Anterior Cervical Diskectomy and Fusion

Overview

Cervical spondylosis and disk degeneration can lead to radiculopathy and myelopathy from progressive foraminal or central stenosis. A 14 year epidemiologic study from Rochester, Minnesota, found the incidence of cervical radiculopathy to be 83.2 per 100,000 population. The majority of the cases were secondary to chronic degenerative arthropathy of the cervical spine. Although the majority of patients suffering from symptomatic cervical spondylosis or intervertebral disk herniation will improve with conservative therapy, many will have persistent or worsening symptoms that require surgery.

The anterior approach provides a safe and effective corridor to the subaxial cervical spine in cases of instability or anterior pathology. First described by Robinson and Cloward, the anterior cervical diskectomy and fusion (ACDF; Fig. 14-1 ) has become an established and commonly performed operation. Once a decompression of the intervertebral disk and neural foramen is performed, an intervertebral graft is inserted to maintain disk space height and enhance fusion. The choice of graft material will be dictated by surgeon preference, and multiple pathologic levels may be treated in the same operation. Upon placement of an autograft or allograft, an anterior cervical plate may be placed to span the most rostral to the most caudal vertebral bodies included in the diskectomies. Although the efficacy of anterior cervical plating for single-level operations remains controversial, plating for multilevel fusions has been shown to decrease pseudarthrosis rates. Furthermore, studies suggest that instrumentation maintains sagittal balance through the segments within the construct, even in single-level fusions.

Indications

▪

Intractable or progressive cervical radiculopathy or myelopathy refractory to conservative management with evidence of spondylosis or disk herniation causing foraminal or central stenosis at corresponding level on imaging
▪

Cervical diskitis
▪

Drainage of anterior cervical epidural abscess
▪

Diskogenic cervical headaches
▪

Anterior cervical tumor
▪

Degenerative or traumatic cervical subluxation
▪

Traumatic cervical instability

Contraindications

▪

No absolute contraindications
▪

Prior neck irradiation
▪

Prior anterior neck surgery
▪

Tracheostomy
▪

Primary posterior pathology (hypertrophied ligamentum flavum)
▪

Ossification of the posterior longitudinal ligament (may require corpectomy or posterior decompression)
▪

Severe osteoporosis

Operative Technique

Equipment

▪

Radiolucent operating table
▪

Intraoperative fluoroscopy
▪

Optical loupes
▪

Headlights
▪

Operative microscope
▪

Radiolucent self-retaining cervical retractor
▪

Monopolar and bipolar electrocautery
▪

Metzenbaum scissors
▪

Kittner swabs
▪

Cloward handheld retractors
▪

Caspar pins with left- or right-sided retractor, depending on the side of approach
▪

Pneumatic drill
▪

Kerrison rongeurs, sizes 1 through 3
▪

Pituitary rongeur
▪

Straight and curved curettes
▪

18-gauge spinal needle
▪

Intervertebral graft material (autograft, allograft)
▪

Plate-and-screw system (optional)
▪

Jackson-Pratt drain (optional)

Patient Positioning

▪

The patient is placed supine on the radiolucent operating table with the head toward anesthesia.
▪

Upon induction of general anesthesia, the patient is intubated. If significant central stenosis or myelopathic symptoms are present, care is taken to avoid extension of the neck. This may require fiberoptic intubation.
▪

The patient’s head is placed on a horseshoe or padded donut.
▪

A small roll is placed under the shoulders transversely to facilitate cervical lordosis.
▪

The elbows and wrists are padded to prevent compression neuropathy, and the arms are tucked to the patient’s sides.
▪

Intraoperative fluoroscopy is placed at the level of the cervical spine transversely in preparation for a lateral view.
▪

When the patient’s shoulders obscure imaging of the operative levels, they may be retracted caudally with tape ( Fig. 14-2 ).

Figure 14-2

The final operative position has the patient secured supine in mild neck extension with a small roll placed transversely across both shoulders. The head is toward anesthesia; the fluoroscopy machine is positioned transversely at the level of the cervical spine in preparation for localization. The shoulders are gently retracted caudally and are taped in place for better radiographic exposure of lower cervical levels.
▪

If planning an iliac crest autograft, the ipsilateral crest is elevated and rotated contralaterally by placing one pillow beneath the ipsilateral buttock.

Marking the Incision

▪

The side of approach is based on surgeon preference. Despite the more lateral location of the right recurrent laryngeal nerve, studies reveal no increase in risk of nerve injury between left- and right-sided approaches. The sagittal orientation of the cervical intervertebral disks is approximately 15 degrees rostral; therefore positioning the patient lying on the right side for a right-handed surgeon—or conversely, lying on the left side for a left-handed surgeon—will facilitate diskectomy.
▪

A transverse incision is marked out from the midline to the lateral border of the sternocleidomastoid (SCM) muscle. The marking should be placed along a natural skin crease or along the Langer line for improved cosmesis. The level of the target disk(s) dictates the rostral or caudal location of the incision ( Figs. 14-3 and 14-4 ).

Figure 14-3

Anatomic landmarks for marking incisions.

Figure 14-4

Left paramedian incision along a natural skin crease in preparation for a C5–C6 anterior cervical diskectomy and fusion.
▪

For C1–C2 and C2–C3, the incision is placed 1 cm below the angle of the mandible. A mandibular osteotomy may be required for access to vertebrae in a patient with a short neck.
▪

For C3–C4, the incision is placed just caudal to the level of the hyoid bone.
▪

For C4–C5, the incision is placed at the level of the thyroid cartilage.
▪

For C5–C6 and C6–C7, the incision is placed at the level of the cricoid cartilage.
▪

C7–T1 may be accessible in certain patients with longer necks. In these cases, the incision is placed as low as possible, just above the clavicle.
▪

These guidelines for the marking of incisions should be confirmed with lateral fluoroscopy.
▪

To obtain an iliac bone autograft, an 8-cm oblique line is marked 6 cm lateral to the anterior superior iliac spine.

Preparation and Draping

▪

Once the incision is marked, the operative field is isolated with circumferential 10 × 10 cm adhesive drapes.
▪

The skin is sterilized in standard fashion.
▪

The iliac incision is prepared if autograft harvesting is planned (see the section on autograft harvesting).
▪

Both cervical and iliac incisions are isolated with sterile towels. A clamp is placed over the iliac incision for localization through the sterile drapes, and a thyroid drape is placed over the cervical incision.
▪

The base of the intraoperative fluoroscopy machine is placed opposite the surgeon; it is draped carefully to avoid contamination of the sterile field and is moved rostrally toward anesthesia. The operative microscope is placed behind the primary surgeon opposite the fluoroscopy machine.