Dislocation of the shoulder is a serious injury commonly seen in sports. It involves the head of the humerous (arm) coming out from the glenohumeral (shoulder) joint. The shoulder generally dislocates as it is forced into an unnatural position. The longer it is out of place the more the muscles spasm making it harder to reduce. For this reason it is important to go straight to a medical profession who is able to help put it back in place. Having a shoulder dislocate is generally quite painful and occasionally the axillary nerve may be damaged, causing numbness or reduced strength of the shoulder/arm.
The most common way to dislocate your shoulder is called an anterior shoulder dislocation. This commonly occurs from trauma such as a car accident or in a tackle where the shoulder is forced into a position of abduction and external rotation. This is the same position as you put your shoulder into when you cock your arm to throw a ball. This position is also known as the apprehension position as it causes concern to those who have had a previous dislocation that hasn’t been fully rehabilitated and is currently unstable.
A posterior shoulder dislocation occurs with either direct trauma to the front of the shoulder or from a fall onto an outstretched arm. This method of dislocation is less common than the anterior method.
The dislocation of a shoulder joint will also cause widespread damage to the ligaments, the joint capsule, the labrum and it will sometimes even fracture the shoulder itself.
The ligaments and joint capsule function to provide support to the shoulder. As they become stretched they no longer preform their job so the shoulder becomes unstable and is at high risk of dislocating until they are fully healed. Ligaments can take up to a year to heal fully and you are at reat risk of redislocation during this timeframe. To compensate for this lack of ligamentous support you need good muscle control, this is a reason why optimal rehabilitation is required.
The most common way for the labrum to be damaged during a dislocation is when it becomes detacted from the anterior wall of the glenoid, this is known as a Bankart lesion.
It is possible to damage the nerves in the shoulder during a dislocation, they can become stretched and may result in numbness through the outside of your arm. Any numbness or weakness generally recovers over time.
Factors that predispose you to a dislocated shoulder include:
- A previously dislocated shoulder.
- Shoulder joint hypermobility (a very flexible shoulder).
Signs and symptoms of a dislocated shoulder include:
- On examination the shoulder will look distinctly different from the other side with a pronounced humeral and a distinctive hollow before the acromium of the shoulder.
- There will normally have been a clunk or pop as the shoulder dislocates.
- There will be a significant amount of pain and the arm may be cradled to help try to reduce the pain.
- For a posterior shoulder dislocation the arm will be held across the body. There will be an inability to turn the arm outwards and there will be less rounding at the front of the shoulder.
Correct rehabilitation following a shoulder dislocation is vitally important as there is a high incidence of redislocation. Careful treatment protocols need to be followed in order to heal the shoulder fully including:
- Immobilisation of the shoulder to allow the connective tissue to heal.
- Simple range of movement exercises need to be started at the correct time to prevent the shoulder from seizing up or from developing frozen shoulder.
- Correct stretching exercises to regain shoulder movement, the wrong stretches will predispose you to another dislocation.
- Correct strengthening exercises to restore strength and stabilise the shoulder. The wrong exercises or the right exercises at the wrong time will aggravate and prevent proper healing.