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
This is the most common form of shoulder instability, often caused by a direct blow, fall, or sudden force that forces the shoulder joint out of its socket. The dislocation typically occurs when the arm is in a vulnerable position, such as when it is extended or rotated awkwardly. Trauma can tear the ligaments, tendons, or cartilage that help stabilize the shoulder, leading to repeated dislocations if not properly addressed. Treatment usually involves immediate reduction (putting the joint back in place) followed by physical therapy to strengthen the muscles and prevent recurrence. Surgery may be considered if the damage to the shoulder's stabilizing structures is significant.
Atraumatic dislocation
Atraumatic dislocations occur without a specific traumatic event, often due to inherent weaknesses in the soft tissues (ligaments, tendons) or the joint capsule. This form of instability may result from hypermobility (loose joints) or abnormalities in the structure of the shoulder that make it more prone to dislocation with minimal force. These dislocations can happen even with normal movements, such as reaching overhead or lifting objects. Non-surgical treatments, such as physiotherapy to strengthen the muscles around the shoulder, are usually effective. In more severe cases, surgical intervention may be needed to tighten the ligaments or repair other structural weaknesses.
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.
