Motion analysis of dynamic cervical implant stabilization versus anterior discectomy and fusion: a retrospective analysis of 70 cases

Purpose Retrospective kinematic analysis of treated level, adjacent levels, and overall cervical spine after single-level dynamic cervical implant (DCI) stabilization versus anterior cervical discectomy and fusion (ACDF). Methods Between June 2009 and March 2013, 70 consecutive patients with a symptomatic single-level cervical degenerative disk disease (DDD) were enrolled in this study and divided into DCI (n=35) group and ACDF (n=35) group. All cases were followed up for more than 5years. The study compared perioperative parameters; clinical outcomes; and radiological parameters. Kinematic analysis included range of motion (ROM) of treated level and adjacent level, overall ROM (C2-C7), and changes in adjacent disk spaces. Results There were no significant differences between the DCI group and ACDF group in terms of improvement in the SF-36, VAS, NDI, and JOA scores. DCI stabilization resulted in better ROM of C2-C7 and the treated level than ACDF did. The ROM of treated level decreased significantly at 24months after surgery and last follow-up in the DCI group, and the C2-C7 ROM showed different degrees of reduction after the 24months after surgery. Radiological evidence of adjacent segment degeneration (ASD) at last follow-up was observed in 4/22 patients (18.2%) in the DCI group and 5/23 patients (21.7%) in the ACDF group which was not a significant difference between groups (p>0.05). Conclusions DCI stabilization for the treatment of cervical DDD cannot preserve the normal kinematics of the cervical spine for a long time, especially the treated level. DCI stabilization cannot decrease the risk of ASD compared with ACDF.