Acromioclavicular (AC) Joint Injury

What are AC joint Injuries?

The acromioclavicular joint is part of the shoulder joint. It is formed by the union of the acromion, a bony process of the shoulder blade, and the outer end of the collar bone or clavicle. The joint is lined by cartilage that gradually wears with age as well as with repeated overhead or shoulder level activities such as basketball or bench pressing.

Symptoms of AC joint Injury

Overuse of the AC joint can lead to erosion of the outer end of the collar bone also called distal clavicular osteolysis. This causes pain in front of the shoulder which worsens with movement of the arm. Pain may radiate to the chest and neck. Movement of the shoulder may produce a clicking or snapping sound and bumps are occasionally felt over the joint. AC joint arthritis is commonly associated with rotator cuff tears and impingement.

Diagnosis of AC joint Injury

When you present with the above symptoms, your doctor will review your medical history and perform a physical examination. Pain and tenderness over the AC joint is elicited by palpation and movement of the arm to compress the joint. An anesthetic injection into the joint can temporarily reduce pain thus identifying the AC joint as the source of pain. X-rays may show loss of joint space, increased bone density or bony overgrowths (spurs). MRI scans may reveal cartilage destruction and abnormal fluid accumulation within the joint.

Treatment of AC joint injury

Your doctor will treat your symptoms non-operatively by limiting or modifying your activities and controlling your pain. Pain is controlled by pain killers, anti-inflammatory medication and corticosteroid injections into the joint. If symptoms persist, surgery may be recommended. Surgery may be performed by a minimally invasive technique using an arthroscope or an open method. It usually involves removal of half an inch of bone at the outer end of clavicle (resection arthroplasty) to prevent the bones in the joint from rubbing against each other. Bone spurs are removed and any adjacent injuries to tendons or ligaments are also repaired during the procedure.

Following surgery, you are placed in a sling for a few weeks and range of motion exercises are begun as early as possible. Your movement and strength are gradually improved and in a period of 5-6 months you may safely return to sports.