Acromioclavicular Joint Sprain

Upper Limb

Overview

Acromioclavicular (AC) joint sprain is a common injury resulting from direct trauma or fall onto the shoulder, causing ligamentous damage to the AC and coracoclavicular ligaments. The severity ranges from Grade I (mild ligamentous stretch) to Grade VI (complete separation with clavicle displacement), with most cases being Grade I-II sprains. Clinical presentation varies based on injury severity, with management typically conservative for lower grades and occasionally surgical for higher grades.

Pathophysiology

Injury to the AC joint occurs through direct impact to the lateral shoulder or fall onto an outstretched arm, causing excessive compression and disruption of the acromioclavicular ligaments and coracoclavicular ligaments (conoid and trapezoid). This results in inflammation, synovial irritation, and instability of the distal clavicle relative to the acromion. In higher-grade sprains, complete ligamentous rupture allows superior displacement of the clavicle, disrupting the normal biomechanics of shoulder girdle function and increasing shear forces through the joint.

Patient Education

Most AC joint sprains heal well with conservative management through activity modification, ice in the acute phase, and gradual return to normal shoulder function with targeted rehabilitation.

Typical Presentation

Site

Superior aspect of the shoulder over the acromioclavicular joint; radiation may occur to the lateral arm and upper trapezius region

Quality

Sharp, localized pain at the AC joint; may describe catching or clicking sensation with arm movement

Intensity

Mild to moderate (2-6/10 depending on grade); typically more severe with Grade III-IV sprains

Aggravating

Cross-body adduction (horizontal flexion), reaching across the chest, overhead activities, direct palpation of AC joint, bench press movements, throwing activities, sleeping on affected side

Relieving

Arm sling (acute phase), rest from aggravating activities, ice application (acute phase), heat (chronic phase), arm support during functional activities

Associated

Swelling and bruising over AC joint, shoulder shrug weakness, reduced horizontal adduction range of motion, visible clavicular prominence (Grade III+), shoulder girdle instability, pain with cross-body adduction test

Orthopaedic Tests

Test descriptions are written with AI assistance from standard clinical texts. Where a test lists Sources, its description has been checked against them; those sources are independent and do not endorse OsteoKit. Accuracy figures and grades (A–D) appear only when checked against the published study; tests without one are marked “No accuracy study”.

Further reading: full test procedures are described in standard clinical examination texts, e.g. Magee & Manske, Orthopedic Physical Assessment (7th ed.), and Cook & Hegedus, Orthopedic Physical Examination Tests: An Evidence-Based Approach (2nd ed.).

Grade B
A+ABCDGood clinical value: meaningfully changes the diagnosis in one direction (LR 5–10 or 0.1–0.2)
best for ruling IN (confirmation).

O'Brien's Test (Modified)

Procedure

Patient standing. Arm raised to 90° of flexion and 10–15° across the body, elbow straight, thumb pointing down. Apply a downward force while the patient resists. Repeat with the palm facing up. Ask where the pain is felt.

Positive Finding

Pain on top of the shoulder at the acromioclavicular joint in the thumb-down position, reduced with the palm up.

Sensitivity / Specificity

41%/95%

Reference: Chronopoulos E et al., Am J Sports Med 2004; PMID 15090381

Interpretation

Where the pain is felt matters: pain on top of the shoulder points to the acromioclavicular joint; deep pain inside the shoulder points to the labrum. A positive result supports the acromioclavicular joint as the pain source. For AC-joint lesions the active compression (O’Brien) test was 41% sensitive / 95% specific (Chronopoulos 2004); combined with cross-body adduction and AC resisted extension the three-test cluster reaches 25% sensitivity / 97% specificity.

Sources

No accuracy study

Acromioclavicular Joint Palpation

Procedure

Patient seated. Inspect both shoulders for a step at the acromioclavicular joint, then palpate along the clavicle to the joint line and compare sides.

Positive Finding

Point tenderness at the joint, sometimes with a visible or palpable step.

Interpretation

Tenderness supports an acromioclavicular source. Combined with a fall onto the point of the shoulder, it fits an acromioclavicular sprain. A visible step suggests ligament disruption; X-ray grades the injury. Chronopoulos (2004) is the diagnostic-accuracy source for AC-joint tests (cross-body adduction ~77% sensitivity; active compression ~95% specificity); the previously cited journals were incorrect.

Sources

No accuracy study

Cross-Body Adduction Test (Horizontal Adduction Test)

Procedure

Patient seated. Raise the arm to 90° of flexion and bring it across the body towards the opposite shoulder, adding gentle overpressure.

Positive Finding

Pain localised to the top of the shoulder at the acromioclavicular joint.

Interpretation

Compresses the acromioclavicular joint. Pain felt at the joint supports it as the pain source; pain at the back of the shoulder is more likely from a tight posterior capsule. Chronopoulos (2004) is the diagnostic-accuracy source for AC-joint tests (cross-body adduction ~77% sensitivity; active compression ~95% specificity); the previously cited journals were incorrect.

Sources

No accuracy study

AC Joint Distraction Test

Procedure

Patient standing, arm relaxed at the side. Apply a gentle downward pull on the arm while palpating the acromioclavicular joint.

Positive Finding

Pain at the joint with the downward pull, or a widening gap that can be felt.

Interpretation

Not a recognised validated test. A palpable gap with traction suggests a ligament injury. Do not apply traction when the joint is obviously displaced; X-ray is needed.

