Shoulder Dislocation


What is Shoulder Instability?



shoulder instability


The shoulder is described as a “ball and socket “joint.


Instability of this joint is when the ball moves or slides in the socket more than is normal or in an uncotrolled manner, and this may be called “subluxation”.


When the ball part of the joint actually comes out of the socket this is called “dislocation”.




What Causes Shoulder Instability?

Shoulders can become unstable for one of three reasons.

1.  Traumatic Dislocation

Dislocation can occur due to trauma causing structural damage to the capsule and cartilage of the shoulder joint. This can be major trauma, as may be seen in a sports related injury or motor vehicle accident, or the trauma may be of a minor, repetitive nature, such as throwing a ball. Traumatic dislocation is the most common form and usually occurs as a result of a fall in which the arm is twisted up and away from the body (as in preparing to throw a ball). The cartilage at the front of the shoulder (the “labrum”) can be damaged, tearing away from the bony attachment.


2.  Atraumatic Dislocation

This form of shoulder dislocation is less common and arises either as a result of an abnormality of the tissues stabilising the shoulder or as a result of “repetitive micro-trauma”. This is experienced by gymnasts, swimmers and people who repeatedly stress the shoulder through a wide range of motion.


3.  Muscle patterning

Development of unbalanced muscle recruitment around the shoulder can occur due to postural abnormalities and cause shoulder instability. This can develop without any known cause or precipitating factor.


What are the Common Signs And Symptoms?

Traumatic dislocation causes severe pain in the arm which is commonly held by the side. Usually the patient is unwilling to allow anyone to touch the arm. Sometimes it is possible to see a swelling in the front of the shoulder.

The symptoms of an atraumatic dislocation (dislocation without any traumatic incident) may be the same as that of a traumatic dislocation. There may be an ache in the shoulder and a feeling of looseness. You may be afraid of placing the shoulder in certain vulnerable positions.

Acute dislocation is usually easy to diagnose based on what you tell the healthcare professional and x-rays. Other investigations may include MRarthrogram or CT scan.

Common Problems

Shoulder instability means your shoulder can dislocate or sublux repeatedly during active movements or exercise.

A traumatic dislocation can lead to disruption of the normal stabilisers of the shoulder and this can result in further episodes of dislocation.


The type of treatment you receive for your shoulder dislocations or subluxations will vary dependent on the cause of the presenting instability.

  • If the injury involves sufficient trauma to dislocate the shoulder, it will need to be reduced in A&E and immobilised in a sling for a period of time.  A course of physiotherapy will help you regain your range of motion and strength.
  • Disruption of the normal bone and soft tissue around your shoulder can result in an unstable shoulder and may require surgery. An anterior stabilisation is the most common surgical procedure for a traumatic shoulder dislocation where the labrum has been torn from the bone.
  • If the shoulder dislocates with minimum force it will usually ‘pop’ back into place with little help.  Physiotherapy is the recommended treatment for this instability and will address any muscle imbalance.
  • Physiotherapy is also the treatment of choice for patients with shoulder instability without any history of trauma.  


Maintaining a good balance of muscle control around the shoulder is the best prevention to shoulder instability.  Strength training for the shoulder should always be done on a background of good posture and core strength.

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