Acromioclavicular joint injury

Background

• Usually occurs from direct trauma to the adducted shoulder

Diagnosis

• Tenderness directly over AC joint, possibly with deformity
• Also palpate sternoclavicular joint, coracoclavicular ligaments for assoc injuries
• AC compression test
• Passively flex arm so is parallel with ground; then passively adduct across body
• Pain suggests AC joint injury

Imaging

• AP shoulder (always obtain comparison view)
• AC joint
• Normal width of AC joint in adults is 1-3mm
• By age 60 width is often less than 1mm
• Children and adolescents have a slightly wider joint space
• CC joint
• Normal distance is 11-13mm
• Comparison to opposite CC joint space is more important
• Increase in CC distance of 25-50% indicates complete CC ligament disruption
• Zanca view (AP w/ 10-15 degree cephalic tilt)
• Consider if AP view is ambiguous or injury is suspicious for type II AC injury or distal clavicle injury:
• Axillary view
• Obtain if coracoid tenderness is present to rule-out associated coracoid fx
• Helps to confirm ant-post position of clavicle in injury types III-IV

Classification

• Type 1 - AC ligament sprain; AC joint intact
• Exam
• Mild swelling, no deformity
• CC ligaments are nontender
• Only distal-most 1-2cm of clavicle is tender
• Active overhead and cross-body ROM are limited by pain
• Xray
• Often no abnormality is seen on xray; slight widening of the AC joint may occur
• Type 2 - AC ligament torn and subluxed; coracoclavicular (CC) ligament may be partially torn but is intact
• Exam
• Prominent and tender AC joint w/ significant swelling
• Minimal tenderness of CC ligaments reflecting lack of significant injury
• There may be instability of the distal clavicle in the horizontal plane
• Xray
• Partial elevation of the distal clavicle w/ no or minimal widening of the CC distance
• Type 3 - AC and CC ligaments torn; complete dislocation of the joint
• Exam
• Deformity of the AC joint is clearly visible
• Marked tenderness of the CC ligaments (helps distinguish Type 3 from type 2)
• Xray
• Elevated distal clavicle and increased CC distance
• Distal clavicle is positioned above the plane of the top of the acromion
• Type 4 - Complete dislocation with posterior displacement of distal clavicle into or through the trapezius
• Exam
• Palpable posterior fullness or deformity despite significant swelling
• SC dislocation may be appreciated
• Type 5 -
• Superior dislocation of the joint of 1-3x the normal spacing
• CC ligament distance is increased 2-3x normal
• Disruption of the deltotrapezial fascia
• Exam
• Shoulder appears to droop
• Severe superior displacement of the clavicle, which may cause tenting, ischemia of skin
• Clavicle is perhced above the muscle and does not reduce when the pt shrugs shoulder
• Xray
• Clavicle is elevated above acromion approximately 1-3x width of the clavicle
• CC distance is increased two to three times the normal range
• Type 6 - Complete dislocation with inf. displacement of distal clavicle into a subacromial or subcoracoid position
• Xray
• Complete disruption of the AC and CC ligaments

==Management==

• Type 1
• Rest, ice, protection with a sling
• ROM and strengthening exercises indicated as soon as tolerated
• Return to sport or work is limited only by pain
• Type 2
• Rest, ice, 3-7 days of immobilization in a sling
• ROM and strenghtnening exercises as soon as tolerated
• Return to sport or work once full ROM and strength are regained
• Type 3
• Rest ice, 2-3 weeks of immobilization in a sling
• ROM and strengthening exercises indicated as soon as tolerated
• Return to sport or work 6-12 weeks following injury
• Ortho consultation within 1 week
• Type 4-6
• Require orthopedic evaluation; emergent if neurovascular compromise exists

Source

UpToDate