What is a shoulder dislocation?
The shoulder is a ball and socket joint. The ball is the humeral head or top of the humerus, the long bone of the arm. The socket is called the glenoid and is a process off of the scapula, or shoulder blade. The shoulder socket is relatively flat - more like a golf tee than a coffee cup. This allows the shoulder great flexibility of movement, but also increases the risk of the shoulder slipping out of place (instability). The shoulder is actually the most commonly dislocated major joint. A subluxation is when the ball starts to come out of place but then immediately slips back. A dislocation is when the ball comes completely out of the socket, usually as the result of an injury. When the shoulder dislocates or subluxates, the stabilizing tissues of the shoulder (the labrum and capsule) are torn. These are sometimes able to heal with time, but in some people, the soft tissue tears do not heal completely and the shoulder becomes more unstable, leading to repeat dislocations.
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Some people may never have a shoulder subluxation or dislocation but will feel vague pain in the shoulder resulting from looseness in the shoulder joint. This is known as multi-directional shoulder instability (MDI). This occurs when the shoulder ligaments are loose, allowing excessive shoulder mobility, which can lead to pain.
What are the symptoms of shoulder dislocation?
A true shoulder dislocation is a very painful injury and most athletes require immediate on-the-field medical care or a trip to the emergency room to have the shoulder put back in place. However, in some patients, the episodes are more subtle and feel like the shoulder is popping or slipping out of place or just loose.
How is a shoulder dislocation diagnosed?
The diagnosis of shoulder instability is usually made by discussion with your sports medicine physician and a physical exam to test the looseness of the shoulder. Some people have naturally loose joints which can contribute to more severe shoulder instability, so other joints may be examined as well. When surgery is considered, X-rays are usually done to make sure there is not a small fracture or chip of bone. A special MRI called an MR arthrogram is also done to evaluate the soft tissue tearing.
How is shoulder dislocation treated?
Treatment is dependent on the severity of the instability. For a first dislocation, most people are treated with a sling followed by physical therapy or a strengthening program. The muscles around the shoulder offer a second layer of stability to the joint, so increasing muscle strength can significantly improve shoulder stability. After multiple dislocations, surgery is generally required. Surgery prevents further dislocations, which are not only painful but can cause long-term damage to the joint. Usually this is an arthroscopic surgery in which the torn labrum and capsule are repaired to restore normal joint stability and tighten the shoulder.
In patients with milder shoulder instability, physical therapy to strengthen the muscles and tendons around the shoulder is generally the best treatment. This involves identifying biomechanical factors that may be contributing to the instability (such as shoulder blade movement and the function of nearby muscles) and correcting them.