Acromioclavicular Joint Separation

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 5 min read
Patient Tools

Read, save, and share this guide

Use these quick tools to make this medical article easier to read, print, save, or share with a family member.

On this page22 sections

Article Summary

An acromioclavicular joint separation, or AC joint separation or shoulder separation, occurs when the clavicle separates from the scapula. It is commonly caused by a fall directly on the 'point' of the shoulder or by a direct blow received in a contact sport. Grade I and II separations very rarely require surgery. Even Grade III injuries usually allow a return to full activity with few restrictions....

Key Takeaways

  • This article explains Other Names in simple medical language.
  • This article explains Background in simple medical language.
  • This article explains Causes in simple medical language.
  • This article explains Differential Diagnosis in simple medical language.
Before reading

RX Patient Tools

Use these quick guides before reading the article, or return to them when you need help preparing questions for a doctor.

Start here Choose the right pathway for symptoms, reports, medicines, or urgent warning signs. Disease article roadmap Read this topic step by step: meaning, symptoms, warning signs, diagnosis, treatment, prevention, and follow-up. Treatment planner Prepare questions about treatment choices, benefits, risks, side effects, and follow-up. Family & caregiver guide Organize symptoms, reports, medicines, questions, and follow-up safely. Nutrition & diet guide Prepare food, hydration, supplement, and medicine-timing questions safely. Prevention guide Organize risk factors, protective habits, screening, and warning signs. Recovery guide Prepare a safe plan for activity, rehabilitation, warning signs, and follow-up.
Educational health guideWritten for patient understanding and clinical awareness.
Reviewed content workflowUse writer and reviewer profiles for stronger trust.
Emergency safety firstUrgent warning signs are highlighted below.
Choose your reading view

Patient View highlights a simple learning journey. Clinical View reveals structure, evidence, and editorial completeness.

Definition

An acromioclavicular joint separation, or AC joint separation or shoulder separation, occurs when the separates from the . It is commonly caused by a fall directly on the ‘point’ of the shoulder or by a direct blow received in a contact sport. Grade I and II separations very rarely require surgery. Even Grade III injuries usually allow a return to full activity with few restrictions. In some cases a painful lump may persist, necessitating partial clavicle excision in selected individuals such as high caliber throwing athletes. Leaving your AC joint injury untreated means your condition can worsen, which can have serious consequences, such as shoulder separation. Serious displacement or . in your shoulder.

Other Names

  • Shoulder Separation
  • Shoulder
  • AC Sprain
  • AC
  • Acromioclavicular

Background

  • This page refers to all traumatic injuries to the Acromioclavicular Joint including
    • Sprains
    • Dislocations
    • Separations
  • Thought to be under-estimated due to many injuries not seeking medical attention
  • Represents 9% of all shoulder injuries (need citation)
  • 50% of all AC dislocations occur to individuals in their 20s (need citation)
  • Types 1 and 2 injuries account for most AC separations
  • Mechanism of injury is primarily by direct impact over the AC joint
    • From fall or contact sport
    • Arm is adducted

Causes

  • Many causes
    • Simple falls
    • High energy
    • Sports

Pathoanatomy

  • AC Joint
    • Diarthrodial joint
    • Motion: primarily gliding, only 8° rotation through AC joint
    • fibrocartilaginous intraarticular disc (similar to of knee)
  • Stabilizers
    • Acromioclavicular  (anterior-posterior stability)
    • Coracoclavicular  (superior-inferior stability)
    • Muscles: Deltoid, Trapezius

Associated Injuries

  • Intra-articular shoulder injury (18.2%)[1]
    • SLAP
    • Rotator Cuff Injury
  • Male > Female
  • Sports
    • Contact and collision sports
    • Skiing
    • Cycling

