====== Anterior cervical discectomy and fusion (ACDF) ======

{{rss>https://pubmed.ncbi.nlm.nih.gov/rss/search/1xKHMNrFM_O6eS23o1nKYoS7XsmrTWmwEA0Sy8rJh160zGgEaF/?limit=15&utm_campaign=pubmed-2&fc=20221212141158}}
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see also [[Anterior cervical corpectomy and fusion]].
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Anterior [[cervical discectomy]] and [[fusion]] have become one of the most common [[neurosurgical procedure]]s

From 1999 to 2008, the annual number of cervical discectomies with subsequent fusion for degenerative disc diseases in the USA increased by 67% 
((McGuire KJ, Harrast J, Herkowitz H, Weinstein JN. Geographic variation in the surgical treatment of degenerative cervical disc disease: American board of orthopedic surgery quality improvement initiative; Part II candidates. Spine (Phila Pa 1976) 2012;37:57–66. doi: 10.1097/BRS.0b013e318212bb61.))

Without special modifications, a routine [[anterior cervical approach]] is usually able to access levels [[C3]]–[[C7]]. In patients with short thick [[neck]]s, access may be even more limited. In some cases, with long thin necks, up to [[C2]]–[[C3]] or as low as [[C7]]-T1 can be approached anteriorly.

In addition, to enhance fusion, [[anterior cervical plate]]s have been developed. They provide immediate stability and maintain spinal alignment 
((Jacobs WC, Anderson PG, Limbeek J, Willems PC, Pavlov P. Single or
double-level anterior interbody fusion techniques for cervical degenerative disc 
disease. Cochrane Database Syst Rev. 2004 Oct 18;(4):CD004958. Review. Update in:
Cochrane Database Syst Rev. 2011;(1):CD004958. PubMed PMID: 15495130.
))
((Johnson MG, Fisher CG, Boyd M, Pitzen T, Oxland TR, Dvorak MF. The
radiographic failure of single segment anterior cervical plate fixation in
traumatic cervical flexion distraction injuries. Spine (Phila Pa 1976). 2004 Dec 
15;29(24):2815-20. PubMed PMID: 15599284.)).

===== Classification =====
[[Anterior cervical discectomy and fusion classification]].
===== Advantages =====

Advantages over posterior (nonfused) approach:

Safe removal of anterior [[osteophyte]]s

Fusion of disc space affords immobility (up to 10%incidence of subluxation with extensive posterior approach).

Only viable means of directly dealing with centrally herniated disc.
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ACDF procedures improve segmental [[sagittal alignment]], cervical overall shape, and angles, but these changes are inconsistently related to higher quality-of-life scores
((Zaidman N , De Witte O . Cervical sagittal balance: a predictor of neck pain after anterior cervical spine surgery? Br J Neurosurg. 2020:1–5. doi:10.1080/02688697.2020.1850643 )).

===== Disadvantages =====

Anterior cervical discectomy and fusion (ACDF) is the most frequently used surgical procedure for treating [[cervical radiculopathy]] and [[myelopathy]]. However, there is concern about the high [[adjacent segment degeneration]] (ASD) rate after ACDF surgery
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Disadvantages over posterior approach: immobility at the fused level may increase stress on adjacent disc spaces. If a fusion is performed, some surgeons prescribe a rigid collar (e.g. [[Philadelphia collar]]) for 6–12 weeks. Multiple-level ACDF can devascularize the vertebral body (or bodies) between discectomies.
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see  [[Two-level or more-level anterior cervical discectomy and fusion]]
===== Indications =====

[[Anterior cervical discectomy and fusion indications]].

===== Technique =====

see [[Anterior cervical discectomy and fusion technique]].

===== Videos =====

{{youtube>yfSkOF_DAfA}}

====Interbody spacer=====

see [[Interbody spacer for anterior cervical discectomy and fusion]]. 

====Follow up====
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 are left to the surgeon's discretion. Due to their relatively low cost and ease of administration,
((Herzog R J, Marcotte P J. Assessment of spinal fusion. Critical evaluation of imaging techniques. Spine (Phila Pa 1976) 1996;21(9):1114–1118.)).

Due to their relatively low cost and ease of administration, standard radiographs are often ordered for all patients following ACDF to assess fusion status.

