A patient with shoulder pain after a fall on her right outstretched and externally rotated arm.
The patient presented to the emergency department after a fall on her right outstretched and externally rotated arm. She supported her right arm at a slight abduction with the opposite hand. Physical examination revealed a flattened deltoid and a decreased range of motion. A clinical diagnosis of anterior dislocation of the glenohumeral joint was suggested.
A standard anteroposterior radiograph of the right shoulder showed the characteristic appearance of an anterior dislocation of the glenohumeral joint and a bony Bankart lesion (Fig. 1). Lateral scapular projection (not shown) confirmed the humeral head in the typical subcoracoid position and a Hill-Sachs lesion. All these findings were better demonstrated by helical computed tomography (CT) (Fig. 2).
The glenohumeral joint is the most common site of subluxation or dislocation in the human body (1). This is a highly mobile joint, in which stability is provided in large part by a strong capsule, three glenohumeral ligaments, and the muscules around the shoulder, particularly the rotator cuff (2). Dislocations of the shoulder occur most commonly in the anterior direction (97%) (3). The usual mechanism is a combination of abduction, extension, and external rotation. These are also classified as subcoracoid, the most common subtype; subglenoid, the second in frequency; subclavicular and intrathoracic subtypes (rare). Approximately 40% of anterior dislocations are recurrent, and are more likely in subcoracoid and subglenoid subtypes (2). Anterior dislocation is readily diagnosed on the anteroposterior view of the shoulder, althought the Y view or the axillary projection are effective as well.
Hill-Sachs and bony Bankart lesions are fractures associated with anterior dislocations. Other associated injuries are avulsion fracture of the greater tuberosity of the humerus (10%-15%), disruption of the rotator cuff and injury of the brachial plexus (7%-45%) (2). The Hill-Sachs defect is a compression fracture on the posterolateral aspect of the humeral head at the junction with the neck, seen in 25% and 75% of acute and recurrent dislocations respectively (2). This is produced at the time of dislocation when the humeral head strikes the anteroinferior margin of the glenoid, and is frequently larger in shoulders dislocated for a long period of time and in recurrent dislocations. The Hill-Sachs lesion is best demonstrated on the anteroposterior projection of the shoulder with the arm internally rotated (3). Posterolateral bone contusions without humeral head indentation may also be identified on MR images (4). The bony Bankart lesion is a fracture of the anterior aspect of the inferior rim of the glenoid, and is less commonly seen (1). This is readily demonstrated on the anteroposterior view with the arm in the neutral position. Additional imaging techniques such as CT arthrography, MR and MR arthrography may be required in order to demonstrate labral and capsular abnormalities (2,4).
Anterior dislocation of the glenohumeral joint: Bankart and Hill-Sachs fractures
Based on the provided X-ray and CT images, the right humeral head is seen displaced anteriorly relative to the glenoid, suggesting an anterior shoulder dislocation (commonly caused by trauma when the arm is abducted, extended, and externally rotated during a fall). A bony compression defect is noted on the posterolateral aspect of the humeral head, which is consistent with a Hill-Sachs lesion. In some images, there appears to be a partial discontinuity of the cortical line on the anteroinferior rim of the glenoid, raising the possibility of a bony Bankart lesion (avulsion fracture of the anteroinferior rim). No obvious large fracture fragment of the greater tuberosity is observed, but small avulsion fractures at the greater tuberosity or humeral tubercles must still be considered. Attention should also be paid to the rotator cuff tendons and soft tissue structures, though visualization is limited. If a rotator cuff injury is clinically suspected, further MRI evaluation is recommended.
Based on the injury mechanism (fall on an abducted, externally rotated arm) and imaging findings showing anterior displacement of the humeral head with a Hill-Sachs compression defect, the most likely diagnosis is “Anterior Shoulder Dislocation (with Hill-Sachs Lesion)”. If further imaging (detailed CT reconstruction or MRI) confirms a fracture of the anteroinferior glenoid rim or labral injury, a bony Bankart lesion can be definitively diagnosed.
Treatment Strategy:
Rehabilitation/Exercise Prescription (FITT-VP Principle):
This report is based on the current imaging and preliminary clinical information for analysis and is provided for reference only. It does not replace in-person clinical consultation or professional medical advice. If further questions arise or the condition changes, patients are advised to seek prompt medical evaluation, including appropriate examinations and treatment.
Anterior dislocation of the glenohumeral joint: Bankart and Hill-Sachs fractures
