The shoulder is a ball and socket joint. This means the round top of the upper arm bone (the ball) fits into the cup-shaped socket that is part of the shoulder blade. A dislocated shoulder is an injury in which the entire ball is out of the socket. In a partly dislocated shoulder, only part of the ball is out of the socket. This is called a shoulder subluxation.
The shoulder is the body’s most mobile joint, which makes it susceptible to dislocation. Because it moves in several directions, the shoulder can dislocate forward, backward or downward, completely or partially, though most dislocations occur through the front (anterior) of the shoulder.
In addition, complications of a dislocated shoulder may include:
- Stretching and even tearing of the muscles, ligaments and tendons that reinforce the shoulder joint
- Nerve or blood vessel damage in or around the shoulder joint
- Shoulder instability, especially in cases of severe dislocation or repeated dislocations
If ligaments or tendons in the shoulder are stretched or torn, or nerves or blood vessels around the shoulder joint are damaged, surgery to repair these tissues may be needed.
Specific pathologies that can be found in the shoulder joint following a traumatic shoulder anterior dislocation include:
- Creation of a Bankart lesion – this can be a soft tissue labral tear or a bony Bankart with a fractured rim of the glenoid with labrum still attached to the detached fracture.
- Hillsach’s lesion – this is a compression fracture of the humeral head created at the time of the dislocation.
- Possible superior labral tear – called a “SLAP” lesion.
It takes a strong force, such as a sudden blow to the shoulder, to pull the bones out of place. A dislocated shoulder may be caused by:
- Sports injuries – shoulder dislocation is a common injury in contact sports, such as football and hockey, and in sports that may involve falls, such as gymnastics and volleyball.
- Trauma not related to sports – a hard blow to the shoulder during a motor vehicle accident is a common source of dislocation.
- Falls – such as from a ladder or from tripping on a loose rug.
Signs & Symptoms
Dislocated shoulder signs and symptoms may include:
- Some swelling and bruising to the shoulder
- Numbness, weakness or tingling near the injury, such as in the neck or down the arm
- A visibly deformed or out-of-place shoulder
- Intense pain
- Inability to move the joint
- Muscles in the shoulder may spasm from the disruption, often increasing the intensity of the pain.
In the emergency room, the arm would be reduced (placed back or relocated) into the shoulder socket. Depending on the amount of pain and swelling, the reduction can be done under some sedation and analgesia or, rarely, under general anaesthesia. When the shoulder bones are back in place, severe pain should improve almost immediately.
For cases where it is a first-time dislocation or a fairly simple dislocation without major bone, nerve or tissue damage, non-surgical treatment is employed:
- Immobilization – using a special splint or sling for a few days to three weeks to keep the shoulder from moving. How long to wear the splint or sling depends on the nature of the shoulder dislocation and how soon the splint is applied after dislocation.
- Medication – prescribing a pain reliever or a muscle relaxant to keep patient comfortable while the shoulder heals.
- Rehabilitation – beginning a gradual rehabilitation program designed to restore range of motion, strength and stability to the shoulder joint after the shoulder splint or sling is removed.
The shoulder joint likely will improve over a few weeks, but will be at increased risk for future dislocation. With each injury, it takes less force to do this.
If the shoulder continues to partly or fully dislocate in the future, surgery may be needed to repair or tighten the ligaments that hold the bones in the shoulder joint together. Surgery may also be needed if the patient has a job in which the shoulder is used a lot.
Many studies have shown a high risk of recurrent dislocation without surgical stabilisation of the torn labrum of the shoulder joint.
Surgery is done using keyhole techniques. A camera is inserted into the injured shoulder joint via a 3mm hole from the back of the shoulder. This allows a complete arthroscopic examination of the shoulder joint and identification of the damaged structures e.g. labral tears, bankart lesions.
Two additional holes are made in the front of the shoulder to allow surgical repair of the torn structures.
In order to reattach the torn labrum back to the glenoid bone, special bioabsorbable suture anchors are used. This surgical implants are placed into the shoulder and help to secure the torn labrum back to bone to allow healing.