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 anterior cervical discectomy (ACD) alone, has been reported to achieve similar clinical outcome that anterior cervical discectomy and fusion without needing intervertebral bone grafts or spacers to get solid fusion.
ACD is known to be associated with a higher risk either of residual increased neck and shoulder pain 3) 4) or of developing a postoperative kyphotic deformity of the cervical spine 5) ; 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% 6).
It has been shown that ACDF induces biomechanical changes leading to modifications of intradiscal pressure pressure recordings in the cervical spine 8) 9) 10) 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 11)
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 paralysis 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, 12).
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) 16).
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 17).
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 18).
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.”
Fifty-nine patients were randomized to ACDF surgery with postoperative physiotherapy (30 patients) or to structured physiotherapy alone (29 patients). The physiotherapy program included general and specific exercises as well as pain coping strategies. Outcome measures included neck disability (Neck Disability Index [NDI]), neck and arm pain intensity (visual analog scale [VAS]), health state (EQ-5D questionnaire), and a patient global assessment. Patients were followed up for 5-8 years. RESULTS After 5-8 years, the NDI was reduced by a mean score% of 21 (95% CI 14-28) in the surgical group and 11% (95% CI 4%-18%) in the nonsurgical group (p = 0.03). Neck pain was reduced by a mean score of 39 mm (95% CI 26-53 mm) compared with 19 mm (95% CI 7-30 mm; p = 0.01), and arm pain was reduced by a mean score of 33 mm (95% CI 18-49 mm) compared with 19 mm (95% CI 7-32 mm; p = 0.1), respectively. The EQ-5D had a mean respective increase of 0.29 (95% CI 0.13-0.45) compared with 0.14 (95% CI 0.01-0.27; p = 0.12). Ninety-three percent of patients in the surgical group rated their symptoms as “better” or “much better” compared with 62% in the nonsurgical group (p = 0.005). Both treatment groups experienced significant improvement over baseline for all outcome measures. CONCLUSIONS In this prospective randomized study of 5- to 8-year outcomes of surgical versus nonsurgical treatment in patients with cervical radiculopathy, ACDF combined with physiotherapy reduced neck disability and neck pain more effectively than physiotherapy alone. Self-rating by patients as regards treatment outcome was also superior in the surgery group. No significant differences were seen between the 2 patient groups as regards arm pain and health outcome 19).
Seventy-four cases of 1-level anterior cervical discectomy and fusion (ACDF1) and 2-level ACDF (ACDF2) (40 ACDF1 and 34 ACDF2 procedures) were retrospectively reviewed. Upright neutral lateral cervical spine radiographs were assessed preoperatively and at 6 weeks and 1 year postoperatively. The measured radiographic parameters included focal lordosis, disc height, C2-7 lordosis, C1-7 lordosis, T1 slope, and C2-7 sagittal vertical axis. Correlation coefficients were calculated to determine the relationships between these radiographic measurements.
The mean values were as follows: preoperative focal lordosis was 0.574°, disc height was 4.48 mm, C2-7 lordosis was 9.66°, C1-7 lordosis was 42.5°, cervical sagittal vertebral axis (SVA) was 26.9 mm, and the T-1 slope was 33.2°. Cervical segmental lordosis significantly increased by 6.31° at 6 weeks and 6.45° at 1 year. C2-7 lordosis significantly improved by 1 year with a mean improvement of 3.46°. There was a significant positive correlation between the improvement in segmental lordosis and overall cervical lordosis. Overall cervical lordosis was significantly negatively correlated with cervical SVA. Improved segmental lordosis was not correlated with cervical SVA in ACDF1 patients but was significantly negatively correlated in ACDF2 patients. There was also a significant positive correlation between the T1 slope and cervical SVA.
In the study population, the improvement of focal lordosis was significantly correlated with an improvement in overall lordosis (C1-7 and C2-7), and overall lordosis as measured by the C2-7 Cobb angle was significantly negatively correlated with cervical SVA. Using lordotic cervical allografts, Gillis et al., successfully created and maintained significant improvement in cervical segmental lordosis at the 6-week and 1-year time points with values of 6.31° and 6.45°, respectively. ACDF is able to achieve statistically significant improvement in C2-7 cervical lordosis by the 1-year followup, with a mean improvement of 3.46°. Increasing the number of levels operated on resulted in improved cervical sagittal parameters. This establishes a baseline for further examination into the ability of multilevel ACDF to achieve cervical deformity correction through the intervertebral correction of cervical lordosis 20).
