Shoulder Dislocation and Instability

Getting to Know Your Shoulder

The shoulder is a complex joint. It is a ball-and-socket joint and the most mobile joint in the body. But with more mobility comes less stability.

The head of the humerus (the “ball”) is much larger than the glenoid fossa, which is the part of the shoulder blade that it sits on. It’s a bit like a golf ball sitting on a tee, held in place by capsular ligaments, the joint capsule, and the rotator cuff muscles.

When any of these supporting structures become overstretched, weakened, or injured, the shoulder can start to feel “loose” or unstable.

So, What Actually Is a Shoulder Dislocation?

A shoulder dislocation occurs when the joint is forced out of position, often causing tissues to tear, stretch, or become damaged beyond their normal limits.

Common symptoms include:

• A sudden audible “pop” (and sometimes another pop if it relocates itself)  

• Visible deformity of the shoulder  

• You might also feel sudden weakness or a “dead arm,” sometimes with pins and needles. This happens because the dislocation can put pressure on the brachial plexus, the network of nerves that supplies your arm, temporarily affecting sensation and movement.

• A sense of apprehension or fear that it may “pop out” again  

• Pain or weakness when throwing

Why Shoulders Dislocate?

Shoulder dislocations can happen in two main ways: traumatic and atraumatic.

Let’s Break That Down

Traumatic dislocation

This happens when the shoulder is forcefully pushed beyond its normal range of motion, such as during a fall or a tackle.

If you experience a traumatic dislocation, it’s important to seek emergency care. In some cases, the dislocation can cause small dents in the humeral head, known as Hill-Sachs lesions or fractures in the glenoid fossa, the part of the shoulder blade that the humeral head sits on. These injuries can affect shoulder stability and may require further assessment.

In younger individuals returning to overhead or contact sports, there is a higher chance of re-dislocation, and surgery may be considered. In older adults, the risk of recurrence is lower, and physiotherapy is often very effective in avoiding surgery.

Atraumatic instability

This occurs without a major injury or dislocation event. Instead, the shoulder may partially slip (called a subluxation).

This can develop over time due to repetitive movements or naturally looser joints (genetic joint laxity).

Treatment Options for a Dislocated Shoulder

The most important first step if you think your shoulder is still dislocated is to go to the emergency department. Don’t wait for physiotherapy; a dislocated shoulder needs to be safely relocated by emergency care physicians.

Treatment options may include:

• Short-term taping  

• Use of sling in severe cases

• Imaging (MRI) if there is concern about significant soft tissue damage  

• Surgical review in cases of severe instability  

• Targeted rehabilitation

Once pain settles, gentle exercises can begin. These focus on strengthening the shoulder blade (scapula) and rotator cuff muscles to improve stability. Your physiotherapist will guide you through your progression.

It’s important to note that completely resting your shoulder for 4–6 weeks is not recommended, as gradual movement is key to recovery.

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