AC Joint Sprain: Causes, Treatment and Recovery Time

The shoulder is a very mobile and complex joint. Due to this complexity and mobility, there are a number of structures, including joints, that can get injured.

This article delves deep into the acromioclavicular joint and explains the causes, treatment, recovery time and prevention of an AcromioClavicular (AC) joint sprain.

What Is The Acromioclavicular Joint?

The acromioclavicular joint, also known as the AC joint, is that bony bump you notice and feel on top of your shoulder joint. It enables us to raise our arms over our heads.

It is formed by 2 bones: the clavicle, which is known as the collar bone and the acromion process which is found on the shoulder blade.

When joints are being formed, the bones are joined to each other by soft tissues called the ligaments. Two ligaments join the acromion to the clavicle. These ligaments are:

  • Acromioclavicular ligament
  • Coracoclavicular ligament

When we talk about AC joint sprain, we are talking about injuries to the ligaments around the AC joint.

What Causes An AC Joint Sprain?

joint sprain

1. Trauma

Trauma is a physical, external injury. A fall that involves landing on your shoulder or bumping into a tree while running or skating may cause a sprain to your ligaments.

Trauma can happen in an accident or while participating in a high-intensity sporting activity such as rugby or wrestling.

2. Overuse

Repeatedly doing an activity for a long period of time places a lot of strain on our ligaments. Jobs like farming which involve lifting, digging, and planting (using the shoulders), may cause pain and if adjustments are not made, may eventually lead to an AC joint sprain.

An overuse injury, unlike trauma, does not happen immediately but the symptoms may show after a period of time.

How Do I Know If It Is A Sprain?

top of the shoulder

  1. Pain at the top of the shoulder
  2. Swelling at the top of the shoulder
  3. Limitation while moving the shoulder joint
  4. Weakness of the shoulder muscles
  5. A prominent bump may be seen at the top of the shoulder joint. This could be the clavicle being separated from the acromion process on the scapula.

Diagnostic Tests

An X-ray is usually carried out to rule out fracture or dislocations that may happen at the shoulder joint and also pinpoint the cause of pain at the shoulder joint.

An MRI will show the severity of the ligament injury and allow your doctor or physiotherapist to carry out the treatment based on the injury seen.

Physiotherapists also run orthopedic tests that help to determine the mode of treatment that will be carried out for effective healing.

Are There Grades Of Injury Severity?

AC joint sprain severity

Yes. There are three grades of ligament injury severity. Knowing these grades help health professionals to know the proper care for the injury. The different grades are:

  1. Grade 1: This is the mildest form of ligament injury and may take a short time to heal. The acromioclavicular ligament is torn but the coracoclavicular ligament is still intact.
  2. Grade 2: This is a moderate form of a ligament sprain. The acromioclavicular ligament is torn and the coracoclavicular ligament is partially torn. The clavicle may appear mildly dislocated since the ligaments that are meant to keep it in place are torn.
  3. Grade 3: This is the most severe ligament injury. The acromioclavicular and coracoclavicular ligaments are torn and almost often require surgery. Dislocation of the clavicle is obvious.

How Is It Treated?

1. Rest

rest the shoulder

The RICE treatment is the go-to treatment for any ligament injury. This treatment is usually done within the first 72 hours of injury. However, depending on the signs you have, your physiotherapist or doctor may suggest that some parts of the RICE treatment should continue for more than 72 hours.


The RICE treatment stands for:

  • R – Rest
  • I – Ice
  • C – Compression
  • E – Elevation

An arm sling, shoulder support or taping may be recommended to reduce the amount of movement at the shoulder. This prevents re-injury of the joint and helps speed up the healing process. The splint may be worn for 4 weeks depending on what your doctor or physiotherapist advises.

2. Ice

Ice helps to reduce swelling and can be used at home. The easiest way to use ice at home is to put crushed or cubed ice in a damp towel and place on your shoulder joint for 15 minutes. This can be done every four hours for the first 72 hours.

3. Compression And Elevation

This may not be necessary for the AC joint but if there is swelling, an elastic bandage can be wrapped around the joint, but not too tight.

Elevation may be done while lying down on your back by placing a pillow under your shoulder or using an arm sling.

4. Pain Killers


Over-the-counter medications are taken to relieve pain. Some of these medications are known as Non-Steroidal Anti Inflammatory Drugs (NSAID). Examples of this class of drugs are ibuprofen, diclofenac, and ketoprofen to mention a few.

