Acromioclavicular (AC) joint sprains are injuries to the ligaments at the joint where the clavicle (collarbone) articulates with the acromion (roof of the shoulder) of the scapula (shoulder blade). Commonly referred to as a “shoulder separation,” an AC joint sprain means the ligaments between the bones are partially or completely torn, affecting the stability of the AC joint. AC joint sprains are graded I through VI from least to most severe.
What Is an AC Joint Separation?
The acromioclavicular (AC) joint is where the clavicle (collarbone) articulates with the acromion (roof of the shoulder) of the scapula (shoulder blade).
AC joint sprains involve injuries to the acromioclavicular ligaments between the clavicle and the acromion and the coracoclavicular ligaments between the coracoid and the clavicle. A sprain indicates that the ligament between the bones is either partially or completely torn, which affects the stability of the AC joint.
The severity of AC joint sprains is graded I through VI, from least to most severe.
Causes and Risk Factors
Common causes and risk factors include:
- Falling and landing on the tip of the shoulder, which is the most common cause
- Direct impact on the tip of the shoulder
- Sports that involve contact or collision
- Racquetball, squash, cycling, and football
- Poor strength in supporting musculature
- Inadequate protective equipment
Symptoms
Common signs and symptoms include:
- Pain, swelling, and deformity on top of the shoulder at the AC joint
- Loss of strength and inability to raise the arm initially following the injury
- Bruising at the site of injury and sometimes the chest, usually within 48 hours
Treatment
Treatment depends upon the severity of the ligament injury.
Initial treatment of lower-grade sprains (Grades I, II, and most Grade III sprains) consists of rest, ice, anti-inflammatory medication to relieve pain, gentle range-of-motion exercises to help prevent shoulder stiffness, and activity modification.
Non-surgical treatment involves using a sling initially for comfort, followed by gentle range-of-motion exercises and progressive strengthening as pain and limitations resolve.
Higher-grade IV, V, and VI sprains require surgery to reduce (re-locate) the AC joint and repair or reconstruct the torn ligaments. Surgical treatment is usually reserved for severe sprains, particularly in heavy laborers, throwing athletes, or patients whose condition has not improved after two to six months of conservative treatment.
Surgery typically involves reducing the clavicle to the acromion, sometimes removing the end of the clavicle if the cartilage surface is damaged, and repairing or reconstructing the acromioclavicular and coracoclavicular ligaments.
Intermediate Grade III sprains may take six to 12 weeks to return to activity but sometimes can cause persistent symptoms that require later surgery.
Recovery and Outcomes
Treatment and outcome depend upon the severity of the ligament injury. The time to return to activities varies by the type of sport and position, the arm injured (dominant versus non-dominant), and the severity of the sprain.
Most low-grade I and II sprains do well, and patients can return to activity within two to six weeks. Intermediate Grade III sprains may take six to 12 weeks to return to activity or may have persistent symptoms requiring surgery. Higher-grade IV, V, and VI sprains require surgery, with return to full activities typically occurring four to six months after surgery.
Following these injuries, the AC joint can remain unstable and may continue to cause pain. The cartilage surface at the AC joint can also be injured and lead to premature post-traumatic arthritis of the AC joint.
Potential complications include:
- Shoulder weakness
- Neurovascular injury, which is rarely associated with the injury
- Persistent pain and inflammation of the AC joint
- Prolonged healing if strenuous activities are resumed too quickly
- Prolonged disability, which occasionally occurs
- Continued AC joint instability or development of post-traumatic arthritis that causes pain
When to See Dr. Chudik
For evaluation and treatment of an AC joint sprain or separated shoulder, call 630-324-0402, schedule an appointment online, or email contactus@chudikmd.com.