Description of the lecture:

Introduction: History and Prevalence

Anterior shoulder instability has a  historical significance, noting evidence from 2000 BC and techniques described by Hippocrates in 400 BC. The glenohumeral joint is the most commonly dislocated joint of the body, with anterior dislocations making up about 90% of cases. Incidence rates range from 11 to 56 cases per 100,000 people each year, with men being three times more likely to experience it. Younger patients have a higher recurrence rate, while older patients are at greater risk for associated injuries1.

Anatomy and Mechanisms

The shoulder's anatomy is crucial for understanding instability. The glenohumeral joint is a ball-and-socket joint, with only about 25-33% of the humeral head covered by the glenoid surface. Shoulder stabilizers are divided into static (ligaments, bones, joint capsule) and dynamic (rotator cuff muscles and tendons) stabilizers. The labrum increases the contact area between the glenoid fossa and the humeral head, enhancing stability. Mechanisms of instability include traumatic (unilateral injuries linked to contact sports) and atraumatic (hyperlax patients with no prior trauma).

Associated Lesions

Common associated lesions include rotator cuff tears, Bankart lesions, bony Bankart lesions, and Hill-Sachs defects. Rotator cuff tears are particularly common in older individuals. Bankart lesions occur in 80-90% of patients with traumatic shoulder instability. Bony Bankart lesions involve a fracture of the anterior inferior glenoid. Hill-Sachs defects are chondral impaction injuries to the posterosuperior aspect of the humeral head.

Glenoid Bone Loss

Glenoid bone loss significantly influences treatment options. A CT scan with 3D reconstruction is crucial for evaluating bone loss. When glenoid bone loss exceeds 20-25%, surgical interventions (bone block procedures) are often necessary. Algorithms help determine surgical treatment based on the degree of bone loss and the presence of Hill-Sachs lesions.

Treatment

Treatment options depend on factors such as age, bone loss, and activity level. Conservative management may be suitable for first-time dislocators, older individuals, and those with minimal bone loss. Surgical options include Bankart repair, arthroscopic anatomic glenoid reconstruction, and non-anatomic procedures like Dynamic Anterior Stabilization (DAS) and the Remplissage technique. The Latarjet procedure is indicated for significant bone defects and recurrent instability.

Learning Objectives:

1. Historical Context: Understand the historical background of shoulder instability, including early evidence and treatment techniques.

2. Anatomy: Gain knowledge of the shoulder's anatomy, focusing on the glenohumeral joint and its stabilizers.

3. Mechanisms of Instability: Differentiate between traumatic and atraumatic mechanisms of shoulder instability.

4. Associated Lesions: Recognize common associated lesions such as rotator cuff tears, Bankart lesions, and Hill-Sachs defects.

5. Glenoid Bone Loss: Understand the significance of glenoid bone loss in treatment decisions and the use of CT scans for evaluation.

6. Treatment Options: Learn about various treatment options, both conservative and surgical, based on patient factors like age, bone loss, and activity level.

7. Understanding Surgical Procedures: Recognize the various surgical approaches and their specific patterns.