Chronic Shoulder Dislocation and Instability
The shoulder joint enables excellent range in motion, but is prone to instability, destabilisation and dislocation.
How the shoulder joint works.
The shoulder joint (also known as the glenohumeral joint) is a ball and socket mechanism, which enables an excellent range of motion. The ball at the top of our upper arm (humerus bone) fits into a shallow socket (glenoid cup) in the shoulder blade (scapula bone).
It is this clever system that allows us to rotate our arms, reach above and over our head, and turn in many directions. However, the shoulder socket is very shallow, which also makes it prone to instability, destabilisation and dislocation.
Strong connective tissues form a ligament system that keeps the head of the upper arm bone centered in the glenoid socket. The shoulder also relies on strong tendons and muscles (the rotator cuff muscles and the pectoral girdle muscles) to keep it stable.
When the muscular system within the shoulder structure is stretched or torn, the shoulder can become unstable and even pop out of the socket (dislocate).
Chronic shoulder instability
People with shoulder instability have loosened shoulder ligaments. Sometimes this looseness is caused by an injury. It can also be caused by repetitive over-use.
Tennis, swimming, volleyball, and other sports that require repetitive overhead motion can stretch the shoulder ligaments. Having loosened ligaments can make it hard to maintain stability in the shoulder.
When the shoulder is loose and slips out of place repeatedly, the condition is described as chronic shoulder instability. Chronic shoulder instability means your shoulder can dislocate during active movement or exercise.
Shoulder dislocation
A dislocated shoulder occurs when the ball comes out of the glenoid socket. Dislocations can occur as either a partial (known as a subluxation) or a full dislocation. Once a shoulder has dislocated once, there is more likelihood of it happening again.
Causes of chronic shoulder instability and dislocation
Trauma
Shoulder dislocations are generally caused by trauma. The trauma may involve a sporting injury, a car accident or a fall.
Traumatic injuries can tear a number of ligaments in the shoulder, including the rubbery tissue in the shoulder socket that helps keep the ball of the joint in place (the labrum). One of the most common labral tears occurs where the biceps tendon meets the glenoid. This type of shoulder injury is called a SLAP lesion. Often, the position of the tear depends on the position of the round humerus head in relation to the bony, shallow glenoid socket. Shoulder trauma can cause fractures (ie broken bone), labral tears, biceps tendon tears, rotator cuff tears and/or a dislocation of the ball and socket joint.
A severe first dislocation can lead to more dislocations in the future, or a feeling of the shoulder being unstable and ‘giving out’.
Repetitive strain
Sometimes, repetitive movements cause a loosening of the ligaments in the shoulder, which can make the shoulder more likely to slip out of place. Workplace environments where workers perform the same motion for hours each day, or overhead sports such as tennis or swimming are the usual culprits for such loosening to occur.
Additionally, movements that stress the shoulder can weaken shoulder ligaments. Incorrect form during weight-based workouts, or poor posture can cause strain that stretches the supporting muscular shoulder structure.
Multidirectional instability
For a small number of people, the shoulder can become unstable even though they have no history of repetitive strain or injury. The shoulder might feel loose or even dislocate in multiple directions - out the back, bottom, or front of the shoulder. This is called multidirectional instability.
People with multidirectional instability don’t have any anatomical problem in the shoulder, but simply have naturally loose ligaments throughout their body. They may also be ‘double jointed’ (ligamentous laxity).
Symptoms of chronic shoulder instability
Some common symptoms of chronic shoulder instability include:
- Pain in and around the shoulder joint
- Repeated shoulder dislocations
- A clicking or popping sound when certain shoulder movement are performed
- A feeling of the shoulder being loose or slipping in and out of the joint
Shoulder Dislocation: Risk factors and diagnosis
Shoulder dislocations are extremely uncomfortable, and can be quite painful for many people. Generally, the pain improves significantly when the shoulder has been placed back in its joint.
Some people are able to put their shoulder back themselves, but this isn’t recommended as further tearing or nerve injury can occur. A dislocation should ideally be reset by a medical professional who knows how to minimise risk of further injury to the shoulder.
Risk factors for shoulder dislocation
Certain factors can put you at increased risk of a dislocation. These include:
- Gender - Approximately 70% of shoulder dislocations occur in males.
- Age - Nearly half of all shoulder dislocations happen in people between the ages of 15 and 29.
- Activity - Many shoulder injuries happen due to trauma such as a fall or sporting injury.
