Arthroscopic findings in the subluxating shoulder.

The arthroscopic findings in 19 shoulders (18 patients) with subluxation are described. The clinical diagnosis of subluxation of the shoulder is primarily based on clinical history with inconsistent physical findings and radiographic studies. Arthroscopic findings in these patients were consistent. Increased translation of the humeral head in the anteroposterior plane was noted secondary to attenuation of the anteroinferior glenohumeral ligament. Incompetence of this ligamentous structure obviated its function as an anterior buttress and allowed the humeral head to translate anteriorly on the glenoid. Fraying, tearing, or detachment of the anteroinferior glenoid labrum and articular defects in the posterolateral humeral head were also consistent findings, thought to be secondary to repeated injury as the humeral head translates forward and backward in the glenoid fossa. In several cases the classic "click" that occurs with subluxation of the shoulder could be reproduced under arthroscopic visualization and corresponded to the defect in the posterolateral humeral head riding over the torn labrum and/or anterior glenoid rim. Shoulder arthroscopy is an accurate method for confirming the clinical impression of subluxation of the shoulder, especially in subtle glenohumeral instability, and should be helpful in selecting specific surgical reconstruction procedures.