Fate of pseudarthrosis detected 2 years after anterior cervical discectomy and fusion: results of a minimum 5-year follow-up.

BACKGROUND CONTEXT: Prior study has shown that 70% of cervical pseudarthrosis after anterior cervical discectomy and fusion (ACDF) detected at 1 year will go on to fusion by 2 year. Pseudarthrosis detected 2 years after ACDF may have different bone healing potential compared to nonunion detected 1 year after surgery. Therefore, it might have a different clinical significance. PURPOSE: To examine the radiographic and clinical prognosis of pseudarthrosis detected 2 years after ACDF with a minimum follow-up of 5 years. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENTS SAMPLE: A total of 249 patients who completed a 5-year follow-up after ACDF. OUTCOMES MEASURES: Clinical outcomes such as neck pain visual analogue scale (VAS), arm pain VAS, and neck disability index (NDI) and radiographic assessment such as X-ray, computed tomography (CT) scan. METHODS: A total of 249 patients who completed a 5-year follow-up after ACDF were retrospectively reviewed. Patients who were diagnosed with pseudarthrosis at 2 years postoperatively were included. Fusion, neck pain VAS, arm pain VAS, and NDI were assessed. The results were compared between the union group (patients who achieved union), and the nonunion group (patients with pseudarthrosis) at 5 years postoperatively. RESULTS: Among the patients who had pseudarthrosis at 2 years postoperatively, the fusion rate at 5 years was 32.6% (14/43). While the union group showed continued improvements in neck pain VAS, arm pain VAS, and NDI until 5 years, the nonunion group showed significant worsening of arm pain VAS and NDI at 5 years, with the values of neck pain VAS, arm pain VAS, and NDI being significantly worse than those of the union group at 5 years. CONCLUSION: The incidence of pseudarthrosis detected at 2 years postoperatively after ACDF was 67.4%, and it remained unfused at 5 years postoperatively. Nonunion identified 2 years after ACDF may be considered a poor prognostic factor because it has less potential to achieve fusion with further follow-up and a higher chance of worsening clinical symptoms. Therefore, the presence of fusion at the 2-year follow-up can be considered an indicator of the success of the surgery.