• Is screw position a greater contributor to adjacent segment disease than plate-to-disc distance following anterior cervical discectomy and fusion?
• Reoperation Strategy for Failure of Cervical Disc Arthroplasty at Index and Adjacent Levels
• Postoperative complications of anterior cervical discectomy and fusion: A comprehensive systematic review and meta-analysis
• Comparison of Stand-Alone Anchored Spacer and Plate-Cage Construct for Surgical Treatment of Multilevel Cervical Degenerative Spondylopathy: A Meta-Analysis
• Anterior Cervical Discectomy and Fusion vs. Anterior Cervical Corpectomy and Fusion for 2-Level Degenerative Cervical Myelopathy: A Systematic Review and Meta-Analysis
• Comparison of Two-Screw versus Four-Screw Internal Fixation on Fusion Speed in Anterior Cervical Discectomy and Fusion: A Prospective Randomized Controlled Trial
• Impact of the day of the week on clinical outcomes following anterior cervical discectomy and fusion surgery
• Deep Surgical Site Infection with Epidural Abscess Following Anterior Cervical Discectomy and Fusion: A Case Report and Incidence Analysis in Sweden

ACD is known to be associated with a higher risk either of residual increased neck and shoulder pain ^1) 2) or of developing a postoperative kyphotic deformity of the cervical spine ³⁾ ; and this, in turn, can lead to the development of degenerative changes at adjacent levels

A 2-page survey was distributed to attendees at the 2015 Cervical Spine Research Society (CSRS) meeting. Respondents were asked to categorize 18 anterior cervical discectomy and fusion-related adverse events as either: “common and acceptable,” “uncommon and acceptable,” “uncommon and sometimes acceptable,” or “uncommon and unacceptable.” Results were compiled to generate the relative frequency of these responses for each complication. Responses for each complication event were also compared between respondents based on practice location (US vs. non-US), primary specialty (orthopedics vs. neurosurgery) and years in practice.

Of 150 surveys distributed, 115 responses were received (76.7% response rate), with the majority of respondents found to be US-based (71.3%) orthopedic surgeons (82.6%). Wrong level surgery, esophageal injury, retained drain, and spinal cord injury were considered by most to be unacceptable and uncommon complications. Dysphagia and adjacent segment disease occurred most often, but were deemed acceptable complications. Although surgeon experience and primary specialty had little impact on responses, practice location was found to significantly influence responses for 12 of 18 complications, with non-US surgeons found to categorize events more toward the uncommon and unacceptable end of the spectrum as compared with US surgeons.

These results serve to aid communication and transparency within the field of spine surgery, and will help to inform future quality improvement and best practice initiatives ⁴⁾.

A systematic review of the literature was performed in PubMed/MEDLINE, Embase, and the Cochrane Library for observational studies published between January 1996 and March 2023 and reporting postoperative complications associated with ACDF. Randomized controlled trials and interventional investigations were not included in this study. Meta-regression was also performed using generalized linear mixed models with a binomial probability distribution on various potential predicting factors.

A total of 222 studies reporting the rate of complications associated with ACDF in 50,584 patients were included in the present study. The overall postoperative complication rate was 16%. The most common complications were excessive neck swelling (11.3%), pseudarthrosis (10.0%), dysphagia (9.5%), cage/graft subsidence (9.4%), worsening myelopathy (7.7%), and hoarseness (2.3%). Nonhome discharge, readmission, and mortality rates were 13.8%, 3.7%, and 0.1%, respectively. Based on meta-regression, more levels of fusion and increased age were significantly associated with an increase in the pooled overall postoperative complication rate. Moreover, the rate of some postoperative complications was significantly associated with several perioperative characteristics.

This study is the most extensive meta-analysis conducted on the existing literature regarding ACDF-related complications and potential risk factors. However, future high-quality prospective studies or clinical trials are highly required to provide further evidence and validate the present findings ⁵⁾.

This study provides a valuable and timely synthesis of ACDF-related complications in clinical practice. It successfully quantifies complication rates and identifies key risk factors, which can guide patient counseling and surgical planning. However, its findings should be interpreted in light of the limitations of observational data and study heterogeneity. Future prospective studies and RCTs are needed to validate these associations and explore modifiable risk factors more thoroughly.

In multiple studies, overall morbidity rates for ACDF varied from 13.2% to 19.3%. These included in descending order; dysphagia (1.7%-9.5%), postoperative hematoma (0.4%-5.6% (surgery required in 2.4% of 5.6%), with epidural hematoma 0.9%), exacerbation of myelopathy (0.2%-3.3%), symptomatic recurrent laryngeal nerve palsy (0.9%-3.1%), cerebrospinal fluid (CSF) leak (0.5%-1.7%), wound infection (0.1-0.9%-1.6%), increased radiculopathy (1.3%), Horner’s syndrome (0.06%-1.1%), respiratory insufficiency (1.1%), esophageal perforation (0.3%-0.9%, with a mortality rate of 0.1%), and instrument failure (0.1%-0.9%). There were just single case reports of an internal jugular veing occlusion and a phrenic nerve injury. Pseudarthrosis occurred in ACDF and was dependant on the number of levels fused; 0-4.3% (1-level), 24% (2-level), 42% (3 level) to 56% (4 levels). The reoperation rate for symptomatic pseudarthrosis was 11.1%. Readmission rates for ACDF ranged from 5.1% (30 days) to 7.7% (90 days postoperatively).

