Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android


  • Separated shoulder

  • AC separation

  • AC dislocation

  • Shoulder separation


  • 840.0 Acromioclavicular (joint, ligament) sprain


  • S43.50XA Sprain of unspecified acromioclavicular joint, initial encounter


  • 4E: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated with Localized Inflammation1


A 42-year-old man presents with right shoulder pain due to a fall he sustained on his outstretched arm while walking his dog one week ago. The patient complains of an ache in the top, anterior aspect of the right shoulder and reports that he cannot lift his arm to wash his hair or complete other overhead activities without a significant increase in pain. Upon palpation, the patient reports pain and tenderness in the acromioclavicular joint, most notably along the acromioclavicular ligament. A step deformity of 5 mm is present with elevation of the clavicle. The Full Can/Empty Can, Neer, and Yergason tests are negative. The Acromioclavicular Resisted Extension Test is positive.



  • Inflammation, irritation, or separation of the joint between the clavicle and acromion (AC joint)2

  • Three ligaments of stability:

    • Acromioclavicular ligament2

    • Coracoacromial ligament

    • Coracoclavicular ligament: Made up of the Conoid ligament and trapezoid ligament2

Essentials of Diagnosis

  • Patient history and clinical examination

  • X-ray

  • Occurs most often from falling on an outstretched arm or hand

  • Occurs when the ligaments are completely torn and there is a dislocation of the joint

  • Look for separation of the clavicle and acromion

  • Step deformity often noticed when the clavicle is raised due to ligament tearing

  • Six grades of sprain to separation: Rockwood Scale

    • Grade I

      • Slight displacement of the joint

      • Partially torn AC ligament

      • Separation <4 mm

    • Grade II

      • Partial dislocation of the joint

      • Complete disruption tear of the AC ligament

      • Partial disruption of the coracoclavicular ligament

      • Separation >5 mm

    • Grade III

      • Partial dislocation of the joint

      • Complete disruption tear of the AC ligament

      • Complete disruption/rupture of the coracoclavicular ligament

    • Grade IV

      • Dislocation of the joint

      • Posterior displacement

      • Requires surgery

    • Grade V

      • Dislocation of the joint

      • Superior displacement

      • Requires surgery

    • Grade VI

      • Dislocation of the joint

      • Inferior displacement

      • Requires surgery

FIGURE 150-1

Palpation of the supraspinatus fossa. (From Lawry GV. Systematic Musculoskeletal Examinations. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.)

General Considerations

  • No synovial joint

  • Osteoarthritis is common without treatment or with prolonged instability


  • Predominately in individuals with a history of activities involving overhead reach: Swimming, tennis, and baseball as well as with occupational activities involving repetitive overhead activity


Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.