|  | Conditions Treatments | Bones, Joints Muscles

What Is the Shoulder AC Joint?

The acromioclavicular (AC) joint is formed where a section of the shoulder blade called the acromion meets the clavicle, or collar bone. It is located above and to the outside of the main ball-and-socket shoulder joint.

  1. The Facts

    • According to Wheeless' Textbook of Orthopaedics, the AC joint allows the shoulder to move in three directions. It does this by tilting the acromion and rotating the clavicle.

    Shoulder Separation

    • The AC joint is stabilized by bands of fibrous tissue called ligaments. When these ligaments are damaged, the resulting injury is called a shoulder separation.

    Degrees of Injury

    • There are three grades of shoulder separation, ranging from mild sprain to complete tearing of the AC ligaments. In a complete tear, the clavicle and shoulder blade "separate," causing a visible deformity in the shape of the shoulder.

    Treatments

    • Shoulder separations are typically treated with shoulder immobilization, application of a cold source, painkillers and physical therapy. Surgery may also be needed to repair severe or recurrent separations.

    Other AC Joint Injuries

    • In addition to shoulder separation, the AC joint is subject to injury from bone fractures and arthritis. Arthritis occurs when cartilage in the AC joint is damaged or wears thin over time.

Bones, Joints Muscles - Related Articles