Figure 6. Shoulder joint rotator cuff muscles

After somebody has had a shoulder dislocation, the damage to their shoulder means that they have a higher chance of further shoulder dislocations. The chance of further instability can be estimated at approximately 60%, but does depend on age and activity level. Physiotherapy does help the shoulder recover from an initial shoulder dislocation, but does not reduce the chance of further shoulder dislocations. A 60% risk of further instability is not acceptable to some of the population, who choose surgery early to lower their chance of further instability to 5%.

There are some significant disadvantages to sustaining repeat shoulder dislocations – for example, 15% of drownings are thought to be associated with a dislocated shoulder. There is a greater risk of osteoarthritis (wear and tear and loss of cartilage in the joint) with increasing numbers of dislocations. In addition, each dislocation usually results in more bone loss from the humeral head and glenoid, which lowers the chance of success of minimally invasive (arthroscopic) surgery, and may mean that an open bone grafting procedure (Laterjet procedure) will be required.

Injury to nerves and blood vessels

Damage to the axillary artery (which runs through the armpit and supplies the arm) occurs in 1–2% of shoulder dislocations, more commonly in the older age group as their blood vessels are less elastic.

Nerve injuries are more common, particularly of the axillary nerve, which occurs in around 10–40% of shoulder dislocations. The axillary nerve wraps around the neck of the humerus, and supplies the deltoid muscle, one of the most important muscles around the shoulder joint, and the skin overlying the side of the shoulder (where a shoulder badge would be worn on the sleeve of a jacket). Most people with axillary nerve damage recover without treatment, as the symptoms go away when the shoulder is put back in position. Less commonly there may be damage to the brachial plexus, which is a network of nerves that run from the neck and supply the arm. This is more likely when dislocation occurs with the arm out to the side, with the elbow bent at 90 degrees and the hand hanging down. Again, the recovery from damage to the brachial plexus associated with shoulder dislocation is usually good.

Figure 9. Nerves passing near the shoulder joint

Significant fractures occur in around one quarter of shoulder dislocations, and are more common when there is a traumatic mechanism of injury, first-time shoulder dislocation, or the person is aged over forty. If there is a fracture and a piece of bone has moved from where it should be (displaced), then it usually needs surgery.

Rotator cuff muscle tears are reported to occur in 14–63% of anterior dislocations, more commonly in older people. Any older person who has had a shoulder dislocation 2 weeks ago and now cannot lift their arm above shoulder level most likely has a massive rotator cuff tear, and should have surgery as soon as possible.

Posterior shoulder dislocation

Posterior shoulder dislocation means the head of the humerus ‘pops out’ in a backwards direction, which is the case in 2–4% of shoulder dislocations. This tends to occur when there is a blow to the front of the shoulder, violent muscle contractions due to a seizure (fit) or electrocution, or the arm is bent across the body and pushed backwards. Injuries that are commonly associated with posterior dislocation include fractures, rotator cuff tears, and Hill–Sachs lesions.

Inferior shoulder dislocation

Inferior shoulder dislocation means the head of the humerus sits below the socket once it has ‘popped out’. Only 0.5% of shoulder dislocations occur inferiorly. It is caused by forceful moving of the arm over the head toward the other side of the body, or by pulling on the arm when it is fully extended over the head as may occur when grasping an object above the head to break a fall. Injuries associated with inferior dislocation include damage to nerves (60%), rotator cuff tears (80%), and injury to blood vessels (3%).

Multidirectional shoulder instability

Multidirectional instability of the shoulder is a condition that sometimes occurs in people who are “double-jointed“, which is also known as having ligamentous laxity. Multidirectional instability of the shoulder occurs in younger patients, and can cause both pain and symptoms of instability. The direction of instability can be anterior, posterior and/or inferior, hence the name.

Patients with multidirectional instability of the shoulder usually do not have any tear or definable anatomical problem in the shoulder. They are best treated with an extensive physiotherapy program lasting at least 6 months, which involves developing a conscious understanding of the position of the ball in the socket and how to keep it there by contracting the correct muscles through the various range of motions of the shoulder.

