AC Joint Injuries
Acromioclavicular joint separations and treatment options
Understanding AC Joint Injuries
The AC joint connects the clavicle to the scapula at the top of the shoulder. Injuries typically occur from direct falls onto the shoulder (common in contact sports, cycling accidents) or falls onto an outstretched hand.
Anatomy: Two sets of ligaments stabilize the AC joint: the AC ligaments (horizontal stability) and the coracoclavicular (CC) ligaments (vertical stability). The severity of injury depends on which ligaments are torn.
Rockwood Classification
• AC ligament sprain
• CC ligaments intact
• No displacement
Non-operative
• AC ligament torn
• CC ligaments sprained
• Slight elevation
Non-operative
• AC + CC ligaments torn
• 25-100% displacement
• Visible bump
Controversial
• Posterior displacement
• Clavicle into trapezius
• All ligaments torn
Surgery recommended
• Severe displacement
• 100-300% CC distance
• Deltotrapezial fascia torn
Surgery required
• Inferior displacement
• Very rare
• High-energy injury
Surgery required
Treatment Approach
• Sling for 1-2 weeks
• Ice and anti-inflammatory medications
• Early range of motion as tolerated
• Gradual return to activity (2-6 weeks)
Grade III: Trial of conservative treatment is reasonable. Surgery can be performed later if symptoms persist.
Acute (<3 weeks): CC ligament repair/reconstruction, hook plate, or TightRope/suture button techniques
Chronic: CC ligament reconstruction with tendon graft, modified Weaver-Dunn procedure
Arthritis: Distal clavicle excision (Mumford procedure)
Scientific References
1. Rockwood CA. Injuries to the acromioclavicular joint. In: Fractures in Adults. 1984
2. Beitzel K, et al. Current concepts in the treatment of AC joint dislocations. Arthroscopy. 2013
Last Updated: January 2025 | Content reviewed by Dr. Deepthi Nandan Reddy, FRCS (Ortho)
