MRI, arthroscopy, and histologic observations of an annular ligament causing painful snapping of the elbow joint.

3Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China. napping of the elbow joint is a pathologic condition in which an interposed or impinged tissue in the elbow joint clicks when the elbow is flexed and extended. The causes of snapping elbow have been attributed to intraarticular loose bodies, instability, synovial plicae [1], and a torn or loose annular ligament [2]. Diagnosis and monitoring of treatment regimens is most commonly done using arthroscopy [1]. The noninvasive nature and internal resolution power of MRI make it an attractive technology to evaluate internal derangements of joints. However, no reports to our knowledge have shown the value and usefulness of MRI in identifying the causes and interposed tissues for snapping elbow. We report a case of painful snapping of the elbow joint caused by a torn or loose annular ligament. MRI clearly showed the interposed tissue of a loose annular ligament in the radiocapitellar joint. The MRI findings correlated well with arthroscopic and histologic data.