Shoulder Pain

What is the AC joint? The AC (acromioclavicular) joint is a joint at the top of the shoulder where the collar bone (clavicle) attaches to the acromion of the shoulder blade (scapula).  This joint acts as a pivot point in the shoulder allowing the arm to be raised overhead.  This joint is stabilized by 3 ligaments (acromioclavicular, coracoclavicular and coracoacromial) that form a triangle around the joint providing support to both the AC joint and the head of the humerus.​

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What is AC separation?

An AC separation occurs most often in contact sports (football, hockey) and sports that may involve falls (soccer, skiing, volleyball) and usually is the result of a fall or blow onto the tip of the shoulder or falling on an outstretched hand. 

How is the severity of an AC separation determined?

An AC separation is graded from I-VI based on the degree of separation between the acromion and clavicle when x-rayed with the arm weighted. 

• A Grade I separation involves only a slight separation and indicated a stretched or partially torn acromioclavicular (AC) ligament. 
•  A Grade II separation involves a complete tear of the acromioclavicular ligament and a partial tear of the coracoclavicular (CC) ligament. 
• A Grade III separation  is a complete tear of both the AC and CC ligaments. 

Grade I and II separations never require surgery and heal by themselves, although therapy may be required.  A Grade III separation rarely requires surgery however a rehabilitation program is required and full function of the shoulder can take 16 - 20 weeks to achieve.  Grade IV - VI separations involve displacement of the clavicle and most often require surgery.

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How is an AC separation treated?

​Immediately after injury, the AC joint can be quite painful regardless of the grade of injury.  Treatment for  Grade I and II injuries include strategies to reduce both pain and inflammation through the use of pain medications, a non-steroidal anti-inflammatory medication, the use of ice and activity modification.  For a Grade II separation, many physicians recommend the use of a sling for 1 - 2 weeks as well as a rehabilitation program to maintain or regain range of motion.  Because the ligaments are compromised due to the injury, heavy lifting and contact sports should be avoided for at least 6 -12 weeks for a Grade II injury.  Grade III injuries, when non-operative, are treated similarly to a Grade II injury except heavy lifting and contact sports should be avoided for 12 - 16 weeks.

How can I prevent an AC separation?

​It is very difficult to prevent an AC separation since the injury is most commonly traumatic in its mechanism.   Strength training can help to protect the shoulder by strengthen the muscles that stabilize the shoulder.  Proper form and appropriate protective equipment for your sport can also help to reduce your risk of injury.