  • Fractures
    • Proximal Fracture
    • Humeral Shaft Fracture
    • Clavicle Fracture
    • Scapula Fracture
    • First Rib Fracture (traumatic or atraumatic)
  • Dislocations & Seperations
    • Acromioclavicular Joint Separation
    • Glenohumeral Dislocation ()
    • Sternoclavicular Joint Dislocation
    • Glenohumeral Instability ()
  • Arthropathies
    • Glenohumeral Arthritis
    • Acromioclavicular Joint Arthritis
  • Muscle & Injuries
    • Pectoralis Major Injuries
    • Pectoralis Minor Injuries
    • Proximal Biceps Tendon Injuries
    • Scapular Dyskinesis
  • Rotator Cuff
    • Rotator Cuff
    • Calcific of the Rotator Cuff
    • Subcoracoid Impingement
  • Bursopathies
    • Subacromial
    • Scapulothoracic Bursitis
  • Ligament Injuries
    • Glenoid Labral Tears
  • Neuropathies
    • Suprascapular Nerve Injury
    • Parsonage-Turner Syndrome
    • Quadrilateral Space Syndrome
    • Winged Scapula
  • Other
    • Paget-Schroetter Syndrome
  • Pediatrics
    • Coracoid Avulsion Fracture
    • Humeral Head Epiphysiolysis (Little League Shoulder)

Symptoms

  • General: Physical Exam Shoulder
  • History
    • Patient should describe some trauma
    • Shoulder at or close to AC joint
  • Physical
    • Most commonly, tenderness over AC joint
    • Inspection may show asymmetry of shoulders or swell at the AC joint
    • Range of Motion is usually reduced due to pain acutely
    • Pain with adduction of the shoulder and possibly with shoulder abduction and flexion
    • Deformity (step-off) of AC joint with type III injuries and higher
    • Type III and V may show instability of the lateral clavicle when depressed manually (“piano key” phenomenon)
  • Special Tests
    • Crossover Test: shoulder flexed to 90°, passively adducted across chest, reproduces pain over the AC joint
    • Resisted AC Joint Extension Test: abduction against resistance with shoulder flexed to 90°
    • OBriens Test: Arm flexed to 90° and then supinated and pronated against resistance

Diagnosis

Radiographs

  • Standard Radiographs Shoulder
  • Zanca view (sometimes referred to as the AC joint view)[2]
    • Beam is tilted cephalic 10 – 15°
    • Provides superior AC joint evaluation
    • Recommend bilateral evaluation for comparison
    • The average distance between the inferior aspect of the clavicle and the coracoid is 1.1 to 1.3 cm
  • Basmania view: scapular Y performed with cross-body adduction stress
  • Stryker notch views can assess for coracoid fracture
  • Note: Weighted stress views are no longer used

CT

  • CT has not been shown to improve diagnostic yield

MRI

  • Can directly assess AC and CC ligaments
  • Useful if surgical intervention is being considered

Ultrasound

  • Can be used to evaluate the AC joint

Classification

Rockwood Classification of Acromioclavicular Injuries

Type AC Ligaments CC Ligaments Deltopectoral Fascia CC Distance AC Joint (Xray)
I Sprained Intact Intact Normal Normal
II Disrupted Sprained Intact <25% Widened
III Disrupted Disrupted Disrupted 25%-100% Widened
IV Disrupted Disrupted Disrupted Increased Posterior displaced clavicle
V Disrupted Disrupted Disrupted 100-300% N/A
VI Disrupted Disrupted Disrupted Decreased Inferior displaced clavicle

Treatment

Types I and II

  • Universally nonoperative
  • Analgesia with ice, NSAIDS, Acetaminophen, et
  • Immobilization: Shoulder Sling
    • Discontinue once asymptomatic
    • Type I: Typically 1-3 weeks
    • Type II: Longer, up to 4 weeks[3]
  • Activity modification
    • Type II injuries may require early rehabilitation program with passive and active shoulder ROM exercises
    • Rotator cuff, scapular stabilization, and trunk strengthening exercises as pain resolves
    • Heavy lifting and contact activities only once extremity is pain free and symmetric ROM is acheived
  • Consider Corticosteroid Injection in refractory cases

Type III

  • Management is controversial
    • Not a lot of high level evidence to guide decision making
    • General consensus is to advocate for initial nonoperative management.
    • Individualized treatment based on patient activity level, impairment, and occupation
    • Consider surgical repair in acute, young patients
    • Comparably high satisfaction with operative and nonoperative treatment though higher complication rates in those treated surgically[4]
  • Nonoperative treatment
    • Similar to Type I, II

Type IV – VI

  • Generally considered surgical
  • Technique
    • Many described in the literature
    • ORIF most common

