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

Acromioclavicular Joint Palpation

Procedure

Palpate the AC joint directly with the patient seated or standing. Apply gradual pressure over the joint line to elicit tenderness. Compare bilaterally.

Positive Finding

Focal tenderness or pain directly over the AC joint

Sensitivity / Specificity

72% / 71%

Hegedus et al., 2008, Archives of Physical Medicine and Rehabilitation

Interpretation

Suggests AC joint pathology, but lacks specificity; commonly positive in AC joint osteoarthritis, sprains, and distal clavicle osteolysis. Must be combined with other tests.

Cross-Body Adduction Test (Horizontal Adduction Test)

Procedure

Patient is seated or standing. Elevate the affected arm to 90° shoulder flexion and adduct the arm across the body toward the opposite shoulder. Apply gentle overpressure at the end of range.

Positive Finding

Pain or reproduction of symptoms localized to the AC joint

Sensitivity / Specificity

72% / 97%

Hegedus et al., 2008, Archives of Physical Medicine and Rehabilitation

Interpretation

Highly specific for AC joint pathology; positive result strongly suggests AC joint involvement in the patient's presentation.

AC Joint Distraction Test

Procedure

With the patient standing, place one hand on top of the shoulder (trapezius) and the other under the elbow. Apply a gentle longitudinal downward distraction force while observing for pain relief or symptom reproduction.

Positive Finding

Relief of AC joint pain with distraction; conversely, increased pain suggests joint compression involvement

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Distraction relief suggests intra-articular AC joint pathology or capsular involvement. Positive distraction test can differentiate AC joint pain from surrounding soft-tissue pain.

Shear Test (AC Joint Shear)

Procedure

Patient stands with arm at side. Stabilize the distal clavicle with one hand while applying an anteroposterior shear force to the proximal humerus (via the elbow) with the other hand.

Positive Finding

Pain or apprehension in the AC joint region, particularly with posterior shear

Sensitivity / Specificity

See current literature / See current literature

Interpretation

May indicate AC joint instability or capsular strain; useful in detecting clavicular displacement in grade II or III sprains.

Resisted Horizontal Adduction (AC Joint Compression)

Procedure

Patient seated or standing with shoulder at 90° flexion and elbow extended. Adduct the arm across the body against resistance applied by the examiner.

Positive Finding

Pain localized to the AC joint or inability to generate force without AC joint pain

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Positive result suggests AC joint pathology affecting the distal clavicle and may indicate superior AC joint capsule irritation or osteoarthritis. Complements cross-body adduction test.

O'Brien's Test (Modified)

Procedure

Patient stands with the shoulder flexed to 90°, elbow extended, and thumb pointing downward (pronated forearm). Apply downward pressure over the arm while the patient resists.

Positive Finding

Deep anterior or AC joint pain with the arm pronated; pain relief when the arm is supinated and the test is repeated suggests AC joint involvement

Sensitivity / Specificity

See current literature / See current literature

Interpretation

Commonly used to assess superior labral pathology but can also provoke AC joint pain; positive AC joint component suggests concurrent AC joint involvement.

⚠ 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

Region

Acromioclavicular joint and distal clavicle

Technique

Soft Tissue

Rationale

Gentle soft tissue mobilization to the surrounding musculature (upper trapezius, deltoid, pectoralis minor) reduces muscular guarding, improves blood flow for healing, and decreases protective muscle spasm without aggravating the acutely inflamed joint

Region

Acromioclavicular joint

Technique

Articulation

Rationale

Grade I-II articulations (gentle oscillations) maintain synovial nutrition, prevent capsular fibrosis, and facilitate pain-free active-assisted range of motion while respecting ligamentous healing timeline

Region

Sternoclavicular joint and clavicle

Technique

MET

Rationale

Muscle energy techniques applied to trapezius and sternocleidomastoid normalize clavicular position and reduce compensatory tension, supporting optimal biomechanics at the AC joint during healing

Region

Cervical spine and upper thoracic spine

Technique

Soft Tissue

Rationale

Addresses referred pain patterns and reduces upper cervical and trapezius tension that commonly develops secondary to shoulder immobilization and altered movement patterns

Region

Shoulder girdle (scapulothoracic region)

Technique

Articulation

Rationale

Gentle scapular mobilization restores normal scapulohumeral rhythm, reduces compensatory tension throughout the shoulder complex, and promotes optimal positioning for AC joint healing

Region

First and second rib, lymphatic drainage

Technique

Lymphatic

Rationale

Lymphatic drainage techniques reduce inflammatory exudate, decrease pain perception, and enhance clearance of inflammatory mediators in the acute and subacute phases

Add-On Approaches

Chinese Medicine

Acupuncture to LI-15 (Jianyu) and TE-14 (Jianliao) points with electroacupuncture supports pain reduction through gate control mechanisms and promotes qi circulation; cupping or gua sha to upper trapezius and shoulder region may reduce acute muscular tension

Chiropractic

Adjustments to the AC joint (grades I-II manipulations in subacute phase) to restore joint mechanics; correction of clavicular position through postural work and scapular stabilization

Physiotherapy

Progressive resistance exercises for rotator cuff and scapular stabilizers; proprioceptive training; functional movement retraining; sport-specific return-to-play protocols

Remedial Massage

Deep tissue and trigger point therapy to deltoid, trapezius, and pectoralis muscles; myofascial release techniques to reduce protective muscle guarding and restore normal shoulder mechanics

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