Seventy-four cases of 1-level ACDF (ACDF1) and 2-level ACDF (ACDF2) (40 ACDF1 and 34 ACDF2 procedures) were retrospectively reviewed. Upright neutral lateral radiographs were assessed preoperatively and at 6 weeks and 1 year postoperatively. The measured radiographic parameters included focal lordosis, disc height, C2-7 lordosis, C1-7 lordosis, T-1 slope, and C2-7 sagittal vertical axis. Correlation coefficients were calculated to determine the relationships between these radiographic measurements. RESULTS The mean values were as follows: preoperative focal lordosis was 0.574°, disc height was 4.48 mm, C2-7 lordosis was 9.66°, C1-7 lordosis was 42.5°, cervical sagittal vertebral axis (SVA) was 26.9 mm, and the T-1 slope was 33.2°. Cervical segmental lordosis significantly increased by 6.31° at 6 weeks and 6.45° at 1 year. C2-7 lordosis significantly improved by 1 year with a mean improvement of 3.46°. There was a significant positive correlation between the improvement in segmental lordosis and overall cervical lordosis. Overall cervical lordosis was significantly negatively correlated with cervical SVA. Improved segmental lordosis was not correlated with cervical SVA in ACDF1 patients but was significantly negatively correlated in ACDF2 patients. There was also a significant positive correlation between the T-1 slope and cervical SVA. CONCLUSIONS In the study population, the improvement of focal lordosis was significantly correlated with an improvement in overall lordosis (C1-7 and C2-7), and overall lordosis as measured by the C2-7 Cobb angle was significantly negatively correlated with cervical SVA. Using lordotic cervical allografts, we successfully created and maintained significant improvement in cervical segmental lordosis at the 6-week and 1-year time points with values of 6.31° and 6.45°, respectively. ACDF is able to achieve statistically significant improvement in C2-7 cervical lordosis by the 1-year followup, with a mean improvement of 3.46°. Increasing the number of levels operated on resulted in improved cervical sagittal parameters. This establishes a baseline for further examination into the ability of multilevel ACDF to achieve cervical deformity correction through the intervertebral correction of lordosis 21).
A total of 1000 consecutive patients who underwent ACDF in an ambulatory surgery center (ASC) (outpatient ACDF) and 484 consecutive patients who underwent ACDF at Vanderbilt University Hospital Nashville, Tennessee (inpatient ACDF) from 2006 to 2013 were included in this retrospective study of patients' medical records. Data were collected on patient demographics, comorbidities, operative details, and perioperative and 90-day morbidity. Perioperative morbidity and hospital readmission were compared between the outpatient and inpatient ACDF groups.
Of the first 1000 outpatient ACDF cases performed in the authors' ASC, 629 (62.9%) were 1-level and 365 (36.5%) were 2-level ACDFs. Mean patient age was 49.5 ± 8.6, and 484 (48.4%) were males. All patients were observed postoperatively at the ASC postanesthesia care unit (PACU) for 4 hours before being discharged home. Eight patients (0.8%) were transferred from the surgery center to the hospital postoperatively (for pain control [n = 3], chest pain and electrocardiogram changes [n = 2], intraoperative CSF leak [n = 1], postoperative hematoma [n = 1], and profound postoperative weakness and surgical reexploration [n = 1]). No perioperative deaths occurred. The 30-day hospital readmission rate was 2.2%. All 90-day surgical morbidity was similar between outpatient and inpatient cohorts for both 1-level and 2-level ACDFs.
An analysis of 1000 consecutive patients who underwent ACDF in an outpatient setting demonstrates that surgical complications occur at a low rate (1%) and can be appropriately diagnosed and managed in a 4-hour ASC PACU window. Comparison with an inpatient ACDF surgery cohort demonstrated similar results, highlighting that ACDF can be safely performed in the outpatient ambulatory surgery setting without compromising surgical safety. In an effort to decrease costs of care, surgeons can safely perform 1- and 2-level ACDFs in an ASC environment 22).
