1228 Is Obtaining a CT Prior to Offering Disc Arthroplasty Necessary? The Results of Surgeons Predicting ACDA Candidacy from MRIs and X-Rays Alone

INTRODUCTION: Contraindications to anterior cervical disc arthroplasty (ACDA) include ossification of the posterior longitudinal ligament (OPLL) and significant bridging osteophytes. CT is the gold standard for identifying these findings, although whether a combination of MRI and plain radiographs is sufficient is not established. METHODS: Ten senior spine surgeons evaluated predetermined ACDA candidates’ preoperative MRIs and X-rays in a blinded, random review over two separate sessions. Reviewers identified the presence of OPLL and/or osteophytes. Intra-rater and inter-rater reliability were determined using kappa. Preoperative CT scans were obtained for all patients and used as the gold standard to determine the presence of OPLL/osteophytes compared to the reviewer’s assessment. RESULTS: Eighty-six patients were included. CT scans changed the planned procedure from ACDA to ACDF in 15/86 (17%) patients. Of these, 4 (26%) patients had OPLL and 11 (73%) had bridging osteophytes. Intra-rater reliability using MRI/x-ray over separate sessions was moderate (κ = 0.44) and inter-rater reliability was fair (κ = 0.24). Sensitivity and specificity of detecting ACDA contraindications on MRI/X-ray were 70% and 52%, respectively. Positive and negative predictive values were 87% and 26%, respectively. CONCLUSIONS: MRI and X-ray have limited reliability for detecting radiographic contraindications to ACDA. These findings support the incorporation of CT into the standard preoperative evaluation for ACDA candidates.