Intracapsular origin of the long head of the biceps tendon with glenoid avulsion of the glenohumeral ligaments.

An 18-year-old woman presented with a history of recurrent glenohumeral dislocations involving her right dominant shoulder. Physical examination suggested physiologic hyperlaxity and anterior instability. Magnetic resonance arthrography demonstrated an anomalous intracapsular origin of the long head of the biceps tendon (LHBT), with normal-appearing LHBT in the intertubercular groove. Diagnostic arthroscopy confirmed the absence of the LHBT attachment on the superior labrum. Instead, the LHBT originated from the capsule of the shoulder joint. Diagnostic arthroscopy also revealed glenoid avulsion of the glenohumeral ligaments (GAGL) lesion as a tear in the anterior-inferior capsule near its insertion on the glenoid and labrum. An arthroscopic anterior capsulolabral repair was performed with rotator interval closure by imbrication of superior and middle glenohumeral ligaments. A retrospective review of the magnetic resonance arthrogram identified irregularity and interposition of contrast between the capsule and the anterior-inferior labrum that was reproduced in the abduction-external rotation view corresponding with the GAGL lesion seen at arthroscopy. At 12 months postoperatively, the patient demonstrated full range of motion and no signs of instability. This case report helps to raise awareness about 2 rare shoulder lesions: the anomalous origin of LHBT and the GAGL lesion. Diagnosing such lesions on preoperative magnetic resonance imaging may aid in operative planning and avoid unexpected intraoperative findings.