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Anterior shoulder dislocation/instability/ recurrent dislocation

What is Anterior Shoulder Dislocation?

This is the terminology given to those who dislocate the shoulder joint. Some individuals don’t dislocate as such but get an insecure feel of shoulder coming out of the joint anteriorly (front) on performing certain movements.

What causes it?

A severe injury, or trauma, is often the cause of an initial shoulder dislocation. During the injury, usually the shoulder comes out in the front as a result of a forceful manoeuvre that resulted in extreme sideward elevation of the arm combined with the outwards rotation of the arm. (Medically called as Abduction and External rotation). This puts the structures in the anterior aspect of the shoulder joint in extreme stress and when the stress level exceeds their capacity to withstand it gives away and shoulder joint loses the stability and dislocates.

What are the symptoms/effects?

The shoulder is the most moveable joint in our body. This has given an ability for the shoulder joint to perform lot of function above the level of head and also in sporty activities such as throwing, bowling, swimming etc. But the downside of this is that the shoulder can also dislocate. Normally the shoulder dislocation is prevented by ligaments, capsules and muscles surrounding it. But during a sporting injury the ligaments in the front of the shoulder joint can rupture and lead on to dislocation. Often the ruptured ligaments in the front of the shoulder joint does not heal and hence results in recurrent episodes of shoulder dislocation. Sometimes even repetitive activity above the level of the head can strain these ligaments (that is the ligament will elongate and become lax). This can cause subtle anterior shoulder instability but not real dislocation.

Once a shoulder joint dislocates, it loses the stability normally offered by the ligaments, hence it is vulnerable to dislocate repeatedly. Number of pathologies has been identified in recurrent shoulder dislocation. The successful treatment depends on identifying the exact nature of the pathology. The pathologies are described in relation to the structure inside the shoulder joint that got injured while the shoulder dislocated.

The key structures that can be injured while a shoulder dislocates anteriorly (in the front) are

  • Glenoid labral attachment of Inferior glenohumeral ligament (Bankart lesion)
  • Humeral attachment of glenohumeral ligament (HAGL lesion)
  • Any part of anterior glenoid labrum
  • Anterior capsule
  • Middle glenohumeral ligament
  • Humeral head itself can fracture as it pivots out of glenoid margin (Hill Sach lesion)

The commonest injury of all the above is to Glenoid labral attachment of the Inferior glenohumeral ligament (Bankart lesion). But it is important to keep in the mind the possibility of other structure injury while treating this condition.

How is it diagnosed?

Acute dislocation: A Physical examination and investigation will confirm the diagnosis. When the shoulder dislocates the prominence of arm is flattened and any shoulder movements are painful. An X ray will confirm that the shoulder is dislocated.

Recurrent Dislocation: The people who dislocate recurrently are apprehensive to put their arm in extreme sideward elevation and rotating it outwards (Abduction and External rotation). This can be revealed by physical examination. Special tests called Anterior apprehension test and Jobe’s relocation test can almost pinpoint the diagnosis. X ray will be done in order to assess for the presence of an associated fracture of the glenoid margin (Bony Bankart) or a Hill Sach lesion. In order to confirm further, a MR Arthrography of the shoulder joint may be a useful investigation. In MR Arthrography, a contrast dye is injected in the shoulder joint. If there is a tear of the ligament the MR Arthrography will reveal leakage of the injected contrast.

What are the treatment options?

Acute dislocation: Initial treatment consists of relocating the shoulder joint in place. This should be performed as an emergency procedure under sedation (injection to make you to sleep). A correct manoeuvre to manipulate the shoulder would relocate the joint. Once the joint is in place, the pain relief is tremendous. A check X ray will confirm that the shoulder is relocated. A rest in sling for 2-3 weeks and then mobilising the shoulder is the usual mode of treatment.

Recurrent Dislocaiton:The treatment requires surgery. The aim of the surgery is to fix the ruptured structure usually the Bankart lesion. The surgery is called Anterior shoulder stabilisation surgery. This is usually performed through small stab incisions with the help of arthroscope. Occasionally, some of the injury character may necessitate an open surgery.