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play

  • Return to play once pain completely resolved and equal active ROM in bilateral shoulders. Followed by adequate strength training.
  • Recovery generally takes 6 weeks for Type II injuries and 12 weeks for Type III injuries

Complications

  • Acromioclavicular Joint Pain
    • Experienced by 1/3 of patients at 6 months after injury and up to 6 years of follow up[5]
  • Decrease in bench press strength (need citation)
  • Cosmetic deformity is very common
  • Crepitus, clicking
  • AC Joint Arthritis
  • Distal Clavicle Osteolysis
RX Medical Knowledge Graph

Explore this medical topic

Continue through verified related conditions, investigations, medicines, and patient guides. These links are educational and do not replace professional medical advice.

Related medical topics

Sacroiliac Joint Arthritis - Causes, Symptoms, Treatment73% relationship confidence Reactive Arthritis - Causes, Symptoms, Diagnosis, Treatment68% relationship confidence Reiter Syndrome - Causes, Symptoms, Treatment68% relationship confidence SLE - Causes, Symptoms, Diagnosis, Treatment68% relationship confidence Symptoms of Systemic Lupus Erythematosus68% relationship confidence Systemic Lupus Erythematosus - Symptoms, Treatment68% relationship confidence Types of Systemic Lupus Erythematosus68% relationship confidence What Is Reactive Arthritis? Causes, Symptoms, Treatment68% relationship confidence
More from this topic
  1. Axial osteosclerosis

    DefinitionAxial osteosclerosis means the bones of the axial skeleton become extra dense and hard. The axial skeleton is the spine, ribs, sternum?, and pelvis?. In axial...

    October 15, 2025 • Arthritis, and Chronic Pain (A - Z)
  2. Phlebectatic Osteohypoplastic Angiodysplasia

    DefinitionPhlebectatic osteohypoplastic angiodysplasia—much better known to clinicians as Servelle–Martorell syndrome? (SMS)—is a rare, congenital? venous malformation that mostly affects one limb. The hallmark triad is (1)...

    September 19, 2025 • Arthritis, and Chronic Pain (A - Z)
  3. Angio Osteohypotrophic Syndrome

    DefinitionAngio-osteohypotrophic syndrome? (Servelle–Martorell syndrome) is a very rare, congenital? (present at birth) vascular anomaly. The core problem is a network of abnormally formed, slow-flow veins? (venous...

    September 19, 2025 • Arthritis, and Chronic Pain (A - Z)
  4. Giant Cell Arteritis

    DefinitionGiant cell arteritis is a serious condition in which the walls of medium- and large-sized arteries? (the blood vessels carrying blood away from the heart) become...

    August 5, 2025 • Arthritis, and Chronic Pain (A - Z)
  5. Osteitis

    DefinitionOsteitis is the medical term for inflammation? of bone tissue. In simple terms, it means the bone itself is reacting with redness, swelling?, and sometimes pain?,...

    July 12, 2025 • Arthritis, and Chronic Pain (A - Z)
  6. Pseudogout

    DefinitionPseudogout, also known as calcium pyrophosphate deposition disease (CPPD), is a joint condition where tiny calcium crystals build up in the cartilage? and fluid of a...

    July 12, 2025 • Arthritis, and Chronic Pain (A - Z)
  7. Juvenile Idiopathic Arthritis (JIA) Dactylitis

    DefinitionJuvenile Idiopathic? Arthritis? (JIA) Dactylitis refers to an inflammatory condition in which an entire finger or toe becomes diffusely swollen, often resembling a “sausage digit.” It...

    July 12, 2025 • Arthritis, and Chronic Pain (A - Z)
  8. Neoplastic (Leukemic) Dactylitis

    DefinitionNeoplastic (leukemic) dactylitis is a rare form of “sausage digit” swelling? caused not by infection? or autoimmune disease?, but by direct infiltration of malignant? blood cells—most...

    July 12, 2025 • Arthritis, and Chronic Pain (A - Z)
  9. Traumatic Dactylitis

    DefinitionTraumatic dactylitis is a specific form of dactylitis—often called “sausage digit”—in which inflammation? affects an entire finger or toe following a physical injury to that digit....

