The Relationship Between Cervical Sagittal Balance and Adjacent Segment Disease After Three-level Anterior Cervical Discectomy and Fusion.

Study Design: Retrospective review of prospectively collected data.

Objective: To determine the relationship between cervical sagittal balance and adjacent segment degeneration (ASD) development after 3-level anterior cervical discectomy and fusion (ACDF).

Summary Of Background Data: ASD is a common complication after ACDF. Previous studies have shown that sagittal imbalance may be associated with ASD development after 1-level or 2-level ACDF. However, these findings may not be generalizable to 3-level procedures.

Materials And Methods: We reviewed prospectively collected data of 46 patients who underwent 3-level ACDF at a tertiary institution. Lateral cervical radiographs taken preoperatively, postoperatively, and at last follow-up were reviewed for ASD. The mean follow-up duration was 5 years. Radiographic parameters measured were cervical sagittal alignment (CSA), segmental sagittal alignment, T1 slope (T1S), sagittal vertical axis, and T1S-cervical lordosis.

Results: ASD was present in 27 (58.7%) patients, but only 1 patient (2.2%) underwent reoperation at 4.8 years. The CSA, sagittal vertical axis, and T1S were similar preoperatively, but the T1S-cervical lordosis was higher in the ASD group (18.28 vs. 9.82, P =0.016). All 4 parameters were similar postoperatively and at last follow-up. The ASD group had a greater change in CSA over the follow-up period (-6.26 vs. -1.47, P =0.05), but they achieved similar sagittal alignment at last follow-up. There was no difference in clinical outcomes between the 2 groups.

Conclusions: Unlike studies on 1-level and 2-level ACDF, this study found that cervical spinal alignment was not associated with ASD development after 3-level ACDF. ASD development also had no impact on clinical outcomes at 2 years.

Level Of Evidence: Level III-nonrandomized cohort study.