Isolated Extra-articular Medial Dislocation of the Long Head of the Biceps Tendon in an Adolescent: A Case Report.

Isolated instability of the long head of the biceps tendon is uncommon and is usually associated with rotator cuff or bicipital pulley injuries. Isolated extra-articular medial dislocation in the absence of associated lesions is particularly rare in the adolescent population. We report the case of a 15-year-old male who presented with anterior shoulder pain after a recreational sports activity. Physical examination revealed localized anterior and anterolateral tenderness, with preserved active and passive range of motion and no clinical signs of instability. Magnetic resonance imaging using MR arthrography demonstrated an isolated extra-articular medial dislocation of the long head of the biceps tendon, characterized by an empty bicipital groove and preserved integrity of the rotator cuff, rotator interval, and labro-bicipital complex. Conservative management with physical therapy focused on pain control and shoulder stabilization was initiated, along with activity modification and injury prevention counseling. The patient showed a favorable clinical course during conservative management. This report highlights the importance of systematic evaluation of the bicipital groove and the entire course of the long head of the biceps tendon on MRI in young patients with anterior shoulder pain, even when classically associated injuries are not identified.