Understanding Shoulder Dislocation: Causes, Symptoms, and Treatment Options

Introduction

The shoulder is a ball and socket joint comprising the humeral head (ball) and glenoid (socket). A shoulder dislocation describes a situation where the humeral head is forced out of the glenoid. The head may be dislocated anteriorly or posteriorly. 
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It is crucial to be able to diagnose a shoulder dislocation and have it treated promptly. Delayed presentation and treatment may lead to chronic and serious shoulder complications. 

Anatomy of the Shoulder Joint

As mentioned above, the main shoulder or gleno-humeral joint is a ball and socket joint. Unlike the hip, the socket or glenoid in this case is very shallow compared to the acetabulum in the hip. It is often described as a golf ball on a tee, where the glenoid is the tee. The reason for this is to allow a great range of motion of the shoulder. The drawback of having a very shallow glenoid is that it does not contain the humeral head very well and makes it prone.

The glenohumeral joint is a ball and socket joint

Golf ball on a tee: there is very little stability here, similar to the glenohumeral joint

The labrum makes the glenoid deeper and helps provide negative suction in the glenohumeral joint.

Causes of Shoulder Dislocation

• Falls on an outstretched hand, e.g. a fall from height,
• Road traffic accidents: direct hard blow to the shoulder,
• Sports injuries: contact sports (rugby, wrestling) or fall from height (gymnastics, horse riding, volleyball).

• Seizures or epileptic attacks,
• Electric shocks.

Symptoms of a Dislocated Shoulder

• The key signs of shoulder dislocation include shoulder pain and swelling, loss of movement and a visible deformity.
• Patients usually use their non-injured hand to support their injured arm.
• The injured shoulder often loses its rounded appearance.
• It is important to seek medical help when this happens and not to move the shoulder. You may use an arm sling if one is available or use a folded shirt to support your injured arm.

The injured right shoulder has lost its rounded contour due to the dislocation.

Investigations for a shoulder dislocation

Once you are seen by a nurse or doctor in the emergency department, the health worker will clinically assess your injured arm to ensure there are no open wounds, you are able to move your elbow, wrist and fingers slightly and that there is no numbness. X-rays are then performed to confirm the dislocation, ascertain if it is an anterior or posterior dislocation and exclude any associated fractures. The three x-rays done will be taken from the front (AP view), the side (Y-scapula view), and the top (Axillary or Valpeau view). If there is a shoulder dislocation, the medical practitioner will proceed to reduce it under conscious sedation. These three sets of x-rays will be repeated after the procedure to ensure the shoulder has been successfully reduced.

For patients with a history of recurrent dislocations, an MRI is performed at a later date to assess for labral tears. A CT scan may be performed if the orthopaedic surgeon suspects a bony malformation of the glenoid that increases the risk of recurrent shoulder dislocations.

Three different views of a normal shoulder: AP, Lateral and Valpeau views:

Shoulders with a dislocation:

AP X-ray showing a shoulder dislocation.

Lateral or Y-Sapular view X-ray showing a dislocation.

Valpeau view showing a posterior dislocation of the humeral head. There is also a fracture of the humeral head known as a Hill Sach’s lesion. This increases the risk of recurrent shoulder dislocations.

 Treatment Options for Shoulder Dislocation

It is crucial to have a dislocated shoulder reduced into its rightful position by a trained medical professional. Manipulation and reduction (M&R) of the shoulder is often performed under conscious sedation. Patients are given both a painkiller as well as a sedative to make them feel drowsy with less pain to make it easier for the health professional to reduce the shoulder. Without sedation, an anxious patient will resist any manipulation applied to their shoulder and the M&R may fail.
There are several techniques used to reduce a dislocated shoulder. The medical professional should use the technique which he or she is most comfortable with.

Many techniques may be used to reduce a dislocated shoulder. It is best done under conscious sedation so that patients are not in much pain and do not resist or fight the procedure.

• • Labral tear (Bankart lesion)
  • Hill Sach’s lesion

The torn labrum (Bankart lesion) makes the glenohumeral joint very unstable.

 Types of shoulder surgical options (arthroscopic vs. open surgery)

• Patients with recurrent shoulder dislocations and having a compromised shoulder anatomy (Labral tear, Bankart lesion, Hillsach’s lesion) are advised to undergo surgery. This is to reduce the risk of further shoulder dislocations in future.
• For those with labral tears, arthroscopic or keyhole surgery is performed to suture back the torn labral to the rim of the glenoid. At the same time, some ligaments around the glenoid are also reattached to the glenoid itself. This helps make the glenoid deeper and the surrounding soft tissue tighter to prevent further dislocations. Anchor sutures are implants used to perform this surgery. The anchors are inserted into the rim of the glenoid while the sutures are passed around the torn labrum. When the sutures are tightened, the labrum is now securely fixed to the run of the glenoid.

Repair of the torn glenoid labrum helps restore stability to the glenohumeral joint

There are some patients who experience recurrent shoulder dislocations as their glenoids are very small in size or they experienced significant bone loss during their dislocation injury. These patients undergo a bony procedure called Laterjet Procedure to increase the width and size of their glenoid bone. This helps to prevent further shoulder dislocation. The Latarjet procedure may be done arthroscopically (key-hole) or as an open procedure.

The Latarjet procedure is a bony operation to widen the glenoid and stabilise the shoulder joint.

Preventing Shoulder Dislocation Recurrence

It is important to restore the normal anatomy of the shoulder to prevent further shoulder dislocations. The operations described above (Bankart repair, Latarjet procedure) are both designed for this.
Physiotherapy and rehabilitation are designed to strengthen the muscles and soft tissue around the shoulder. They also improve the shoulder's range of motion without causing further dislocations. Those at risk of dislocations are advised to avoid shoulder positions that make them prone to dislocations. Examples include sleeping with the arm behind their head, reaching for something in the backseat of a car and throwing a ball with the shoulder flexed and externally rotated.

Conclusion

Shoulder dislocations are serious injuries and must be promptly identified and rectified. Neglected or recurrent shoulder dislocations may lead to chronic and debilitating problems. MRI scans are essential to identify soft tissue injuries that may lead to recurrent dislocations. Surgery is performed to restore the labrum and bony structure of the glenoid. Physiotherapy and rehabilitation continue to be crucial in all shoulder injuries.