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Analysis of Associating Factors With C2-7 Sagittal Vertical Axis After Two-level Anterior Cervical Fusion: Comparison Between Plate Augmentation and Stand-alone Cages

Kwon, Woo-Keun MD; Kim, Pyeong Soo MD; Ahn, Seong Yong MD; Song, Jye Young MD; Kim, Joo Han MD, PhD; Park, Youn-Kwan MD, PhD; Kwon, Taek-Hyun MD, PhD; Moon, Hong Joo MD, PhD

doi: 10.1097/BRS.0000000000001776
Cervical Spine

Study Design. A retrospective review.

Objective. We investigated the longitudinal change of cervical alignment parameters including C2-7 lordosis, C2-7 sagittal vertical axis (SVA), T1 slope, and segmental angle (SA) after two-level anterior cervical discectomy and fusion (ACDF).

Summary of Background Data. Cervical alignment may influence postoperative clinical outcomes. Several studies have suggested that cervical alignment may serve as a parameter for assessing cervical deformities similar to those used to assess thoracolumbar spine deformities. However, to our knowledge, no studies have investigated the effect of ACDF on cervical sagittal alignment.

Methods. We enrolled patients whom had ACDF, 23 patients with stand-alone cages and 22 with plate augmentation. Radiologic parameters including C2-7 lordosis, C2-7 SVA, T1 slope, and SA at the operated level were evaluated preoperatively and at 1 week and 6 months postoperatively. The differences between preoperative and 6-month postoperative parameter values were designated as Δvalues. T1S-CL was calculated as the T1 slope minus C2-7 lordosis. Clinical outcome were obtained by the Visual Analog Scale (VAS) and the Neck Disability Index (NDI).

Results. ΔC2-7 SVA was significantly correlated with ΔT1S-CL and ΔC2-7 lordosis. ΔC2-7 lordosis was significantly correlated with ΔSA. ΔC2-7 lordosis had a significantly greater impact on ΔT1S-CL than did ΔT1 slope. The ΔSA and ΔC2-7 lordosis in the ACDF-plate were significantly higher than those in the in ACDF-cage. ΔT1S-CL and ΔC2-7 SVA in the ACDF-plate were significantly lower than those in the ACDF-cage.

Conclusion. C2-7 SVA after two-level ACDF was affected more significantly by the SA and C2-7 angle than by the T1 slope. Two-level ACDF with plate restored more cervical lordosis by obtaining more segmental lordosis at the operated level and was more effective in terms of cervical alignment compared with ACDF using stand-alone cages.

Level of Evidence: 3

Department of Neurosurgery, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.

Address correspondence and reprint requests to Hong Joo Moon, MD, PhD, Department of Neurosurgery, Korea University Guro Hospital, Korea University College of Medicine, 148 Gurodongro, Gurogu, 08308, Seoul, Korea; E-mail:

Received 9 April, 2016

Accepted 23 May, 2016

The manuscript submitted does not contain information about medical device(s)/drug(s).

This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning(NRF-2015R1C1A1A02037471).

No relevant financial activities outside the submitted work.

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