Radiographic Evaluation of the Distal Radioulnar Joint: Technique to Detect Sigmoid Notch Intra-Articular Screw Breach in Distal Radius Fractures

Abstract

Purpose: To describe the “extended tangential” and “sunrise” radiographic views and assess their ability to detect distal radioulnar joint (DRUJ) screw penetrance and help direct safer screw placement. Materials and Methods: Distal radius variable angle volar locking plates were applied to 10 cadaveric arms: 5 were plated with a distal ulnar locking screw breaching the sigmoid notch and 5 without a screw violating the DRUJ. A mini C-arm captured PA, “sunrise,” and “extended tangential” views. For each cadaver, blinded hand fellowship trained surgeons answered whether there was sigmoid notch screw breach and whether that screw should be repositioned. Results: The interrater and intrarater reliabilities for identifying articular screw breach were slight to fair (0.19 and 0.39) for the PA views, moderate (0.55 and 0.55) for the “extended tangential view,” and substantial (0.80 and 0.80) for the “sunrise view,” respectively. The interrater and intrarater reliabilities for decision to move the screw were slight to fair (0.16 and 0.33) for PA, moderate (0.49 and 0.58) for “extended tangential view” and substantial (0.67 and 0.72) for the “sunrise view,” respectively. The sensitivity for diagnosing intra-articular breach was 39%, 68%, and 79% for the PA, “extended tangential,” and “sunrise” views, respectively. The specificity was 77%, 96%, and 93%, respectively. For clinical decision-making on when to move the screw, the views had a sensitivity of 60%, 75%, and 82% and specificity of 63%, 79%, and 83%, respectively. Conclusions: The “extended tangential view” and the “sunrise view” improved one's ability to identify DRUJ screw breach and for directing screw repositioning over standard views. We recommend the “sunrise” and “extended tangential” view be obtained intraoperatively to help guide clinical decision-making. Although the “extended tangential view” is more easily obtained with a mini c-arm than the “sunrise view,” both views should be considered to fully evaluate the DRUJ joint. Clinical Relevance: Both the “extended tangential” and “sunrise” views help improve sigmoid notch visualization, identify DRUJ screw penetrance, direct screw positioning, and prevent unnecessary screw repositioning.