Background
Scapular malposition and posterior shoulder tightness are key pathologic processes
in the shoulder of throwing athletes. The objective of this study was to investigate
the effects of posterior capsule tightness, posterior rotator cuff muscle tightness,
or both on scapular position.
Methods
Ten shoulders from 5 fresh frozen cadaveric male torsos were tested in maximum internal,
neutral, and maximum external shoulder rotations at 0°, 45°, and 90° of shoulder abduction.
Scapular rotation—namely, upward and downward rotation, internal and external rotation,
and anterior and posterior tilt—and the scapula-spine distance were measured by using
a MicroScribe digitizer (Revware, Raleigh, NC, USA). Each shoulder underwent 4 experimental
stages: intact; isolated posterior rotator cuff muscle (infraspinatus and teres minor)
tightness; both posterior rotator cuff muscle and capsule tightness; and isolated
posterior capsule tightness.
Results
Posterior muscle tightness significantly decreased upward rotation (P< .05) only in maximum shoulder internal rotation at 45° or 90° of shoulder abduction,
whereas posterior capsule tightness did not affect upward rotation (P= .09 to .96). Posterior capsule tightness significantly increased scapular internal
rotation (P< .01), but posterior muscle tightness did not change scapular internal rotation (P= .62 to .89). Posterior capsule tightness significantly increased both the superior
and inferior scapula-spine distance (ie, caused scapular protraction) in maximum shoulder
external rotation at 90° of abduction (P< .01).
Conclusion
Posterior shoulder tightness resulted in scapular malposition. However, the muscular
and capsular components of that tightness affected the scapular position differently.
For the treatment of scapula malposition, stretching of the posterior shoulder capsule
and muscles is recommended.
Level of evidence
Keywords
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Article Info
Publication History
Published online: August 13, 2019
Footnotes
The Research & Development Committee of VA Long Beach Health Care System approved this study.
Identification
Copyright
© 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.