    July 12, 2025 • Arthritis, and Chronic Pain (A - Z)
  10. Osteomyelitis-Induced Dactylitis

    DefinitionOsteomyelitis?‐induced dactylitis is the inflammation? of an entire finger or toe (“digit”) that arises when an infection? of the bone (osteomyelitis) spreads into the surrounding soft...

    July 12, 2025 • Arthritis, and Chronic Pain (A - Z)
RX Clinical Pathway Engine

Continue through a complete learning pathway

Move from understanding the topic to symptoms, tests, treatment, medicines, monitoring, and prevention.

Search the complete library
  1. Understand the condition Begin with the essential facts and a clear explanation of the topic.
  2. Recognize symptoms Learn common symptoms, signs, and patterns of presentation.
  3. Know when to seek help Review urgent warning signs and when professional assessment may be needed.
  4. Understand causes and risks Explore causes, risk factors, mechanisms, and contributing conditions.
  5. Explore tests and diagnosis Learn how clinicians assess the condition and which investigations may be discussed.
  6. Learn treatment approaches Review general treatment categories and management principles.
  7. Understand medicines safely Continue to medicine education, uses, precautions, and monitoring.
  8. Plan monitoring and follow-up Understand monitoring, complications, rehabilitation, and follow-up learning.
  9. Review prevention and self-care Explore prevention, healthy routines, and questions to discuss with a clinician.

Conditions & Diseases

Background, symptoms, causes, diagnosis, and care.

Explore this library

Tests & Investigations

Laboratory, imaging, screening, and diagnostic education.

Explore this library

Medicines

Uses, safety, monitoring, and related medicine knowledge.

Explore this library

Cancer Knowledge

Cancer types, screening, oncology, and treatment education.

Explore this library
Doctor visit helper

Prepare before seeing a doctor

A simple rural-patient checklist to help you explain symptoms clearly, ask better questions, and avoid unsafe self-treatment.

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Orthopedic doctor, rheumatologist, or physiotherapist depending on cause.

What to tell the doctor

  • Write which joints hurt, swelling, morning stiffness duration, fever, injury, and walking difficulty.
  • Bring X-ray, uric acid, ESR/CRP, rheumatoid factor, or previous reports if available.

Questions to ask

  • Is this injury, osteoarthritis, rheumatoid arthritis, gout, infection, or another cause?
  • Which exercises, supports, or lifestyle changes are safe?
  • Do I need blood tests or X-ray?

Tests to discuss

  • Joint examination and range of motion
  • X-ray when chronic arthritis or injury is suspected
  • ESR/CRP, uric acid, rheumatoid tests when inflammatory arthritis is suspected

Avoid these mistakes

  • Do not ignore hot swollen joint with fever.
  • Avoid repeated steroid injections/tablets without a clear diagnosis and follow-up.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Doctor / qualified healthcare provider
Tests to discuss with doctor
  • Basic vital signs: temperature, pulse, blood pressure, oxygen level if needed
  • Relevant blood, urine, imaging, or specialist tests only after clinical assessment
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Acromioclavicular Joint Separation

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

Internal learning pathway

Explore related RX articles

Related guides from RX Harun are grouped to help readers move from overview to symptoms, tests, treatment, and safe next steps.

Arthritis, and Chronic Pain (A - Z)
  1. Axial osteosclerosis DefinitionAxial osteosclerosis means the bones of the axial skeleton become extra dense and hard. The axial…
  2. Phlebectatic Osteohypoplastic Angiodysplasia DefinitionPhlebectatic osteohypoplastic angiodysplasia—much better known to clinicians as Servelle–Martorell syndrome? (SMS)—is a rare, congenital? venous malformation…
  3. Angio Osteohypotrophic Syndrome DefinitionAngio-osteohypotrophic syndrome? (Servelle–Martorell syndrome) is a very rare, congenital? (present at birth) vascular anomaly. The core…
  4. Giant Cell Arteritis DefinitionGiant cell arteritis is a serious condition in which the walls of medium- and large-sized arteries?…
  5. Osteitis DefinitionOsteitis is the medical term for inflammation? of bone tissue. In simple terms, it means the…
  6. Pseudogout DefinitionPseudogout, also known as calcium pyrophosphate deposition disease (CPPD), is a joint condition where tiny calcium…