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Dislocation & instability

Shoulder Dislocations and Instability

The shoulder is the most mobile joint in the body. This is important to allow movement of the arm and hand above the head and behind the back. The anatomy of the shoulder enables this joint to be so mobile.

The shoulder joint is made up of three bones:

1) The upper arm bone (humerus)

2) The shoulder blade (scapula)

3) The collarbone (clavicle).

The head, or ball, of the upper arm bone fits into a socket in the shoulder blade called the glenoid. The glenoid is shallow which allows good range of movement at the shoulder joint but also means it is prone to dislocation.


During movement of the arm the ball slides forwards and backwards in the shallow socket, which is normal and pain free.  Sometimes the ball can slide too much causing pain and/or the sensation of the ball coming out of socket. The ball may move slightly out of socket, called a partial dislocation or subluxation, or it can come completely out of the socket. This is termed complete dislocation.

Excessive movement of the ball in the socket is controlled by:


Classification of shoulder instability

Shoulder instability is often sub-classified into traumatic and non-traumatic instability depending on whether it began with a dislocation caused by a significant injury.

1) Traumatic Instability

The shoulder can be dislocated as a result of an injury where there is enough force to pull the shoulder out of joint. For example, a tackle during rugby or football. When this happens for the first time it is normal to need to go to A&E for the ball to be ‘put back in the socket’. Symptoms of instability following a dislocation may include recurrent dislocations or subluxations, pain and a feeling of apprehension when the arm is moved in certain positions.

Treatment of traumatic instability


For some patients’ specialist physiotherapy following a dislocation can help restore movement, strength and return to normal function without the need for surgery.


Sometimes injury to the structures around the ball and socket can cause ongoing pain and repeated dislocations. Surgery may be required to repair the damaged structures and this more likely if you are young and plan to return to sport. The most commonly occurring injury from a shoulder dislocation in a younger person is a tear of the labrum. This is called a Bankart lesion and the surgical proceedure to repair this is termed a Bankart repair.

Physiotherapy following surgery is very important to ensure the surgery is successful, particularly if you plan to return to sport or have a job that places high demands on the shoulder.  At YSP we will guide you through your surgeon’s post-operative guidelines to safely increase movement and strength at the shoulder. Treatment will progress to high level and sport specific activities to ensure you are confident in returning to your sport, job and everyday activities. We will not just focus on your shoulder but incorporate strengthening of other areas of the body to help reduce stress on the shoulder as you return to normal activities. We will endeavour to find safe ways to maintain your fitness during rehabilitation.


2) Non-traumatic instability

Symptoms of non-traumatic instability may also include pain, apprehension, subluxations or dislocations but there is no history of a significant injury that resulted in an initial dislocation. Dislocations can occur with minimal force such as turning over in bed or reaching up. It often ‘pops’ back into place without needing to attend A&E.

People with non-traumatic instability often have hypermobile joints (double jointed) and may have instability in both shoulders. It is not the joint laxity itself that causes instability but a change in how important muscles around the shoulder are working. It is often associated with a change in activity such as an increase in training, particularly in sports that involve an overhead movement as seen in swimming or bowling.

Treatment of non-traumatic instability

It is the general consensus between orthopaedic consultants and physiotherapists that treatment in the first instance is non-surgical and provided by a specialist physiotherapist with experience with shoulder instability. At YSP we all have a keen interest in shoulder instability and have all completed master’s level studies and post graduate training in the area. Physiotherapy will involve assessing control of movement at the shoulder and we will produce an individualised training program to restore normal movement. We will assess strength and control in other areas of the body and incorporate this into your program. This is a key component of rehabilitation; it should not focus on the shoulder in isolation.

Rehabilitation of non-traumatic shoulder instability is often lengthy, and requires dedication, but it is often very successful. Unfortunately, some people still have on-going problems and will require a surgical opinion. In most cases surgeons will not consider operating on this condition until at least 6 months of rehabilitation under supervision of a specialist physiotherapist has been completed. At YSP we have strong links surgeons who specialise in the treatment of shoulder instability and can make a referral if this is required.

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