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Shoulder Instability

Frozen Instability- Why does this happen?
The shoulder is a loose  ball and socket joint.  The round head of the humerus sits in a shallow socket on the shoulder blade.  This allows a large range of shoulder movement in all directions.
The shallow socket, the glenoid, has a rim of soft tissue called the 'labrum' which makes the socket deeper.  The rotator cuff muscles attach from the shoulder blade to the humerus keeping the ball in the socket.  The ligaments and capsule also help to hold the joint together. 
Shoulder Instability occurs when the ball comes out of the socket during certain activities.  This happens because the soft tissue around the joint is loose and the rotator cuff muscles are weak. 
Shoulder Instability can be classified in 3 ways:
Traumatic Structural Instability  -  This occurs when there has been a single, such as throwing a ball, or repeated injury to the joint.  These injuries cause the shoulder to dislocate (come out of the socket) or sublux (come part way out of the socket).  This results in damage to the soft tissue around the shoulder which makes the joint unstable.  In this type of injury the ball will come out from the socket forwards.
Atraumatic Instability  -  When there has been no injury but the shape of the joint or soft tissue means the humerus is not held in the socket.  There is poor contact for the joint and the ball moves excessively in the socket.
Habitual Non-Structural  -  Again when there has been no injury but the rotator cuff muscles are not working properly to hold the ball in the socket.  Certain muscles are pulling more strongly than others at different points in the movement, causing the ball to move excessively in the socket.
What are the symptoms?
  • Shoulder Instability is associated with recurring shoulder dislocation or subluxation.
  • Some people will feel a looseness in the shoulder on certain activities e.g. throwing a ball.
  • On provacative movements some people will experience a sudden sharp pain. 
Diagnosing Shoulder Instability 
Your GP or Physiotherapist can usually diagnose Shoulder Instability simply by examining your arm, knowing where your pain is and how it started.  If a more detailed examination is required you may be referred to an Orthopaedic Surgeon.
X-rays and other investigations, such as MRI Scans, are often necessary to establish if there is damage to the labrum, ligaments or tendons.
What is the treatment?
Modifying activities  -  The first thing to do is break the pain cycle.  While it is important to stop activities that make the pain worse, to let the soft tissue recover, you must not stop using your arm.  Muscles need some activity to keep them healthy.
Painkillers and anti-inflammatory medications  -  These may be prescribed by your GP if the pain is constant and you are struggling to sleep.  This is a temporary measure to break the pain cycle, but can continue as required.
Exercise  -  Exercise is the most effective way of helping to improve the stability of the joint.  Strengthening and stability exercises for the rotator cuff muscles will help keep the ball in the socket and prevent further instability.  Click here for a list of exercises suitable for Shoulder Instability.
Physiotherapy  -  If exercise alone does not improve symptoms then physiotherapy treatment may be required.  Click here for more information about Physiotherapy.
Surgery  -  If investigation shows there is damage to the soft tissue around the shoulder joint you may be referred for surgery to repair the soft tissue and tighten the structure which will stabilise the joint. 
Remember an important part of treatment for Shoulder Instability is your home exercises and modifying activities.