- Anatomy - Shallow joint sockets, weak shoulder muscles, and loose ligaments all increase the risk of a shoulder dislocation.
- Previous dislocation - Shoulder dislocations stretch and tear the ligaments and muscles that hold the shoulder in place, making further dislocations more likely.
How is shoulder dislocation and instability diagnosed?
A shoulder dislocation is easy to diagnose, as the shoulder will be visibly deformed.
The patient will also be unable to move their shoulder, and will hold it either to their side, across the body, or above their head depending on whether the dislocation has occurred in a forward, backward, or downward direction.
In terms of shoulder instability, diagnosis begins with a physical examination. Your GP will ask you about your symptoms and the history of the problem. They will also physically examine your shoulder. Specific movement tests will help your doctor assess any instability and / or looseness that’s occurring.
Imaging tests may help confirm diagnosis and identify and secondary issues. These tests typically include X-rays to view bone structure, and an MRI to highlight problems with ligaments and tendons surrounding your shoulder joint. Sometines, dye injected into the joint is used in a MR arthrogramme (MRA), to highlight the structures under investigation.
Shoulder Dislocation:
Treatments and Surgery
Treatment for shoulder dislocations
Treatment for a dislocation is generally a two-step process: assessment and adjustment. Following a dislocation, your GP will arrange scans to assess whether any fractures will make reducing the joint unsafe; or potentiate further damage. Your doctor will assess for damage to bone, nerves and blood vessels before putting the shoulder back in place (referred to as reducing the shoulder).
For complicated dislocations, imaging such as a CT or MRI/MRA may be indicated to check for injury to surrounding muscles, cartilage or other soft tissues.
Once the shoulder has been put back into place, another X-ray is commonly performed to confirm the shoulder is in its correct position.
Shoulder dislocation surgery
When the shoulder is considered unstable and prone to re-dislocate, surgery may be recommended to prevent further dislocations and the subsequent nerve and tissue damage they can cause.
Surgery commonly involves repairing any torn ligaments, and also tightening any ligaments around the shoulder that have loosened.
The specialists at Adelaide Shoulder & Upper Limb Clinic perform shoulder surgery using arthroscopically (key-hole) wherever possible to promote faster healing times, and reduce risk of infection.
Arthroscopic (also known as key-hole) surgery is performed through a series of small cuts. Tiny instruments and a small camera are inserted through the cuts, and guided by the surgeon using the visual cues sent back by the camera. This way, a large open wound is not necessary and the procedure can be performed inside the body under the visualisation of a camera.
Most arthroscopic surgeries shave a 95% patient satisfaction rate, with a complication rate of less than 1% across the board.
Treatment for shoulder instability
Chronic shoulder instability is often initially treated with conservative options. These may include:
- Resting the shoulder and restricting movement to help the tendons recover
- Shoulder exercises designed to strengthen the rotator cuff muscles
- Activity moderation to prevent further dislocations if necessary
- Anti-inflammatory medication and pain killers to reduce pain and swelling around the shoulder joint
If instability continues despite physical therapy, or if the shoulder remains unstable and/or dislocates frequently, surgical intervention may be recommended.
Shoulder instability surgery
Surgical repair of a torn labrum and surrounding ligaments can repair recurrent shoulder instability and decrease the incidence of recurrent shoulder dislocations.
This type of surgery is also performed arthroscopically (key hole), using a tiny camera to look inside the shoulder and to guide the procedure. The surgery is performed using special instruments designed especially for this type of surgery. Once again, this type of surgery has a high rate of success, faster recovery times than open surgery, and carries a lower risk of infection.
The specialists at Adelaide Shoulder & Upper Limb Clinic perform shoulder arthroscopic surgery as an outpatient procedure at several locations around Adelaide in South Australia.
Shoulder Surgery Recovery
After surgery, your shoulder will be temporarily immobilised in a shoulder sling. This sling is generally required for 2 to 6 weeks after the procedure (depending on the severity of your injury and the amount of surgery required to fix your problem).
When the sling is removed, your surgeon will recommend a gentle shoulder exercise schedule designed to regain your shoulder movement and build up your strength. These exercises will be gradually added to your rehabilitation plan.
Patient resources for shoulder conditions
The specialists at Adelaide Shoulder & Upper Limb Clinic practice at several locations around Adelaide including Dulwich, Elizabeth Vale, Bedford Park and Stirling Hospital. Check out Adelaide Shoulder & Upper Limb Clinic’s articles on shoulder related and post surgery information.
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