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Cages in ACDF are Associated With a Higher Nonunion Rate Than Allograft

A Stratified Comparative Analysis of 6130 Patients

Pirkle, Sean, BA; Kaskovich, Samuel, BSA; Cook, David J., BA, BEng; Ho, Alisha, BA; Shi, Lewis L., MD; Lee, Michael J., MD

doi: 10.1097/BRS.0000000000002854

Study Design. A retrospective database review.

Objective. The purpose of this study was to analyze the rate of nonunion in patients treated with structural allograft and intervertebral cages in anterior cervical discectomy and fusion (ACDF).

Summary of Background Data. Existing literature consists primarily of single-center studies with inconsistent findings.

Methods. We performed a retrospective analysis of 6130 patients registered in the PearlDiver national database through Humana Insurance from 2007 to 2016. All ACDF patients with anterior plating who were active in the database for at least 1 year were included in the study. Patients with a fracture history within 1 year of intervention, past arthrodesis of hand, foot, or ankle, or a planned posterior approach were excluded from the study. Patients were stratified by number of levels treated, tobacco use, and diabetic condition. Nonunion rates of structural allograft and intervertebral cage groups after 1 year were compared using Chi-squared analyses.

Results. Four thousand sixty-three patients were included in the allograft group, while 2067 were included in the cage group. Overall nonunion rates were significantly higher in the cage group (5.32%) than in allograft group (1.97%) (P < 0.01). When controlling for confounders, increased rates of nonunion were consistently observed in the cage group, achieving statistical significance in 25 of the 26 analyses.

Conclusion. The increased rate of nonunion associated with intervertebral cages may suggest the superiority of allograft over cages in ACDF.

Level of Evidence: 3

The long-term success of anterior cervical discectomy and fusion is associated with solid fusion. In this study, we found that both anterior cervical discectomy and fusion with structural allograft and cage have high fusion rates. However, these data suggest that the use of a cage is associated with a significantly higher rate of nonunion as compared to structural allograft.

Department of Orthopaedic Surgery and Rehabilitation Medicine, University of Chicago Medical Center, Chicago, IL.

Address correspondence and reprint requests to Sean Pirkle, BA, 5120 S Greenwood Ave, Apt #2, Chicago, IL 60615; E-mail:

Received 30 May, 2018

Revised 1 August, 2018

Accepted 9 August, 2018

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.

Relevant financial activities outside the submitted work: grants.

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