Further reading

No accuracy study

AC Joint Shear Test

Procedure

Patient seated. Clasp your hands over the shoulder, with the heel of one hand on the clavicle and the heel of the other on the spine of the scapula, and squeeze them together.

Positive Finding

Pain or abnormal movement at the acromioclavicular joint.

Interpretation

Compresses the joint and supports it as the pain source. Use it with palpation and the cross-body adduction test.

Further reading

No accuracy study

Resisted Horizontal Adduction (AC Joint Compression)

Procedure

Patient seated, arm at 90° of flexion. Ask the patient to push the arm across the body against your resistance.

Positive Finding

Pain localised to the acromioclavicular joint.

Interpretation

Loads the joint through muscle contraction. Pain at the joint supports it as the source; pain at the front of the chest points instead to pectoralis major. Chronopoulos (2004) is the diagnostic-accuracy source for AC-joint tests (cross-body adduction ~77% sensitivity; active compression ~95% specificity); the previously cited journals were incorrect.

Sources

⚠ Red Flags

  • •Severe neurovascular compromise with arm swelling, numbness, or colour changes suggesting vascular injury
  • •Suspected brachial plexus injury with neurological symptoms in multiple dermatomes
  • •Severe trauma with suspected concurrent fractures or multi-ligament injuries requiring imaging confirmation
  • •Signs of infection if wound is present (increasing warmth, redness, drainage)

⚡ Yellow Flags

  • •Occupational demands requiring early return to overhead or contact activities
  • •Anxiety about returning to sport or work with associated fear-avoidance behaviour
  • •Unrealistic expectations for rapid pain resolution or return to activity
  • •History of repetitive shoulder injury or chronic overuse patterns
  • •Poor pain coping strategies or catastrophizing thoughts about the injury

Osteopathic Techniques

Type I and II injuries, and most type III, are managed without surgery: a sling, ice, pain relief and physiotherapy. Surgery may be considered for large displacement, heavy manual or elite sporting demands, or no improvement. No trials of manual techniques were found.

Region

AC joint, clavicle and SC joint

Technique

Muscle energy, AC joint, clavicle and SC jointNo trials found

Rationale

Gentle, patient-powered correction of AC or clavicle restriction once the sprain settles. No trials.

How it's done, cautions & evidence

How it's done

Patient seated or supine. Monitor the AC or SC joint with one hand and use the arm as a lever to take the joint to its barrier (for example, external rotation for an internally rotated AC joint, or more abduction for an adducted clavicle). The patient pushes gently against isometric resistance for 3–5 seconds, relaxes, and the joint is taken to the new barrier. Repeat 3–5 times, then re-check.

Cautions

Very safe, but not used with a fracture, a ruptured ligament, tendon or muscle, a joint infection, or when no dysfunction is found.

Evidence in Acromioclavicular Joint Sprain

Searched 24 Oct 2026: no trials of AC joint or clavicle MET in AC joint sprains.

Region

Rotator cuff, deltoid and periscapular muscles

Technique

Soft tissue, shoulder and periscapular musclesNo trials found

Rationale

Eases guarding in the muscles around the shoulder. No trials in AC sprains.

How it's done & evidence

How it's done

Hands-on kneading, stroking and sustained pressure to the muscles around the shoulder: the rotator cuff, deltoid and the muscles around the shoulder blade. In trials it was given alongside shoulder exercise.

Evidence in Acromioclavicular Joint Sprain

Searched 24 Oct 2026: no trials of shoulder soft tissue technique in AC joint sprains.

Rehabilitation Exercises

Pendulum Circles (Codman's Pendulums)

Range of MotionBeginner

Cross-Body Shoulder Stretch (Modified with Pain Monitoring)

StretchingBeginner

Shoulder Flexion Pulley Slides

Range of MotionBeginner

Sleeper Stretch (Internal Rotator Stretch)

StretchingIntermediate

Isometric Shoulder External Rotation (with Towel Roll)

StrengtheningBeginner

Scapular Retraction (Prone, no weight)

StrengtheningBeginner

Side-Lying External Rotation with Light Resistance Band

StrengtheningIntermediate

Prone Horizontal Abduction (90/90 position, no weight initially)

StrengtheningIntermediate

Scapular Wall Slides (Supine or Standing)

PosturalBeginner

Quadruped Shoulder Stability (Bird-Dog Variation)

BalanceIntermediate

Push-Up Plus (Wall or Incline)

StrengtheningIntermediate

Loaded Carry (Suitcase Carry with Light Weight)

StrengtheningAdvanced

Referral Criteria

  • •Persistent severe pain beyond 4-6 weeks unresponsive to conservative management
  • •Suspected high-grade sprain (Grade III-VI) with visible clavicular displacement requiring orthopedic assessment for possible surgical reconstruction
  • •Neurovascular compromise or nerve injury symptoms that do not resolve with conservative treatment
  • •Inability to regain functional shoulder strength and range of motion after 8-12 weeks of rehabilitation
  • •Recurring or chronic AC joint instability with recurrent subluxation episodes
  • •Concurrent injuries to rotator cuff or superior labrum requiring specialist imaging and management
  • •Failure to return to sport/work activities after 3 months despite appropriate rehabilitation
  • •Persistent psychological distress or fear-avoidance beliefs significantly impacting rehabilitation compliance