Radiological outcomes following hyperlordotic cage insertion in anterior cervical discectomy and fusion

Abstract

Background: Cervical alignment is associated with myelopathy and quality of life. Anterior cervical discectomy and fusion (ACDF) aims to decompress neural structures and optimise cervical alignment. This study examines the quantitative impact of the hyperlordotic 15° ACDF cage on cervical alignment, and compares it to that of the standard lordosis cage. Methods: A retrospective analysis of radiographical parameters of cervical alignment was conducted in 80 consecutive ACDF patients from two institutions between 2013 and 2017. Forty received 15° cages, 40 received standard cages. Pre- and post-operative Cobb angles and sagittal vertical axes (SVA) were generated from radiographical imaging utilising the SurgimapTM program. Changes in lordosis and SVA were compared within and between groups, and the significance of the change evaluated using the Student t-test. Results: In both groups, post-operative device level, segmental, and global Cobb angles were superior to preoperative values (P<0.05), especially among patients with preoperative kyphosis (P<0.05). Trends suggested greater changes in lordosis in the 15° group, but they did not reach statistical significance (P=0.06– 0.23). However, subgroup analyses indicated greater device level Cobb angle change in patients less than 65 yo (P=0.049), and those with preoperative lordosis (P=0.003). Neither standard nor hyperlordotic cages significantly improved SVA in this study. Conclusions: Hyperlordotic and standard cages both improve cervical lordosis segmentally and globally. Hyperlordotic cages were not shown to be statistically superior to standard cages in this study. Prospective studies featuring consistent imaging modalities are necessary to further delineate their utility.