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Table of Contents    
Year : 2021  |  Volume : 69  |  Issue : 4  |  Page : 937-943

Instrumented Four-Level Anterior Cervical Discectomy and Fusion: Long-Term Clinical and Radiographic Outcomes

1 Department of Neurosurgery, Cairo University, Cairo, Egypt; Department of Neurosurgery, Western University, Windsor Campus, Windsor, Ontario, Canada
2 Department of Neurosurgery, Western University, Windsor Campus, Windsor, Ontario, Canada; Department of Neurosurgery, Qassim University, Buraydah, Saudi Arabia
3 Department of Neurosurgery, Jacobs School of Medicine and Biomedical Sciences at University at Buffalo, United States
4 Department of Neurosurgery, Western University, Windsor Campus, Windsor, Ontario, Canada

Date of Submission28-Jun-2020
Date of Decision16-Jan-2021
Date of Acceptance30-Mar-2021
Date of Web Publication14-Aug-2021

Correspondence Address:
Dr. Mohamed A R Soliman
58 Abas El Akad, Nasrcity, Cairo

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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.323898

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 » Abstract 

Background: There is a paucity of data on outcomes following four-level anterior cervical discectomy and fusions (ACDFs), especially the sagittal balance (SB) parameters.
Objective: We aimed to review the long-term clinical and radiographic outcomes for 41 consecutive patients that underwent instrumented four-level ACDF.
Materials and Methods: Records of 27 men and 14 women, aged 40–68 years, who underwent instrumented four-level ACDF and plating at C3–C7 (n = 37) or C4–T1 (n = 4) were retrospectively analyzed. Clinical outcomes that were assessed were the visual analog scale (VAS) for pain, neck disability index (NDI), Odom's criteria, improvement of symptoms, intraoperative and postoperative complications, SB, and need for revision surgery.
Results: The mean follow-up was 65 ± 36.3 months. The mean VAS for arm and neck pain significantly improved from 7.7 ± 1.4 to 3.5 ± 1.7 (P < 0.001). The NDI score significantly improved from 31 ± 8.2 to 19.3 ± 8.1 (P < 0.001). Concerning Odom's criteria, the grades were excellent (14), good (17), fair (9), and poor (1). Concerning intraoperative and postoperative complications, 10 cases developed dysphagia, 3 cases developed temporary dysphonia, 2 cases developed a postoperative hematoma, 1 patient developed C5 palsy, 1 vertebral artery (VA) injury, and 1 case had superficial infection. The average length of stay (LOS) was 2.9 ± 3.7 days. Three patients needed another surgery (one adjacent segment and two posterior foraminotomies). Regarding the mean change in SB parameters, Cobb's angle (CA) (C2–C7) was 14° ± 8.3°, fusion angle (FA) was 10.9 ± 10.9°, cervical straight vertical alignment (cSVA) was 0.6 ± 0.5 cm, T1 slope was 2.3° ± 3.4°, and disc height (DH) was 1.3 ± 0.9 mm.
Conclusion: Instrumented four-level ACDF is safe with a satisfactory outcome and supplementary posterior fusion was not required in any case.

Keywords: Anterior cervical discectomy and fusion (ACDF), clinical outcomes, degenerative disc disease, instrumentation, multilevel, radiographic outcomes, sagittal balance
Key Message: There was significant postoperative improvement of VAS and NDI. The mean change in Cobb's angle (C2–C7) was 14° ± 8.3°, fusion angle was 10.9 ± 10.9°, cSVA was 0.6 ± 0.5 cm, T1 slope was 2.3° ± 3.4°, and disc height was 1.3 ± 0.9 mm. Instrumented four-

How to cite this article:
R Soliman MA, Alkhamees AF, Khan A, Shamisa A. Instrumented Four-Level Anterior Cervical Discectomy and Fusion: Long-Term Clinical and Radiographic Outcomes. Neurol India 2021;69:937-43

