ACROMIOCLAVICULAR SEPARATION

History
. Direct force by far most commonmechanism
. Fall onto point of shoulder
. Acromion gets driven downward and clavicle is stabilized by sternoclavicular
(SC) ligaments
. Sequence of ligamentous injuries: acromioclavicular (AC) ligaments,
coracoclavicular (CC) ligaments, deltoid and trapezial muscle
attachments, skin
. Inferior dislocation (type VI separation) likely caused by downward
force on clavicle
. Injury may also be caused by indirect forcewith humeral head being
driven into acromion
. Will cause no damage to CC ligaments
. A common athletic injury
. Football
. Hockey
. Lacrosse
. Bicycling (esp. mountain biking)
. Snowboarding
. Motorcycle accidents
. Tend to be complex with associated injuries
. Patients report pain, swelling at AC
. Chronically may have deformity, clicking, pain
Physical exam
. Inspection of deformity
. Rule out posterior buttonholing of clavicle through deltotrapezial
fascia
. Neurovascular and rotator cuff strength exam
. Palpation of AC and CC regions
. Cross-body adduction
. Injuries to rule out acutely
. Clavicular shaft fracture
. Acromion and coracoid fractures
. Brachial plexus injuries
. SC joint injuries
. Pneumothorax
. Scapulothoracic dissociation
. Chronically must rule out other sources of pain
. SLAP tear
. Cervical radiculopathy
. Rotator cuff tear
Studies
. Preferably done standing
. AP (Zanca view)
. cephalic tilt to avoid superimposition of AC joint on scapula
. Reduced exposure needed as in AP view of glenohumeral joint
. Axillary view
. Rule out posterior displacement of clavicle
. Rule out coracoid and acromion fractures
. Film other side if questionable
. Standing AP view of both shoulders
. Measure CC distances and calculate % increase on affected side
. CC distance normally 1.0–1.3 cm
. Weighted views
. Help distinguish type II from type III
. Not needed, as they seldom change treatment plan or decision
to perform surgery
. MRI
. Can delineate ligamentous injury and arthritis, useful for surgical
planning
Differential Diagnosis
. Lateral clavicle fracture
. Periosteal sleeve fracture
. Bipolar AC separation + SC joint injury
. Combined AC separation + coracoid process fracture
. Glenohumeral joint dislocation