Comparative Radiological Outcomes of Stand-alone Cage versus Cage and Plate in Anterior Cervical Discectomy and Fusion: A Retrospective Cohort Study

Abstract

Background Anterior cervical discectomy and fusion (ACDF) is one of the most commonly used techniques for neural decompression in degenerative cervical radiculopathy and cervical myelopathy. Controversies regarding the superiority of cage augmentation with anterior cervical plate remain, yet several surgeons are still performing ACDF with a stand-alone cage (ACDF-SA). Our study aimed to compare the radiological outcomes between the ACDF augmented with anterior cervical plate (ACDF-CPA) and ACDF-SA in single-level cervical degenerative disc disease. Methods A retrospective data review was conducted for patients who underwent ACDF between January 2011 and December 2019. All adult patients who underwent single-level ACDF for cervical radiculopathy and myelopathy with at least 12 months of follow-up were included in the study. Patients who had a systemic infection, trauma injury, history of malignancy, inadequate radiographs, and less than 12 months of follow-up were excluded from the study. Radiological outcomes, including cage subsidence, fusion rate, and adjacent segment degeneration, were assessed by two senior orthopaedic spine fellows. Adjusted risk ratios were used to compare the radiological outcomes of ACDF-SA and ACDF-CPA, adjusting for age and gender. Results A total of 43 patients were included. Among them, 58% of the patients underwent a stand-alone cage ACDF, while 42% had anterior cervical plate augmentation. The overall fusion rate at 6 months was 76%. The ACDF-SA group's fusion rate was 88%, while that of the ACDF-CPA group was 61%. At 12 months, the overall fusion rate was 81% and was comparable between the two groups. Cage subsidence and adjacent segment degeneration rates were similar between the groups at 6 and 12 months. Adjusted relative risk analysis showed a 50% higher probability of fusion at 6 months in the ACDF-SA group compared with the ACDF-CPA group (95% confidence interval [CI]: 1.01-2.22) and a 22% higher probability at 12 months, though not statistically significant (95% CI: 0.90-1.64). Female gender was associated with higher fusion rates and lower subsidence risk at 12 months. Conclusion Augmentation with the anterior cervical plate in ACDF did not show superiority to the conventional stand-alone cage in mono-segmental ACDF. Our study showed similar outcomes regarding cage subsidence, adjacent segment disease, and fusion rates at 12 months. However, the stand-alone cage achieved faster fusion at 6 months than the plate group.

Keywords: adjacent segment degeneration; anterior cervical discectomy and fusion (ACDF); anterior cervical plate; stand-alone cage.

Fig. 1

Lateral X-ray of the cervical spine with stand-alone cage, the blue line indicating the midpoint of the lower margin of the upper vertebra and the upper margin of the lower vertebra at the fusion site for which the cage subsidence is measured.