The humerus (ball) and the glenoid (socket) are stabilized by the capsule, labrum, and rotator cuff. The shoulder may dislocate if these tissues are torn during an injury.
After a forceful injury to the shoulder, the joint may dislocate anteriorly or posteriorly. With a dislocation, the shoulder is usually extremely painful and has very limited motion. Muscle relaxation is often required to reduce the shoulder back into the joint. You should immediately call your doctor for instructions or go to the ER when a severe injury is suspected.
Along with a thorough history and physical, shoulder X-rays often confirm the diagnosis. They can also help identify fractures that may have occurred at the same time. An MRI may be ordered to further evaluate the damage to the capsule, labrum, and rotator cuff. A CT scan may be ordered if a fracture is seen or suspected.
In some cases, immobilization and subsequent therapy are sufficient to restore stability and function to the shoulder joint. An arthroscopy or an open surgery may be recommended. Postoperatively, it is very important to protect the shoulder to allow tissue healing. A graduated therapy program is then implemented.
The clavicle (collar bone) is connected to the scapula(shoulder blade) by the AC joint. The joint can be felt on the superior and lateral aspect of the shoulder. The joint can be separated or fractured by a direct blow to the shoulder or a fall on the arm. The joint can also develop arthritis which may or may not be related to a previous injury.
An AC dislocation or separation is not the same as a shoulder dislocation (link to that section here), which occurs at the glenohumeral (ball and socket) joint. With an AC joint injury, the superior aspect of the shoulder is swollen and tender. The clavicle may or may not appear prominent and the shoulder may have a droop compared to the other shoulder.
The spectrum of injury is graded from one to six with Grade 1 being the least severe. This may be confirmed with an X-ray. In some cases, an MRI is also indicated.
Often, all that is necessary is rest, ice, and medication to treat the pain and swelling. Activities are gradually increased over time. With a more severe injury, surgery may be recommended to reduce the joint and repair or reconstruct the torn ligaments. At times, the distal clavicle may also need to be removed. In some cases, the distal clavicle may remain prominent after it has healed, even though it is no longer painful.