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Created At: Nov 03, 2025 Updated At: Nov 03, 2025
Author: Dr. Garima Bishwas
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Sudden shoulder pain from a fall, impact, or overexertion can make daily tasks feel impossible. Activities like dressing, lifting, or even lying on your side may become painful. For athletes, cyclists, laborers, and anyone prone to falls or physical strain, one of the most common shoulder injuries is an AC joint injury.

The acromioclavicular (AC) joint connects the collarbone (clavicle) to the highest point of the shoulder blade (acromion). It plays a key role in shoulder movement and stability.

Athletes in contact sports, cyclists who fall on their shoulders, or workers lifting heavy objects are particularly at risk.

In this blog, we’ll explore what an AC joint injury is, how it happens, and the best treatment options available.

What Is an AC Joint Injury?

An AC joint injury refers to damage at the junction where the collarbone (clavicle) meets the top of the shoulder blade (acromion). It is commonly referred to as an "AC separation" or "shoulder separation."

This type of injury may involve:

Strain (mild stretching of the ligaments)
Partial tears
Complete dislocations (the collarbone gets pushed out of position)

A mild AC joint injury may feel like soreness after a workout, while severe forms can visibly dislocate the shoulder and cause intense pain.

Anatomy of the AC Joint

The AC joint is essential for raising the arm overhead and providing shoulder flexibility.

Ligaments Supporting the AC Joint:

AC Ligament: Directly stabilizes the joint.
Coracoclavicular (CC) Ligaments: Two strong bands (trapezoid and conoid) that support vertical shoulder stability.

When these ligaments stretch or tear, pain and instability occur.

These ligaments prevent excessive movement and allow for fluid shoulder motion. Damage to any part of this structure can significantly affect upper-body function.

Types/Grades of AC Joint Injury

Grade	Description	Severity
I	Minor strain or ligament stretching	Mild
II	Partial tear of the AC ligament	Moderate
III	Complete tear of the AC and CC ligaments	Severe
IV	Clavicle dislocation into/behind the muscle	Severe
V	Major displacement with muscle detachment	Very severe
VI	Downward displacement (rare)	Very severe

AC Joint Injury Common Causes

Injuries to the AC joint can result from both trauma and overuse. Common causes include:

Direct fall onto the shoulder (e.g., falling off a bike or slipping)
Sports collisions, especially in rugby, hockey, and football
Heavy lifting with poor form
Traffic accidents involving the shoulder hitting the ground or dashboard
Repetitive strain from certain jobs or exercises (e.g., bench pressing, swimming)

Symptoms of AC Joint Injury

You might suspect an AC joint injury if you notice:

Sharp pain at the top of the shoulder
Visible bump or deformity on top of the shoulder
Swelling or bruising around the joint
Pain when lifting the arm, especially overhead
Limited range of motion
Clicking, popping, or instability in the shoulder

AC Joint Injury Diagnosis

1. Physical Examination:

Palpation to identify pain spots
Arm movement tests
Evaluation of the range of motion and strength

2. Imaging Tests:

X-ray: Best for identifying bone displacement and grading the injury (Rockwood classification)
MRI: Useful for evaluating ligament tears and soft tissue damage

Accurate diagnosis helps determine whether surgery is necessary.

AC Joint Injury Treatment Options

a. Non-Surgical Treatment

For Grades I–III, conservative treatment often helps:

Rest and avoid strenuous activity.
Ice therapy to reduce swelling
Arm sling for 1–2 weeks
Anti-inflammatory medications (e.g., ibuprofen)
Physiotherapy for mobility and strength
Gradual return to normal activity under guidance

b. Surgical Treatment

Surgery is considered for Grades IV–VI or when:

Chronic pain persists.
Cosmetic deformity affects function.
Conservative treatment fails.

Surgical procedures include:

AC joint reconstruction with grafts or screws
Fixation techniques to stabilize the joint
Post-operative physiotherapy for 2–3 months

AC Joint Injury Recovery Timeline

Recovery varies based on severity and treatment.

Grade	Recovery Time
Grade I–II	2–6 weeks
Grade III	6–12 weeks
Post-surgery	3–6 months

Rehabilitation Phases:

Rest & Immobilization (1–2 weeks)
Mobility Exercises (2–4 weeks)
Strength Training (4–8 weeks)
Return to Activity (after 8+ weeks)

AC Joint Injury Prevention Tips

Minimize your risk with these proactive measures:

Wear protective gear in contact sports.
Always warm up and stretch before workouts.
Avoid lifting heavy objects without proper posture.
Strengthen rotator cuff and deltoid muscles.
Correct slouching or poor posture at work.

When to See a Doctor for AC Joint Injury

Seek medical attention if:

Severe swelling or an obvious bump appears.
Shoulder feels unstable or weak.
Pain lasts more than two weeks.
You experience numbness or tingling in the arm.

Timely care can prevent chronic pain and loss of function.

Summary

AC joint injuries are common but manageable. With proper rest, diagnosis, and physiotherapy, most people regain full shoulder function without surgery.

Disclaimer: Consult a physiotherapist or orthopedic expert for a personalized shoulder recovery plan.

Need help with shoulder pain? Visit Omansh.org to connect with our physiotherapy experts today.