ACGelenkSchädeldislokation

An acromioclavicular joint (AC joint) injury refers to damage to the joint at the top of the shoulder where the clavicle meets the acromion of the scapula. It is commonly called an AC joint sprain or dislocation and is most often caused by a fall onto the shoulder or a direct blow in contact sports. The joint is stabilized by the acromioclavicular ligaments and the coracoclavicular ligaments; disruption of these structures destabilizes the joint and guides treatment.

Classification is usually by the Rockwood system, with Grade I as a simple sprain of the AC ligaments; Grade II as AC ligament rupture with intact coracoclavicular ligaments; Grade III as rupture of both AC and CC ligaments with partial clavicular elevation; Grade IV–VI as progressively greater displacement compromising surrounding structures and being less common.

Clinical presentation includes localized pain and tenderness over the AC joint, swelling, and pain with shoulder movement, particularly cross-body adduction. A piano-key sign and visible deformity may be present in higher grades. Diagnosis uses plain radiographs in multiple views (AP, dedicated AC or Zanca views) and bilateral imaging for comparison; MRI or ultrasound may assess associated soft-tissue injury.

Management: Grades I–II are typically treated nonoperatively with rest, immobilization (slings), analgesia, and gradual rehabilitation. Grade III remains controversial and is often managed nonoperatively in nonathletes or noncompetitive patients, with operative treatment considered for high-demand athletes or persistent instability. Grades IV–VI usually require surgical stabilization.

Prognosis is generally good with most patients regaining function, though return to full activity may take several months and depends on injury grade and treatment.