Shoulder instability

The shoulder is one of the most commonly dislocated joints.  Instability means that the shoulder can dislocate (be pulled out of joint) or experience subluxation (move more than it should).  The shoulder joint is a ball and socket joint like the hip, but this instbility is more common because the shoulder joint is much more shallow than the hip which allows it to be a very mobile/flexible functional joint.  Both dislocation and subluxation happen for a variety of reasons.

The three main causes of shoulder instability are:

  • Traumatic dislocation – where the shoulder undergoes an injury with sufficient force to pull the shoulder out of joint such as a violent tackle in rugby, or a fall onto an outstretched hand
  • Non-traumatic dislocation –caused by repeated shoulder movements gradually stretching out the soft tissue cover around the joint causing the rotator cuff muscles to become weak, regularly working with your hands above your head may contribute to this
  • Positional non-traumatic – the ability to dislocate your shoulder without any form of trauma. This may start off as a party trick, but if repeated, it can happen during everyday activities. If you are able to do this it is strongly recommended that you don’t

What causes instability?

Traumatic dislocation:

This is where the shoulder undergoes an injury with enough force to pull the shoulder out of joint, such as a violent tackle in rugby or a fall onto an outstretched hand. This much more common in men under the age of 30.

If this happened the shoulder usually requires putting back in position (reduction) in Accident and Emergency. Following a first time dislocation, the arm is usually put in a sling and you may be sent for a course of physiotherapy.

The shoulder joint is a ball and socket joint, which is held together by a combination of ligaments and muscles. There is also a rim of cartilage around the socket called the labrum. The labrum deepens the socket to make the shoulder more stable.

When the shoulder is dislocated, sometimes the rim of cartilage is pulled away from the socket damaging the labrum. Often this does not heal and the shoulder can remain unstable.
Once your shoulder has been damaged in this way, you may find that your shoulder dislocates again fairly easily. This damage to the labrum is often called a 'Bankart lesion'; named after the doctor who first described this injury.

If enough force is present during a dislocation, a small part of bone from the shoulder socket (glenoid fossa) may break off with the labrum. This is often called a 'Bony Bankart lesion'.

Shoulder stabilisation surgery may be required and an operation to repair the damage to the labrum and therefore re-stabilise the shoulder joint will be recommended.  This type of repair may also be called a Bankart repair or a Latarjet procedure by your surgeon.

Non-traumatic dislocation:

Repeated shoulder movements may gradually stretch out the soft tissue cover around the joint (the joint capsule). This can happen with athletes such as throwers and swimmers. Following capsular stretching, the rotator cuff muscles can become weak – affecting how the muscles around the shoulder interact with each other and in turn, leading to an imbalance of the shoulder.

In this type of shoulder instability, referral for specialist physiotherapy is the first form of management and treatment can be effective for as long as exercises are continued.

Posititional non-traumatic:

This condition refers to the ability to dislocate your shoulder without any form of trauma. This may start off as a voluntary dislocation, perhaps as a party trick, but if repeated, eventually it can happen during everyday activities. It can affect both shoulders and can be associated with people who have lax joints. If you are able to do this it is strongly recommended that you don’t

This type of instability is due to abnormal muscle patterning around the shoulder, meaning the strong power muscles around the shoulder, such as the pectoral muscles, are constantly ‘switched on’.

These muscles then pull the already loose shoulder out of joint during movement. The main treatment with for this type of instability is specialist physiotherapy, which looks at retraining movement patterns of the shoulder, using specialist rehabilitation methods and accurately performed exercises.  As with any form of rehabilitation compliance with advice and exercise is key to success.

How can I manage my instability/dislocation?

If you are in a sling following a first time dislocation your physiotherapist or doctor will advise you when to remove it in order to exercise

Change your activity / rest

You can start to move your arm when advised by your physiotherapist or doctor and you should then try to slowly increase your range of movement over the next 3 to 4 weeks.  Making changes to activities does not mean you have to stop using or moving the shoulder altogether but you should try to avoid activities that involve lifting your arm above your head or contact sports in the first 3 months.  Following this advice can prevent future dislocations.

Maintaining good posture

Shoulder movements are affected by your posture. Standing and sitting with your shoulders back in a good position will help your movements as well as prevent the tendons in your shoulder catching on other structures.

Analgesia – Painkillers and / or anti-inflammatories

Pain killers such as paracetamol and anti-inflammatories can be effective in reducing the pain and enabling you to comply with rehabilitation.  If you have not taken these before you should speak to a pharmacist or your GP.


Icing your shoulder can be a very effective way of reducing your pain. Place a wet flannel and a pack of frozen peas on your shoulder for up to 20 minutes every hour. Check the skin under the ice every five minutes to avoid an ice burn. Once the pain begins to settle you can then start to ice your shoulder less frequently (refer to ice and heat information section)

A range of exercises can be found in the video section of our website to help maintain range of movement and strengthen the shoulder which your physiotherapist will direct you towards.


Lying on your shoulder can be very painful, try and sleep on your back or the opposite shoulder with a pillow under the armpit of the affected shoulder.  You should continue to wear your sling in bed until advised to remove it by your physiotherapist or doctor

How do I stop a dislocation in the future?

if you have a history of recurrent shoulder dislocations you should contact your doctor or local Community MSK Service and following assessment by a physiotherapists it may be appropriate to recommence a shoulder stability rehabilitation or your symptoms may warrant referral to one of our shoulder specialist surgeons for a surgical opinion.  Whatever the outcome you will be supported and guided throughout the process.

Before trying to self-manage using the information on this website, if you have any of the following symptoms please contact your GP.

  • Left shoulder pain associated with shortness of breath, clamminess
  • Night pain that prevents sleep
  • Swelling or redness
  • Shoulder pain associated with fever or night sweats
  • Pain following traumatic injury  e.g. fall sports injury, epileptic fit or electric shock
  • Pins, needles or numbness