Acromioclavicular Joint Sprain

AC Joint Anatomy

• Acromion process of the scapula
• Distal end Of clavicle
• The Articulation of these two bones make up the AC joint
• Also the coracoid process of scapula plays a role in joint stabilization

MECHANISM

• Falling On an OutStretched Hand (FOOSH) 
• FOOSH with elbow flexed,straight out, or directly on point of shoulder
• Direct blow to acromion process superiorly
• Longitudinal force applied to clavicle
• Can be acute or chronic. chronic in the case of repetitive stress to AC

History

• Can be chronic or acute but more commonly acute
• Extreme pain localized at AC joint that can radiate
• Mechanism Ex.) Football player falling on the tip of the shoulder after a catch

Observation

• Obvious displacement of clavicle
• Damage to coracoclavicular ligament causes Step deformity
• Elevating arm will cause pause
• Patient typically tries to carry their arm (cradle arm)

Palpation

• Point tender at AC joint
• Obvious deformity
• Warm skin
• Swelling
• Reducible AC by piano key sign

Special Tests

• AC joint traction test
• AC joint compression test
• Apley's scratch test

Differential Diagnosis

• Superior Labrum tear Anterior to Posterior (SLAP)
• Rotator cuff pathology
• Scapular fracture (at corocoid)
• Distal clavicle fracture

Prevention

SURGICAL INTERVENTION vs conservative intervention

• No significant difference in terms of strength and ROM
• Conservative intervention requires shorter immobilization period
• Surgical intervention provides less of an obvious deformity