How to cite this URL:
R Soliman MA, Alkhamees AF, Khan A, Shamisa A. Instrumented Four-Level Anterior Cervical Discectomy and Fusion: Long-Term Clinical and Radiographic Outcomes. Neurol India [serial online] 2021 [cited 2022 Jan 23];69:937-43. Available from:

Four-level anterior cervical discectomy and fusion (ACDF) is not a commonly performed procedure even amongst experienced spine surgeons. Although there are sufficient studies covering one-, two-, and three-level ACDF, there are no sufficient studies reporting the outcomes following four-level ACDF, especially radiographic outcomes.[1] There will be an extension of fusion length in the future,[2] due to the increasing number of two- or three-level ACDF surgeries.[3] In the past, there were raised concerns with noninstrumented multilevel ACDF due to high complications, and most of the patients were put in a halo vest for prolonged immobilization.[1] Nowadays, there is an increasing use of the four-level ACDF, especially after the recent systematic review by the American Association of Neurological Surgeons and the Congress of Neurological Surgeons demonstrated that the anterior approaches have similar functional outcomes to the posterior approaches for multilevel cervical fusions.[4] Furthermore, the anterior approach is preferred in deformity cases to achieve optimal cervical lordosis.[5] Also, after using instrumented fusion, there was a higher fusion rate, stability, and an increase in the lordotic curvature.[1],[6] Despite the advantages of ACDF, it has its own complications.[6] To address some of the questions regarding four-level ACDF, we aimed to report the clinical and radiographic outcomes. Also, this is the first study to discuss the details of sagittal balance (SB) changes after four-level ACDF.

 » Materials and Methods Top

This manuscript was written as per the Strengthening of the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.[7]

Study sample and surgical indications

We retrospectively reviewed 41 consecutive patients who underwent a four-level ACDF for cervical radiculopathy or myelopathy by a single surgeon. Exclusion criteria and selection algorithm are shown in [Figure 1]. The study was an exempt from an institutional review board review due to its retrospective nature.{Figure 1}


Patients' demographics, clinical picture, and clinical outcomes [visual analog scale (VAS), neck disability index (NDI) score, Odom's criteria] were collected from our detailed medical records. Intraoperative complications were collected from operative reports. Radiographic outcomes included need for revision surgery either because of adjacent segment disease (ASD), progressive spondylosis, or pseudarthrosis and fusion problems. Patients were followed for at least a year.

Surgical technique

An oblique skin and subcutaneous incision along the anterior border of sternomastoid was made. Then, the platysma was split in parallel with its fibers. Sharp dissection was taken down lateral to the esophagus and trachea and medial to the carotid till reaching the anterior surface of the Cervical spine(CS), followed by fluoroscopy to confirm the levels. Two, on each side, self-retaining trimline retractors were intermittently placed under the longus colli after its dissection. Complete removal of the disc, posterior longitudinal ligament, and osteophytes was performed. Then, bilateral foraminotomies were performed. A high-speed drill was used to shave and decorticate the above and below cartilaginous endplates from foramen to foramen. Then, placement of an appropriate size lordotic cornerstone bone graft (Medtronic, Memphis, TN, USA) was done. The other three levels were done with the same technique. Then, drilling any anterior osteophytes to make the anterior surface of the vertebral body (VB) flat and ready for the locking Atlantis® plate (Medtronic, Memphis, TN, USA) of appropriate size was done. Two screws of an excellent purchase were placed into each of the VB of the five levels followed by locking the screws. Finally, we confirmed the position of the construct by an X-ray. Adequate hemostasis was done. Then, closure in layers with no drain insertion was performed.

Radiological parameters and SB

Bony fusion and SB parameters were assessed on computerized tomography (CT) and X-ray as described in [Table 1] and [Figure 2] and [Figure 3]. The parameters were measured and recorded prior to surgery and at the final visit.{Table 1}{Figure 2}{Figure 3}

Statistical analysis

Using Pearson's Chi-square test and Fisher's exact test, we analyzed cross-tabulation tables and Spearman's correlation coefficient was used to analyze the clinical results for significant statistical relations. Student's t-tests were used to analyze the statistically significant difference among means. The level of statistical significance was fixed at 5%.

