AC Joint Sprains (Shoulder Separation): Symptoms, Causes & Evidence-Based Management

Published by: Sports Performance PhysiotherapyWebsite: https://www.sportsperformancephysio.com/

Shoulder pain at the top of the shoulder following a fall, tackle, or collision is often due to an AC (acromioclavicular) joint sprain, sometimes called a shoulder separation injury. Although it’s common in contact and collision sports, AC joint injuries can occur in anyone who sustains a direct impact to the shoulder or suffers a forceful fall.

This comprehensive guide explains what AC joint sprains are, how they are graded, how they are diagnosed, and the most effective physiotherapy-focused treatment approaches — with practical sports-specific insights.

What Is the AC Joint?

The acromioclavicular (AC) joint is the junction where your collarbone (clavicle) meets the acromion of the shoulder blade (scapula) — the topmost point of the shoulder. This small but important joint forms part of the shoulder girdle and helps with arm elevation, overhead and across body movements.

Stability around the AC joint is provided by:

• The acromioclavicular ligaments

• The coracoclavicular ligaments (trapezoid and conoid)

• The capsule surrounding the joint itself

Damage to these structures leads to pain, instability, and functional loss after injury.

How Do AC Joint Sprains Happen?

AC joint sprains most often occur from:

• A direct blow to the top of the shoulder (e.g., tackle, collision)

• A fall onto the shoulder or onto an outstretched hand (FOOSH)

• Contact sports like rugby, AFL, football, and snow sports

These forces drive the acromion downward and/or the clavicle upward beyond the joint’s normal range, stretching or tearing the stabilising ligaments.

Symptoms of an AC Joint Sprain

Common symptoms include:

• Pain on the top of the shoulder

• Tenderness and swelling over the AC joint

• Visible step deformity or bump (especially with higher-grade injuries)

• Pain with overhead movement, pushing or reaching across the body

• Shoulder weakness and reduced function

Severity of symptoms typically reflects the degree of ligament damage.

Grading AC Joint Sprains: What It Means

AC joint sprains are classified using the Rockwood grading system, ranging from Grade I to VI, based on ligament involvement and displacement.

Grade I – Mild Sprain

• Slight stretch of the ligaments

• No significant joint displacement

• Pain with motion but no obvious deformity

• Usually managed conservatively

Grade II – Partial Ligament Tear

• Rupture of the AC ligament and sprain of the coracoclavicular ligaments

• Minor instability; possible small bump

• Rehab typically 3–6 weeks

Grade III – Complete Tear

• AC and coracoclavicular ligaments fully torn

• Notable bump at the top of the shoulder

• Functional recovery often 6–12+ weeks

• Generally managed conservatively

Grades IV–VI – Severe Displacement

• Rare; usually require surgical evaluation

• Large displacement of the clavicle and significant instability

• Long recovery and possible operative intervention

Guided rehabilitation timelines vary depending on sport, load demands, and individual functional goals.

Diagnosis & Assessment

At Sports Performance Physiotherapy in Drummoyne we use:

• A detailed history of injury mechanism

• Physical examination including palpation, range of motion, and stress tests

• Imaging (X-ray) to confirm AC joint separation and grade if required

X-rays for Grade I–II injuries generally do not change management.

Occasionally ultrasound or MRI may be used to assess associated soft tissue injury or evaluate chronic or higher-grade cases.

Early confirmation helps tailor the best rehabilitation strategy and avoid prolonged dysfunction.

Evidence-Based Management & Rehabilitation (Grade II–III)

1. Acute Phase (0–2 Weeks)

• Protect and reduce pain (ice, sling may be used briefly to minimise symptoms)

• Shoulder taping may assist

• Avoid painful overhead or heavy pressing and carrying

• Early controlled range of motion within pain limits

• Pendulum and gentle mobility exercises

• Pain-free isometric shoulder and scapular exercises

2. Subacute Phase (2–6 Weeks)

• Continue pain-free mobility work

• Increase scapular stabilisation exercise complexity

• Introduce light rotator cuff and deltoid strengthening

• Neuromuscular control exercises

• Banded shoulder extension and shrug progressions

3. Advanced Strength & Stability (6–12+ Weeks)

• Progressive resistance training for shoulder and scapular muscles

• Sport-specific movement preparation

• Plyometric and functional loading

• Gradual return to contact or load-bearing sport tasks

A balanced program reduces re-injury risk and promotes long-term joint stability.

Return to Sport & Continuing Recovery

Return to sport depends on:

• Pain-free range of motion

• Symmetrical strength and control in all planes

• Confidence in contact and tackle

• Completion of sport-specific drills

Most Grade I–II sprains resolve within 4–12 weeks with structured physiotherapy and appropriate load management. Grade III and higher injuries may take longer and occasionally require surgical consultation.

Prevention Tips

To reduce risk of AC joint sprains:

• Improve scapular control and rotator cuff strength

• Progress training loads gradually

• Use protective equipment in contact sports

• Learn safe fall and contact techniques

Summary

AC joint sprains range from mild ligament strains to complete separations and can significantly impact shoulder function if overlooked.

Early diagnosis, structured rehabilitation, and sport-specific progression offer the best outcomes for return to performance.

If you suspect an AC joint sprain or are struggling with shoulder pain following impact, a comprehensive physiotherapy assessment is your next best step.

If you are experiencing shoulder pain in Drummoyne or the Inner West, book an assessment with our sports physiotherapy team.

Book an appointment with Sports Performance Physiotherapy

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References (APA 7 Format)

Deans, C. F., Gentile, J. M., & Tao, M. A. (2019).
Acromioclavicular joint injuries in overhead athletes: A concise review of injury mechanisms, treatment options, and outcomes. Journal of Shoulder and Elbow Surgery, 28(5), 990–998.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6542865/

Field, B. (2025).
Assessment & management of the AC joint [Masterclass outline]. Sports MAP Network. 

Sports Medicine Australia. (n.d.).
Acromioclavicular (AC) joint injury fact sheet. 

Sports Injury Clinic. (n.d.).
AC joint sprain/separation: Diagnosis, taping & exercises. 

Physioworks! (2025).
AC joint pain — Acromioclavicular joint sprain.