AC Joint Shoulder Separation


An AC joint separation is also called shoulder separation. AC stands for Acromioclavicular. The AC Joint is where the collarbone or clavicle meets the highest point of the shoulder blade or acromion. In a shoulder separation injury, the AJ joint comes apart. Typically, this type of injury is caused by a direct fall onto the shoulder and damages the ligaments that stabilize the AC joint. In severe injuries, even the ligaments supporting the clavicle are torn, which will separate the collarbone and the shoulder blade or scapula creating a bump above the shoulder. The severity of an AC joint separation can be generalized into the following:

  • Mild – X-rays are normal because the collarbone has not shifted. AC ligaments are sprained.
  • More serious – Collarbone is slightly misaligned creating a smaller bump above the shoulder due to tearing in AC ligaments and even the coracoclavicular (CC) ligament.
  • Severe – AC joint is noticeably out of position resulting in a larger bump above the shoulder due to severe tearing in both the AC and CC ligaments.
AC Joint Diagram

AC Joint Diagram

The AC joint comes apart during a separation injury. It is the joint that combines the Acromion and Clavicle bones.


Nonsurgical – Options for nonsurgical treatment to effectively manage pain include cold packs, a sling, and medication. Even if there is a significant shoulder bump in professional athletes, many will return to normal function without the need of surgery. Pain around the AC joint may persist due to the development of arthritis, abnormal contact between bone ends while in motion, or injury to the cartilage between the clavicle and acromion. It is beneficial to wait and see if reasonable function returns without surgery.

Surgical – Surgical treatment may be an option if the shoulder bump or deformity is severe or pain does not go away. During surgery, Dr. Stowell may trim back the end of the collarbone so it does not rub against the shoulder blade bone or acromion to help relieve pain. To decrease the severity of the shoulder bump, Dr. Stowell may reconstruct the ligaments that attach to the underside of the collarbone. If a plate is used to assist with surgery, it is usually removed after the shoulder separation has healed.

Physical Therapy – Whether with non-surgical or surgical treatment, shoulder rehabilitation through physical therapy is highly recommended to restore motion, flexibility, and strength optimally.

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