Surgery on the C3-4 Level and the Presence of Ligamentum Flavum Hypertrophy Increases the Risk of 30-Day Reoperation Rate After Anterior Cervical Discectomy and Fusion.

Background And Objectives: Cervical myelopathy caused by C3-4 level degeneration often exhibits different characteristics after anterior cervical discectomy and fusion (ACDF) than other cervical levels. This study compared the outcomes of C3-4 ACDF with surgeries at other levels and identified risk factors of 30-day reoperation after ACDF.

Methods: We retrospectively analyzed patients who underwent ACDF for degenerative cervical disease from 2018 to 2023. The patients were divided into 2 groups based on the level of surgery: C3-4 and non-C3-4 groups. Radiological outcomes, including cervical alignment and range of motion (ROM), were analyzed. Clinical outcomes were assessed with patient-reported outcomes and the rates of 30-day reoperation and complications after ACDF. Patient-reported outcomes included visual analog scale for neck pain, visual analog scale for arm pain, and modified Japanese Orthopedic Association scores. Risk factors of 30-day reoperation were assessed.

Results: Of 259 patients, 74 (28.6%) and 185 (71.4%) were in the C3-4 and non-C3-4 groups, respectively. The C3-4 group exhibited lower C2-7 ROM (P = .019), higher C3-4 ROM (P = .015), and greater C3-4 %ROM (P = .014). The C3-4 group demonstrated lower preoperative and 1-month postoperative modified Japanese Orthopedic Association scores (P < .001; P < .001, respectively). The rate of 30-day reoperation was significantly higher in the C3-4 group (9.5%) compared with the non-C3-4 group (2.2%) (P = .014). In addition, C3-4 surgical level (odds ratio = 4.99, P = .034) and ligament flavum hypertrophy (odds ratio = 5.84, P = .018) were identified as independent risk factors of 30-day reoperation after ACDF.

Conclusion: Surgery on C3-4 level showed a higher risk of 30-day reoperation than other levels. It is likely due to C3-4 surgical level, and ligament flavum hypertrophy contributes to cord compression, particularly in the unstable early postoperative period.