Conclusions: Complications attributed to ACDF included; dysphagia, hematoma, worsening myelopathy, recurrent laryngeal nerve palsy, CSF leaks, wound infection, radiculopathy, Horner’s Syndrome, respiratory insufficiency, esophageal perforation, and instrument failure. There were just single case reports of an internal jugular vein thrombosis, and a phrenic nerve injury. As anticipated, pseudarthrosis rates increased with the number of ACDF levels, ranging from 0-4.3% for 1 level up to 56% for 4 level fusions ⁶⁾

Twenty-seven patients with 54 levels and a mean age of 50.8 years were enrolled between January 2005 and August 2006. They underwent ACDF using polyetheretherketone cages packed with demineralized bone matrix without plate fixation at two contiguous levels. Mean follow-up period was 25.5 months (range, 13-60). Clinical outcome was evaluated using two Visual Analog Scales and the Neck Disability Index (NDI). We assessed fusion, regional alignment (RA) of the operated levels and cervical global alignment (GA) preoperatively in the immediate 1-week postoperative period and at the final follow-up. An interspinous distance ≥2 mm was used as an indicator of pseudoarthrosis at each level.

Findings: All patients showed improvements in clinical outcome, with 96% of patients showing mild NDI scores (<14). Radiological solid fusion was obtained at 48 of 54 levels (88.9%) and in 21 of 27 patients (77.8%). Lower cervical levels were significantly more vulnerable to pseudoarthrosis (100%). Fusion rate had no significant correlation with outcome (p > 0.05). RA of the operated levels was improved at the final follow-up compared with preoperatively in 76% of patients, although it had decreased compared with the immediate postoperative period due to subsidence in 84% of patients. In total, 80.8% of patients showed improvements in GA. Furthermore, improvements in RA showed a significant positive correlation with those in GA (p = 0.001), although improvement in RA and GA did not correlate significantly with clinical outcome (p > 0.05).

Conclusions: Though some degree of subsidence occurred in most cases, RA had improved at the last follow-up compared with preoperatively, which contributed to the significant improvement in GA. However, improvement of RA and GA was not correlated with outcomes ⁷⁾

see Vocal cord palsy after anterior cervical discectomy.

Cervical adjacent segment disease

Hoarseness, approximately in 5% ⁸⁾.

Dysphagia after anterior cervical discectomy

see Postoperative hemorrhage after anterior cervical discectomy and fusion

Cerebrospinal fluid fistula after anterior cervical discectomy and fusion.

see Esophageal perforation.

A spinal subdural hematoma is a rare clinical entity with considerable consequences without prompt diagnosis and treatment. Throughout the literature, there are limited accounts of spinal subdural hematoma formation following spinal surgery. This report is the first to describe the formation of a spinal subdural hematoma in the thoracic spine following surgery at the cervical level. A 53-year-old woman developed significant paraparesis several hours after anterior cervical discectomy and fusion of C5-6. Expeditious return to operating room for anterior cervical revision decompression was performed, and the epidural hematoma was evacuated without difficulty. Postoperative imaging demonstrated a subdural hematoma confined to the thoracic level, and the patient was returned to the operating room for a third surgical procedure. Decompression of T1-3, with evacuation of the subdural hematoma was performed. Postprocedure, the patient’s sensory and motor deficits were restored, and, with rehabilitation, the patient gained functional mobility. Spinal subdural hematomas should be considered as a rare but potential complication of cervical discectomy and fusion. With early diagnosis and treatment, favorable outcomes may be achieved ⁹⁾.

Legatt et al., report herein a case of anterior cervical discectomy and fusion (ACDF) surgery in which findings on somatosensory evoked potential (SSEP) monitoring led to the correction of carotid artery compression in a patient with a vascularly isolated hemisphere (no significant collateral blood vessels to the carotid artery territory). The amplitude of the cortical SSEP component to left ulnar nerve stimulation progressively decreased in multiple runs, but there were no changes in the cervicomedullary SSEP component to the same stimulus. When the lateral (right-sided) retractor was removed, the cortical SSEP component returned to baseline. The retraction was then intermittently relaxed during the rest of the operation, and the patient suffered no neurological morbidity. Magnetic resonance angiography demonstrated a vascularly isolated right hemisphere. During anterior cervical spine surgery, carotid artery compression by the retractor can cause hemispheric ischemia and infarction in patients with inadequate collateral circulation. The primary purpose of SSEP monitoring during ACDF surgery is to detect compromise of the dorsal column somatosensory pathways within the cervical spinal cord, but intraoperative SSEP monitoring can also detect hemispheric ischemia. Concurrent recording of cervicomedullary SSEPs can help differentiate cortical SSEP changes due to hemispheric ischemia from those due to compromise of the dorsal column pathways. If there are adverse changes in the cortical SSEPs but no changes in the cervicomedullary SSEPs, the possibility of hemispheric ischemia due to carotid artery compression by the retractor should be considered ¹⁰⁾.

