Instability

What is it?

This occurs when the structures surrounding the shoulder joint are compromised and the ball is not stable within the socket. The joint is ‘loose’ and becomes unreliable, either partially moving out of joint (subluxation) or totally, known as dislocation. The shoulder joint is prone to instability due to its large range of movement.

Why does it occur?

There are several causative mechanisms. Most commonly as a result of the shoulder being forced out of its joint during trauma. This force can result in direct damage to the soft tissues, such as the ligaments and labrum (Bankart tear) or the bony head of the shoulder (Hill-Sachs). Therefore leaving structures damaged and therefore vulnerable to further dislocations.

Alternatively, some people may suffer instability when only a small force is applied. This is otherwise known as ‘atraumatic dislocation’ and occurs when the surrounding structures are lax as a result of overuse or congenital conditions. The joint will often relocate without need to attend hospital and the latter are often known as ‘double-jointed’.

Finally a subset of patients suffer with inappropriate muscle recruitment. Otherwise known as ‘muscle patterning’.  

What are the symptoms?

You may feel that the shoulder is painful after injury or that it ‘gives way’, or have suffered several shoulder dislocations.

How is it diagnosed?

A detailed history and examination is essential to determine the mechanism of injury and therefore appropriate treatment modality. X-rays and magnetic resonance imaging can then be used to confirm the suspected diagnosis.

How is it treated?

  1. Non-surgical treatment

    The condition can take months to resolve before progress is noted. Lifestyle changes and modifying activity that provokes symptoms are key. Medications that reduce inflammation such as non-steroidal anti-inflammatories like aspirin and ibuprofen can be beneficial. Most importantly, physiotherapy exercises that aim to improve strength in the muscles supporting the shoulder can improve shoulder stability.

  2. Surgical treatment

This is most commonly performed using arthroscopy, where several small incisions are made around the joint. A scope is inserted to visualize the affected area and instruments are recruited to repair any tears in the capsule and reattach the labrum to the glenoid or ‘socket’.