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  • Shoulder impingement
  • Impingement syndrome shoulder
  • Subacromial compression


  • 726.19 Other specified disorders of bursae and tendons in shoulder region


  • M75.80 Other shoulder lesions, unspecified shoulder




  • Shoulder pain and dysfunction due to compression and abrasion of one or more of the rotator cuff tendons, the long head of the bicep tendon, and/or the subacromial bursa beneath the coracoacromial arch due to an abnormal mechanical relationship
  • The coracoacromial arch consists of the undersurface of the acromion, coracoacromial ligament as well as the undersurface of the acromioclavicular (AC) joint.
  • Impingement is the most commonly diagnosed shoulder problem and likely has numerous potential mechanisms, which can impact both treatment and prognosis.


Essentials of Diagnosis


  • Multifactorial and thought to be related to intrinsic and/or extrinsic mechanisms
    • Extrinsic mechanisms (extratendinous, cause decreased sub-acromial space and subsequent micro-trauma with repetitive movements)
      • Mechanical wear under the coracoacromial arch
      • Aberrant movement patterns due to rotator cuff and or periscapular muscular dysfunction
      • Capsular abnormalities
        • Capsular tightness (particularly posterior capsule)
        • Capsular laxity (poor humeral head dynamic control)
      • Sub-optimal posture
        • Muscle imbalances
      • Overuse/repetitive motions occurring above 90 degrees of elevation
    • Intrinsic factors (directly associated with the narrowing of the sub-acromial space)
      • Vascular supply/changes to the cuff tendons
      • Acromial morphology (structural variations).
        • Type I (flat)
        • Type II (curved)
        • Type III hooked)
      • Degenerative and/or structural changes to the AC joint
      • Other trophic changes in the coracoacromial arch or humeral head
  • Classification
    • Primary impingement is usually associated with degenerative changes to any of the following tissues:
      • Rotator cuff tendons
      • AC joint
      • Coracoacromial arch
    • Secondary Impingement is the result of muscle imbalances and/or joint instability, which can result in altered dynamics and subsequent secondary impingement.
    • Neer stages
      • Stage I: Edema and hemorrhage of the subacromial bursa; patient is generally <25 years of age
      • Stage II: Histologic changes of tendinosis to the effected tendons; patient usually between 25 to 40 years of age
      • Stage III: Partial or complete rupture of the cuff and or bicep tendons and potential associated changed to the acromion and AC joint; patient usually >40 years of age.
    • Third class of impingement, not subacromial in nature: internal impingement
      • Occurs between the undersurface (articular side) of the rotator cuff tendons and the posterior/superior surface of the labrum in the position of abduction and external rotation that occurs with throwing.
    • Regardless of classification, all types of impingement are proposed to be mechanisms of rotator cuff and biceps tendinopathy
    • Treatment varies based on impingement type, contributing factors, and associated tissue quality.
    • Diagnosis is usually made by clinical examination and often accompanies 3 or more special tests2
      • Neer’s impingement test
      • Hawkins-Kennedy impingement sign/test
      • Passive horizontal adduction test
      • Pain with resisted abduction
      • Painful arc sign/test
      • Pain in the C5-C6 dermatome region
      • Infraspinatus muscle test1
      • Diagnostic test properties for subacromial impingement

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