AC Joint Injury

Background

Acromioclavicular (AC) joint injuries involve damage to the ligaments that stabilize the joint between the acromion (part of the scapula) and the clavicle. These injuries are common in athletes and active individuals, particularly from direct trauma to the shoulder, such as a fall onto the shoulder or a collision in contact sports.

AC joint injuries range from mild sprains to complete dislocations with significant ligament damage and clavicular displacement.

Symptoms

Symptoms of AC joint injuries include:

• • Pain at the top of the shoulder, especially with arm movement or lifting
• • Swelling, bruising, and tenderness over the AC joint
• • Visible bump or deformity due to clavicle displacement (in severe injuries)
• • Limited shoulder motion
• • Sensation of instability or weakness during overhead activities
• • Pain with cross-body movements

Diagnosis

Diagnosis of an AC joint injury begins with a clinical examination, noting tenderness, deformity, and pain with specific movements such as cross-body adduction. X-rays are typically used to evaluate the alignment of the clavicle and acromion and to classify the severity of the injury.

Advanced imaging such as an MRI is often not needed.

Treatment Options

The vast majority of AC joint injuries can be managed non-operatively. Even high-grade (Type V) AC joint injuries can be successfully managed non-operatively in the majority of patients.