Randomized controlled trials comparing cervical disc arthroplasty and anterior cervical discectomy and fusion outcomes in degenerative spine disease: a systematic review and meta-analysis

J Neurosurg Spine 43:703–716, 2025

This systematic review and meta-analysis synthesizes randomized controlled trials comparing cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) for degenerative cervical disc disease. Across 25 RCTs (4530 patients), CDA demonstrated higher overall and neurological success, reduced adjacent-segment disease and fewer reoperations, but increased heterotopic ossification and longer operative times.

The authors performed multilevel meta-analysis and meta-regression to explore heterogeneity, finding myelopathy inclusion and follow-up completeness influenced results; sensitivity analyses excluding industry-funded trials showed consistent findings. Conclusions emphasize CDA’s potential benefits for selected patients while recommending longer-term and subgroup-specific trials.

Cervical Disc Arthroplasty (CDA) vs. Anterior Cervical Discectomy and Fusion (ACDF): CDA shows comparable or potentially greater overall and neurological success rates compared to ACDF for degenerative cervical spine disease.

Motion Preservation: CDA preserves cervical spine range of motion at the operated level, while ACDF is associated with loss of motion and potentially increased risk of adjacent segment degeneration (ASD).

Adjacent Segment Disease (ASD): CDA is associated with a significantly lower rate of ASD compared to ACDF, suggesting a protective effect against degeneration of adjacent spinal segments.

Reoperation Rates: CDA results in lower total reoperation rates compared to ACDF, indicating fewer subsequent surgical interventions.

Heterotopic Ossification (HO): CDA has a significantly higher rate of HO, a complication where bone forms in soft tissue, which can potentially reduce the motion-preserving benefit of the procedure.

Operative Time: CDA procedures are associated with significantly longer operative times than ACDF, with no significant difference in blood loss or hospital length of stay between the two techniques.

Pain and Disability Outcomes: No significant differences were found between CDA and ACDF in terms of improvement in arm pain, neck pain, or disability scores (Neck Disability Index) as measured by patient-reported outcomes.

Patient Selection: The benefits of CDA over ACDF are most applicable to patients with 1-2 level degenerative disease, preserved cervical alignment, and no significant instability or deformity; findings may not generalize to more complex cases.

Three-level ACDF versus 3-level laminectomy and fusion: are there differences in outcomes?

Neurosurg Focus 55(3):E2, 2023

OBJECTIVE The authors sought to compare 3-level anterior with posterior fusion surgical procedures for the treatment of multilevel cervical spondylotic myelopathy (CSM).

METHODS The authors analyzed prospective data from the 14 highest enrolling sites of the Quality Outcomes Database CSM module. They compared 3-level anterior cervical discectomy and fusion (ACDF) and posterior cervical laminectomy and fusion (PCF) surgical procedures, excluding surgical procedures crossing the cervicothoracic junction. Rates of reaching the minimal clinically important difference (MCID) in patient-reported outcomes (PROs) were compared at 24 months postoperatively. Multivariable analyses adjusted for potential confounders elucidated in univariable analysis.

RESULTS Overall, 199 patients met the inclusion criteria: 123 ACDF (61.8%) and 76 PCF (38.2%) patients. The 24-month follow-up rates were similar (ACDF 90.2% vs PCF 92.1%, p = 0.67). Preoperatively, ACDF patients were younger (60.8 ± 10.2 vs 65.0 ± 10.3 years, p < 0.01), and greater proportions were privately insured (56.1% vs 36.8%, p= 0.02), actively employed (39.8% vs 22.8%, p = 0.04), and independently ambulatory (14.6% vs 31.6%, p < 0.01). Otherwise, the cohorts had equivalent baseline modified Japanese Orthopaedic Association (mJOA), Neck Disability Index (NDI), numeric rating scale (NRS)–arm pain, NRS–neck pain, and EQ-5D scores (p > 0.05). ACDF patients had reduced hospitalization length (1.6 vs 3.9 days, p < 0.01) and a greater proportion had nonroutine discharge (7.3% vs 22.8%, p < 0.01), but they had a higher rate of postoperative dysphagia (13.5% vs 3.5%, p = 0.049). Compared with baseline values, both groups demonstrated improvements in all outcomes at 24 months (p < 0.05). In multivariable analyses, after controlling for age, insurance payor, employment status, ambulation status, and other potential clinically relevant confounders, ACDF was associated with a greater proportion of patients with maximum satisfaction on the North American Spine Society Patient Satisfaction Index (NASS) (NASS score of 1) at 24 months (69.4% vs 53.7%, OR 2.44, 95% CI 1.17–5.09, adjusted p = 0.02). Otherwise, the cohorts shared similar 24-month outcomes in terms of reaching the MCID for mJOA, NDI, NRS–arm pain, NRS–neck pain, and EQ-5D score (adjusted p > 0.05). There were no differences in the 3-month readmission (ACDF 4.1% vs PCF 3.9%, p = 0.97) and 24-month reoperation (ACDF 13.5% vs PCF 18.6%, p = 0.36) rates.

CONCLUSIONS In a cohort limited to 3-level fusion surgical procedures, ACDF was associated with reduced blood loss, shorter hospitalization length, and higher routine home discharge rates; however, PCF resulted in lower rates of postoperative dysphagia. The procedures yielded comparably significant improvements in functional status (mJOA score), neck and arm pain, neck pain–related disability, and quality of life at 3, 12, and 24 months. ACDF patients had significantly higher odds of maximum satisfaction (NASS score 1). Given comparable outcomes, patients should be counseled on each approach’s complication profile to aid in surgical decision-making.

Lower Hounsfield units on CT are associated with cage subsidence after anterior cervical discectomy and fusion

J Neurosurg Spine 33:425–432, 2020

A consequence of anterior cervical discectomy and fusion (ACDF) is graft subsidence, potentially leading to kyphosis, nonunion, foraminal stenosis, and recurrent pain. Bone density, as measured in Hounsfield units (HUs) on CT, may be associated with subsidence. The authors evaluated the association between HUs and subsidence rates after ACDF.

METHODS A retrospective study of patients treated with single-level ACDF at the University of California, San Francisco, from 2008 to 2017 was performed. HU values were measured according to previously published methods. Only patients with preoperative CT, minimum 1-year follow-up, and single-level ACDF were included. Patients with posterior surgery, tumor, infection, trauma, deformity, or osteoporosis treatment were excluded. Changes in segmental height were measured at 1-year follow-up compared with immediate postoperative radiographs. Subsidence was defined as segmental height loss of more than 2 mm.

RESULTS A total of 91 patients met inclusion criteria. There was no significant difference in age or sex between the subsidence and nonsubsidence groups. Mean HU values in the subsidence group (320.8 ± 23.9, n = 8) were significantly lower than those of the nonsubsidence group (389.1 ± 53.7, n = 83, p < 0.01, t-test). There was a negative correlation between the HU values and segmental height loss (Pearson’s coefficient −0.735, p = 0.01). Using receiver operating characteristic curves, the area under the curve was 0.89, and the most appropriate threshold of HU value was 343.7 (sensitivity 77.1%, specificity 87.5%). A preoperative lower HU is a risk factor for postoperative subsidence (binary logistic regression, p < 0.05). The subsidence rate and distance between allograft and polyetheretherketone (PEEK) materials were not significantly different (PEEK 0.9 ± 0.7 mm, allograft 1.0 ± 0.7 mm; p > 0.05).

CONCLUSIONS Lower preoperative CT HU values are associated with cage subsidence in single-level ACDF. Preoperative measurement of HUs may be useful in predicting outcomes after ACDF.