Seventy-one patients who underwent 3-level ACDF and 26 patients who underwent 4-level ACDF were identified and followed for an average of 7.6 ± 4.2 years. There was 1 case (3.9%) of deep wound infection in the 4-level group and 1 case in the 3-level group (1.4%; p = 0.454). Postoperatively, 31% of patients in the 4-level group complained of dysphagia, compared with 12.7% in the 3-level group (p = 0.038). The fusion rate was 84.6% after 4-level ACDF and 94.4% after 3-level ACDF (p = 0.122). At last follow-up, a significantly higher proportion of patients in the 4-level group continued to have axial neck pain (53.8%) than in the 3-level group (31%; p = 0.039); the daily oral morphine equivalent dose was significantly higher in the 4-level group (143 ± 97 mg/day) than in the 3-level group (25 ± 10 mg/day; p = 0.030). Outcomes based on Odom's criteria were also different between cohorts (p = 0.044), with a significantly lower proportion of patients in the 4-level ACDF group experiencing an excellent/good outcome.
In this study, patients who underwent 4-level ACDF had significantly higher rates of dysphagia, postoperative neck pain, and postoperative narcotic usage when compared with patients who underwent 3-level ACDF. Pseudarthrosis and deep wound infection rates were also higher in the 4-level group, although this did not reach statistical significance. Additionally, a smaller proportion of patients achieved a good/excellent outcome in the 4-level group than in the 3-level group. These findings suggest a significant increase of perioperative morbidity and worsened outcomes for patients who undergo 4- versus 3-level ACDF 23).
Fifty-four operated cervical disc hernia cases were retrospectively examined in 2 groups. Discectomy and osteophytectomy were carried out in Group A by using a high-speed drill, while a curette was used for group B. Preoperative and postoperative computerized tomography and direct radiography were performed. Cervical disc height, cervical and segmental lordotic angles were calculated. The visual analogue scale and Odom's criteria were used in the assessment of pain and clinical healing. The fusion ratio of both groups was compared. The Mann-Whitney U test was used to compare data from the groups.
Satisfactory results were obtained in the groups where high-speed drill and curette were used. Independently from the surgical technique, pain scores were significantly reduced in both groups after surgery. No radiologically significant differences were identified between the two groups within the postoperative period 24).
Twenty-five cases with single level cervical disc herniation (CDH) who underwent microdiscectomy were included to this study. Reconstruction was performed using empty bladed cervical PEEK cages. Clinical (Visual analogue scale (VAS) and Odom scores) and radiological results (intervertebral disc and foraminal heights, mean cervical spine lordosis angle, and fusion rate) were reviewed one day and one year after surgery.
There were 18 males and 7 females, aged between 25 and 54 years (mean: 40.8). Mean neck and arm VAS scores reduced from 2.9 to 1.4, and from 7.2 to 1.8, respectively. Odom scores were found to be 1.6 and 1.4 at 1st day and one year postoperatively, respectively. Subsidence was seen in three cases (12%). There was no significant change in heights of neural foramina and intervertebral discs, and no change in cervical spine lordosis, when compared postoperative 1st day and one year radiographs. Fusion was detected in 92% of cases in one year.
Bladed cervical cages are safe with almost no risk of dislocation. Empty cages provide acceptable rates of fusion and subsidence 25).
A total of 112 patients were enrolled and randomly assigned to receive saline or dexamethasone. Data gathered included demographics, functional status (including modified Japanese Orthopaedic Association myelopathy score, neck disability index, 12-Item Short-Form Health Survey score, and patient-reported visual analog scale score of axial and radiating pain), functional outcome swallowing scale score, interval postoperative imaging, fusion status, and complications/reoperations. Follow-up was performed at 1, 3, 6, 12, and 24 months, and CT was performed 6, 12, and 24 months after surgery for fusion assessment. RESULTS Baseline demographics were not significantly different between the 2 groups, indicating adequate randomization. In terms of patient-reported functional and pain-related outcomes, there were no differences in the steroid and placebo groups. However, the severity of dysphagia in the postoperative period up to 1 month proved to be significantly lower in the steroid group than in the placebo group (p = 0.027). Furthermore, airway difficulty and a need for intubation trended toward significance in the placebo group (p = 0.057). Last, fusion rates at 6 months proved to be significantly lower in the steroid group but lost significance at 12 months (p = 0.048 and 0.57, respectively).
Dexamethasone administered perioperatively significantly improved swallowing function and airway edema and shortened length of stay. It did not affect pain, functional outcomes, or long-term swallowing status. However, it significantly delayed fusion, but the long-term fusion rates remained unaffected. Clinical trial registration no.: NCT01065961 ( clinicaltrials.gov ) 26).