AC Joint Separation

What Is an AC Joint Separation?

An AC joint separation is the medical term for what, in layperson’s language, is usually called a shoulder separation. AC stands for acromioclavicular joint, which is the joint connecting the shoulder blade to the clavicle or collarbone rather than the humerus or upper arm bone. An AC joint separation involves damage to the ligaments supporting the AC joint, either sprains or tears, commonly caused by a fall on the shoulder. This can result in pain, shoulder deformity, and loss of forelimb mobility. AC joint separations vary in severity, from less-serious sprains to more-serious complete tears.

AC joint injuries are especially common among athletes. For example, a 2013 study found that nearly 30 percent of all shoulder injuries in the NFL involved the acromioclavicular joint. Fortunately, with time and proper treatment, most AC joint injuries heal successfully. Let the orthopedic specialists and other medical practitioners at Baptist Health assist you, if you or a family member is dealing with a painful shoulder condition.

What Are the Symptoms of an AC Joint Separation?

Several symptoms are common to AC joint injuries:

  • Pain
  • Bruising
  • Swelling
  • Weakness in the upper arm or shoulder
  • A visible deformity, typically a bump at the top of the shoulder.

AC joint injuries can be categorized accordingly:

  • Mild sprains of the AC ligament are the least severe form of injury. There is no visible deformity and X-rays of the shoulder appear normal.
  • Tears in the AC ligament and sprains in the coracoclavicular (CC) ligament form the second, more serious category. There is an externally visible bump and the clavicle and shoulder blade are misaligned.
  • With the severest form of injury, both the AC and the CC ligaments are torn. There is a large external deformity and the clavicle and shoulder blade are visibly misaligned.

What Causes an AC Joint Separation?

The most common cause of AC joint separation is a fall onto the shoulder. With sufficient damage to the ligaments, the shoulder blade or scapula drops away from the clavicle, creating misalignment and giving rise to the shoulder bump. Professional athletes and other persons engaged in contact sports such as football, soccer, or hockey are prime candidates for AC joint separation injuries. Cyclists, equestrians, and others at risk for falling also have reason for concern.

How Is an AC Joint Separation Diagnosed?

Your physician will diagnose an AC joint injury in the following manner:

  • Document your symptoms and medical history.
  • Conduct a physical examination of your shoulder and adjacent parts of the body. He or she will inspect the injured area visually, as well as checking for swelling, bruising, flexibility, and unusual joint movements.
  • Order an X-ray of the shoulder. Unless the damage is relatively severe, the X-ray may not reveal anything.

Examination of the shoulder will require physical contact by your doctor. You should be prepared to experience some pain but every effort will be made to keep discomfort to a minimum.

How Is an AC Joint Separation Treated?

Many AC joint injuries heal on their own but more serious cases require medical attention.

At-home Treatments

There are some steps you can take at home to treat an AC joint injury:

  • Rest
  • Apply ice
  • Take over-the-counter pain medications, such as aspirin, ibuprofen, or naproxen sodium, to control the pain.


A downside of resting your shoulder for any length of time is a gradual decrease in muscle strength and mobility. Rehabilitation helps you regain what you’ve lost during recuperation. A program of stretching-and-strengthening exercises, overseen by a licensed physical therapist, can play a critical role in fully restoring the health of your shoulder and upper arm. 


Surgery is reserved for the most serious cases of AC joint injury, typically those involving complete breaks in the ligaments, along with clavicle fractures. The surgical repair of an AC joint often requires the reconstruction of the AC and CC ligaments, as well as the removal of the distal end of the collarbone (that is, the part closest to the acromion).

The outlook for someone with an AC joint injury is generally positive. Depending on severity and whether surgery is required, persons with a separated shoulder typically recover in a period ranging from a several days to three months.

Can AC Joint Separations be Prevented?

It is possible to prevent AC joint injuries in some instances. Athletes should never skimp on stretching exercises or warmups before competition, because supple ligaments are less likely to stretch or injure than tight or stressed ligaments. Wearing appropriate protective gear is also critical to safely. Finally, exhaustion is an ally to injury. You’re more susceptible to bodily harm when tired, so never exercise beyond your limits.

Learn More About Treating Shoulder Injuries at Baptist Health

AC joint injuries can be a major source of pain and immobility. If you are experiencing the symptoms of AC-joint injury or another form of shoulder pain, contact the Baptist Health Orthopedic Team to schedule an appointment.

Next Steps with MyChart

Discover MyChart, a free patient portal that combines your Baptist Health medical records into one location. Schedule appointments, review lab results, financials, and more! If you have questions, give us a call.