Radiographic and Clinical Changes After Single-Level Anterior Cervical Discectomy and Fusion at C5–C6 and C6–C7: A Retrospective 12-Month Follow-up Study

AIM: This study aimed to evaluate radiographic sagittal angle changes and clinical outcomes after single-level anterior cervical discectomy and fusion (ACDF) performed at either the fifth–sixth cervical vertebral level (C5–C6) or C6–C7.
MATRERIAL and METHOD: This retrospective study included 56 patients who underwent single-level ACDF at C5–C6 or C6–C7 and completed 12 months of clinical and radiographic follow-up. Patients were divided into two equal groups according to the operated level: C5–C6 (n = 28) and C6–C7 (n = 28). Radiographic assessment included C2–C7 Cobb angle, and T1 slope on standing lateral cervical radiographs. Clinical outcomes were evaluated using neck and arm visual analog scale (VAS) scores, the Neck Disability Index (NDI), and the modified Japanese Orthopaedic Association (mJOA) score. Preoperative and postoperative values were compared within groups, and postoperative changes were compared between surgical levels.
RESULTS: The overall mean C2–C7 angle increased postoperatively, indicating a mean lordotic gain of 4.7° ± 2.6°. The mean lordotic gain was greater in the C5–C6 group than in the C6–C7 group (6.4° ± 2.9° vs. 3.1° ± 2.2°, p = 0.03). No significant between-group difference was observed for preoperative or postoperative T1 slope. Neck and arm VAS scores decreased significantly at 12 months, while mJOA and NDI scores improved significantly. However, clinical improvement did not differ significantly between the C5–C6 and C6–C7 groups.
CONCLUSION: Single-level ACDF was associated with significant clinical improvement and increased C2–C7 lordosis at 12 months. C5–C6 surgery showed greater lordotic gain than C6–C7 surgery, while clinical outcomes were comparable between levels. Larger prospective studies and longer follow-up are needed to determine the clinical relevance of this radiographic difference.