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STUDY DESIGN Secondary analysis of subjects in the control Anterior Cervical Discectomy and Fusion (ACDF) arm of Medtronic Investigational Device Exemption (IDE) trials for cervical disc arthroplasty (CDA) OBJECTIVES.: To compare Patient Reported Outcomes (PROs) in patients with radiographic nonunion to patients with a solid fusion. SUMMARY OF BACKGROUND DATA The true prevalence of nonunion after ACDF is unknown. Nonunion may be under-reported, as some patients are not symptomatic enough to justify radiographic evaluation. METHODS 345 subjects enrolled in the control arm of IDE trials for CDA who had single-level ACDF with allograft and plate with 24 month data formed the study cohort. Using the 24-month post-op evaluation, subjects were divided into those who had radiographic fusion and those who did not using strict study criteria. SF-36, NDI, Neck and Arm pain NRS scores were reported at 12, 24, 36, 60 and 84 months post-op. For subjects who had secondary surgery failures, the last observations before the secondary surgery were carried forward to future visits for the analysis. RESULTS 44 (13%) patients had radiographic non-union and 301 (87%) were fused at 24 months post-op. At 24 months, PROs were similar between the two groups. Seven patients in the Nonunion group (16%) and 10 (3%) in the Fused group had additional surgery at the index level prior to the 24 -follow-up (p = 0.003). Over the 84-month follow-up a total of 9 patients in the Nonunion group (21%) and 22 (7%) in the Fused group had additional surgery at the index level (p = 0.009). CONCLUSION While the radiographic non-union rate at 24 months was 13%, PROs show that many of the radiographic non-unions were asymptomatic. Although the majority of patients with radiographic non-union did not undergo additional surgery, the rate of secondary surgeries at the index level was significantly higher in the radiographic non-union group. LEVEL OF EVIDENCE 2.