The appearance of the lateral ulnar collateral ligament on magnetic resonance imaging.

The lateral ulnar collateral ligament is an important element of the elbow's lateral capsuloligamentous complex, and loss of integrity contributes to posterolateral rotatory instability. However, the normal appearance on magnetic resonance imaging is poorly defined. The purpose of this study was to assess the appearance of the lateral ulnar collateral ligament of asymptomatic elbows on magnetic resonance imaging. We performed magnetic resonance imaging on 20 asymptomatic elbows. The lateral ulnar collateral ligament was identified as a hypointense structure originating from the lateral epicondyle and inserting on the proximal ulna in 10 cases (50%) and was ambiguous in the other 10 elbows. The identified lateral ulnar collateral ligament images included areas of high signal intensity, which was confusing because it suggested ligamentous disruption within the ligament. These results indicate that magnetic resonance imaging is not reliable for diagnosing lateral ulnar collateral ligament injuries at the present time. Further progress in magnetic resonance imaging will be clinically useful for diagnosing abnormalities of the lateral ulnar collateral ligament.