[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Acromioclavicular joint separation

[Conditions](https://durgical.com/en/conditions/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/)

# Acromioclavicular joint separation

An acromioclavicular separation is an injury to the joint at the top of the shoulder where the collarbone meets the shoulder blade; severe ones lift the bone.

Updated 2026-10-29

## Structures involved

Tap one to see what it is and open it in 3D.

- [AC ligament](https://durgical.com/en/anatomy/acromioclavicular-ligament/)
- [AC capsule](https://durgical.com/en/anatomy/acromioclavicular-joint-capsule/)
- [Conoid ligament](https://durgical.com/en/anatomy/conoid-ligament/)
- [Trapezoid ligament](https://durgical.com/en/anatomy/trapezoid-ligament/)
- [Clavicle](https://durgical.com/en/anatomy/clavicle/)
- [Scapula](https://durgical.com/en/anatomy/scapula/)
- [AC disc](https://durgical.com/en/anatomy/acromioclavicular-joint-disc/)
- [Coracoacromial ligament](https://durgical.com/en/anatomy/coracoacromial-ligament/)
- [Front deltoid](https://durgical.com/en/anatomy/deltoid-anterior-part/)
- [Upper trapezius](https://durgical.com/en/anatomy/descending-part-of-trapezius-muscle/)

## What it is

Injury of the joint between the acromion and the outer end of the [clavicle](https://durgical.com/en/anatomy/clavicle/), from a sprain of its capsule and ligaments to complete tearing of the coracoclavicular (conoid and [trapezoid](https://durgical.com/en/anatomy/trapezoid/)) ligaments with the clavicle displaced. Severity is graded with the Rockwood classification.

## Who gets it

Common in young adults, mostly men, in contact sports (football, rugby), cycling, motorcycling and falls. It is among the commonest shoulder injuries in athletes.

## Causes

- Fall or direct blow on the point of the shoulder with the arm adducted, driving the acromion downward
- Less often, a fall on the outstretched hand or the elbow transmitting force upward

## Risk factors

- Contact sports, cycling and motorcycling
- Young male sex
- Falls from height or road traffic collisions

## Pathophysiology

The acromioclavicular ligaments and capsule give horizontal stability; the conoid and trapezoid (coracoclavicular) ligaments give vertical stability. A downward force on the acromion tears the acromioclavicular ligaments first and then the coracoclavicular ligaments; with more energy the deltoid and [trapezius](https://durgical.com/en/anatomy/trapezius-muscle/) are stripped and the arm sags, so the clavicle seems to rise.

## Classification

- Rockwood I: [acromioclavicular ligament](https://durgical.com/en/anatomy/acromioclavicular-ligament/) sprain, no displacement
- Rockwood II: acromioclavicular ligaments torn, coracoclavicular ligaments intact, slight displacement
- Rockwood III: both ligament groups torn, clavicle displaced by about the width of the clavicle
- Rockwood IV: clavicle displaced backward into or through the trapezius
- Rockwood V: marked upward displacement with deltoid and trapezius fascia stripped
- Rockwood VI: rare, clavicle displaced below the acromion or coracoid

## Symptoms and signs

- Pain and tenderness over the top of the shoulder after a fall
- Step or bump at the end of the clavicle in higher grades
- Pain on reaching across the body or overhead
- Swelling and bruising over the acromioclavicular joint

## Red flags

- [Skin](https://durgical.com/en/anatomy/skin/) tented by the clavicle, or an open injury
- Numbness, weakness or poor circulation in the arm
- Posterior (type IV) or inferior (type VI) displacement, which often has associated injuries
- Breathing difficulty or [chest](https://durgical.com/en/anatomy/region/chest/) injury after high-energy trauma

## Diagnosis

**Clinical**
Tenderness over the acromioclavicular joint, a visible step and pain on cross-body adduction. Examination with the patient sitting or standing lets the arm's weight show the deformity.

**Tests**
Generally not needed.

**Imaging**
X-rays including a Zanca view (beam tilted upward) and comparison with the other side; an axillary view shows posterior displacement. Ultrasound or MRI help in unclear cases and associated injuries.

## Differential diagnosis

- Distal clavicle fracture
- Shoulder dislocation
- Rotator cuff tear
- Coracoid or acromion fracture
- Acromioclavicular osteoarthritis

## Goal of treatment

Relieve pain, restore pain-free shoulder function and strength, and restore stable alignment when displacement is severe.

## Treatment

**Conservative**
Types I and II: sling for comfort, cold and analgesics (including nonsteroidal anti-inflammatory drugs), with early range of motion as pain allows.

**Rehabilitation**
Physiotherapy for range of motion, then scapular and rotator cuff strengthening before return to sport.

**Conservative**
Type III: most patients are first treated without surgery; operative repair is considered for some overhead athletes or manual workers, and criteria vary between texts.

**Surgical**
Types IV to VI, and type III cases that fail non-operative care: reduction and stabilisation, such as coracoclavicular ligament reconstruction or fixation with a plate or suture device.

## Complications

- Persistent prominence of the clavicle (cosmetic bump)
- Acromioclavicular osteoarthritis or osteolysis of the distal clavicle
- Chronic pain and scapular dyskinesis
- After surgery: loss of reduction, hardware problems, infection or coracoid or clavicle fracture

## Prognosis

Low-grade injuries usually recover fully within weeks. Many type III injuries do well without surgery, although some patients keep pain or weakness with overhead work. High-grade injuries generally do well after stabilisation.

## Prevention

- Protective technique and equipment in contact sports
- Safe cycling and motorcycling

## Test yourself

Think of the answer, then tap the question to see it.

## Which ligaments are torn in a Rockwood type III acromioclavicular separation?

Both the acromioclavicular ligaments and the coracoclavicular (conoid and trapezoid) ligaments.

## What is the typical mechanism of an acromioclavicular joint separation?

A fall or direct blow on the point of the shoulder with the arm adducted, driving the acromion downward.

## Which X-ray view best shows the acromioclavicular joint?

The Zanca view, an anteroposterior view with the beam tilted upward; an axillary view shows posterior displacement.

## In which Rockwood type is the clavicle displaced backward through the trapezius?

Type IV.

## How are Rockwood types I and II usually treated?

Without surgery: sling for comfort, analgesia and early range of motion followed by rehabilitation.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/acromioclavicular-joint-separation/)

## Related conditions

- [Clavicle fracture](https://durgical.com/en/conditions/clavicle-fracture/)
- [Shoulder dislocation](https://durgical.com/en/conditions/shoulder-dislocation/)
- [Rotator cuff tear](https://durgical.com/en/conditions/rotator-cuff-tear/)
- [Proximal humerus fracture](https://durgical.com/en/conditions/proximal-humerus-fracture/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Acromioclavicular Joint Injury](https://www.ncbi.nlm.nih.gov/books/NBK493188/) (StatPearls (NCBI Bookshelf), 2022).

[← All conditions](https://durgical.com/en/conditions/)

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/conditions/acromioclavicular-joint-separation/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/acromioclavicular-joint-separation/