Acromioclavicular joint injury

Background

• Occurs via direct trauma to the adducted shoulder
• Acromioclavicular and coracoclavicular ligaments may be affected
• Routine use of stress radiographs is controversial (low yield)

Diagnosis

1. Tenderness directly over AC joint (w/ possible deformity)
2. AC compression test
   1. Passively flex arm so it's parallel with ground; then passively adduct across body
      1. 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
         1. 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, concern for type II 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
   1. AC ligament sprain; AC joint intact
   2. 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
   3. X-ray
      1. Often no abnormality is seen on xray; slight widening of the AC joint may occur
2. Type 2
   1. AC ligament torn; coracoclavicular (CC) ligament may be partially torn but is intact
   2. Exam
      1. Prominent and tender AC joint w/ significant swelling
      2. Minimal tenderness of CC ligaments reflecting lack of significant injury
      3. May be instability of the distal clavicle in the horizontal plane
   3. X-ray
      1. Partial elevation of the distal clavicle w/ no or minimal widening of CC distance
3. Type 3
   1. AC and CC ligaments torn; complete dislocation of the joint
   2. Exam
      1. Deformity of the AC joint is clearly visible
      2. Marked tenderness of CC ligaments (helps distinguish Type 3 from type 2)
   3. X-ray
      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
   1. Complete dislocation w/ posterior displacement of distal clavicle in/through trapezius
   2. Exam
      1. Palpable posterior fullness or deformity despite significant swelling
      2. SC dislocation may be appreciated
   3. X-ray
      1. Axillary view required to visualize the posterior dislocation
5. Type 5
   1. More severe form of type III injury
   2. Superior dislocation of the joint of 1-3x the normal spacing
   3. CC ligament distance is increased 2-3x normal
   4. Disruption of the deltotrapezial fascia
   5. Exam
      1. Shoulder appears to droop
      2. Severe superior displacement of clavicle (may cause tenting, ischemia of skin)
      3. Clavicle is perhced above the muscle and does not reduce when pt shrugs shoulder
   6. X-ray
      1. Clavicle is elevated above acromion approximately 1-3x width of the clavicle
      2. CC distance is increased 2-3x normal range
6. Type 6
   1. Complete dislocation w/ clavicle displaced inferiorly
   2. X-ray
      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

See Also

Shoulder (Acute - Trauma)

Source

UpToDate