About Courses Library Newsletter Contact

Multidisciplinary Shoulder & Elbow Society Library

Our comprehensive library has everything you need to help you better understand your patients' shoulder or elbow problems.

The Rockwood Classification for AC Joint Separations

ac joint dislocations ac joint separations acromioclavicular joint classification systems shoulder instability the rockwood classification the unstable shoulder
The Rockwood Classification for Acromioclavicular Joint Separations

The Rockwood Classification for AC Joint Separations

The Rockwood classification is the most widely used system for categorizing acromioclavicular (AC) joint separations, dividing injuries into six types based on ligament disruption, clavicle displacement, and soft tissue involvement.1 Developed in 1984 as an expansion of earlier classifications, it provides a framework for diagnosis and treatment decisions.

Dameron and Rockwood classification (Intact Coracoclavicular ligaments even in high-grade ACJ dislocation).1,2

Type I

  • AC ligament: Mild sprain
  • Coracoclavicular (CC) ligaments: Intact
  • Radiographic findings: Normal appearance with maintained AC joint alignment
  • Clinical notes: Minimal pain and swelling, typically treated conservatively

Type II

  • AC ligament: Ruptured
  • CC ligaments: Sprained but intact
  • Radiographic findings: AC joint widening (>7 mm) with <25% vertical clavicle elevation
  • Clinical notes: Visible deformity with moderate pain, often managed non-operatively

Type III

  • AC ligament: Ruptured
  • CC ligaments: Ruptured
  • Radiographic findings: CC distance increased 25-100% compared to contralateral side
  • Clinical notes: Complete AC joint dislocation with significant deformity; treatment remains controversial

Type IV

  • Displacement: Clavicle posteriorly displaced into trapezius muscle
  • Soft tissue: Detached deltoid and trapezius muscles
  • Radiographic findings: Posterior clavicle position on axillary view
  • Notes: Rare injury requiring surgical intervention

Type V

  • Displacement: Clavicle subcutaneously elevated
  • Radiographic findings: CC distance >100% of contralateral side (>25 mm)
  • Soft tissue: Severe detachment of deltotrapezial fascia
  • Clinical notes: Dramatic shoulder deformity, typically surgical candidate

Type VI

  • Displacement: Clavicle inferior to coracoid process
  • Anatomy: Lodged beneath coracobrachialis and biceps tendons
  • Notes: Extremely rare, usually from high-energy trauma

The classification relies on standard radiographs (AP, axillary, and weighted views) to assess ligament integrity and displacement patterns. While Types I-II are consistently managed non-operatively and Types IV-VI surgically, Type III remains debated due to variable outcomes with both approaches. Interobserver reliability is moderate, reflecting challenges in radiographic interpretation of soft tissue injuries.

References

  1. Rockwood CA. Fractures in adults. pp 860–910. Philadelphia: Lippincott, 1984. 
  2. Wahal N, Kendirci AS, Abondano C, Tauber M, Martetschläger F. Acromioclavicular Joint Lesions in Adolescents—A Systematic Review and Treatment Guidelines. Journal of Clinical Medicine. 2023; 12(17):5650. https://doi.org/10.3390/jcm12175650

Categories

All Categories ac joint dislocations ac joint separations acromioclavicular joint adhesive capsulitis advice anatomy antuna and seebauer classification arthroscopic subacromial decompression bursa capsule case of the week case study cervical spine cervicogenic pain charcot classification classification systems classifications clinical pearls codman conservative continous learning continuing education corticosteroid cortisone cross-body adduction test cubital tunnel syndrome deltoid drop-arm sign dunning-krugger effect elbow elbow arthritis elbow arthroscopy elbow contractures elbow ct scan elbow imaging elbow osteoarthritis elbow pain elbow radiographs elbow septic arthritis elbow stability elbow stiffness elbow surgery elbow x-rays empty can epidemiology external rotation resistance flexor pronator strain force couple frozen shoulder full can gerber classification glenohumeral joint glenohumeral joint osteoarthritis glenohumeral ligament glenoid bone loss hawkins-kennedy hemiarthroplasty historical definitions impingement infographic injection injury instability joint journal of shoulder and elbow surgery labral tears labrum lift-off test ligaments management muscles myofascial pain neck pain neer's sign neuropathic arthropathy neuropathy nonoperative normal shoulder orthopaedic special test orthopaedic special tests orthopaedics osteoarthritis osteomyelitis pain relief painful arc pathogenesis pathomechanics patient guide physiotherapy quiz question quiz question of the week radiculopathy range of motion rehabilitation revision surgery rotator cuff rotator cuff related pain rotator cuff tendinopathy scapular tilt scapulothoracic motion screw axes glenohumeral joint shoulder shoulder & elbow specialists shoulder arthritis shoulder dislocation shoulder instability shoulder motion shoulder osteoarthritis shoulder pain shoulder stability shoulder stiffness slap spurling test stability stable shoulder stanmore classification subacromial impingement subacromial pain syndrome subacromial space surgery synovial membrane the rockwood classification the unstable shoulder thomas & matsen classification throwing injuries total shoulder arthroplasty trauma traumatic anterior shoulder dislocation treatment tubs ulnar collateral ligament injury ulnar nerve upper trapezius
FREE GIFT: SHOULDER CARE ALGORITHM INFOGRAPHIC

Join Our Newsletter & Get a FREE Membership

By signing up you for our newsletter you will get a FREE membership to the Multidisciplinary Shoulder & Elbow Society and we will send you our Shoulder Care Algorithm Infographic which was created and is used by our shoulder & elbow fellowship trained orthopaedic surgeons. On top of that you will receive our weekly newsletter which includes articles, educational resource, surgeon clinical pearls, along with access to instructional courses and the annual meeting.

You're safe with me. I'll never spam you or sell your contact info.