Approximately 12% of shoulder injuries affect the acromioclavicular joint, making it one of the most common injuries among athletes and active individuals.

Here's the good news: the vast majority of acromioclavicular sprains (grades I and II) heal naturally without surgery. Your shoulder has a remarkable ability to repair itself when given the right conditions.

You will learn how to recognize an acromioclavicular sprain, understand the classification by grades (I to VI), and, most importantly, what treatment options are available depending on the severity of your injury.

What is an acromioclavicular sprain?

An acromioclavicular sprain (also known as an AC sprain or acromioclavicular separation) is an injury to the ligaments that hold your collarbone and acromion (the top part of your shoulder blade) together.

This joint is located at the top of your shoulder, where you can feel the small bump of your collarbone. The ligaments that stabilize this area are:

• Acromioclavicular ligaments: which directly connect the collarbone to the acromion
• The coracoclavicular ligaments: which anchor the collarbone to the coracoid process (a small bony protrusion below the collarbone)

When these ligaments are stretched or torn as a result of trauma, the joint loses its stability. In severe cases, the collarbone rises visibly, creating a characteristic "bump" at the top of the shoulder.

This injury particularly affects those who participate in contact sports (rugby, hockey, judo), cyclists, and skiers. Now that you understand the anatomy involved, let's look at how this injury is classified according to its severity.

What are the different grades of acromioclavicular sprains?

The Rockwood classification grades the severity of the sprain into six types, depending on the extent of ligament damage and displacement of the clavicle.

Grade I: Mild sprain

The acromioclavicular ligaments are stretched but intact. No tears, no displacement.

• Healing time: 1 to 3 weeks
• Treatment: Conservative (without surgery)

Grade II: Moderate sprain

The acromioclavicular ligaments are partially or completely torn, but the coracoclavicular ligaments remain intact. The clavicle becomes slightly unstable (sign of "piano key").

• Healing time: 4 to 6 weeks
• Treatment: Conservative in the vast majority of cases

Grade III: Complete separation

Both the acromioclavicular and coracoclavicular ligaments are torn. The collarbone is visibly raised, creating a deformity at the top of the shoulder.

• Healing time: 8 to 12 weeks
• Treatment: Conservative or surgical depending on your activity level

Grades IV to VI: Severe displacement

These rare grades involve major displacement of the clavicle (posterior, superior, or inferior) and associated muscle tears.

• Recovery: 4 to 6 months (with surgery)
• Treatment: Surgical

Grades I and II account for approximately 70% of AC sprains, grade III accounts for 20%, and grades IV to VI account for less than 10% combined. These classifications help you understand where you stand, but how can you recognize this injury in the first place?

What are the symptoms of an acromioclavicular sprain?

Symptoms vary depending on the grade, but certain signs are consistent.

Immediate symptoms (first few hours)

Sharp pain at the top of the shoulder

The pain is located very precisely at the AC joint (the highest point of your shoulder). It is intense at the moment of trauma and may radiate into the shoulder.

Difficulty raising the arm

Raising the arm above the shoulder becomes very difficult or impossible. Movements that bring the arm in front of the body are particularly painful.

Visible deformity (grades III to VI)

In grade III sprains and above, you will notice an abnormal "bump" at the top of the shoulder: this is the end of your collarbone sticking up.

Localized swelling

Swelling quickly appears at the AC joint. Unlike other shoulder injuries, the swelling is clearly visible and palpable.

Symptoms in the following days

• Bruising (blue) around the joint
• Intense pain on palpation
• Nighttime pain that disrupts sleep
• Instability or clicking during certain movements (grades II and III)

When to seek emergency care

Seek immediate medical attention if you experience:

• A dramatic deformation of the shoulder
• A complete inability to move the arm
• Numbness or tingling in the arm
• Paleness of the arm or absence of a pulse at the wrist
• Pain that intensifies after 48 hours

If you recognize several of these symptoms after a clear trauma, it is time to confirm the diagnosis.

What causes an acromioclavicular sprain?

Unlike shoulder pain, which develops gradually, AC sprains always occur following a clear trauma. There must be a specific triggering event.

Traumatic mechanisms

Direct fall onto the shoulder (70% of cases)

This is the most common mechanism. The impact is directly on the tip of your shoulder, with your arm close to your body. The force pushes the acromion down while the collarbone remains in place, creating a separation.

Examples: falling off a bicycle, tackling in rugby, falling while skiing, motorcycle accident.

Fall onto outstretched hand or arm (20% of cases)

The force of the impact travels up the arm and compresses the AC joint.

Direct blow to the shoulder (10% of cases)

A direct blow to the top of the shoulder can cause a dislocation.

High-risk sports

• Contact sports: rugby, ice hockey, soccer, judo
• Cycling sports: road cycling, mountain biking, motocross
• Snow sports: downhill skiing, snowboarding
• Equestrian sports: horseback riding, rodeo

Important point If your pain developed gradually, without any obvious accident, it is not not an AC sprain. This is probably another condition of muscular or tendinous origin. Now that we know what causes this injury, let's see how to diagnose it.

