Technique ACDF

Anterior Cervical Discectomy and Fusion

 

ACDF C5 6

 

Position

 

Place the patient in the supine position

- small roll placed under the shoulder blades to drop the shoulders from the field

- exposes the anterior neck

- strap the shoulders at the side with minimal traction 

- allows visualization of the lower cervical spine on lateral radiographs

- apply skull traction with Gardner-Wells tongs

- keep head rotation to a minimum because deep dissection will depend on identifying the vertebrae midline

- prevents inadvertent injury to adjacent structures

- reverse Trendelenburg position facilitates venous drainage and results in less bleeding during surgery

 

Dissection

 

Anatomic landmarks for incision 

- hyoid bone overlying C3

- thyroid cartilage overlying the C4/5 interspace

- cricoid cartilage overlying the C6 level

 

Use transverse incision for exposure in most cases

- more cosmetic

- from the midline to the anterior border of SCM in Langer's lines

- divide the deep cervical fascia and platysma muscle exposing the middle layer of the cervical fascia

- bluntly dissect the pretracheal fascia and palpate the carotid pulse

 

When three or more levels are approached, use a longitudinal incision

 

Dissection through the pretracheal fascia places several structures at risk

- superior and inferior thyroid arteries extend through the pretracheal fascia from the carotid artery to the midline

- travel at the C3/4 and C6/7 levels, respectively

- intervening area provides a relatively avascular plane for dissection

 

Recurrent laryngeal nerves

- right recurrent laryngeal nerve ascends in the neck after passing around the subclavian vessels

- courses medially and cranially at the C6–C7 level, often along with the inferior thyroid artery

- left recurrent laryngeal nerve ascends after curving around the aortic arch along the tracheoesophageal groove

- more midline and protected position

- left-sided procedure may be safer, especially when lower cervical segments are approached

- the thoracic duct is often visible on the left at the C7–T1 level and must be protected

 

Retract the sternocleidomastoid muscle and the carotid sheath medially

- contents (common carotid artery, internal jugular vein, and vagus nerve)

 

Retract the midline structures, including the trachea, esophagus, and thyroid gland medially

- complete blunt dissection through the deeper levels to the prevertebral fascia and vertebral bodies

 

Once the midline is identified, incise the prevertebral fascia

- elevate the medial edges of the longus colli muscles

- place blunt self-retaining retractors under the leading edges of the muscle

- Tramline retractor is used (Medial Lateral)

- take care to avoid dissecting along the longus colli muscle because of injury to the cervical sympathetic plexus

- screws in vertebral bodies for vertebral distraction

 

Discectomy

 

Identify

- vertebral bodies by their concave appearance 

- the discs by their more convex contour

 

Localize the disc space with a radiopaque marker and lateral radiograph

 

Remove disc

- incise the disc with an annulotomy blade

- cut lateral to medial away from the vertebral artery

- remove the disc contents and endplate cartilage to the PLL

- use thorough evaluative preoperative imaging to determine the presence of a sequestered disc behind the PLL

- palpate the PLL for the presence of a rent that may also indicate a sequestered fragment

- in the event that a rent is noted, or if an expected disc fragment is not identified, remove the PLL with Kerrison rongeurs

- beware of routine removal of the PLL, because reports of postoperative epidural hematoma have been associated with this technique

 

Removal of endplate and uncovertebral osteophytes is controversial

- disc space distraction reduces ligamentum flavum buckling and increases neuroforaminal area

- it is believed that fusion will arrest spur progression, and stability may allow for resorption over time

- however, this is not a consistent phenomenon

- the location and size of the offending spur must be carefully considered when performing decompression

- exposure of the uncinate processes is critical to safely remove osteophytes

- utilize a high-speed burr to excise the spur from medial to lateral

 

Foraminotomy

- judge the adequacy of foraminotomy

- ability to place the tip of a curret anterior to the exiting nerve root without significant resistance