MR imaging findings of lateral ulnar collateral ligament abnormalities in patients with lateral epicondylitis.

Objective: The purpose of this paper was to use MR imaging to determine whether a relationship exists between lateral epicondylitis and abnormalities of the lateral ulnar collateral ligament.
Subjects and Methods: The study group comprised 35 consecutive patients who were referred for MR imaging to rule out lateral epicondylitis. On MR imaging, "lateral epicondylitis" was defined as increased signal intensity of the extensor tendons close to their insertion on the lateral epicondyle. The severity of the lateral epicondylitis was graded as mild, moderate, or severe. The origin of the lateral collateral ligamentous complex was characterized, and the lateral ulnar collateral ligament was graded as normal, thickened, partially torn, or torn. Eleven patients underwent elbow surgery after the initial MR examination.
Results: In 15 patients, MR imaging revealed characteristics of mild lateral epicondylitis. In 13 of these patients, the lateral ulnar collateral ligament was normal; one patient showed a thickened ligament; and one patient had a thinned ligament. In 11 patients, MR imaging showed features of moderate lateral epicondylitis. In eight of these patients, the lateral ulnar collateral ligament was thickened, and in the remaining three patients the ligament was normal. All nine patients with severe lateral epicondylitis showed abnormalities of the lateral ulnar collateral ligament on MR imaging. In one of these patients the lateral ulnar collateral ligament was thickened, in three patients we saw a partial tear, and in the remaining five patients we saw a complete tear of the ligament.
Conclusion: In our study, MR imaging features of lateral epicondylitis were often associated with thickening and tears of the lateral ulnar collateral ligament.