Mid-term outcomes of revision anterior fusion versus cervical disc arthroplasty in patients with prior single-level anterior cervical fusion.

Background context: Revision cervical surgery presents unique challenges due to altered anatomy and biomechanics from the previous fusion. Revision anterior cervical discectomy and fusion (ACDF) offers the benefit of immediate stability but further reduces cervical mobility and may increase stress on remaining segments, potentially leading to additional degeneration. By performing a cervical disc arthroplasty (CDA) in the presence of a prior ACDF, a hybrid surgery (HS) construct is created, potentially combining the benefits of fusion stability with CDA motion preservation.

Purpose: To compare the outcomes of one-level ACDF or CDA in patients with a history of prior one-level ACDF.

Study design: Retrospective cohort study.

Patient sample: Patients undergoing one-level ACDF or CDA with a history of prior one-level ACDF, with records in the Pearl Diver database from 2010 to April 30, 2023. All patients had 1-year minimum follow-up; surgeries for trauma, infection, or neoplasm, and those with concomitant cervical procedures were excluded.

Outcome measures: The primary outcome was any cervical reoperation at 2-years and 5-years postoperatively. Types of reoperations, 90-day complications, 2-year complications, and 2-year cost were evaluated.

Methods: The ACDF and CDA groups were propensity score matched in a 3:1 ratio. Univariate analyses (chi-square and independent samples t-tests) were performed to compare demographics, comorbidities, and outcomes after matching. Kaplan Meir analysis was performed to compare 5-year reoperation-free survival between the ACDF and CDA groups; survival rates were compared using the Log Rank test.

Results: After matching, 792 ACDF and 264 CDA patients were included. No significant differences in demographics or comorbidities were observed. The overall rate of 90-day complications was 3.9% in the ACDF and 3.0% in the CDA group; no significant differences in complication rates were found. ACDF patients experienced higher rates of pseudoarthrosis (6.4 vs. 1.1%, p=.001) at 2-years postoperatively. Overall, two-year reoperation rates were similar between groups (ACDF: 10.7 vs. CDA: 7.6%, p=.172). Over the 5-year postoperative period, no significant differences in ACDF, ACDF or CDA, other cervical, or any cervical reoperations were observed. The rate of any cervical reoperation was 13.5% in the ACDF group and 13.3% in the CDA group (p=1.000). No significant differences in 5-year reoperation-free survival were found between ACDF and CDA patients.

Conclusions: Both single-level ACDF and CDA yielded similar complication and reoperation rates at 2- and 5-years postoperatively in patients with a history of prior single-level ACDF. Either approach appears to be a viable treatment strategy in patients requiring reoperation after single-level ACDF. However, future studies are required to validate these findings in more homogenous patient populations, and to compare the functional and radiographic outcomes of ACDF and CDA in the revision setting.