Acromioclavicular joint sprain

• Several ligaments surround this joint and, depending on the severity of the injury, one or all of the  ligaments may be torn. Severe sprains tear the acromioclavicular and coracoclavicular ligaments.
• The acromioclavicular joint is commonly injured when the clavicle is fractured.
• Patients have pain and tenderness at the acromioclavicular joint

Clinical assessment

• Point tenderness over the ACJ is very typical with either an ACJ sprain or osteoarthritis. 
• O’Brien test
  • sensitivity of 16–100%
  • specificity of 90–96.6% – highly suggestive of localised ACJ pathology, most often a sprain or osteoarthritis.
  • superficial pain localized to AC joint is suggestive of AC joint pathology     
  • deep pain is suggestive of a SLAP lesion

Investigations

 Xray: 

• soft tissue swelling/stranding
• widening of the acromioclavicular joint
  • normal: 5-8 mm (narrower in the elderly)
  • greater than 2-4 mm asymmetry (compared to radiographs of the contralateral side)
• increased coracoclavicular distance
  • normal: 10-13 mm
  • greater than 5 mm asymmetry (compared to the contralateral side)
• superior displacement of the distal clavicle
  • the inferior edge of the acromion should be level with the inferior edge of the clavicle

 Referral and management

Type	AC ligament	CC ligament	Exam	Radiographs	Reducibility	Treatment
Type I	Sprain	Normal	AC tendernessNo AC instability	Normal	Reducible	Sling
Type II	Torn	Sprain	AC horizontal instability	AC joint disruptedIncreased CC distance < 25% of contralateral	Reducible	Sling
Type III	Torn	Torn		AC joint disruptedIncreased CC distance 25-100% of contralateral	Reducible	Controversial
Type IV	Torn	Torn	Skin tentingPosterior fullness	Lateral clavicle displaced posterior through trapezius on the axillary lateral XR	Not reducible	Surgery
Type V	Torn	Torn	Severe shoulder droop, does not improve with shrug	Increased CC distance > 100% of contralateral	Not reducible	Surgery
Type VI	Torn	Torn	Rare; Associated injuries; paresthesias	Inferior dislocation of lateral clavicle, lying either in subacromial or subcoracoid position	Not reducible	Surgery

• brief sling immobilization, rest, ice, physical therapy for type I and II
  • good results when clavicle displaced < 2cm
  • rehab
    • early shoulder range of motion
    • regain functional motion by 6 weeks
    • return to normal activity at 12 weeks
  • consider corticosteroid injections Supportive shoulder strapping provides ACJ stability, reduces pain and is easy to corticosteroid injected into the ACJ using an aseptic technique