Shoulder dislocation causes

The shoulder joint is the most frequently dislocated joint of the body. Because it moves in several directions, your shoulder can dislocate forward, backward or downward, completely or partially, though most dislocations occur through the front of the shoulder. In addition, fibrous tissue that joins the bones of your shoulder can be stretched or torn, often complicating the dislocation.

It takes a strong force, such as a sudden blow to your shoulder, to pull the bones out of place. Extreme rotation of your shoulder joint can pop the ball of your upper arm bone out of your shoulder socket. Partial dislocation — in which your upper arm bone is partially in and partially out of your shoulder socket — also may occur.

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 downhill skiing, gymnastics and volleyball.
• Trauma not related to sports. A hard blow to your shoulder during a motor vehicle accident is a common source of dislocation.
• Falls. You may dislocate your shoulder during a fall, such as from a ladder or from tripping on a loose rug.

Shoulder dislocation Risk Factors

Males in their teens or 20s, a group that tends to be physically active, are at highest risk of shoulder dislocation.

Risk factors for shoulder dislocation include:

• Gender: Around 70% of shoulder dislocations occur in males;
• Age: Almost half of dislocations occur between the ages of 15 and 29;
• Mechanism: 95% of anterior shoulder dislocations are due to traumatic injury, most commonly resulting from a fall (60%). Almost half of dislocations occur during sports or recreation. Those who play certain sports, or who undertake activities with high physical demands (such as individuals in the armed forces) are at increased risk;
• Location: 47.7% of dislocations occur at home, while 34.5% occur at sites of sports or recreation;
• Anatomy and function: It is likely that factors such as shallow joint sockets, weak shoulder muscles, and loose ligaments increase the risk of shoulder dislocation, although these factors have not been proven in studies; and
• Previous shoulder dislocation: The strongest risk factor for shoulder dislocation is previous dislocation.

Dislocated shoulder signs and symptoms

Shoulder dislocation is associated with symptoms of pain, deformity and an inability to move the shoulder joint. Sometimes a dislocation may tear ligaments or tendons in the shoulder or damage nerves. There may be numbness, tingling, or coldness of the arm if nerves or blood vessels are involved. The person may also be aware of the feeling of the humerus ‘popping out’ of the socket as the injury occurs.

Dislocated shoulder symptoms to look for include:

• Deformity
• Swelling
• Numbness
• Weakness
• Bruising

The shoulder joint can dislocate forward, backward, or downward. A common type of shoulder dislocation is when the shoulder slips forward (anterior instability). This means the upper arm bone (head of humerus) moved forward and out of its socket. It may happen when the arm is put in a throwing position.

It is important for the doctor to be able to establish the cause of instability if one is apparent. This may involve a traumatic dislocation event, repetitive micro-trauma (for example due to overhead activity), or inherited hyper-mobile joints. Pain or instability may be associated with specific positions. Symptoms of instability or dislocation at night may suggest severe instability.

Following shoulder dislocation, there may be some remaining instability of the shoulder once it is back in place. Anterior (forward) instability following shoulder dislocation usually is evident due to pain, fear or discomfort when the arm is in a ‘stop sign’ position. Posterior (backward) instability results in symptoms when the arm is crossing the body and turned inward. Inferior (downward) instability may present as pain or tingling while carrying heavy objects or with pulling downwards on the arm. In some instances, instability is multidirectional (in several directions).

Dislocated shoulder diagnosis

People with anterior (forward) shoulder dislocation tend to hold their arm by their side, supported by their other arm. They tend to resist attempts at movement. On inspection, there may be some deformity at the shoulder joint, due to the head of the humerus sitting in the wrong place.

When the shoulder is dislocated posteriorly (backwards), there is a flattening of the shoulder at the front, and a fullness at the back of the shoulder where the dislocated humeral head is sitting. The arm is held across the body and turned in, and cannot be turned out. With inferior (downward) shoulder dislocation, the arm is unable to be moved out to the side, and tends to be held above the person’s head with the forearm resting on the head.

The doctor will assess for damage to bone, nerves and blood vessels before they put the shoulder joint back in place (known as ‘reducing‘ the shoulder).

You’ll be assessed and examined when you get to the hospital emergency room. You’ll usually have an X-ray to check whether you’ve broken any bones and confirm the dislocation.

