Assessment of Bony Fusion With an Integrated Cage/Screw Device for Anterior Cervical Fusion With Computed Tomography

STUDY DESIGN: Retrospective review. OBJECTIVE: Determine the rate of bony union of an integrated cage/screw polyether-ethyl ketone (PEEK) cervical interbody fusion device with computed tomography (CT) and provide long-term outcomes of patients treated with such. SUMMARY OF BACKGROUND DATA: Anterior cervical discectomy and fusion (ACDF) is a common treatment option for patients with degenerative cervical conditions that have failed conservative treatment. Stand-alone anchored cages offer the theoretical advantage of decreasing soft tissue dissection off the anterior vertebral body and mitigating risk to surrounding structures while still achieving solid fusion. METHODS: A retrospective review was conducted from a single institution's enrollment data during a postmarket surveillance study for the Stalif-C (Centinel Spine, West Chester, PA). Three surgeons independently reviewed CT scans from 1 and 2-year follow-up visits to assess for fusion. The criteria for fusion were the presence of bridging bone in at least one of 5 regions (anterior, posterior, right, left uncovertebral joint, and intracage) on 2 consecutive slices of the CT scan using 1 mm coronal and sagittal reformats. These same surgeons repeated their assessment of the imaging studies at a minimum of 2 weeks after the initial review. The resulting fusion rates were then averaged to provide a mean fusion rate at the 1 and 2-year points. RESULTS: A total of 34 patients were enrolled in the study with 2 patients withdrawing consent after the procedure. Thirty had completed their 1-year follow-up with imaging studies comprising 32 levels treated. Twenty-three patients (25 levels) completed a 2-year follow-up at the time of this study. The average bony fusion rate at 1 year was 37% (range: 19%-56%) and at 2 years was 50% (range: 40%-60%). CONCLUSION: The rate of bony fusion as assessed by CT scans at 1 and 2 years was 37% and 50%, respectively. This is well below previously published fusion rates for standalone constructs. LEVEL OF EVIDENCE: Level III.