An AC Injury, more commonly referred to as a Shoulder Separation, is an injury to the acromioclavicular (AC) joint which is located at the top of the shoulder. A shoulder separation occurs at the spot where the clavicle and the scapula meet. This injury is often confused with a shoulder dislocation, however these are two distinct injuries.
A Separated Shoulder is most often the result of a traumatic incident such as a sports injury or slip and fall. In some instances, these injuries may be caused by arthritic condition which weaken the cartilage around the AC joint.
Because the severity of the injury may vary, Separated Shoulder injuries are classified into six grades or types.
Type I Shoulder Separation:
An injury to the capsule surrounding the AC joint. The bones are not pushed out of position and the most common symptom is pain.
Type II Shoulder Separation:
Injury to the AC joint capsule and one of the clavicle stabilizing ligaments. This ligament may be partially torn and a visible bump over the injury may be present.
Type III Shoulder Separation:
The injury is the same as a Type II injury but damage to the ligament is more severe and a bump over the injury is clearly present.
Type IV Shoulder Separation:
This injury is less common and occurs when the clavicle is forced behind the AC joint.
Type V Shoulder Separation:
In this type of AC Injury all of the injuries of a Type IV injury are present and the clavicle causes a puncture of the muscle above the AC joint
Type VI Shoulder Separation:
This type of AC Injury is exceedingly rare. In this form of injury the clavicle is pushed downwards lodging it below the scapula.
Signs and symptoms of an AC Injury may include:
- Pain in the shoulder
- Visible bump at the area of injury
- Swelling or bruising
- Limited range of motion
- Weakness in the affected shoulder and arm