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Risk Factors for Postoperative Subsidence of Single-Level Anterior Cervical Discectomy and Fusion: The Significance of the Preoperative Cervical Alignment

Lee, Young-Seok MD; Kim, Young-Baeg MD, PhD; Park, Seung-Won MD, PhD

doi: 10.1097/BRS.0000000000000400
Cervical Spine

Study Design. Retrospective cohort study.

Objective. To investigate and analyze the preoperative risk factors affecting subsidence after anterior cervical discectomy and fusion (ACDF) to reduce subsidence.

Summary of Background Data. Subsidence after ACDF may be caused by various risk factors, although the related information is scarce.

Methods. Seventy-eight patients who underwent single-level ACDF between 2005 and 2011 were included. Patients were categorized into the subsidence (n = 26) and nonsubsidence groups (n = 52). Preoperative factors such as age, sex, operative level, bone mineral density, cervical alignment, segmental sagittal angle, and anterior/posterior disc height were assessed. The use of plates and the anterior/posterior disc height gap were examined as perioperative factors. The clinical outcome was assessed using a visual analogue scale for neck and arm pain.

Results. Subsidence occurred in 26 (33.3%) of 78 patients. A significant difference was found in clinical outcomes between the subsidence and nonsubsidence groups (P < 0.05). The fusion rate was 61.5% in the subsidence group. The mean time to subsidence was 4.8 months. Logistic regression analysis revealed that cervical alignment (P = 0.017), age (P = 0.022), and use of plates (P = 0.041) affected subsidence. In patients who received a stand-alone cage, the risk of subsidence was significantly greater in the kyphotic angle group than in the lordotic angle group (odds ratio = 13.56; P < 0.001).

Conclusion. After ACDF, the main factors affecting subsidence are cervical alignment, age, and use of plates. Our data suggest that surgeons should consider the kyphotic curvature and/or age when deciding on the use of plates.

Level of Evidence: 4

Subsidence after anterior cervical discectomy and fusion caused lower fusion rate and poor clinical and radiological outcomes. After anterior cervical discectomy and fusion, the main factors affecting subsidence are cervical alignment, age, and use of plates.

From the Department of Neurosurgery, Chung-Ang University College of Medicine, Seoul, Korea.

Address correspondence and reprint requests to Young-Baeg Kim, MD, PhD, Department of Neurosurgery, Chung Ang University College of Medicine, 224-1 Heukseok-dong, Dongjak-gu, Seoul, 156-755, Republic of Korea; E-mail:

Acknowledgment date: December 11, 2013. First revision date: February 19, 2014. Second revision date: March 11, 2014. Third revision date: April 9, 2014. Acceptance date: April 11, 2014.

The device(s)/drug(s) is/are FDA approved or approved by corresponding national agency for this indication.

No funds were received in support of this work.

No relevant financial activities outside the submitted work.

© 2014 by Lippincott Williams & Wilkins