Imaging description

To reiterate, the anterior bundle of the ulnar collateral ligament (UCL) is best seen on coronally oriented MR arthrogram images. Based on prospective research, the insertion of the anterior bundle on the sublime tubercle should be tight with no visible recess between the coronoid process and the UCL in teenage and young adult baseball players. In young overhead-throwing athletes, an undersurface tear of the distal UCL is diagnosed if contrast is seen to extend between the sublime tubercle and the undersurface of the UCL. (Figure 24.1). This has been described as the T-sign. This finding or T-sign cannot be extrapolated as being abnormal in older adults as research has shown that this sign can be present in older adults in whom degenerative changes of the UCL may predominate.

Importance

Because of the difficulty in diagnosing partial tear of the anterior bundle of the UCL at physical examination and at arthroscopy, preoperative diagnosis with MR arthrography plays an important role in this injury. If this surgically treatable injury is missed, it causes an increase in patient morbidity and limitation in athletic performance due to a delay in the diagnosis.

Typical clinical scenario

The patient is usually a young adult male who is an overhead-throwing athlete (in the USA this is typically a baseball pitcher) and has slowly developed symptoms of medial elbow joint instability that are worse during the acceleration phase of the throwing motion.