Clinical outcomes of locking stand-alone cage versus anterior plate construct in two-level anterior cervical discectomy and fusion: a systematic review and meta-analysis

Abstract

Two-level cervical degenerative disc disease (cDDD) can be effectively treated by anterior cervical discectomy and fusion (ACDF) similarly to single-level cDDD. Traditionally an anterior plate construct (APC) approach has been utilized, but ACDF without plate with a locking stand-alone cage (LSC) approach has emerged as an alternative option. The aim of this study was to compare the clinical outcome of LSC and APC in contiguous two-level ACDF used to treat cDDD the current literature. Searches of seven electronic databases from inception to March 2018 were conducted following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Extracted data were analysed using meta-analysis of proportions. The nine observational studies that satisfied all criteria described a pooled cohort of 687 contiguous two-level cDDD cases managed by ACDF, with 302 (44%) and 385 (56%) managed by LSC and APC approaches, respectively. When compared with APC, LSC was associated with significantly increased subsidence likelihood (OR 2.75; p < 0.001), greater disc height (MD 0.60mm; p = 0.04) and reduced cervical lordosis (MD - 2.52°; p = 0.04) at last follow-up. Operative outcomes, fusion rates, functional scores and postoperative dysphagia rates were comparable. Although significant radiological differences were most evident, the comparability between LSC and APC in contiguous two-level ACDF with respect to all other clinical outcomes does not implicate one approach as clearly superior to the other in two-level ACDF. Larger, randomized studies with longer follow-up are required to delineate outcomes further to validate the findings of this study. These slides can be retrieved under Electronic Supplementary Material.