Shoulder instability is a condition when the ball of the shoulder is dislocated from the socket, causing problems for people. The shoulder anatomy can be explained by using a ball and socket model. The ball is able to move about in the socket, providing nearly full range of motion for the shoulder. However, this model can cause instability when the ball slips out of the socket when injured. Anterior instability is caused by the ball slipping out from the front of the socket. Anterior instability is usually caused by trauma, with a sudden impact on the shoulder either directly or indirectly.
One of the most important structures that stabilize our shoulder is the inferior glenohumeral ligament, commonly known as IGHL. The IGHL limits gross anterior-inferior subluxations and prevents any sudden movement. During an anterior shoulder injury, the sudden huge impact normally exceeds the amount of force the ligaments can withstand, thus causing tears and stretching. This will in turn lead to instability of the shoulder.
When there is the presence of Bankart lesions repair, it implies that there is a failure of the IGHL at the gelnoid insertion. The most common lesion in anterior shoulder instability is the Bankart lesion. The tear is big enough to involve the labrum, the middle labrum as well as the superoanterior labrum. Without the labrum, the ball will get dislocated from the shoulder socket and causes subluxation. As the ball pops out of the socket, the labrum is often torn in the process. Patients suffering from a Bankart lesion will experience their scapular periosteum rupturing as theirlabroligamentous ligaments are forcefully detached from the glenoid.
3 types of instability are devised for medical practitioner to plan for bankart surgery:
- Type 1 – Presence of a partial Bankart lesion with a small detachment of the capsulolabral complex but no indication of the capsule stripping from the glenoid labrum
- Type 2 – Moderate detaching of the labrum and the capsule from the glenoid, with preservation of the labral shape.
- Type 3 – Severe detaching of the capsulolabral complex, with attenuation of the glenoid labrum
Our shoulders play an important role in our day to day activities. It is of utmost importance to protect it. Building strong shoulder muscles is the best defence against dislocations and instability. A delay in diagnosis may lead to more serious long term problems such as arthritis. Patients should seek immediate medical assistance prevent it from getting worse.