5. Physiotherapy


Physiotherapy plays a major role in rehabilitating injured parts of the body. The main goal of physiotherapy is to return you to how you were before the injury.

A physiotherapist will draw up treatment goals and plans with you and as you achieve your goals, they add more goals when they feel that you can handle them.

Physiotherapists prescribe exercises and teach some lifestyle modifications like how you should sleep without causing more harm to the injured joint.

6. Surgery

Surgery is usually recommended for grade 3 ligament injury. The surgery that is most commonly recommended is the ligament reconstruction surgery. In this surgical procedure, the injured ligaments are usually replaced by tendons from other parts of the body.

7. Exercises

As the injury heals, exercises will be included in your treatment plan to strengthen the muscles surrounding the joint. At the initial stage, exercises with assistance are encouraged before strengthening exercises so the affected shoulder is not overworked. Exercises are usually introduced into treatment 1- 3 weeks after injury depending on the severity.

exercise the shoulder

Some of these exercises are:

Isometric Rotator Cuff Muscles Strengthening

Rotator cuff muscles are the muscles that stabilize the joint. As there is a ligament injury, the surrounding muscles need to be strong to support the ligaments as they heal.

  • Place a towel or pillow under your armpit
  • Squeeze the pillow or towel between your upper arm and body
  • Hold for 5 – 10 seconds and release
  • Repeat 5 times

Biceps Strengthening Exercises

The biceps muscle is known as the muscle that bends the elbow joint. However, this muscle also contributes to shoulder flexion. There won’t be so much movement at the shoulder during the first 2 weeks after injury, therefore, the biceps can be strengthened till movement is recommended at the shoulder joint.

  • Hold a weight in your hand with your arm straight
  • Bend your elbow as far as you can go
  • Slowly return to starting position
  • Repeat 10 times

Shoulder Blade Squeeze

  • Stand tall
  • Pull your shoulders to the back which will make your shoulder blades move towards each other
  • Hold for 5 minutes

Shoulder Shrug

  • Stand tall or sit upright
  • Move your shoulders up and down (like you are shrugging)
  • Repeat 5 – 10 times

Shoulder Flexion Exercises

  • Hold on to a long stick or a towel in front of you with your two arms
  • Take your two hands up with the towel in front of you. Lift your hands over your head
  • Return to the initial position and repeat 5 times.

Shoulder Extension Exercises

  • Hold an object like a stick or rolled up towel at your back with your elbows extended
  • Take your hands up behind your back as far as you can
  • Return to the starting position and repeat 5 – 10 times.

How Long Does It Take To Heal?

shoulder strengthening

The healing process depends on the severity of the injury and how soon the injury is attended to by your doctor or physiotherapist. Seeking medical treatment early helps to ensure a speedy healing process.

For a grade 1 injury, it takes about 6 weeks for the ligaments to heal.

For a grade 2 injury, it may take 6 – 12 weeks.

For a grade 3 injury, which usually involves surgery, may take about 3 months.

What Happens If It Is Not Well Treated?

1. Shoulder instability

Due to the injured ligament not healing well, there is an unnecessary movement of the separated bones which makes the shoulder unstable. The ligaments may also heal wrongly and not properly stabilize the AC joint.

2. Muscle wasting

Due to pain and muscle weakness from the AC sprain, you may not want to move the shoulder joint which makes your muscles inactive and they begin to shrink in size. This shrinking is known as muscle wasting.

How Can It Be Avoided?

  • Reduce overusing your shoulders. Take stretch breaks when you are doing activities over your head.
  • Try to avoid any direct force to your shoulder if you can.
  • Strengthen your muscles in order to avoid re-injury to the ligament. Seeing your doctor and physiotherapist on a regular basis will ensure the AC joint remains intact.

In Conclusion

An acromioclavicular joint sprain is an injury to the ligaments that maintain the joint and keeps it in place. Quick intervention can save your shoulder joint and speed up recovery. Waiting before seeing a medical professional can lead to a lot of complications.

How helpful was this post?

Since you found this post helpful...

Kindly share it on social media with the buttons below

We are sorry that this post was not helpful to you!

Let us improve this post!

Adekanmi Lipede, M.Sc, MPH

Adekanmi Lipede is a licensed physiotherapist with a Master's degree in physical activity and public health from Loughborough University. She joined 25 Doctors in 2018 and is passionate about educating people about the best steps to take when trying to be physically fit or when recovering from a mobility-related condition. For fun, she loves to exercise and read.
Adekanmi Lipede, M.Sc, MPH