P13. ACDF fusion rates

Abstract

BACKGROUND CONTEXT Anterior cervical discectomy and fusion (ACDF) is a common procedure for the treatment of cervical radiculopathy and myelopathy. PURPOSE Multilevel ACDFs are often used to address multi-level cervical stenosis. The purpose of this study is to provide a chronological, level-specific characterization of fusion order and fusion rates. Such information will be useful when advising patients preoperatively and adequately assessing their post-operative arthrodesis. STUDY DESIGN/SETTING Three-level ACDF cases from March 2016 to October 2019 were reviewed. In total, 57 cases were selected with the following fusion locations: one fusion at C2-5, eight at C3-6, 43 at C4-7, and three at C5-T1. Radiographic measurements were taken at 6 weeks, 6 months, and 1 year postoperatively. Due to incomplete follow-up, we report outcomes for 50, 39, and 23 patients at 6-weeks, 6- months, and 1-year postoperative time points, respectively. PATIENT SAMPLE The studied cohort consisted of 26 males and 29 females with an average age of 59.1 (±9.6) years. OUTCOME MEASURES The primary outcomes measured were fusion rates. Radiographic measurements were performed at 6 weeks, 6 months, and 1 year postoperatively. Fusion criteria are further described in the “methods” section. METHODS Flexion and extension lateral radiographs were obtained for enrolled patients. The junior author independently measured distances between spinous processes at all levels with anterior plating in addition to the immediate noninstrumented cranial level and the immediate non-instrumented caudal level. All measurements were performed with at least 1.5x magnification. Fusion criteria for all levels consisted of £1mm of movement on flexion and extension with an absence of a radiolucent gap between graft and endplate. Additionally, there has to be at least 4mm movement at the non-fusion levels to ensure adequate patient effort with neck flexion/extension. RESULTS At 6 weeks postoperatively, the following fusion rates were observed: 5/50 (17.9%) were fused at the top level; 14/50 (28%) were fused at the middle level, and 3/50 (6%) were fused at the bottom level. At 6 months postoperatively, the following fusion rates were observed: 19/39 (48.7%) patients were fused at the top level, 19/39 (48.7%) were fused at the middle level, and 2/39 (5.1%) were fused at the bottom level. Lastly, at 1 year postoperatively, we observed the following fusion rates: 18/23 (78.3%) were fused at the top level, 23/23 (100%) were fused at the middle level, and 5/23 (21.7%) were fused at the bottom level. Complete bony fusion at all three levels was observed in 5/23 (21.7%) patients at 1 year postoperatively. CONCLUSIONS The preliminary data suggest that the bottom level has highest risk for pseudarthrosis after 3-level ACDF, and the middle level has the highest fusion rate (100%) at 1 year postoperatively. Dr. Lee A. Tan is the co-senior author on this abstract. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.