Check fluoroscopy frequently
May feel momentary loss of resistance as wire crosses fracture line
K-wire risks: Inadvertent removal or cord/brainstem injury
An outer sleeve is passed over the K- wire with fixation pins anchored to the body of C3 to act as the guide for the inner drill guide and the drill.
The superior edge of the annulus of the C2/ 3 disc and cortex of C2 is bored using a wider bore cannulated drill to create a space to countersink the screw head. The K- wire is removed once the outer sleeve is secured firmly in place.
A power drill using a 3 mm drill bit is used to drill a pilot hole along the trajectory marked by the K- wire, using the outer sleeve as the guide. If necessary, the head of the patient or the partially drilled body of C2 can be manipulated, and the distal fragment reduced to achieve a suitable anatomical position.
The drill is then advance into the distal fragment, taking it just past the outer cortex of the odontoid peg into the apical ligament. This hole is then tapped with a 4- mm tap through the outer sleeve. At the end of this step, the length of the screw can be measured using the markings on the tap.

The screw is undersized by the distance between the fracture fragments, to account for the final compression of the fragments.

2) Screw Insertion

inserted into the pilot hole using biplanar imaging and tightened ensuring that the fracture fragments are well compressed, and the screw head is counter sunk

There is evidence to suggest that early operative intervention results in a lower rate of non- union (Apfelbaum et al., 2000; Rao and Apfelbaum, 2005).

Elderly patients and patients with osteoporosis have a significantly higher risk of screw failure.

Loosening and back out of the screw can occur, where there is failure of bony union resulting in persistent stress at the fracture site.

as the oesophagus is more fibrotic and thus less tolerant of retraction (Vasudevan et al., 2014).

Due to difficulty of retraction
injury to the superior laryngeal nerve, which supplies the cricothyroid muscle and provides sensory innervation to the mucosa of the larynx, it pierces the thyrohyoid membrane at approximately the C3/ 4 level.