Internal Impingement

Topic updated on 01/25/16 2:10pm
  • Internal impingement refers to pathology on undersurface of rotator cuff 
    • in contrast to subacromial or "external" impingement which occurs on bursal side of rotator cuff) 
    • internal impingement covers a spectrum of injuries including
      • fraying of posterior rotator cuff
      • posterior and superior labral lesions
      • hypertrophy and scarring of posterior capsule glenoid (Bennett lesion)
      • cartilage damage at posterior glenoid
  • Epidemiology
    • major cause of shoulder pain in throwing athletes
  • Pathoanatomy
    • caused by impingement of posterior under-surface of supraspinatus tendon on greater tuberosity insertion on the posterosuperior glenoid rim 
      • impingement occurs during maximum arm abduction and external rotation during late cocking and early acceleration phases of throwing  
      • causes"peel-back" phenomenon of posterosuperior labrum
    • thought to be due to combination of
      • tightness of posterior band of IGHL 
      • anterior micro instability
  • Associated conditions
    • associated with GIRD 
  • Glenohumeral joint anatomy 
  • Glenohumeral stability
    • static restraints
      • glenohumeral ligaments
      • glenoid labrum 
      • articular congruity and version
      • negative intraarticular pressure
    • dynamic restraints
      • rotator cuff muscles
      • biceps
      • periscapular muscles
  • Glenohumeral ligaments
    • Superior GHL  
      • restraint to inferior translation at 0° degrees of abduction (neutral rotation) 
    • Middle GHL  
      • resist anterior and posterior translation in the midrange of abduction (~45°) in ER 
    • Inferior GHL  
      • posterior band
        • most important restraint to posterior subluxation at 90° flexion and IR
      • anterior band
        • primary restraint to anterior/inferior translation 90° abduction and maximum ER (late cocking phase of throwing) 
      • superior band
        • most important static stabilizer about the joint
  • Symptoms
    • diffuse pain in posterior shoulder along the posterior deltoid
      • shoulder pain worse with throwing
        • especially during late cocking and early acceleration
  • Physical exam
    • increased external rotation
    • decreased internal rotation 
      • loss of > 20° of IR at 90°
        • must stabilize the scapula to get true measure of glenohumeral rotation
    • often can demonstrate rotator cuff weakness
  • Radiographs
    • recommended views
      • complete shoulder series
    • findings
      • usually unremarkable
      • AP may show a Bennett lesion (glenoid exostosis) 
  • MRI
    • can show associated rotator cuff and/or labral pathology
      • such as partial articular sided supraspinatus tendon avulsion (PASTA) or tear 
      • signal at greater tuberosity and/or posterosuperior labrum 
  • Nonoperative
    • posterior capsule stretching PT for 6 months
      • indications
        • most internal impingement can be treated non-operatively
      • technique 
        • posterior capsule stretching with sleeper stretches
        • rotator cuff stretching and strengthening
  • Operative
    • arthroscopic debridement and/or repair of rotator cuff tear and labrum 
      • indications
        • failed nonoperative treatment
        • partial thickness rotator cuff tear (PASTA) compromises the integrity of the rotator cuff
          • partial rotator cuff tears >50%  
        • Bennett lesions
    • posterior capsule release vs anterior stabilization
      • indications
        • failed nonoperative treatment
        • shoulder instability
      • technique 
        • surgical techniques are controversial
          • some perform a posterior capsule release
          • some perform anterior stabilization
      • complications
        • inferior suprascapular nerve (infraspinatus) is at greatest risk during posterior capsule release


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Qbank (6 Questions)

(OBQ11.140) Internal impingement commonly occurs in overhead athletes and is very common amongst elite baseball pitchers. In which phase of throwing does this pathologic process occur? Topic Review Topic

1. Wind-up
2. Early cocking
3. Late cocking
4. Deceleration
5. Follow-through

(OBQ10.174) A 19-year-old left-hand dominant collegiate baseball pitcher has left shoulder pain with late cocking and early acceleration of the ball. His velocity has decreased over the past 2 months. Rotator cuff strength is normal, he denies symptoms of instability, and Hawkins impingement testing is unremarkable. MRI with contrast reveals no intra-articular lesions. What is the most likely physical exam finding in this patient? Topic Review Topic

1. Positive sulcus sign
2. Decreased external rotation of the affected shoulder
3. Positive Speed's test
4. Decreased abduction of the affected shoulder
5. Decreased internal rotation of the affected shoulder

(OBQ09.142) Mineralization of the posterior-inferior glenoid has been implicated as a possible source of pain in which athletic population? Topic Review Topic

1. football players
2. swimmers
3. basketball players
4. rowers
5. baseball pitchers

(OBQ08.4) The term internal impingement is used in throwers to describe a condition where the posterior-superior glenoid labrum impinges on which structure? Topic Review Topic

1. The anterior rotator cuff
2. The posterior rotator cuff
3. The anterior glenohumeral ligaments
4. The posterior glenohumeral ligaments
5. The biceps tendon

(OBQ07.38) A baseball pitcher has aching pain in the posterior shoulder after throwing. On exam, he has a 30 degree internal rotation deficit and is diagnosed with internal impingement. Stretching should focus on which aspect of the joint capsule? Topic Review Topic

1. Superior
2. Anterior
3. Antero-inferior
4. Inferior
5. Postero-inferior

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