SCIENTIFIC ARTICLE Interpretation of Post-operative Distal Humerus Radiographs After Internal Fixation: Prediction of Later Loss of Fixation Femke M. A. P. Claessen, MD, PhD,* Nicky Stoop, BSc,* Job N. Doornberg, MD, PhD,† Thierry G. Guitton, MD, PhD,† Michel P. J. van den Bekerom, MD,‡ David Ring, MD, PhD,* on behalf of the Science of Variation Group§ Purpose Stable fixation of distal humerus fracture fragments is necessary for adequate healing and maintenance of reduction. The purpose of this study was to measure the reliability and accuracy of interpretation of postoperative radiographs to predict which implants will loosen or break after operative treatment of bicolumnar distal humerus fractures. We also addressed agreement among surgeons regarding which fracture fixation will loosen or break and the influence of years in independent practice, location of practice, and so forth. Methods A total of 232 orthopedic residents and surgeons from around the world evaluated 24 anteroposterior and lateral radiographs of distal humerus fractures on a Web-based platform to predict which implants would loosen or break. Agreement among observers was measured using the multi-rater kappa measure. Results The sensitivity of prediction of failure of fixation of distal humerus fracture on radiographs was 63%, specificity was 53%, positive predictive value was 36%, the negative predictive value was 78%, and accuracy was 56%. There was fair interobserver agreement (k ¼ 0.27) regarding predictions of failure of fixation of distal humerus fracture on radiographs. Interobserver variability did not change when assessed for the various subgroups. Conclusions When experienced and skilled surgeons perform fixation of type C distal humerus fracture, the immediate postoperative radiograph is not predictive of fixation failure. Reop- eration based on the probability of failure might not be advisable. (J Hand Surg Am. 2016;- (-):-e-. Copyright Ó 2016 by the American Society for Surgery of the Hand. All rights reserved.) Type of study/level of evidence Diagnostic III. Key words Interobserver study, elbow trauma, distal humerus fracture. From the *Orthopaedic Hand and Upper Extremity Service, Harvard Medical School, Mas- sachusetts General Hospital, Boston, MA; the †Orthotrauma Research Center Amsterdam, University of Amsterdam Orthopaedic Residency Program; and the ‡Shoulder and Elbow Unit, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands. Received for publication November 30, 2015; accepted in revised form July 13, 2016. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: David Ring, MD, PhD, Department of Surgery and Perioperative Care, Dell Medical School, 1400 Barbara Jordan Boulevard, Suite 1.114AC. MC: R1800, Austin, TX 78723; e-mail: david.ring@austin.utexas.edu. 0363-5023/16/---0001$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2016.07.094 Ó 2016 ASSH r Published by Elsevier, Inc. All rights reserved. r e1