 » Results Top


Patients' demographics are reported in [Table 2].{Table 2}

Perioperative complications and clinical outcomes

The mean neck and arm VAS scores improved from 7.7 ± 1.4 to 3.5 ± 1.7 (P < 0.001). The NDI score improved from 31 ± 8.2 to 19.3 ± 8.1 (P < 0.001). Out of the 25 patients who had weakness preoperatively, 24 had good recovery of motor power and one patient remained at preoperative baseline. Nine patients developed immediate postoperative dysphagia which resolved within 3 months (22%), one patient developed transient postfall dysphagia 2 weeks postoperatively which resolved in 3 months, and finally, one patient developed mild dysphagia 2 months postoperatively, barium swallow and CT–CS were obtained, which showed scaring between the plate and esophagus. None of the patients needed a gastric tube for feeding. Two patients developed immediate postoperative hoarseness, which resolved within 3 months (5.1%), and one patient developed transient posttraumatic hoarseness 2 weeks postoperatively which resolved at 3 months. Two cases developed postoperative hematoma requiring evacuation. One patient developed temporary C5 palsy which resolved within 6 months. There was one case with intraoperative VA injury that occurred during plate-screw placement and was revised immediately; bleeding was controlled using Gelfoam® and compression followed by taking the patient to the angiosuite and VA angiography was done which demonstrated VA spasm requiring an anticoagulation regimen temporarily; no neurological deficit occurred. One case developed superficial wound infection treated by dressing and antibiotics. The mean LOS was 2.9 ± 3.7 days. According to Odom's criteria, 75.6% showed excellent or good outcomes [Table 3].{Table 3}

ASD and another cervical spine surgery

During the follow-up period (67.7 ± 33.5 (range, 12–130) months), four (9.8%) patients had an ASD and only one required surgery 16 months from the first surgery. Three (7.3%) patients needed another surgery (range, 2–39 months). So, one patient needed ACDF, and two needed posterior foraminotomies (residual compression (1) and most probably due to the ongoing degenerative process (1)).

Radiological parameters and sagittal balance

Of the 21 patients, 85.7% that accepted to have follow-up scans achieved solid fusion. In all the 21 patients, there was a significant mean improvement of the cervical lordotic fusion angle (FA) of 10.92° ± 10.93° (P < 0.05), cervical lordosis (CL) CA of 14.04° ± 8.3° (P < 0.05), cervical straight vertical alignment (cSVA) of 0.64 ± 0.52 (P < 0.05), and DH of 1.26 ± 0.88 mm (P < 0.001). There was a nonsignificant mean increase of the T1 slope angle of 2.31° ± 3.42° (P = 0.24) [Table 4]. There were no cases of hardware failure.{Table 4}

 » Discussion Top

Clinical outcome and perioperative complications

Thirty-five percent of multilevel ACDF complications are because of instrumentation- and graft-related causes and carry a reoperation rate of 10–100%.[8] In our series, the outcomes are comparable to similar studies, with a larger number of patients and a longer follow-up.[8],[9],[10],[11] Dysphagia occurred in 22% of our patients, whereas the literature estimates this complication occurring in 11–46.2% of cases. [5,8-10, 12, 13] In our cohort, 7.3% of patients experienced transient hoarseness which is similar to other studies (0–11.8%).[8],[9],[10],[12],[13] De la Garza-Ramos et al.[10] reported that 12.5% of the patients that developed dysphagia required temporary gastrostomy. Our rate of VA injury is also comparable to the previously reported literature (0–7.7%).[10],[12] C5 palsy was reported only in De la Garza-Ramos et al. (3.9%)[10] and Kim et al.[12] (0%) series compared to 2.4% in our series. Dural tear was reported only in Wang et al. series (3.1%) and wasn't seen in any other series including our series.[8],[9],[10],[12] De la Garza-Ramos et al.[10] reported a wound infection incidence of 3.9%, while this occurred in 2.4% of our patients and none of Kim et al.[12] series. About 4.8% of the patients had postoperative hematoma requiring surgery which is slightly higher than the reported literature (0–3.1%).[9],[12] There was no reported neural deficits, esophageal injury, embolism, thrombosis, cerebral ischemia, or death in all the series.[8],[9],[10],[11],[12] Our average LOS (3 ± 3.8 days) is similar to other series.[9],[10] According to Odom's criteria, 75.6% showed excellent or good outcome with a mean follow-up of 67.7 months compared to 88.5% in Koller et al.[8] series with a mean follow-up of 27.4 months, 57.7% De la Garza-Ramos et al.[10] series with a mean follow-up period of 91 months. The only series that reported the NDI was of Wang et al.,[9] with an improvement of the mean NDI scores from 31.6 ± 8.7 to 12.2 ± 6.3, compared to 31 ± 8.2 to 19.3 ± 8.1 in our series.

