Assessment of instability of the long head of the biceps tendon by MRI

To determine whether MRI can identify instability of the long head of the biceps tendon (LBT) in the rotator interval.

A retrospective review was carried out of 19 patients, all arthroscopically examined, nine of whom had surgically confirmed instability of the LBT.

A LBT perched on the lesser tuberosity correctly indicated all nine cases of instability with one false positive. In six of seven cases where the LBT was oval in shape, no instability of the biceps tendon existed, whereas LBT instability was present in eight of 12 patients with a flat long head of the biceps tendon. In seven of eight acutely angled intertubercular sulci there was no instability of the LBT while eight of 11 obtusely angled sulci were associated with LBT instability. By consensus impression, instability of the LBT could be determined with 67% sensitivity, 90% specificity, 86% positive predictive value, and 75% negative predictive value.

A flat LBT perched on the lesser tuberosity with an obtusely angled intertubercular sulcus suggests the diagnosis of instability of the LBT in the correct clinical setting.