Scapular Dyskinesia

Original Editor - Jon DeVaul, PT, DPT

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Clinically Relevant Anatomy

Typical movement of the scapula occurs in the sagital, coronal, and transverse planes. The primary movements consist of two translations: superior/inferior, and protraction/ retraction, as well as three rotations: upward/downward, internal/external, and anterior/posterior. Upward rotation is primary and posterior tilt secondary during normal overhead UE elevation with internal/external rotation being minimal until 100°. (43 Ludewig,49 McClure JOSPT)

Review of the normal ratio of glenohumeral (GH) to scapulothoracic (ST) motion analyzed by Doody et al (16) under three-dimensional analysis found that the ratio of GH to ST motion changes from 7.3: 1 in the first 30° of elevation to 0.78: 1 between 90 and 150°. Bagg and Forrest found a ratio of 4.4:1 during early phase, and 1.7:1 within 80 to 140° of shoulder elevation. (book(8)

Clinical Presentation

Kibler classification of scapular dysfunction. (Book 25)

1. Type I or Inferior dysfunction.  The primary external visual feature is the prominence of the inferior angle as a result of anterior tilting of the scapula in the sagital plane. Inferior pattern presentation is better visualized while in the hands-on-hips position or during eccentric lowering from overhead elevation, scaption, or abduction. According to Kibler, Type 1 pattern is most commonly found in patients with rotator cuff dysfunction.
   
2. Type 2 or Medial dysfunction.  The primary external visual feature is the prominence of the entire medial scapular border due to internal rotation of the scapula in the transverse plane. As with Type 1, the Type 2 presentation becomes more evident in the hands-on-hips position and during active eccentric lowering from overhead. Medial pattern dysfunction most often occurs in patients with glenohumeral joint instability.
   
3. Type 3 or Superior dysfunction.  Characterized by excessive and early elevation of the scapula during UE elevation. This pattern has been referred to as compensatory shoulder hiking or shrug and is most often seen in patients with rotator cuff dysfunction and deltoid-rotator cuff force couple imbalances. (Book 5 Inman)
   

Diagnostic Procedures

Current tests and measures, while proven to be reliable, have not altogether shown strong validity by demonstrating correlation with biomechanical motion, symptoms, pathology, or outcomes. (34 Kuhn JOSPT) Recommendations for appropriate clinical measures include:

• Clinical observation of scapular dyskinesis.
  

             Kibler classification of dysfunction Type 1, 2, or 3.  It is recommended that several repeated bouts of arm elevation be observed to assess the affects of fatigue on scapular stabilization.

• Symptom altering tests.

             Scapular reposition test. (66 JOSPT)  Baseline AROM and pain is evaluated.  This test is positive if pain is reduced as the therapist assists active elevation by applying a posterior tilt and external rotation motion to the scapula. This application may be used in conjunction with other tests such as Neer's, Hawkin's-Kennedy, and Jobe's relocation. Level of evidence: 4.

             Scapular assistance test. (59 JOSPT)  Baseline AROM and pain is evaluated.  The therapist then applies an assist to scapular dynamics.  This test is positive if ROM is increased or pain is reduced as the therapist manually assists scapular upward rotation during active UE elevation.  

• Manual muscle testing.
  

              MMT for the middle and lower trapezius, and serratus anterior.

• Pectoralis minor muscle tightness.
  

              Current measures examine mm length at resting positions, not at maximal length.  Unfortunately, there are no validated clinical measures to identify a patient as having a tight pectoralis minor muscle.   

Outcome Measures

http://www.dash.iwh.on.ca/assets/images/pdfs/quickdash_q06.pdf

Management / Interventions

Intervention is aimed at reducing posterior capsule(46) and pectoralis minor restriction(53) and restoring periscapular mm balance through exercises promoting early and increased serratus anterior, lower, and middle trapezius activation while minimizing upper trapezius activity(41). 

•      Manual gr 4 mobilization to reduce posterior capsule tension, cross-body stretch (46).
  
•      Manual stretching and soft tissue mobilization to decrease pec minor tension (cadaveric studies imply that a position of 150 degrees elevation with 30 degrees scapular retraction is optimal). (53)
  
•      Exercises of sidelying forward flexion, external rotation, prone extension, and prone horizontal abduction to strengthen middle and lower trapezius over upper trapezius. (17)(19)
  
•      Quadruped and variable push-up positions to activate serratus anterior (41).

Key Evidence

Unfortunately, scapular dyskinesia is a condition with minimal level 1 evidence for support of either diagnosis or treatment.  Support for above mentioned tests and interventions appears below.

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