This spine surgery is one of the most prevalent performed, and the frequency of its performance is rapidly increasing as the aging population grows. Although ASCs offer significant cost advantages over hospital-based surgical centers, concern over the safety of outpatient ACDF has slowed its adoption.
The earliest descriptions of the technique have always been attributed to Cloward, Smith, and Robinson. However, in the French literature, this procedure was also described by others during the exact same time period (in the 1950s). At a meeting in Paris in 1955, Belgians Albert Dereymaeker and Joseph Cyriel Mulier, a neurosurgeon and an orthopedic surgeon, respectively, described the technique that involved an anterior cervical discectomy and the placement of an iliac crest graft in the intervertebral disc space. In 1956, a summary of their oral presentation was published, and a subsequent paper-an illustrated description of the technique and the details of a larger case series with a 3.5-year follow-up period-followed in 1958. The list of authors who first described ACDF should be completed by adding Dereymaeker's and Mulier's names. They made an important contribution to the practice of spinal surgery that was not generally known because they published in French 3).
ACD is known to be associated with a higher risk either of residual increased neck and shoulder pain 4) 5) or of developing a postoperative kyphotic deformity of the cervical spine 6) ; and this, in turn, can lead to the development of degenerative changes at adjacent levels.
From 1999 to 2008, the annual number of cervical discectomies with subsequent fusion for degenerative disc diseases in the USA increased by 67% 7).
It has been shown that ACDF induces biomechanical changes leading to modifications of intradiscal pressure pressure recordings in the cervical spine 9) 10) 11) and to increased stress and motion of vertebral segments adjacent to the fused ones.
The operation is usually straightforward but has multiple pitfalls and nuances 12)
see PDF article of Sonntag VK, Han PP, Vishteh AG. Anterior cervical discectomy. Neurosurgery. 2001 Oct;49(4):909-12. PubMed PMID: 11564253.
In the operating room, the patient must not be hyperextended during intubation.
Somatosensory evoked potentials are routinely monitored.
The patient is placed supine with the neck slightly hyperextended. The head is not turned.
Superficial landmarks serve as the reference points to determine the level of the skin incision, but intraoperative radiographs or fluoroscopic studies are obtained to verify the level.
The cervical spine is approached from the right side unless the patient has undergone a prior approach from the left side. If so, the original incision line is used. If a patient has subclinical vocal cord palsy on the side of the incision, proceeding with an incision on the opposite side is risky. The potential for recurrent laryngeal nerve palsy is highest on the right side, although the risk has not been documented in recent reports. The thoracic duct, however, can be injured when the approach is from the left side.
After copious irrigation, the wound is closed. It is inspected once more by placing two self-retaining Cloward retractors in the wound, keeping one self-retaining retractor deep in the wound. The walls of the wound are checked for any bleeding, which is then controlled, and the opposite retractor is removed slowly. The same maneuver is performed on the other side. The platysma layer is closed with interrupted 3-0 Vicryl suture (Ethicon, Inc., Somerville, NJ), and the skin is closed with a running subcuticular 4-0 Vicryl suture. The suture line is reinforced with Steri-Strips (3M Healthcare, St. Paul, MN) or Dermabond (Closure Medical Corp., Raleigh, NC).
For interbody fusions, autograft was the gold standard for decades; however, limited availability and donor site morbidities have led to a constant search for new materials. Clinically, it has been shown that calcium phosphate ceramics, including hydroxyapatite (HA) and tricalcium phosphate (TCP), are effective as osteoconductive materials and bone grafts.
Many options for interbody spacer and graft biologic exist for multilevel anterior cervical discectomy and fusion (ACDF).
Cornerstone HSR, Medtronic Sofamor Danek….
see Cervical cage.
Following ACDF, imaging modalities such as standard radiography and computed tomography (CT) are used to assess the fusion, instrumentation failure, and postoperative change such as adjacent segment disease
No standard algorithm for postoperative imaging following ACDF has been defined formally, and the frequency and type of imaging obtained is left to the surgeon's discretion. Due to their relatively low cost and ease of administration, 13).
Due to their relatively low cost and ease of administration, standard radiographs are often ordered for all patients following ACDF to assess fusion status.
The ACDF procedure itself can induce regional slope change (C5-s and C7-s) directly at the surgical level and can also influence upper cervical slope change (C1-s and C2s) indirectly. Then the change in the upper cervical spine can induce a change in the sagittal vertical axis (St-SVA) and spino-cranial angle (SCA) 17).
Flexion-extension radiographs are obtained 6 weeks after the operation in patients with a fusion construct. If evidence of fusion is present and there are no signs of pseudarthrosis, patients are started on exercise therapy at that time. Patients who do not undergo a fusion procedure can start exercise 2 to 3 weeks after surgery.
CT is a more sensitive alternative to plain radiography when assessing fusion because of its ability to detail bridging trabecular bone 18).
CT scans following ACDF are not routinely ordered. A CT results in alteration of the treatment in 60% of patients with an abnormal MRI and/or radiograph and persistent symptoms. In contrast, if the patient only has persistent symptoms, only 39% of them will go onto further intervention, suggesting that CT has a limited utility in this population. The probability of detecting abnormal findings on CT subsequent to ACDF is significantly greater when the patient presents with persistent symptoms or abnormal preliminary imaging. Alterations in the treatment course based on abnormal postoperative CT are dependent on postoperative symptoms. Those patients who undergo CT without indication (i.e., without preimaging symptoms or abnormal imaging) are significantly more likely to have negative findings on CT, and even with abnormal CT findings, they are less likely to have an alteration in the treatment course. As such, postoperative CTs following ACDF should be limited to patients who have persistent debilitating symptoms or those with abnormal imaging. This practice will avoid unnecessary cost and patient exposure to ionizing radiation 19).
For patients who undergo a fusion procedure, anterior and lateral radiographs are obtained in the recovery room to verify the position of the graft, the plate, and the screws. Patients without an internal fixation device wear a rigid collar for 4 to 6 weeks. In patients who receive internal fixation and in those who undergo no fusion, external orthosis is not applied routinely, except to control pain. Patients are discharged the day after surgery. A problem with swallowing is the usual reason why patients are kept longer in the hospital. Within 7 to 10 days of discharge, patients are seen in the office for a “wound check.”