ACJ Dislocation

This leaflet provides general information to help you understand ACJ dislocation ("shoulder separation") and the available treatment options.

Not everyone with an ACJ dislocation needs surgery.

At the heart of my practice is Shared Decision-Making. Whether we pursue conservative management (Plan A) or surgical intervention (Plan B), the goal is to create a tailored treatment plan that aligns with your lifestyle, values, and functional goals.

The Anatomy of the Shoulder Joint

The shoulder is one of the most complex joints in the body, relying on several structures working together.

How the Shoulder Works

Three main bones form the joint:

• Humerus (upper arm bone)
• Clavicle (collarbone)
• Scapula (shoulder blade)

The Four Key Joints

• Glenohumeral Joint – the main ball-and-socket joint
• Acromioclavicular (AC) Joint – collarbone meets shoulder blade
• Subacromial Space – tunnel above the rotator cuff
• Scapulothoracic Joint – shoulder blade glides over rib cage

The "Cushioning" (Articular Cartilage)

A smooth, slippery coating on the ball and socket surfaces that lets the bones glide over each other without friction, for pain-free movement.

The Labrum (Stabilising Ring)

A rim of rubbery tissue that deepens the shallow shoulder socket — like a "bumper" or suction cup that keeps the joint stable and prevents dislocation.

The Rotator Cuff

Four deep muscles keep the ball centred in the socket and let you lift and rotate your arm:

• Supraspinatus
• Infraspinatus
• Subscapularis
• Teres Minor

What Is an ACJ Dislocation?

An ACJ dislocation ("shoulder separation") is an injury to the joint where the collarbone meets the shoulder blade. Sudden trauma stretches or tears the supporting ligaments, allowing the collarbone to displace — graded I to VI by the amount and direction of displacement.

Grades of Injury

Severity follows the ligament damage:

• Grades I–II – sprain or partial ligament injury
• Grade III – complete injury, visible bump
• Grades IV–VI – severe displacement, often surgical

What Causes It?

Typically sudden trauma:

• Direct fall onto the point of the shoulder (cycling, skiing)
• Indirect fall onto an outstretched hand
• Impacts in contact sport or road traffic accidents
• High-energy trauma may involve other injuries

Symptoms & Examination

Symptoms

• Pain at the top of the shoulder after injury
• A visible bump or step over the joint
• Pain reaching across the body or overhead

Examination

• Deformity and tenderness over the AC joint
• Skin and surrounding shoulder girdle assessed
• Nerves and circulation checked

Diagnosis

• X-ray – the standard test, defines the grade
• CT scan – if further bony injury is suspected

X-ray showing ACJ dislocation

Treatment Options: A Shared Decision

I will discuss all available treatment options with you, explaining the benefits and risks of each. Your preferences, values, and lifestyle will be considered as we work together to create a treatment plan best suited to your needs — this shared decision-making process ensures you are fully informed and involved in your care.

Treatment Depends On

• Grade of injury (I–VI)
• Direction and amount of displacement
• Your arm demands and sport
• Symptoms after initial healing

Plan A — Non-Surgical

Typically Grades I–III

• Immobilisation: sling from a few days up to a few weeks
• Pain Control: regular painkillers or prescribed pain relief
• Early Motion: gentle exercises as comfort allows (2–3 weeks)
• Physiotherapy: restore strength and movement

Plan B — Surgical

Grades IV–VI, or persistent Grade III

• Persistent Symptoms: despite appropriate therapy
• Displacement: significant, high-grade injuries
• Floating Shoulder: combined injuries around the shoulder
• Stabilisation: artificial ligament to the coracoid bone
• Approach: open, or keyhole in selected cases
• The Procedure: known as ACJ Stabilisation, this uses an artificial ligament to hold the collarbone back down onto the coracoid bone; keyhole techniques are possible in selected cases. A separate leaflet will be provided for the surgery.

Management Pathway

Questions You May Wish to Ask

• What treatments should I try first?
• How long should I try them for?
• What improvement can I expect?
• What happens if I don't have surgery?