An acromioclavicular joint separation, or AC separation, is a very frequent injury among physically active people. In this injury the clavicle (collar bone) separates from the scapula (shoulder blade). It is commonly caused by a fall directly on the "point" of the shoulder or a direct blow received in a contact sport.
Grade 5—Involves tearing of the joint covering (capsule) and ligaments connecting the shoulder blade (scapula) and collar bone (clavicle), and the end of the collar bone (clavicle) tears through the muscle covering (fascia) above it. Results in a large, permanent bump over the top of the shoulder at the AC joint.
The most common cause of an AC joint separation is falling on the shoulder (Fig. 3). As the shoulder strikes the ground, the force from the fall pushes the scapula down. The collarbone cannot move enough to follow the motion of the scapula.
Grade 2—Involves tearing of the joint covering (capsule) and stretching (but not tearing) of ligaments connecting the shoulder blade (scapula) and collar bone (clavicle). Frequently results in a small, permanent bump over the top of the shoulder at the AC joint.
A type III separation involves injury to both the AC joint ligaments the CC ligaments. This results in complete separation between the acromion and clavicle, and treatment for this type is controversial.
A shoulder separation is not the same as a dislocation. In a dislocation, your upper arm bone (the humerus) pulls out of the shoulder joint. Shoulder separations are common, especially in active young adults. Your shoulder blade connects to your upper arm bone and to your collarbone with ligaments.
The acromioclavicular joint is a diarthrodial joint defined by the lateral clavicle articulating with the acromion process as it projects anteriorly off the scapula. The AC joint is a plane type synovial joint, which under normal physiological conditions allows only gliding movement.
The acromioclavicular, or AC, joint is a joint in the shoulder where two bones meet. One of these bones is the collarbone, or clavicle. The second bone is actually part of the shoulder blade (scapula), which is the big bone behind the shoulder that also forms part of the shoulder joint.
Shoulder separation is an injury to the ligament between the shoulder blade and collarbone. Whereas shoulder dislocation occurs when the top of the arm bone loses contact with the socket of the shoulder blade.
If the distance between the two bones is between increased between 25 and 100% it is a grade 3 and if it is more than that it is a grade 5. A grade 4 ac separation is one where there is significant posterior movement of the clavicle relative to the acromion.
Grade III- The most severe shoulder separation. This completely tears both the AC and CC ligaments and puts the AC joint noticeably out of position, with a larger bump.
Most people do well without surgery. The severe injury (Grade 3) can be treated either nonoperatively or operatively. Non-operative treatment involves immobilisation in a sling for two to three weeks followed by a course of physiotherapy.
Grade 4, 5, and 6 separations are severe injuries with high degree of displacement of the clavicle with respect to the acromion and usually require surgery.
A separated shoulder determined to be grade 4–6 typically requires surgery to repair. Treatment for grade 3 is less clear-cut. Some grade 3 injuries require surgery, while others do not, depending on the patient and the type of activity she or he wants to return to after treatment.
AC Joint Separation Grading Scale A grade 1 AC joint separation is a mild shoulder separation where the AC ligament is partially torn or stretched. A grade 2 AC joint separation is a partial separation of the AC joint. The AC ligament is completely torn but the coracoclavicular (CC) ligaments are still intact.
Leaving your AC joint injury untreated means your condition can worsen, which can have serious consequences, such as: Severe shoulder separation. Serious displacement or collarbone fracture.