Heterotopic ossification (HO) has been reported following total hip, knee, cervical arthroplasty, and lumbar arthroplasty, as well as following posterolateral lumbar fusion using recombinant human morphogenetic protein 2 (rhBMP-2). Data regarding HO following anterior cervical discectomy and fusion (ACDF) with rhBMP-2 are sparse. A subanalysis was done of the prospective, multicenter, investigational device exemption trial that compared rhBMP-2 on an absorbable collagen sponge (ACS) versus allograft in ACDF for patients with symptomatic single-level cervical degenerative disc disease.

To assess differences in types of HO observed in the treatment groups and effects of HO on functional and efficacy outcomes, clinical outcomes from previous disc replacement studies were compared between patients who received rhBMP-2/ACS versus allograft. Rate, location, grade, and size of ossifications were assessed preoperatively and at 24 months, and correlated with clinical outcomes. RESULTS Heterotopic ossification was primarily anterior in both groups. Preoperatively in both groups, and including osteophytes in the target regions, HO rates were high at 40.9% and 36.9% for the rhBMP-2/ACS and allograft groups, respectively (p = 0.350). At 24 months, the rate of HO in the rhBMP-2/ACS group was higher than in the allograft group (78.6% vs 59.2%, respectively; p < 0.001). At 24 months, the rate of superior-anterior adjacent-level Park Grade 3 HO was 4.2% in both groups, whereas the rate of Park Grade 2 HO was 19.0% in the rhBMP-2/ACS group compared with 9.8% in the allograft group. At 24 months, the rate of inferior-anterior adjacent-level Park Grade 2/3 HO was 11.9% in the rhBMP-2/ACS group compared with 5.9% in the allograft group. At 24 months, HO rates at the target implant level were similar (p = 0.963). At 24 months, the mean length and anteroposterior diameter of HO were significantly greater in the rhBMP-2/ACS group compared with the allograft group (p = 0.033 and 0.012, respectively). Regarding clinical correlation, at 24 months in both groups, Park Grade 3 HO at superior adjacent-level disc spaces significantly reduced range of motion, more so in the rhBMP-2/ACS group. At 24 months, HO negatively affected Neck Disability Index scores (excluding neck/arm pain scores), neurological status, and overall success in patients in the rhBMP-2/ACS group, but not in patients in the allograft group.

Implantation of rhBMP-2/ACS at 1.5 mg/ml with polyetheretherketone spacer and titanium plate is effective in inducing fusion and improving pain and function in patients undergoing ACDF for symptomatic single-level cervical degenerative disc disease. At 24 months, the rate and dimensions (length and anteroposterior diameter) of HO were higher in the rhBMP-2/ACS group. At 24 months, range of motion was reduced, with Park Grade 3 HO in both treatment groups. The impact of Park Grades 2 and 3 HO on Neck Disability Index success, neurological status, and overall success was not consistent among the treatment groups. The study data may offer a deeper understanding of HO after ACDF and may pave the way for improved device designs ¹¹⁾.

see Cage subsidence

Anterior cervical pseudarthrosis.

Analysis of 1000 consecutive patients undergoing Anterior cervical discectomy and fusion (ACDF) in an outpatient setting demonstrated surgical complications occur at a low rate (<1%) and can be appropriately diagnosed and managed in 4-hour ASC PACU window. Comparison with inpatient ACDF surgery cohort demonstrated similar results, highlighting that ACDF can be safely performed in an outpatient ambulatory surgery setting without compromising surgical safety. To decrease cost of care, surgeons can safely consider performing 1- and 2-level ACDF in an ASC environment ¹²⁾.

A retrospective case series of 37 patients, paying special attention to immediate complications related to the use of mechanical retraction of soft tissue (dysphagia, dysphonia, esophageal lesions and local hematoma); and a comparative analysis of the outcomes after changes in the retraction method.

All selected cases had a positive neurological symptom response in relation to neuropathic pain. Dysphagia and dysphonia were found during the first 72 h in 94.1% of the cases in which automatic mechanical retraction was used for more than one hour during the surgical procedure. A radical change was noted in the reduction of the symptoms after the use of only manual protective blades without automatic mechanical retraction: 5.1% dysphagia and 0% dysphonia in the immediate post-operative period, P = 0.001.

Soft tissue damage due to the use of automatic retractors in MACDF is not minor and leads to general discomfort in the patient in spite of good neurological results. These problems most often occur when automatic retractors are used continuously for more than 1 hour, as well as when they are used in multiple levels. Dysphagia, dysphonia and local pain decreased with the use of transient manual blades for retraction, and with intermittent release following minimally invasive principles ¹³⁾.