Prospective, Randomized, Double-Blind Clinical Study Evaluating the Correlation of Clinical Outcomes and Cervical Sagittal Alignment

BACKGROUND: Sagittal alignment of the cervical spine has received increased attention in the literature as an important determinant of clinical outcomes after anterior cervical diskectomy and fusion. Surgeons use parallel or lordotically fashioned grafts depending on preference or simple availability. OBJECTIVE: To quantitatively assess and compare cervical sagittal alignment and clinical outcome when lordotic or parallel allografts were used for fusion. METHODS: A prospective, randomized, double-blind clinical study that enrolled 122 patients was performed. The mean follow-up was 37.5 months (range, 12-54 months). RESULTS: The mean postoperative cervical sagittal alignment was 19 degrees (range, -7 degrees-36 degrees) and 18 degrees (range, -7 degrees-37 degrees) in the lordotic and parallel graft patient groups, respectively. The mean segmental sagittal alignment was 6 degrees (range, -4 degrees-19 degrees) and 7 degrees (range, -3 degrees-19 degrees) in the lordotic and parallel graft patient groups, respectively. There were no statistically significant differences in clinical outcome scores between the lordotic and parallel graft patient groups. However, patients who had maintained or improved segmental sagittal alignment, regardless of graft type, achieved a higher degree of improvement in Short Form-36 Physical Component Summary and Neck Disability Index scores. This was statistically significant (P < .038). CONCLUSION: The use of lordotically shaped allografts does not increase cervical/segmental sagittal alignment or improve clinical outcomes. Maintaining a consistent segmental sagittal alignment or increasing segmental lordosis was related to a higher degree of improvement in clinical outcomes.