It is no secret that proper scapula alignment and muscle activation makes for a healthy shoulder.  There are many forms of dysfunction that may be present.

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Generally speaking problems revolve around muscular tightness/weakness and faulty movement patterns.  The term “SICK” scapula is often used and refers to Scapula Inferior Coracoid Dyskinesis.  Common examples of a “sick”  scapula include:

  • Type I – Inferior border prominence.  This is typically related to tightness in the pec minor and weakness in the lower trapezius.  Keep in mind the upper trapezius will naturally dominate the lower trap in the force couple with the serratus anterior for upward rotation.  You may also see increased thoracic kyphosis which will inhibit the normal resting position of the scapula.
  • Type II – Medial border prominence.  In this case the scapula is internally rotated or protracted and there is liekly weakness present in the rhomboids and middle trapezius.  The serratus anterior may also likely be weak with evidence of scapular winging.  This position places the humerus in relative internal rotation and increases risk of impingement with arm elevation.
  • Type III – Superior border presence.  Here the scapula appears elevated in the face of an overactive upper trap and/or levator scapulae.  With active arm elevation, you may notice excessive shrugging or superior humeral head migration in light of the imbalance.  Again, the lower trapezius is probably weak and being overpowered.

Click here for a great graphic display from the Journal of the American Academy of Orthopaedic Surgeons of how the scapular muscles work collectively as a force couple to promote optimal movement in the shoulder.

In many of the throwers and overhead athletes I see in the clinic, they often exhibit either medial border prominence of inferior border prominence.   Additionally, I frequently observe GIRD (glenohumeral internal rotation deficit) values of 20 degrees or higher in those patients who come in with symptomatic shoulders (rotator cuff and/or labral issues).  What does this mean?

Well, in a nutshell, it means addressing posterior capsule tightness in the throwing shoulder is important for avoiding internal impingement and SLAP tears.  Tightness (or too much GIRD) can increase the load/tension in the late cocking phase of throwing thereby contributing to friction between the cuff and labrum, as well as excessive torsion on the proximal biceps tendon.  Any excessive humeral head migration with repetitive throwing is a recipe for injury over time.


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