Anterior approaches to the cervical spine were first described contemporaneously in 1958 by Cloward ¹ and Smith and Robinson ². Since its introduction, anterior cervical diskectomy and fusion (ACDF) has not only gained widespread acceptance but has become one of the most common spinal procedures. Before the introduction of this novel technique, outcomes from both surgical and nonsurgical treatments of cervical spondylosis were poor. As the surgical technique has been refined to use an assortment of hardware, implant, and biologic options, new concerns regarding the sequelae of cervical arthrodesis, most significantly adjacent segment degeneration, have caused surgeons to reconsider the indications, risks, and alternatives of this common procedure. Nonetheless, ACDF remains a mainstay of surgical treatment of a wide pathologic spectrum affecting the cervical spine.

9.2 Patient Selection

The selection of appropriate surgical candidates for ACDF is a key determinant of the surgical risk profile, the likelihood of symptom resolution, and long-term outcome. As such, several criteria must be considered, including the presence of radiculopathy or myelopathy, the presence of axial neck pain, sagittal alignment, and adequate correlation between clinical findings and radiologic images. Patients with significant dorsal compressive pathology, active malignancy, active infection, a history of neck radiation, or significant osteoporosis or osteopenia are often poor candidates.

Although in many instances there is continued debate regarding anterior versus posterior approaches for pathologic processes affecting the cervical spine, there several specific indications for which ACDF is the preferred approach. The most common conditions for which cervical fusion may be indicated are the following:

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  Radiculopathy with abnormal cervical lordosis (with or without axial neck pain).

  
  
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  Radiculopathy with disk herniation (with or without axial neck pain or abnormal cervical lordosis).

  
  
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  Myelopathy owing to ventral pathology or cervical kyphosis.

  
  
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  Radiculopathy or myelopathy associated with significant axial neck pain.

  
  
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  Spondylothesis or pathologic segment motion.

In some cases, patients with the above conditions are best treated through alternative approaches because of specific characteristics of their pathology. For example, radiculopathic patients without axial neck pain and with normal lordosis may be considered for posterior laminoforaminotomy, particularly if the disk herniation is lateral rather than central. Multilevel cervical disease is an additional treatment confounder, and in this patient population, cervical corpectomy may be considered because it can allow for more aggressive neurologic decompression. In most cases, however, ACDF causes minimal disruption of the vertebral end plates, allowing for adequate graft loading, lower rates of subsidence, and improved sagittal alignment.

9.3 Preoperative Preparation

The patient is placed in the supine position with the neck in slight extension. The posterior cervical spine is supported with a rolled sheet, towels, or a 1-liter intravenous fluid bag to maintain normal lordosis ( ▶ Fig. 9.1). A chin strap or light cervical traction can be used if the surgeon prefers; however, significant extension is to be avoided, particularly in the myelopathic patient. Adjusting the operative table to a lounge position with the back and headrest up as well as rotating the patient’s head can improve operative ergonomics and visualization.

Surgeon preference often dictates whether a right- or left-sided approach is used. Traditional wisdom is that right-handed surgeons prefer a right-sided approach and vice versa; however, some important exceptions exist. The course of the recurrent laryngeal nerve is more variable on the right side; therefore, some surgeons prefer the left-sided approach because of the nerve’s more consistent anatomical location ( ▶ Fig. 9.2). Interestingly, however, the literature does not demonstrate a significant difference between approaches in the incidence of recurrent laryngeal nerve palsy. Other surgeons prefer the approach dictated by the orientation of the pathology (i.e., a right-sided approach for the treatment of left foraminal stenosis and vice versa). In revision cases, evaluation for recurrent laryngeal nerve injury is crucial before considering a contralateral approach as bilateral injuries can be devastating.

9.4 Operative Procedure

9.4.1 Anatomy and Exposure

A transverse skin incision is typically used unless extensive exposure of three or more levels is required. The skin incision can be planned using palpable landmarks and its accuracy confirmed by fluoroscopic imaging. The hyoid bone is a landmark for C3–4, the thyroid cartilage for the C5 body, and the cricoid cartilage for the C5–6 disk space. The C6 lateral (carotid) tubercle is also often palpable ( ▶ Fig. 9.3 a). A transverse natural skin crease is often used for improved cosmetic results. The incision begins just lateral to the midline and extends just past the anterior border of the sternocleidomastoid.

The incision is opened sharply, and the platysma muscle is identified. A supraplatysmal dissection can be performed in a superior-inferior orientation either bluntly with Metzenbaum scissors or monopolar cautery. The platysma is opened at its medial border, elevated, and incised horizontally again using scissors or monopolar cautery. A vertical, muscle-splitting incision can also be used. A subplatysmal dissection can also improve surgical exposure. Next, the medial border of the sternocleidomastoid is identified, and the natural avascular plane is then developed between the trachea and esophagus medially and the carotid sheath laterally. Care must be taken to remain medial to the carotid sheath, and a finger from the nondominant hand can be used to regularly detect the carotid pulse. The omohyoid muscle can often be mobilized, so transection of its tendonous midpoint is not frequently required.

When the alar fascia is encountered, a Kittner or peanut dissector can be quite useful to sweep away the loose connective tissue layer directly overlying the anterior vertebral bodies. Hand-held Cloward retractors are used to provide initial exposure of the anterior vertebral column and the adjacent longus colli muscles. The prevertebral fascial layer is opened sharply to expose the anterior longitudinal ligament medially and the longus colli muscles laterally. Before proceeding, localization can be confirmed using lateral fluoroscopy by placing a blunt instrument such as a Penfield 4 dissector onto the disk space.

Once the anterior vertebral column has been exposed and localization confirmed, the medial attachment of the longus colli muscles is released and elevated by subperiosteal dissection using either a key periosteal elevator or monopolar electrocautery. Self-retaining, radiolucent retractor blades with or without teeth are sized and placed medial and lateral beneath the elevated edge of the longus muscle ( ▶ Fig. 9.3 b). Placement of the retractor blades beneath the residual cuffs of the longus colli muscles stabilizes the retraction system, facilitates exposure, and protects important structures such as the esophagus and carotid artery from the teeth on the retractor blades. A second pair of retractor blades can be placed in a longitudinal fashion to aid in extended exposures for multilevel procedures ( ▶ Fig. 9.4). The removal of anterior osteophytes may be required for proper retractor positioning. This “gardening” of the anterior spine not only improves disk space visualization but also allows the cervical plate to lay flush against the vertebral body ( ▶ Fig. 9.5). This can be accomplished with a Cushing rongeur or the high-speed drill.

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