Regarding the long-lasting debate of anterior versus posterior approach, El-Ghandour et al.[14] took us a step toward the answer for which approach is better. More than 30% of their cohort were greater than or equal to four-level ACDFs. This study showed that there was a greater improvement in VAS and NDI with a shorter hospital stay and operative duration in the ACDF while the posterior decompression group had no dysphagia. Both approaches had similar myelopathic improvement.

ASD and another cervical spine operation

The views vary regarding the ASD cause: postoperative spine biomechanical alterations versus natural progression of the disease.[15],[16] Also, there is a contradiction on whether the ASD rate is higher in multilevel versus single-level fusion. Bydon et al.[17] found that the ASD rates that needed reoperation were not different significantly in cases undergoing one-, two-, or greater than or equal to three-level fusion (P = 0.910). Similarly, Pereira et al.[18] series showed that 8.7% of the three-level ACDF patients developed ASD, whereas none of the four-level ACDF patients were on the long-term follow-up. Wang et al.[9] reported 6.3% of their series developed asymptomatic ASD and none of them required surgery. Generally, symptomatic ASD after ACDF is as high as 15%,[19] whereas in our study, 9.8% of patients developed ASD with only 2.4% requiring surgery. Kim et al.[12] reported revision surgery for 5.9% of their patients (one requiring redo-ACDF due screw pull-out and two required removal of hardware and posterior fusion for pseudoarthrosis); however, none of our patients required revision of the ACDF or posterior fusion surgery.

In regard to the need for another surgery, there is a challenging problem that the spine surgeons face in the patients with a long-segment multilevel decompression and fusion is that the construct tends to load the distal bone–screw interface more than the proximal with more observed failure rate distally leading to kicking out of the plate and the graft.[20] Also, there is a debate on unicortical versus bicortical plate screws in regards to the biomechanical rigidity,[21],[22] with bicortical screws demonstrating slightly increased stability.[23],[24] However, in our series, we used the longest unicortical screw and we didn't observe any catastrophic plate/graft dislodgement despite not using postoperative neck support such as neck collar or halo vest. Bolesta et al.[6] reported that one-third of their three- and four-level ACDF and plate series required a second surgery because of ASD, implant failure, and nonunion, and they recommended posterior fusion for multilevel surgeries. Also, Lowery et al.[25] reported a 71% failure rate in their four-level ACDF series and 37% of his series required a second surgery. About 12.5% of Wang et al.[9] series required a second surgery. Wewel et al.[5] series reported a 56% failure rate with only 6.25% requiring a second surgery. In our series, 7.3% underwent another cervical surgery and 14.3% fusion failure none of them required revision of the graft, screws, or posterior fusion. This may be attributed to the shaving of the cartilaginous endplate from foramen-to-foramen using the drill as well as using a cornerstone bone graft. This increases the exposure of the graft to decorticated bone.

