Shoulder dislocations – by Physiotherapist Zach Walter 

Due to the shoulder being an already unstable joint, it is susceptible to separation of the humeral head from the joint capsule. Today we will explore all things shoulder dislocations. 

The unstable joint  

  • The shoulder joint (known as the glenohumeral joint) is comprised of the head of the humerus bone inserting into the outer aspect of the shoulder blade (the glenoid fossa).  
  • A thick tissue known as the Labrum, encapsulates the humeral head to deepen the socket to provide further stability.  
  • The rest of the joint is supported by ligaments and muscles which attach at the shoulder blade and humerus bones. 
  • Unlike the hip joint, the shoulder is a very mobile and unstable joint. It is commonly referred to as “a golf ball sitting on a tee”, with the golf ball representing the head of the humerus, and the tee as the glenoid.  

  

The types of dislocations  

  • Anterior dislocation (95% of dislocations): The mechanism for this type of injury is where the arm is raised away from the body and rotated backwards (“stop sign” position). This is the most common type of dislocation. 

  

  • Posterior dislocation: Much less common, this injury occurs where the humerus is forced backwards into the shoulder joint. This may occur with falling on an outstretched arm or reaching for the dashboard during a motor vehicle accident.  

  

Who is most at risk? 

  • Prior dislocations  
  • Younger populations  
  • Patients with more than normal shoulder movement (hypermobility) 
  • Those with rotator cuff tears   
  • Recurrence rates  
  • There is a very high risk of recurrence of shoulder dislocations, particularly for those under 20 years old.  
  • Below are the age group percentages for risk of recurrence: 
  • Less than 20 years old – Up to 95%  
  • 20 – 25 years old – 50-75 %  
  • less than 25 years old – less that 50% 
  • 20-40 years old – 40% risk 
  • Above 40 – less than 15% risk 

  

What do I do if I have sustained a shoulder dislocation? 

This is a surgical emergency and requires successful relocation within the first 24 hours to avoid the risk of being unable to manually re-position the humerus within the shoulder socket. 

  

Who can re-locate a dislocated shoulder? 

Getting to the emergency department as early as possible is important as the procedure for relocating the shoulder needs to be carried out by a doctor or surgeon in order to adequately assess the shoulder and also reduce the risk of further complications.   

  

Collateral damage  

  • When the humerus is forced against the socket during an anterior shoulder dislocation, the lower part the socket (Labrum) may detach from its attachment to the shoulder blade. This is known as a Bankart lesion. Most commonly this will involve only the soft tissue, but may see part of the bone breaking away in some cases. 
  • Commonly occurring with the Bankart lesion is a Hill Sachs lesion. This is where contact of the humeral head against the socket causes a dent to the bone’s surface. 
  • In some cases, there may be some vascular or nerve injuries as a result of the dislocation. Vascular injuries are infrequent and increasingly rare in younger populations. Patients may experience reduced pulse pressure or cooling of the hands and require further angiography in these cases.  
  • Often vascular injuries will be complicated by nerve injuries, which are more common. This is where the network of neural tissue known as the brachial plexus may be damaged causing some transient weakness, pins and needles or numbness to the upper arm.  
  • For 14-65% of cases, particularly the older populations, the group of muscles which are responsible for stabilising the shoulder joint may be torn following a shoulder dislocation. These muscles are known as the rotator cuff muscles.  

What can Physiotherapy offer?  

Physiotherapy is critical in the management of shoulder dislocation by providing: 

  • Accurate shoulder assessment and interpretation of scans  
  • Education around the severity of the injury and its complications 
  • Advice around immobilisation, further scans and general management strategies 
  • Formulate a tailored exercise plan to assist patients to achieve their goals and/or return to their respective sport. 
  • Hands-on treatment when necessary 
  • Identify and referral for when surgical opinion is necessary. 

If you have experienced a shoulder dislocation, speak to one of our practitioners to ensure your recovery is optimised. 

 

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