If you have a fracture, you may have further scans to investigate the area in more detail. Fractures with a shoulder dislocation require specialist orthopaedic care, and you may need surgery.

If you don’t have any fractures, your arm will be gently manipulated back into its shoulder joint using a procedure known as reduction.

In the more chronic setting, several tests may be performed to assess for shoulder instability. Pain and instability in certain positions may indicate the direction and degree of instability. The apprehension test involves moving the shoulder into a ‘stop sign’ position. If the patient shows fear (apprehension), discomfort or guarding, the test is considered positive and indicates anterior instability is present.

Investigations and tests

Following shoulder dislocation, the doctor will arrange a shoulder x-ray, usually before they attempt to put the joint back in place (reduce it). This is to confirm the dislocation, and to look for any fractures which would make reducing the joint unsafe. Once the joint has been put back, another x-ray will be done to confirm the joint is in the correct position. When there are more complicated injuries, CT or MRI scans may be necessary to check for injury to muscles, cartilage, other ‘soft tissues’ and subtle bone damage.

How to fix a dislocated shoulder

Dislocated shoulders should be put back in place (reduced) as soon as x-rays have been taken. It is essential that this procedure is carried out by trained medical staff, as there is a risk of damage to blood vessels, nerves and the possibility of fracture if it is not done properly.

Pain relief options

Options for pain relief while shoulders are put back in place include:

• No sedation: Anesthesia may not be required for people who have dislocated their shoulder before, and have done it again with minimal trauma. This works best with techniques that do not require significant force, such as external rotation, scapular manipulation, or Milch technique (see below);
• Nitrous oxide (laughing gas);
• Sedation with injection of anesthetic into the veins may be required to reduce muscle spasm and relieve pain. The patient is briefly asleep while the shoulder is put back in place. Common options include the drugs known as midazolam, fentanyl, propofol and ketamine. Procedural sedation requires appropriate monitoring and supervision, and the ability to provide airway support if it is required.

How to treat a dislocated shoulder

• Again, it must be emphasized that putting a dislocated shoulder back in place must not be attempted by untrained individuals.

There is no one technique that is better than the others for reducing a dislocated shoulder. The choice is usually made based on the condition of the individual and the preference of the clinician. The individual will be informed of the risks of reduction, which include risks of anesthetic, fractures, rotator cuff injuries (usually present before reduction), and damage to arteries and nerves, which are rare when good technique is used.

Certain people may be referred to orthopedic surgeons (specialist bone doctors) before an attempt is made to put the joint back in place. People who may be considered for this course of action include elderly patients (due to their increased risk of fracture or nerve and blood vessel injury during relocation attempts), and anyone younger than 10 years of age (due to risk of fractures that may affect the growth of the bone).

Options for reduction of anterior shoulder dislocation include:

• Traction/counter-traction: This is the least traumatic and most advisable method to use. A sheet or towel is wrapped under the armpit to apply counter-traction from the opposite side of the patient to the clinician who is providing gentle continuous traction at the wrist or elbow, in a direction that is slightly abducted (30 degrees) and forwardly flexed (30 degrees);.
• Scapular manipulation: With the individual lying on their stomach, or sitting upright, the shoulder blade is rotated by pushing the tip toward the spine and the socket downwards, while an assistant provides gentle forward or downward traction on the arm. This disengages the humeral head from the socket, and allows it to reduce into anatomical position. This technique is quick (1–5 mins) and well tolerated, and is successful in over 80% of attempts;
• External rotation: This manoeuvre takes 5–10 minutes. The individual is lying on their back, with the elbow bent to 90 degrees. The clinician holds the individual’s elbow and wrist, and very slowly the individual allows their arm to rotate outwards as the clinician guides the movement. Whenever pain or spasm is felt, the movement is stopped and the muscles are allowed to relax. The “clunk” associated with reduction using other techniques may not be evident. Reduction usually occurs once the arm is externally rotated between 70 and 110 degrees;
• Milch technique: If reduction using external rotation is unsuccessful, the Milch technique can be added. The fully outwardly rotated arm is taken out to the side into an overhead position, maintaining external rotation throughout. Gentle traction is applied in line with the arm bone, and there is direct pressure placed over the humeral head via the clinician’s thumb in the armpit. This technique is successful in over 86% of cases.
• Spaso technique: Gentle vertical traction and outward rotation is applied to the dislocated arm while the individual is lying on their back.

