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Home › Body Atlas › Joints › Acromioclavicular Joint (Detail)
Joint Shoulder

Acromioclavicular Joint (Detail)

articulatio acromioclavicularis

The acromioclavicular joint transmits upper limb forces to the clavicle through a plane synovial joint stabilised primarily by the coracoclavicular ligaments (conoid and trapezoid) for vertical stability and the AC ligaments for horizontal stability. AC joint osteoarthritis is extremely common (radiographic changes in 50% of individuals over 50) and is one of the most common causes of superior shoulder pain. AC joint resection arthroplasty (Mumford procedure) reliably relieves arthritic pain.

An expanded entry for Acromioclavicular Joint.

Anatomical Data

Structure

Bones
  • Lateral clavicle
  • Medial acromion process
  • Articular disc (fibrocartilage, partially covers the joint in most individuals)
Ligaments
  • AC ligament (horizontal stability)
  • Coracoclavicular ligaments, conoid and trapezoid (vertical stability)
Biomechanics

Function & Actions

Movements
  • Rotation of the clavicle during shoulder elevation (40-50 degrees)
  • Minor gliding for scapular tilting
Clinical Relevance

Clinical Notes

AC joint OA produces superior shoulder pain reproduced by horizontal adduction (crossover) test and direct AC joint palpation. Intra-articular injection confirms diagnosis with temporary relief. Arthroscopic distal clavicle resection (open Mumford or arthroscopic equivalent) removes the arthritic distal clavicle while preserving the CC ligaments, the gold standard surgical treatment.

Pathology

Common Injuries & Conditions

AC Joint Osteoarthritis

Degenerative AC joint pain reproduced by horizontal adduction managed with injection and distal clavicle resection.

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