BACKGROUND CONTEXT Cervical sagittal balance influences spinal biomechanics and may be affected by anterior cervical discectomy (ACD), potentially affecting clinical outcomes. PURPOSE To evaluate longitudinal changes in cervical sagittal alignment over 5 years following single-level ACD with or without fusion or arthroplasty and assess associations with clinical outcomes. STUDY DESIGN Post hoc analysis of the Netherlands Cervical Kinematics (NECK) trial (NTR1289). PATIENT SAMPLE Patients undergoing single-level ACD with or without fusion or arthroplasty for cervical radiculopathy were evaluated at baseline, 1-, 2-, and 5-years follow-up. OUTCOME MEASURES C0-C2 angle, C2-C7 Cobb angle, segmental Cobb angle, C7 angle, T1 angle, T1-CL (T1 angle minus C2-C7 lordosis) and C2-C7 sagittal vertical axis (SVA) were measured on lateral radiographs. Clinical outcomes included the Neck Disability Index (NDI) and Visual Analog Scale (VAS) for arm and neck pain. METHODS Linear mixed models assessed longitudinal changes, corrected for potential confounders. Linear regression evaluated associations between alignment and clinical outcomes. RESULTS Out of 109 enrolled patients, 81 patients had a lateral X-ray available at baseline. C2-C7 Cobb angle increased from 9.0° at baseline to 13.8°, 12.3°, and 13.6° at 1-, 2-, and 5-year follow-up (p<0.001). T1-CL decreased from 12.5° to 4.7°, 6.4°, and 6.8° (p<0.05). SVA decreased from 16.1 mm to 10.5 and 10.7 mm at 1 and 2 years (p<0.05), returning to 14.8 mm at 5 years. C0-C2 angle increased from 19.4° at 1 year to 23.1° at 5 years (p<0.005). Men showed greater subaxial lordosis; women greater upper cervical lordosis. At 1 year, a more positive segmental Cobb angle was associated with lower arm pain (B=-1.99, p=0.02) and higher SVA with increased arm pain (B=0.48, p=0.04). CONCLUSIONS Single-level ACD with or without fusion or arthroplasty is associated with long-term increases in cervical lordosis with sex-specific compensatory patterns. Alignment-outcome cross-sectional associations were limited to early follow-up, suggesting that restoring adequate segmental lordosis at surgery may reduce early postoperative arm pain.
