MATERIAL and METHODS: Major databases, registries, and other relevant material were screened for prospective trials directly comparing AECD and ACDF. No restrictions were imposed. Meta-analysis was not conducted due to high heterogeneity.

RESULTS: After screening a total of 1339 articles, 2 studies enrolling 225 patients were included. One of these is a randomizedcontrolled- trial, including 120 patients, with a 14% lost to follow-up, showing no statistically significant differences in clinical outcomes according to the visual analogue scale (VAS) of the neck/arm and the North American Spine Society criteria regarding pain/neurological status. Radiological follow-up showed no adjacent-segment disease, with both groups presenting a statistically non-significant progression of a pre-existing adjacent-disc degeneration, and no difference in kyphosis. Recurrence was registered in 7.4% and 6.1% of patients who underwent AECD and ACDF, respectively. No statistically apparent differences in complications were observed. The second is a cohort study, including 135 patients with a 14.8% lost to follow-up. No statistically significant difference was found in clinical outcomes assessed using the VAS of the neck/arm and the neck disability index. No radiological data were provided. Recurrence was reported in 4% and 2% of patients in the AECD and ACDF group, respectively. No remarkable differences in complications were reported. Both studies reported that the surgical time was statistically shorter in AECD.

CONCLUSION: A definitive conclusion cannot be drawn. Single-level AECD seems to have results equivalent to ACDF, presenting even some benefits. Technical limitations combined with required surgical skills and experience should be considered. We recommend cautious employment in anticipation of future updates. Keywords : Endoscopic, Anterior, Cervical, Discectomy, Herniation, Minimally invasive