Acromio-clavicular joint

Why does it occur?

The cause is a fall onto the shoulder often while playing sport, falling from a bicycle or motorcycle, or a horse.

What are the symptoms?

Pain and swelling at the tip of the shoulder. More severe injuries have a marked step deformity as the clavicle (collar bone) over rides the acromion (shoulder tip).


An x-ray will show the dislocation. Sometimes comparative views are taken with the un-injured side and weights are strapped to the wrist to demonstrate the dislocation.

The injury is graded on the x-ray appearance of how far displaced the collarbone is.

Gd 1 sprain of ACJ no displacement

Gd 2 Joint capsule torn slight displacement

Gd 3 100% displacement coraco-clavicular ligaments torn

Gd 4 posterior displacement of clavicle

Gd 5 More than 100% displcacement

Gd 6 Cavicle stuck under coracoid process of shoulder

Treatment options

  • Non-operative treatment

Gd 1,Gd2, and some Gd3 injuries settle with rest, pain killers and gentle mobilization.

Gd3 injuries that do not settle and all Gd4-6 injuries need surgical treatment

  • Operative treatment

There are many procedures available to reconstruct an acromio-clavicular joint dislocation. Each has its advantages and disadvantages. I use a synthetic ligament to stabalise the collar bone. This does not need temporary supplementary fixation and thereby avoids a second procedure.


Wound infection - 1-2%

Continuing deformity -  often there is mild asymmetry compared to the uninjured side after  reconstruction of the acromio-clavicular joint.  Even if this is quite noticeable most patients are happy that their shoulder function and comfort are near normal.

Surgical scar- this area can form unsightly raised scars which are of concern to those wishing to wear off the shoulder clothes.

Nerve and blood vessel injury- rare but are reported following this type of surgery.

Rehabilitation after surgery

A sling is used for 2 or 3 weeks while the soft tissues settle down and the would heals. The sling is then discarded and active rehabilitation commenced. Near full function is often achieved after a further 2 to 3 weeks.

Frequently asked questions