Shoulder dislocations

The shoulder joint has a unique design allowing movement in all directions as required for normal upper limb function. Unfortunately, she shallow nature of the joint makes it susceptible to dislocate. There are various ligaments blended into the shoulder capsule (lining of the joint) that provide additional stability. The shoulder can dislocate to the front (anterior dislocation) or to the back (posterior dislocation) and very rarely in a downward direction (inferior dislocation). The rest of this information sheet will focus on the anterior dislocation as this is the most common type of shoulder dislocation. It often occurs in contact sports or car accidents when a large force is exerted onto the shoulder with the arm away from the body. In rugby, this can happen during a tackle or when a player dives to score a try. The shoulder can also dislocate after a fall onto an outstretched arm or even during epileptic seizures. Patients that are very lax and supple may dislocate their shoulders with minimal force, sometimes even voluntarily.

After a shoulder dislocation, the risk for further shoulder dislocations is increased, especially when it occurs at a very young age. Once a shoulder has dislocated, certain important stabilizing structures may be injured. The most common finding after a shoulder dislocation is a torn labrum (the attachment of the shoulder ligaments and capsule). This is called a Bankart lesion. The edge of the glenoid may also be broken or rounded off making the shoulder even more unstable. The humeral head may be dented after contact with the edge of the glenoid. This is called a Hill Sachs lesion, and also contributes to subsequent instability. Older patients are at risk of rotator cuff tears during shoulder dislocations. Rarely, the shoulder capsule becomes detached from the humerus. This is called a HAGL lesion (Humeral Avulsion of the Glenohumeral Ligament).

Initial presentation:

When a shoulder dislocates to the front it is usually obvious that the shoulder is not in joint. The patient is in severe pain and the shoulder has an obvious deformity. Shoulder movement is restricted and very painful. The shoulder needs to be reduced as soon as possible at the nearest Emergency Unit. The patient is examined for any numbness, pins, and needles or muscle weakness, before and after reduction of the shoulder. X-rays are performed to confirm the diagnosis and to look for any associated fractures. They are repeated after reduction to confirm that the shoulder has been adequately reduced. The shoulder is then placed in a sling for a couple of weeks.

Symptoms following a shoulder dislocation:

After the initial dislocation, the pain will usually settle within a week or two. Pain (apprehension) may be still felt when the shoulder is placed in a position of throwing because that is the position where the shoulder is most vulnerable to dislocate. A click may be felt during certain shoulder movements.

Diagnostic work-up after a previous shoulder dislocation:
A thorough shoulder examination is performed to assess how unstable the shoulder is. The orthopedic surgeon will also look for signs of generalized ligamentous laxity (being “double-jointed”) X-rays are routinely performed to assess for bone loss of the glenoid and to identify a Hill-Sachs lesion on the humeral head. When bone loss is present, a CT –scan may be performed as it provides more detail on the amount of bone loss. An ultrasound scan will be done in older patients to identify any rotator cuff tears. MRI scans are helpful to identify labral and capsular tears as well as additional injuries.

Treatment:

The treatment of an unstable shoulder is determined by patient factors, the type of instability, the injury pattern and ultimately the risk of re-dislocation.

Physiotherapy:

Physiotherapy is often the first choice of treatment especially when the shoulder is unstable in multiple directions due to generalized ligamentous laxity. Rotator cuff strengthening and proprioception (shoulder awareness) exercises are performed.

Surgical management:

Surgery may be the preferred choice of treatment in younger patients, especially those involved in contact sports or manual labor due to the high risk of repeated shoulder dislocations in this group. There is good evidence that supports early surgery in these high-risk patients. (Cochrane review, Handoll et al, 2004)

Bankart Repair:

The torn labrum with attached ligaments and capsule (Bankart lesion) is repaired back onto the edge of the glenoid (shoulder socket) using a few anchors (small screws with sutures attached). This was traditionally done with open surgery but is now mostly performed arthroscopically (keyhole surgery). When additional stability is required, a remplissage procedure may also be performed (attaching the capsule and rotator cuff at the back of the shoulder into the humeral head defect. (See rehab following Bankart repair)

Capsular shift:

In patients with generalized ligamentous laxity (“double-jointed”) the shoulder is often unstable in multiple directions. The lax capsule becomes progressively stretched out with repeated dislocations. If conservative management fails, the capsule can be re-tightened surgically. This can be done arthroscopically (“key-hole surgery”) or as an open procedure.
HAGL repair:
When a HAGL lesion (Humeral Avulsion of the Glenohumeral Ligament) is the cause for ongoing shoulder instability, the shoulder capsule has to be repaired back onto the humerus. This is performed with arthroscopic (“key-hole”) or open surgery depending on the location of the lesion.

Latarjet procedure:

This open surgical procedure is often chosen when a soft tissue operation such as a Bankart repair has an increased risk to fail, for example, patients with glenoid bone loss, large Hill Sachs lesions and patients involved in contact sports. The coracoid process (a bony protuberance in the front of the shoulder) is transferred to the edge of the glenoid and fixed with 2 screws. This creates stability by increasing the diameter of the glenoid surface as well as tensioning the lower part of the subscapularis muscle. The capsule is repaired at the end of the operation which also restores stability. (See rehab following Latarjet Procedure)

Bone block procedure:

In certain patients, especially those with extensive glenoid bone loss, a block of bone graft may be taken from the hip (iliac crest) and fixed onto the glenoid to restore the glenoid width and therefore stability. This is known as the Eden-Hybinette procedure.