How is an acromioclavicular sprain diagnosed?

The diagnosis is based primarily on clinical examination, supplemented by X-rays to determine the exact grade.

Clinical examination

Your physical therapist or doctor will look for:

History of trauma

The details of your accident are crucial. A typical mechanism (falling on the shoulder, direct impact) strongly suggests an AC sprain.

Visual inspection

• Visible deformity at the top of the shoulder (grades III to VI)
• Localized swelling at the AC joint
• Bruise

Palpation and tests

• Extreme tenderness on palpation of the AC joint
• Piano key test: the collarbone sinks and then rises again
• Horizontal adduction test: bringing the arm in front of the body causes localized pain.

X-rays

X-rays are essential for:

• Confirm the diagnosis
• Determine the exact grade (I to VI)
• Eliminate a fracture of the collarbone or acromion

Radiographic views : front view of both shoulders for comparison, axillary profile, sometimes X-rays with weight bearing (weight in hands) to accentuate the displacement. Did you know? In Quebec, physical therapists can order X-rays if the injury occurred less than 72 hours ago.

Additional tests (complex cases)

• Ultrasound: visualize the ligaments and assess the extent of the tears
• MRI: assess muscle damage and detect associated injuries
• Computed tomography: for grades IV to VI in order to plan surgery

Once the diagnosis has been confirmed and the grade determined, the question becomes: how should this injury be treated?

What are the treatments depending on the grade of acromioclavicular sprain?

Treatment varies considerably depending on the grade. Grades I and II heal very well without surgery, grade III is controversial, and grades IV to VI require surgery.

Treatment of grades I and II: conservative approach

Phase 1: Protection and relief (0 to 7 days)

• Relative rest: Avoid painful activities without completely immobilizing yourself.
• Scarf: 1 to 4 days maximum if the pain is intense
• Ice: 15 to 20 minutes, 3 to 4 times a day for 48 to 72 hours
• Medication: Pain relievers (acetaminophen) or anti-inflammatory drugs as recommended

Phase 2: Gradual mobilization (7 to 21 days)

• Gentle mobility exercises (Codman pendulum swings, assisted passive elevation)
• Gradual return to light daily activities

Phase 3: Strengthening and functional return (3 to 6 weeks)

• Strengthening the rotator cuff
• Scapular stabilization
• Return to sport: 2 to 3 weeks (grade I), 4 to 6 weeks (grade II)

Treatment of grade III: conservative vs. surgical debate

Approximately 60% to 70% of patients recover very well with conservative treatment (8 to 12 weeks). Surgery may be recommended for:

• High-level athletes (overhead sports)
• Manual workers who place heavy demands on their shoulders
• Highly active young patients
• Failure of conservative treatment after 3 months

Optimal time frame : If surgery is chosen, ideally performed within 2 to 3 weeks of the injury.

Treatment of grades IV to VI: surgical

These grades almost always require surgery because the displacement is too severe to heal properly.

Post-surgical recovery :

• Immobilization: 4 to 6 weeks in a sling
• Physical therapy: begins after 6 weeks, protocol lasting 4 to 6 months
• Return to sports: 6 to 12 months

Surgery is only one step. It is rehabilitation that determines your final result.

What is the role of physical therapy in rehabilitation?

Whether your sprain is treated conservatively or surgically, physical therapy for shoulder pain is essential to regain optimal function.

Rehabilitation protocol according to grade

Grades I and II (conservative)

• Pain management and restoration of mobility
• Progressive strengthening (scapular stabilization, rotator cuff)
• Functional rehabilitation
• Schedule: 4 to 12 sessions over 4 to 8 weeks

Grade III (conservative)

• Similar protocol but longer (12 to 16 weeks)
• Focus on maximum reinforcement to compensate for residual instability

Grades treated surgically

• Phase 1 (0 to 6 weeks): Immobilization, passive exercises only
• Phase 2 (6 to 12 weeks): Weaning off the sling, beginning of active movements
• Phase 3 (3 to 6 months): Strengthening with progressive resistance
• Phase 4 (6 to 12 months): Return to sports (criteria: full mobility, strength ≥90%)
• Schedule: 15 to 25 sessions over 6 to 12 months

Even with good physical therapy, there is a lot you can do at home to optimize your recovery.

What can you do at home for an acromioclavicular sprain?

Your recovery is not limited to physical therapy sessions. What you do every day at home directly influences the speed and quality of your recovery.

