AC Joint Injury

What is an AC joint injury?

The AC joint, or acromioclavicular joint, is found where the collarbone (clavicle) meets the acromion process (the highest part of the shoulder, which is part of the scapula). These two bones are held together by fibrous ligaments, with cartilage found in between that assists with stability and function. Sometimes this joint can become disrupted, known as a shoulder separation. These types of injuries may be caused in a variety of ways including falls, blunt trauma to the shoulder, bike accidents, or football tackles. Dr. Joseph Lamplot, orthopedic shoulder specialist, treats patients in Arlington Heights, Kildeer, Lake Zurich, Barrington, and the surrounding Northwest Suburbs of Chicago, IL, who have experienced an AC joint injury.

Is a shoulder separation the same thing as a dislocated shoulder?

No, these are two different types of injuries to the shoulder. A separation of the AC joint occurs between the collar bone and the end of the shoulder blade and typically causes pain or deformity on top of the shoulder. Conversely, a dislocated shoulder occurs in the part of the shoulder where the upper arm (humerus) fits into the shoulder socket (glenoid). Both injuries are painful and result in tears of ligaments and cartilage. However, a dislocated shoulder is often more severe and may require the upper arm to be physically moved back into place within the shoulder socket. An AC joint injury, or shoulder separation, occurs more frequently and is less likely to require surgery.

How is an AC joint injury classified?

Since AC joint injuries vary in severity, they are usually classified based on a standardized scale:

• Grade 1: The patient will typically experience temporary shoulder pain with no deformities because the ligaments remain intact.
• Grade 2: The patient often experiences more pain because the ligaments that connect the bones are sprained or slightly torn. This may cause the bones that make up the AC joint to move out of their proper position.
• Grade 3: This describes a more severe injury where the ligaments connecting the AC joint are completely torn, and the bones that make up the AC joint will no longer be held in their proper position. A deformity, or prominent collar bone, may be noticed.
• Grades 4-6: These types of AC joint injuries are the most severe form and involve total tears of the ligaments and connective tissue in this joint of the shoulder. Patients with this type of injury will often require surgery.

What are the symptoms of an AC Joint Injury?

• Severe pain at the time of the injury
• Decreased range of movement of the shoulder
• Pain, weakness, and/or swelling
• Deformity (unusual bump) visible on the shoulder

How do I know if I have an AC joint injury?

To determine if a patient has experienced an AC joint injury, Dr. Lamplot will first evaluate the patient’s medical history, including an emphasis on their physical activity, engagement in sporting activities, previous injuries or surgeries, as well as the patient’s concerns. Dr. Lamplot will also perform a physical exam of the injured shoulder to help him determine the location of the pain, as well as any other symptoms that may help him to diagnose this injury. Lastly, diagnostic imaging such as an MRI scan or X-rays may be requested to give Dr. Lamplot a better picture of the patient’s shoulder, to make a diagnosis.

How is an AC Joint injury treated?

Nonsurgical treatment options:

• Rest, ice, compression, and stabilization of the injured shoulder
• Stretching and an individually tailored physical therapy program
• Pain management with nonsteroidal anti-inflammatory medications (NSAIDs)

Surgical treatment options:

Dr. Lamplot may recommend surgical treatment for patients with a severe AC joint injury, or for patients who have an injury that is not alleviated by nonsurgical methods. The type of surgery required will depend on the structures damaged as well as the severity of the injury. Dr. Lamplot will evaluate each patient to determine the best procedure to alleviate pain and fix their injury. He will often perform a type of minimally invasive technique to repair or reconstruct any damaged ligaments or soft tissue in the shoulder.