Shoulder Dislocation (Instability)
The shoulder is a joint, which has a huge range of motion but this means that it is inherently unstable and relies on the surrounding structures (muscles and ligaments) to stop dislocating. If any of these structures are damaged, the shoulder can become unstable. The shoulder can be unstable in any direction. I will only consider the anterior variations (the most common) here.
There are several different types of instability:
· Traumatic
· Atraumatic
· Muscular Imbalance
Traumatic dislocation
Atraumatic dislocation
Muscular imbalance
This is the least common form of instability and occurs when the coordination between the muscles of the shoulder is lost. The shoulder is inherently unstable and relies on the fine balance between the muscles to keep it from dislocating. For example: the muscle of the chest wall (pectoralis major) are usually quiet when the arm is lifted up from the side. If this muscle starts to contract at the same time as the arm is being lifted up, it will try to pull the top of the arm (the shoulder) forwards and can lead to dislocation.
There is usually nothing wrong inside the shoulder itself and physiotherapy can have very good results, although it is a long, alow process.