However, the use of such “routine” postoperative radiographs has been found to be unwarranted in asymptomatic patients
((Shau D N, Bible J E, Samade R. et al. Utility of postoperative radiographs for cervical spine fusion: a comprehensive evaluation of operative technique, surgical indication, and duration since surgery. Spine (Phila Pa 1976) 2012;37(24):1994–2000.))
((Bartels R HMA, Beems T, Schutte P J, Verbeek A L. The rationale of postoperative radiographs after cervical anterior discectomy with stand-alone cage for radicular pain. J Neurosurg Spine. 2010;12(3):275–279.))
((Ugokwe K T, Kalfas I H, Mroz T E, Steinmetz M P. A review of the utility of obtaining repeated postoperative radiographs following single-level anterior cervical decompression, fusion, and plate placement. J Neurosurg Spine. 2008;9(2):175–179.)).

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)
((Lee HJ, Choi DY, Shin MH, Kim JT, Hong JT. Sequential alignment change of the 
cervical spine after anterior cervical discectomy and fusion in the lower
cervical spine. Eur Spine J. 2016 Jan 28. [Epub ahead of print] PubMed PMID:
26821140.
)).

===Flexion-extension radiographs===

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===

CT is a more sensitive alternative to plain radiography when assessing fusion because of its ability to detail bridging trabecular bone
((Selby M D, Clark S R, Hall D J, Freeman B J. Radiologic assessment of spinal fusion. J Am Acad Orthop Surg. 2012;20(11):694–703.)).

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
((Derakhshan A, Lubelski D, Steinmetz MP, Benzel EC, Mroz TE. Utility of
Computed Tomography following Anterior Cervical Diskectomy and Fusion. Global
Spine J. 2015 Oct;5(5):411-6. doi: 10.1055/s-0035-1554773. Epub 2015 Jun 5.
PubMed PMID: 26430596; PubMed Central PMCID: PMC4577315.
)).

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.” 

===== Complications =====
see [[Anterior cervical discectomy and fusion complications]].

===== Outcome =====
see [[Anterior cervical discectomy outcome]].

===== Multicenter observational registry analysis =====
A multicenter observational registry analysis of 1-year radiographic and clinical outcomes following anterior cervical discectomy and fusion (ACDF) using [[hydroxyapatite-infused cervical PEEK cage]].

Radiographic and clinical outcome data were collected preoperatively and at 6 weeks, 3 months, 6 months, and 12 months postoperatively. To assess fusion, dynamic flexion-extension radiographs were independently evaluated with a validated method. Clinical outcomes were assessed using the following disease-specific measures: Neck Disability Index (NDI) and visual analog scale (VAS) for neck, left arm, and right arm pain. Patient satisfaction was also evaluated.

A total of 789 ACDF patients (men: 51.5 %/women: 48.5%; mean body mass index: 29.9 kg/m2) were included at the time of analysis, and 1565 segments have been operated. Successful fusion was confirmed in 91.3% of all operated levels after 6 months and 92.2% after 12 months. Mean NDI scores improved significantly (P < 0.01) preoperatively (46.3, n = 771) to postoperatively (12 months: 25.2, n = 281). Consistently, mean VAS neck (preoperative: 64.2, n = 770; 12 months: 28.6, n = 278), VAS right arm (preoperative: 42.6, n = 766; 12 months: 20.4, n = 277), and VAS left arm (preoperative: 41.1, n = 768; 12 months: 20.8, n = 277) decreased significantly (P < 0.01). Patients reported high satisfaction rates after surgery with no significant changes in postoperative patient satisfaction between 6 weeks and 12 months (95.1%, n = 273).

ACDF with HA-infused [[PEEK cage]]s demonstrates promising radiographic and clinical outcomes, supporting the potential benefits of incorporating HA into PEEK cages to enhance fusion rates and improve patient outcomes.

Clinical relevance: This study demonstrates a >90% fusion rate by level with reliable improvements in patient-reported outcomes, along with a high rate of [[patient satisfaction]], in a large patient cohort undergoing ACDF with HA-infused PEEK cages
((Kelly MJ, Gelfand B, Radcliff K, Mo FF, Felix BA, Babak Kalantar S. Interim 1-Year Radiographic and Clinical Outcomes Following Anterior Cervical Discectomy and Fusion Using Hydroxyapatite-Infused Polyetheretherketone Interbody Cages. Int J Spine Surg. 2024 Feb 20:8585. doi: 10.14444/8585. Epub ahead of print. PMID: 38378231.)).