Radiological outcomes and SB

Kyphosis is one of the most prevalent deformities of the CS.[26] Once the cervical kyphosis onset starts, the progression of the deformity begins, with head and neck shifting forward leading to chronic abnormal tensile forces on the facet capsules and posterior ligaments with muscle fatigue, further kyphosis progression, and imbalance. This can alter the load distribution which may result in foraminal narrowing and patients present with radiculopathy. Also, the spinal cord may be stretched and compressed against the kyphotic deformity leading to worsening myelopathy. The main aim of the surgery is to stabilize and correct the deformity with the restoration of the SB as well as decompressing the neural elements.[27],[28],[29],[30] In our cohort, the radiculopathy improved dramatically in all the patients due to widening of the disc space using a lordotic graft that in turn improved the kyphotic deformity and widened the nerve root foramina.

There is also suggested evidence of the correlation between the improvement of the SB and the clinical outcomes; however, it was only reported in a few studies with a small sample size.[31] The cervical CA (C2–C7) is the most commonly used radiographic parameter.[32]

Although there is much literature reporting postoperative changes in the SB,[29],[33] there is no clear evidence of the optimal degree of lordosis to be postoperatively achieved. So, correcting the kyphosis as close to the neutral position became an accepted general rule.[34] Jenkins et al.[35] found that there is an increase in the neck pain in patients with more kyphotic angle and Ferch et al.[30] found that there is a significant improvement in the myelopathy scores with an approximately 4° postoperative cervical lordotic angle, whereas the Jagganathan et al.[36] study showed no significant correlation between the postoperative functional outcome and net change in the segmental kyphosis. A prospective, randomized study was conducted by Villavicencio et al. to evaluate the clinical outcome and its relationship with the lordotic alignment (both segmental and cervical). They found that there is a significant improvement of outcome scores when improving or maintaining the segmental SB, whereas they found that the clinical outcomes did not significantly correlate with the CA improvement.[37]

There are only two publications that have discussed only the sagittal alignment changes in the four-level ACDF.[8],[13] However, our study is the first series to discuss the regional SB in four-level ADCF. Koller et al. reported an increase in the CL by 10.9°. However, they did not find any positive correlation between the CA and the clinical outcome and neurologic recovery of statistical significance. They also had two cases of poor clinical outcome and they found that CL reconstruction had a good clinical outcome when the patient's CL is beyond 0°.[8] Zhou et al.[13] recorded an increase in the CL by 14° with no correlation with the clinical outcomes.

A percentage of 74.4% of our patients achieved excellent or good clinical outcomes. However, we did not find any positive correlation between the CA, FA, cSVA, and T1 slope and the clinical outcome and neurologic recovery of statistical significance. Also, we didn't find a certain angle associated with a good clinical outcome. We think the improvement of the SB might play an important role in the restoration of the lordotic curve and decreases the risk of further kyphosis which might lead to neurologic worsening, failure of the fusion construct, and/or requiring the addition of posterior fusion surgery.

ACDF techniques using lordotic interbody grafts in conjunctions with the anterior plating achieve segmental distraction and improvement of the lordotic cervical sagittal alignment.[27],[38] The mean correction of the cervical SB in our series was 11.6° ± 10.5°. This degree of correction is similar to the results reported by Koller et al.[8] and Zhou et al.[13]


Our study has the inherent limitations of a single-surgeon retrospective review study such as information bias. We could not assess patient-reported outcomes such as Nurick's score, SF-36, or Japanese Orthopaedic Association(JOA) because of the retrospective nature of this study. Also, not all the patients accepted to do follow-up images to measure the change in the cervical SB. Furthermore, due to the retrospective nature of the study, we were only able to assess the radiographic outcomes of only 21 patients.

 » Conclusion Top

We encourage future prospective studies with a long-term follow-up on instrumented four-level ACDF to help in reporting the patient's reported clinical outcome after eliminating the confounding variables and its relationship with the postoperative change in the cervical SB global SB and to compare the outcomes with the posterior fusion. However, our series is one of the largest studies and the longest follow-up to date on four-level ACDF with SB data. None of our patients required posterior fusion surgery.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

 » References Top

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