P45. Titanium cervical cage subsidence: postoperative CT analysis defining incidence and associated risk factors

Abstract

<h3>BACKGROUND CONTEXT</h3> Substantial variability in both the measurement and classification of subsidence limits the strength of conclusions that can be drawn from previous studies. <h3>PURPOSE</h3> The purpose of this study was to precisely characterize patterns of cervical cage subsidence utilizing computed tomography scans, determine risk factors for cervical cage subsidence and investigate the impact of subsidence on pseudarthrosis rates. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study. <h3>METHODS</h3> We performed a retrospective review of a patients who underwent one- to three-levels of ACDF utilizing titanium interbodies with anterior plating between the years 2018 to 2020. Subsidence measurements were performed by two independent reviewers on CT scans obtained 6 months postoperatively. Subsidence was then classified as mild if subsidence into the inferior and superior endplate were both ≤2mm, moderate if the worst subsidence into the inferior or superior endplate was between 2 to 4mm, or severe if the worst subsidence into the inferior or superior endplate was ≥4mm. <h3>RESULTS</h3> A total of 51 patients (100 levels) were included in this study. A total of 48 levels demonstrated mild subsidence (<2mm), 38 demonstrated moderate subsidence (2–4mm), and 14 demonstrated severe subsidence (>4mm). Risk factors for severe subsidence included male gender, multilevel constructs, greater mean vertebral height loss, increased cage height, lower Taillard Index, and lower screw tip to vertebral body height ratio. Severe subsidence was not associated with an increased rate of pseudarthrosis. <h3>CONCLUSIONS</h3> Following ACDF with titanium cervical cages, subsidence is an anticipated postoperative occurrence and is not associated with an increased risk of pseudarthrosis. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.