Acromioclavicular joint injury

Background

Usually occurs from direct trauma to the adducted shoulder

Diagnosis

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

Imaging

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

Classification

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

Treatment

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

Source

UpToDate