Acromioclavicular Joint Injuries

What is an Acromioclavicular Joint Injury?

An acromioclavicular (AC) joint injury is an injury to the joint at the top of the shoulder, where the collarbone (clavicle) meets part of the shoulder blade (Scapula).

It commonly occurs after a fall directly onto the shoulder, particularly during sports or other activities. Depending on the severity of the injury, the supporting tissues around the joint may be stretched, partially torn or completely torn.

Most AC joint injuries can be treated without surgery, but some severe injuries may require an operation. The appropriate treatment depends on the severity of the injury, your symptoms and your activity requirements.

What is the AC joint?

The AC joint is the small joint at the top of your shoulder where the collarbone meets the shoulder blade.

Strong tissues around this joint help keep the collarbone in its normal position and allow the shoulder to move properly.

When these tissues are injured, the collarbone may become more prominent or move out of its normal position.

How does an AC joint injury happen?

An AC joint injury usually happens after a direct blow to the shoulder.

Common causes include:

• Falling directly onto the shoulder

• A sports injury

• Falling from a bicycle or motorcycle

• A road traffic accident

• A heavy impact during contact sports

The severity of the injury can vary from a mild stretching of the supporting tissues to a complete disruption that causes the collarbone to move out of its normal position.

What are the symptoms of AC joint injury?

You may experience:

• Pain at the top of the shoulder

• Swelling or tenderness around the AC joint

• Pain when lifting the arm

• Difficulty lying on the affected shoulder

• Pain when carrying or lifting objects

• A visible bump at the top of the shoulder in more severe injuries

• Weakness or discomfort during sports or overhead activities

The pain is usually most noticeable directly over the top of the shoulder.

How is an AC joint injury diagnosed?

Your doctor will ask how the injury happened and examine your shoulder.

X-rays are usually used to assess the position of the collarbone and the severity of the injury.

In some situations, additional imaging may be recommended if there is concern about other injuries around the shoulder.

The diagnosis is based on your symptoms, examination and imaging findings.

Are all AC joint injuries the same?

No.

AC joint injuries can range from a mild injury to a complete disruption of the tissues supporting the joint.

In a mild injury, the tissues may only be stretched or partially damaged.

In a more severe injury, the tissues may be completely torn and the collarbone may move significantly from its normal position.

The treatment depends on the severity of the injury and how much it affects you.

Does every AC joint injury need surgery?

No.

Most AC joint injuries can be treated without surgery.

Treatment may include:

• A sling for a short period to reduce pain

• Pain-relieving medicines when appropriate

• Ice during the early period

• Gradual shoulder movement

• Physiotherapy and strengthening exercises

• Gradual return to normal activities

Even when the collarbone remains slightly prominent, many people can have good shoulder function without surgery.

When might surgery be recommended?

Surgery may be considered in selected patients, particularly when:

• The injury is severe

• Pain or instability continues despite appropriate non-surgical treatment

• The shoulder remains significantly affected during daily activities

• The patient has high physical or sporting demands

• There is persistent difficulty with overhead activities or heavy lifting

The decision is individualized. The appearance of the shoulder alone does not necessarily mean that surgery is required.

What type of surgery may be recommended?

The type of surgery depends on the severity of the injury and your symptoms. AC joint reconstruction may be recommended when the tissues supporting the joint have been significantly damaged and the shoulder remains painful or unstable. The aim is to restore the normal position of the collarbone and improve the stability of the joint.

What happens if surgery is not done?

Many people recover well without surgery, even when there is some change in the shape of the shoulder.

The pain usually improves with time, followed by gradual recovery of shoulder movement and strength.

However, some people may continue to have discomfort, weakness or difficulty with certain activities. If symptoms persist and interfere with daily life or sports, further assessment may be appropriate.

When can I return to normal activities?

The time required depends on the severity of the injury and the treatment received.

You can usually begin gentle shoulder movement as pain allows, followed by gradual strengthening.

Your return to lifting, overhead activities and more demanding work should be gradual and based on your recovery.

When can I return to sports?

Returning to sports depends on the severity of the injury and the type of sport.

You should have good shoulder movement, strength and control before returning to activities involving contact, falling or heavy use of the shoulder.

A gradual return to sport is safer than returning as soon as the pain improves.

Will the bump on my shoulder disappear?

Not always.

After a more severe AC joint injury, the collarbone may remain slightly more prominent even after the pain has settled and the shoulder has recovered good function.

The appearance of the shoulder does not always reflect how well the shoulder is functioning.

If the shoulder is pain-free and functioning normally, the remaining bump may not require any treatment.

When should I see an orthopaedic surgeon?

You should consider an orthopaedic evaluation if:

• You have significant pain after a direct injury to the shoulder

• You notice a new bump at the top of your shoulder

• You have difficulty lifting your arm

• Pain persists despite initial treatment

• You have difficulty returning to work, exercise or sports

• You continue to have pain or weakness after the injury

An assessment can determine the severity of the injury and whether non-surgical treatment or surgery is appropriate.