Neurosurgery Resident Barrow Neurological Institute Phoenix, Arizona, United States
Introduction: Fusion rates and long-term outcomes are well studied for ACDF of three levels or less, but much less is known regarding surgery on four segments. We evaluated long-term fusion rates and outcomes after four-level ACDF without posterior supplementation.
Methods: We retrospectively reviewed patients who underwent four-level ACDF at a single institution with at least one-year follow-up. Fusion was evaluated using dynamic radiographs at one-year follow-up, with clinical outcomes using Neck Disability Index (NDI) and Short Form-36 (SF-36) being recorded at this time.
Results: A total of 65 patients and 260 levels met criteria and were included, with a mean follow-up of 2.7 years. Complete fusion at all four levels was observed in 27 patients (41.5%). Of the 38 patients (58.5%) without complete fusion, there was a mean of 1.34 levels demonstrating pseudoarthrosis. The fusion rate per level, however, was 80.4%. The most common level demonstrating non-union was the distal segment (C6/7), showing pseudoarthrosis in 30 patients (46.9%), followed by the most proximal segment (C3/4) demonstrating non-union in 9 patients (12.8%). At one-year, patients reported a mean improvement in NDI by 15.7 (25.8% improvement) as well as a mean improvement in SF-36 of 5.8 (18.1% improvement). Only one patient (1.5%) required revision surgery for symptomatic pseudoarthrosis, and five patients (7.2%) requiring revision for symptomatic adjacent segment disease.
Conclusion : Four-level ACDF without posterior supplementation demonstrated a high fusion rate per level, but more than half of patients demonstrated pseudoarthrosis of at least one level, most commonly the distal end of the construct at C6/7. The clinical relevance of cases involving one or two levels of radiographic pseudoarthrosis is likely minimal, as only one patient required revision for symptomatic pseudoarthrosis in addition to significant improvements in patient-reported outcomes at one-year follow-up. This is the largest series to examine long-term radiographic outcomes in four-level ACDF to date.
How to Improve Patient Care: The authors believe that four-level ACDF is effective and can be good alternative to posterior fusion in patients with multi-level disease.