Other techniques have been described, but are considered complex, or associated with complications. Reduction is achieved when there is a “clunk” as the humeral head returns to the socket, and the individual is able to place the affected hand on the opposite shoulder. Reduction will be confirmed with an x-ray.

Dislocated shoulder rehabilitation

The period of immobilization following reduction is variable, though immobilization in a standard sling has not been shown to effect the chance of recurrence. Immobilization is usually achieved using a sling to maintain a position of internal rotation. However, recent reports have concluded that immobilization in a position of external rotation of the humerus may result in lower rates of recurrent dislocation. The problem with this technique is the significant inconvenience the individual experiences by having their arm positioned in an externally rotated position for 24 hours per day. This concept requires further studying before it is adopted for routine use.

Your doctor may immobilize the shoulder in a sling or other device for several weeks following treatment. Plenty of early rest is needed. The sore area can be iced 3 to 4 times a day.

The period of immobilization is followed by rehabilitation with physiotherapy targeted towards restoring the range of motion and improving the strength of the shoulder joint to maximize its stability.

After the pain and swelling go down, the doctor will prescribe rehabilitation exercises for you. These help restore the shoulder’s range of motion and strengthen the muscles. Rehabilitation may also help prevent dislocation of the shoulder again in the future. Rehabilitation will begin with gentle muscle toning exercises. Later, weight training can be added.

If shoulder dislocation becomes a recurrent problem, a brace can sometimes help. However, if therapy and bracing fail, surgery may be needed to repair or tighten the torn or stretched ligaments that help hold the joint in place, particularly in young athletes.

At times, the recurrently dislocating shoulder can result in some bone damage to the humerus or shoulder socket. If your surgeon identifies some bone damage, he or she may recommend a bone transfer type of surgery.

Follow-up

If you continue to have pain, your provider will probably ask you to come back in 1 week to decide if you need to:

• See an orthopedist (bone doctor)
• Begin physical therapy or range of motion exercises

Dislocated shoulder Self-care at Home

Make an ice pack by putting ice in a sealable plastic bag and wrapping a cloth around it. DO NOT put the bag of ice directly on the area, as the ice could damage your skin.

On the first day of your injury, apply the ice every 10 to 15 minutes, for 20 minutes each time. After the first day, ice the area every 3 to 4 hours for 20 minutes each time. Do this for 2 days or longer, or as instructed by your provider. After two or three days, when the pain and inflammation have improved, hot packs or a heating pad may help relax tight and sore muscles. Limit heat applications to 20 minutes at a time.

For pain, you can take ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn), aspirin, or acetaminophen (Tylenol). You can buy these pain medicines without a prescription.

• Talk with your provider before using these medicines if you have heart disease, high blood pressure, kidney disease, or have had stomach ulcers or bleeding.
• DO NOT take more than the amount recommended on the bottle.
• DO NOT give aspirin to children.

You may be given a shoulder sling to use for a few weeks.

• Once you have less pain, begin range of motion exercises so that your shoulder does not get stuck in place. This is called contracture. Check with your provider before doing any of these motions.
• After your injury has healed, DO NOT lift heavy objects for 8 to 12 weeks.
• Rest your shoulder. Don’t repeat the specific action that caused your shoulder to dislocate, and try to avoid painful movements. Limit heavy lifting or overhead activity until your shoulder feels better.

Arm and shoulder exercises

Some gentle arm and shoulder exercises may be recommended for you to do at home with your arm out of its sling.

These will help:

• reduce stiffness
• relieve some of the pain
• build up strength in your shoulder muscles

It’s likely you’ll feel some aching, discomfort or stretching when doing these exercises. However, if you experience intense pain for more than 30 minutes, do the exercise less forcefully and less often.

Once your injury heals and you have good range of motion in your shoulder, continue exercising. Daily shoulder stretches and a shoulder-strengthening and stability program can help prevent a recurrence of dislocation. Your doctor or a physical therapist can help you plan an appropriate exercise routine.

Shoulder exercises