Everything You Need to Know About an AC Joint Sprain
What is an AC Joint Sprain?
An AC joint sprain is an injury to the acromioclavicular joint, which is where your collarbone (clavicle) meets the top of your shoulder blade (acromion). This joint helps control shoulder movement and stability. When the ligaments around this joint are stretched or torn, it’s called a sprain. It can range from mild (slight stretch) to severe (complete tear or dislocation of the joint).
An analogy…
Think of the AC joint like a hinge holding up a shelf (your arm). If that hinge is stretched or damaged, the shelf still hangs, but it might wobble or sag, just like your shoulder can feel unstable or painful when the AC joint is sprained.
What are other names that an AC joint sprain can be referred to?
Shoulder Separation, AC Joint Injury, Sprained AC Joint, Torn AC Joint, AC Joint Subluxation, AC Joint Dislocation, Acromioclavicular Joint Injury
What causes an AC joint sprain?
The AC joint is held together by strong ligaments that connect the collarbone to the acromion. A sprain happens when force is placed directly on the shoulder, such as a fall onto the tip of the shoulder, a heavy tackle, or a fall with the arm outstretched. This can stretch or tear the ligaments, causing pain, swelling, and possibly a visible bump where the collarbone sits higher than normal.
What are the signs and symptoms of an AC joint sprain?
- Pain at the top of the shoulder, especially after a fall or impact
- Swelling or bruising over the AC joint
- Pain when lifting the arm, especially overhead or across the body
- A visible lump or bump at the top of the shoulder
- Shoulder weakness or limited range of motion
- In severe cases, the collarbone may appear raised or out of place
What tests are used to diagnose an AC joint sprain?
Cross-Body Adduction Test: This is a physical test used to check for AC joint problems. The practitioner asks you to lift your arm and move it across your body, like you’re reaching toward the opposite shoulder. If this movement causes pain at the top of the shoulder, it suggests irritation or injury to the AC joint.
How long does an AC joint sprain take to heal?
Recovery depends on the severity of the sprain:
- Grade 1 (mild): 1–2 weeks
- Grade 2 (moderate): 3–6 weeks
- Grade 3 (severe): May take 6+ weeks; sometimes surgery is considered
Rest, proper rehab, and protection of the joint are essential during healing.
How does an AC joint sprain happen?
- Falls onto the shoulder or outstretched arm
- Sports involving contact or collisions
- Weak shoulder or upper back muscles
- Poor shoulder mechanics during lifting or throwing
What treatment can help an AC joint sprain?
- Ice packs in the first 48–72 hours
- Sling for support (especially in moderate to severe cases)
- Manual therapy and soft tissue release
- Gradual strengthening and mobility exercises
- Taping or shoulder bracing for protection in early stages
- Return to sport or activity with proper guidance
What exercises or stretches can I do for an AC joint sprain?
- Pendulum swings
- Wall walks
- Scapular setting exercises
- Resistance band shoulder strengthening
- Overhead reaching and functional tasks
What products can help with an AC joint sprain?
Shoulder external rotation stretch supine with shoulder in neutral
Lie on your back with your symptomatic arm on a pillow by your side.
Hold a broom stick in both hands with both elbows at a right angle.
Use your good arm to push the stick across your body towards your symptomatic arm, turning the forearm outwards.
You should feel a stretch at the front of your shoulder.
Do not allow your upper arm to move away from your body.
Hold this position.
PROM GHjt ER(N) stretch in doorway
Stand up straight facing the edge of a stable structure with the elbow of your affected hand tucked into your side, bent to 90 degrees.
Place the palm of your hand against the stable structure.
Keeping your elbow tucked into your side, rotate your body away from your affected arm by stepping your feet away from the wall.
Feel the stretch across the front of your shoulder.
Hold this position.
Scapular retraction
Start in a seated position and place your hands on your hips.
Let your shoulders fall forward by rounding the upper back, then squeeze your shoulder blades together, drawing them back and down as your elbows come out and back.
Keep your shoulders pressed down and away from the ears at all times.
