Three-level Anterior Cervical Discectomy and Fusion with or without an Investigational Posterior Stabilization System Assessed through 24 Months: A Multi-Center Randomized Controlled Trial.

Study design: Prospective Randomized Controlled Trial.

Objective: 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).

Background: 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 non-union. Supplementing ACDF with PCF to form a circumferential cervical fusion (CCF) improves biomechanical stability but increases the surgical burden for the patient.

Methods: This multi-center study compared outcomes in participants with 3-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.

Results: 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 to ACDF (17/102, 17%) (P<0.001). The 24-month secondary endpoint was also improved with CCF compared to ACDF (51% [30/59] vs 23% [13/57]; P=0.002). Revision rates were lower for CCF (1/59, 2%) compared to ACDF (13/57, 23%) (P<0.001), with 11 of 13 ACDF revisions addressing symptomatic non-union. Adding supplemental PCF with PCSS did not increase the rates of adverse events (ACDF=65%, CCF=46%, P=0.005).

Conclusions: This study represents the first randomized controlled trial assessing treatment of 3-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.