We examined labroligamentous structures in unstable anteroinferior glenohumeral joints using MR arthrography (MRA) to demonstrate that not all instabilities are Bankart lesions. We aimed to show that other surgical protocols besides classic Bankart repair are appropriate for labroligamentous lesions. The study included 35 patients (33 males and 2 females; mean age: 30.2; range: 18 to 57 years). MRA was performed in all patients. The lesions underlying patients’ instability such as Bankart, anterior labral periosteal sleeve avulsion (ALPSA), and Perthes lesions were diagnosed by two radiologists. MRA yielded 16 diagnoses of Bankart lesions, 5 of ALPSA lesions, and 14 of Perthes lesions. Albeit invasive, MRA seems to be a more reliable and accurate diagnostic imaging modality for the classification and treatment of instabilities compared to standard MRI. 1. Introduction Anterior shoulder instability is one of the most common orthopedic problems. Glenohumeral (GH) instability occurs mostly in young, active males and is usually caused by traumatic injury. Recurrent subluxations and dislocations of the GH joint occur as a result of changes in bone, cartilage, and soft tissues and are referred to as habitual dislocation of the shoulder [1, 2]. This problem, which causes severe morbidity that interferes with daily and sporting activities, is associated with many bone and soft tissue changes. The glenohumeral ligament, its inferior part in particular, is one of the most important passive stabilizers of the shoulder. The glenoid labrum contributes to stability of the shoulder by deepening the glenoid fossa with ligamentous attachments [3, 4]. A number of anterior instabilities can be associated with glenohumeral ligament lesions and with lesions of complex ligamentous structures that the glenohumeral ligament forms with neighboring tissues. The main instabilities are Bankart lesion (avulsion of the anterior glenoid labrum from the bone), glenoid edge fracture, Hill-Sachs lesion (osseous defect due to dislocation of the posterosuperior lateral humeral head), and loose body . In addition, the Perthes lesion, a labroligamentous avulsion in which the scapular periosteum remains intact, and the ALPSA lesion, a medial displacement of the anteroinferior labral ligamentous complex with an intact scapular periosteum, should be considered potential causes of shoulder instability [5, 6]. The identification of anterior labral avulsion, capsular laxity, and other pathologies of the GH joint is of great significance in treatment planning. The methods used to identify these
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