Subacromial impingement syndrome

• 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

• Pattern 4E: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated With Localized Inflammation

Description

• 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 ...