PEACE & LOVE principles for the acute phase (0 to 72 hours)

PEACE : Protection (scarf for a maximum of 3 to 4 days), Elevation (arm raised), Avoid anti-inflammatory drugs (opt for acetaminophen), Light compression, Education about the injury LOVE : Load (gradual load from 48 to 72 hours), Optimism, Vascularization (light cardio exercise), Exercises prescribed as soon as possible

Progressive exercises at home

Caution Consult your physical therapist before starting these exercises. Week 1-2 Codman pendulum (small circles, 3 times/day), assisted elevation with healthy arm Week 2-4 : Scapular retraction (bring shoulder blades together, hold for 5 seconds) Weeks 3-6 External rotation with elastic band (elbow at 90°) Weeks 4-8 : Gradual strengthening with light weights (0.5 to 2 kg)

Tips for optimizing healing

Sleep Sleep on your back with a pillow under the injured arm, or on your healthy side with a pillow between your arms. Avoid sleeping on the injured shoulder. Activities to avoid :

• 0-2 weeks: Heavy loads, overhead lifting, sudden movements
• 2-6 weeks: Contact sports, heavy weights, pull-ups
• 6-12 weeks: Returning to sports too quickly, heavy overhead loads

Recovery from an AC sprain requires patience, but with a good home program and professional follow-up, you maximize your chances of regaining full function.

What are the possible complications and prognosis?

The vast majority of AC sprains heal without major complications, but it is important to be aware of the risks and expected outcomes.

Prognosis according to grade

| Grade | Healing | Timeframe | Return to sports |

|-------|----------|-------|-----------------|

| I | 100% | 2-3 weeks | 2-4 weeks |

| II | 95-100% | 4-6 weeks | 6-8 weeks |

| III (conservative) | 70-80% excellent | 8-12 weeks | 10-16 weeks |

| III (surgical) | 85-95% | 4-6 months | 6-12 months |

| IV-VI (surgical) | 80-90% | 6-12 months | 9-12 months |

Note : Grade III conservative treatment may leave a cosmetic deformity (small bump) that is generally not disabling. Success factors : Young age, good adherence to physical therapy, early rehabilitation, non-smoker. Your commitment to rehabilitation makes all the difference.

Frequently asked questions about acromioclavicular sprains

Can I work with an AC sprain?

It depends on the grade and the type of work. Office work: return after a few days (grade I), 1 to 2 weeks (grade II). Physical work: 3 to 4 weeks off (grade I), 6 to 8 weeks (grade II), 12 weeks or more (grade III).

Should I wear a scarf?

The sling can be useful for up to 2 to 4 days to relieve pain. Prolonged immobilization is not recommended as it can lead to stiffness. Remove the sling several times a day to move gently.

Can I drive with an AC sprain?

Grade I: as soon as the pain allows (a few days). Grade II or III: wait at least 1 to 2 weeks. Consult your physical therapist for personalized advice.

How long before I can go back to the gym?

Light exercise (cycling, walking): after 1 week (grade I). Upper body exercises: avoid for 3 to 4 weeks (grade I), 6 to 8 weeks (grade II), 12 weeks (grade III). Resume very gradually with 30% to 50% of your usual load.

Will the bump on top of my shoulder go away?

Grades I and II: generally no permanent deformity. Grade III: deformity often persists with conservative treatment, although it may decrease slightly with muscle strengthening. If it really bothers you, discuss surgical options with an orthopedic surgeon.

Do I need surgery for my grade III?

Not necessarily. Approximately 60% to 70% of grade III sprains heal very well without surgery. Surgery is mainly considered for high-level athletes, manual laborers, or if conservative treatment fails after 3 months.

How many physical therapy sessions will I need?

Grade I: 4 to 8 sessions over 4 to 6 weeks. Grade II: 8 to 12 sessions over 6 to 8 weeks. Conservative Grade III: 12 to 16 sessions over 12 weeks. Surgery: 20 to 30 sessions over 6 to 12 months.

Conclusion

An acromioclavicular sprain is a common shoulder injury that occurs as a result of direct trauma. Although it may look impressive and be painful at first, the vast majority of these injuries heal very well.

Key points to remember:

• Grade I and II injuries heal excellently with conservative treatment in 2 to 6 weeks.
• Grade III can be treated conservatively or surgically depending on your profile.
• Grades IV to VI generally require surgical intervention.
• Physical therapy is essential for regaining optimal function.
• Your participation in the rehabilitation program directly influences your final outcome.

If you have suffered a shoulder injury and are experiencing the symptoms described in this article, consult a physical therapist or doctor promptly to obtain an accurate diagnosis and begin appropriate treatment.

Sources

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• Gorbaty JD, Hsu JE, Gee AO. Classifications in brief: Rockwood classification of acromioclavicular joint separations. Clin Orthop Relat Res. 2017;475(1):283-287.

• Mouhsine E, Garofalo R, Crevoisier X, Farron A. Grade I and II acromioclavicular dislocations: results of conservative treatment. J Shoulder Elbow Surg. 2003;12(6):599-602.

• Bannister GC, Wallace WA, Stableforth PG, Hutson MA. The management of acute acromioclavicular dislocation. A randomized prospective controlled trial. J Bone Joint Surg Br. 1989;71(5):848-850.

• Cook JB, Shaha JS, Rowles DJ, et al. Early versus delayed surgical treatment of acute acromioclavicular joint dislocations. J Shoulder Elbow Surg. 2014;23(9):1351-1358.