===== Longitudinal Nationwide Register Studies =====
This [[study]] utilized data from the Finnish national spine register ([[FinSpine]]), covering all centers from [[Finland]] which perform ACDF surgery. Patients undergoing primary ACDF surgery for DCSD between June [[2016]] and February [[2024]] without prior [[cervical spine surgery]] were included (n=5,517). Patients were grouped based on the patient symptom status ("Improved" vs. "Indifferent or worse") at 12 months post-surgery. Predictive factors were identified using [[classification tree analysis]] followed by [[binary logistic regression]].

At 12 months, 76.8% (n=1799) of patients reported symptom [[improvement]], while 23.2% (n=542) reported that symptoms were indifferent or worse. Loss to follow-up for the outcome variable was 57.6% at 12-months. The Following factors were associated with better outcomes: shorter preoperative [[pain]] duration (≤1 year, OR: 1.95, P<0.001), lower preoperative [[Neck Disability Index]] (NDI) scores (≤42, OR: 1.37, P=0.012), and non-smoking (OR: 1.37, P=0.030). The initial diagnosis also influenced outcomes: patients treated for herniated discs and [[nerve root]] stenosis were more likely to report improvement compared to those with central canal stenosis or   - myelopathy (P<0.001). Gender, age, BMI, working status, regular use of pain medication, perioperative complications, muscle weakness, levels fused and use of plate versus stand-alone cage were not independently predictive of outcomes.

Shorter preoperative pain [[duration]], lower NDI scores, and non-smoking status were significant predictors of good outcomes at 12 months after ACDF surgery for DCSD. These findings can help to guide preoperative patient counselling and enhance evidence-based decision making for treating DCSD
((Klimko N, Danner N, Salo H, Kotkansalo A, Leinonen V, Huttunen J. Outcome after [[Anterior Cervical Decompression and Fusion]] - A Nationwide FinSpine Register Study of Independent Predictors of Outcome at 12 Months after Surgery for Degenerative Cervical Spine. Spine (Phila Pa 1976). 2025 Mar 6. doi: 10.1097/BRS.0000000000005323. Epub ahead of print. PMID: 40047144.))

===== Case series =====
see [[Anterior cervical discectomy and fusion case series]].

===== Case reports =====

Maki et al. aimed to identify potential relationships between pathological and radiological assessments of bony fusion after anterior cervical discectomy and fusion (ACDF). ACDF can resolve neurological symptoms related to cervical spondylosis, such as myelopathy and radiculopathy. Intervertebral bony fusion is a key outcome for successful ACDF, often assessed on radiography and computed tomography (CT) images. However, the pathological findings of tissues demonstrating bony fusion after ACDF have not been well studied. This report presents the cases of two female patients, aged 62 and 40 years, who underwent additional ACDFs for recurrent cervical radiculopathy. Findings from CT imaging identified intervertebral calcification in the titanium spacers placed in the first ACDF. In both cases, recurrent compression of nerve roots was observed radiologically. Cervical nerve root block identified habitual symptoms related to recurrent radiculopathy. To resolve the clinical symptoms, additional ACDFs were performed in two cases. In the second ACDF, the titanium cases from the prior ACDF were removed. Histopathological examination of the tissues from the removed cages revealed growth of cartilage tissue. This is the first report concerning the histopathological evaluation of the tissue in titanium spacers placed in ACDF. Completion of intervertebral calcification in titanium spacers placed in ACDF may not signify completion of intervertebral bony fusion after ACDF
((Maki Y, Kawasaki T, Nakajima K, Takayama M. Pathological Examination of Radiologically Fused Interbody Tissue Five Years After Anterior Cervical Discectomy and Fusion Using the Titanium Cage System: A Report of Two Cases. Cureus. 2022 Aug 16;14(8):e28059. doi: 10.7759/cureus.28059. PMID: 36134104; PMCID: PMC9481214.)).

===== References =====