Discussion:
- the hyperextension
phase of throwing may be the most important component of internal impingement;
- in the late cocking position (abduction, external rotation, extension) may cause the postero-superior edge of the glenoid labrum to become
caught between the humeral head and rotator cuff (surface of the infraspinatus and posterior fibers of supraspinatus tendon);
- posterior glenoid impacts the articular surface of the infraspinatus and posterior fibers of the supraspinatus tendon;
- w/
anterior instability, there will be anterior translation of the humeral head on the glenoid which accentuates impingement
of the rotator cuff against the posterosuperior glenoid rim;
- exam findings:
- tenderness over the coracoid has been attributed to a contracture of the pectoralis minor tendon secondary to scapular malposition.
- MRI findings: posterolateral humeral head edema, posterior labram fraying, partial rotator cuff tear;
- treatment:
- capsular stretching and dynamic strengthening of the rotator cuff musculature
- arthroscopic findings may reveal an isolated posterior cuff tear (or undersurface fraying) and fraying of the posterior labrum , and increased
anterior capsular volume;
- w/ posterior impingment and recurrent anterior instability, anterior reconstruction (either open reconstruction or
arthroscopic anterior reconstruction)
may be indicated;
- references:
-
Posterior shoulder pain in throwing athletes with a Bennett lesion: Factors that influence throwing pain,
-
The posterior impingement sign: Dx of rotator cuff and posterior labral tears secondary to internal impingement in overhand athletes.
Am J Orthop 2004;33:412-415.
- Posterior superior glenoid impingement: expanded spectrum. CM Jobe. Arthroscopy. Vol 11. 1995. p 530-536.
- Internal impingement: Findings on MRI and arthroscopic evaluation. Arthroscopy 2004;20:701-704.
- Arthroscopic findings in the overhand throwing athlete: Evidence for posterior internal impingement of the rotator cuff. Arthroscopy 2000;16:35-40
