Three-Level Anterior Cervical Discectomy and Fusion With or Without an Investigational Posterior Stabilization System Assessed Through 24 Months: A Multicenter Randomized Controlled Trial.

Abstract

Prospective randomized controlled trial. This trial was designed to understand safety and effectiveness outcomes in subjects with three-level cervical degenerative disc disease treated with anterior cervical discectomy and fusion (ACDF) alone or supplemented with a posterior cervical fusion (PCF) performed using an investigational posterior cervical stabilization system (PCSS). ACDF remains the most common surgical treatment for cervical disc disease. Long-segment (3+ disc levels) procedures are associated with increased risk of complications including symptomatic nonunion. Supplementing ACDF with PCF to form a circumferential cervical fusion (CCF) improves biomechanical stability but increases the surgical burden for the patient. This multicenter study compared outcomes in participants with three-level symptomatic cervical disc degeneration treated with either ACDF or CCF. The CCF procedure incorporated PCF with PCSS. The primary endpoint was 12-month fusion success, defined by bridging bone across the interbody and range of motion <2° across all treated disc levels. The 24-month secondary endpoint was a composite of fusion success, neck disability index (NDI) improvement, neurological status success, and freedom from surgical revision. This protocol-defined interim analysis included 202 participants with 12-month outcomes and 116 participants with 24-month outcomes. Twelve-month fusion success was higher for CCF (61/100, 61%) compared with ACDF (17/102, 17%) ( P <0.001). The 24-month secondary endpoint was also improved with CCF compared with ACDF [51% (30/59) vs. 23% (13/57); P =0.002]. Revision rates were lower for CCF (1/59, 2%) compared with ACDF (13/57, 23%) ( P <0.001), with 11 of 13 ACDF revisions addressing symptomatic nonunion. Adding supplemental PCF with PCSS did not increase the rates of adverse events (ACDF=65%, CCF=46%, P =0.005). This study represents the first randomized controlled trial assessing treatment of three-level cervical disc disease. Long-segment ACDF demonstrated low fusion rates and high rates of revision. Adding supplemental PCF with PCSS improved fusion without increasing the risk of surgical complications.