Dr. Ebraheim's animated educational video describing internal impingement of the shoulder.
Internal impingement is a pathology on the undersurface of the rotator cuff (joint side). Internal impingement is a PASTA lesion plus a SLAP tear.
PASTA lesion (Partial Articular surface Supraspinatus Tendon Avulsion. SLAP tear is a tear at the top of the glenoid labrum
Subacromial impingement is a pathology underneath the acromion (bursal side).
Internal impingement may involve:
•Scarring and tightness of the posterior capsule.
oPatient will have diffuse pain on the posterior aspect of the shoulder.
oCan lead to a glenohumeral internal rotation deficit (GIRD)
Internal impingement is mainly seen in overhead throwing athletes. A thrower with shoulder pain should be evaluated for internal impingement. Internal impingement usually occurs during the late cocking and early acceleration phase of throwing.
The greater tuberosity of the the humerus abuts against the posterosuperior glenoid, which entraps the rotator cuff between the glenoid and the humeral head.
Stages involved in throwing:
•Wind up
•Early cocking
•Acceleration
•Follow-through
Presentation:
The posterior undersurface of the supraspinatus tendon impinges on the posterosuperior glenoid labrum. This occurs during maximum abduction and eternal rotation of the shoulder with late cocking and early acceleration of throwing. Shoulder pain is worse with throwing. Loss of more than 25 degrees of internal rotation at 90 degrees compared to the other side. The loss of internal rotation is due to posterior capsular contracture. The external rotation increases which may lead to anterior capsule and glenohumeral ligament stretching and thinning. The center of rotation of the humeral head shifts posteriorly and superiorly which leads to impingement of the labrum and the rotator cuff as the arm is abducted and externally rotated.
Glenohumeral Internal Rotation Deficit (GIRD). GIRD usually occurs in the throwing shoulder. The loss of internal rotation is measured in degrees and the scapula must be stabilized during measurements.
Imaging
Bennett Lesion
•Equal to mineralization or exostosis of the posterior inferior glenoid.
•May be found on the AP view or axillary view due to hypertrophy, scarring and traction of the capsule.
MRI Arthrogram of the shoulder (Pasta + Slap)
•Will show rotator cuff partial articular pathology (PASTA lesion) and labral pathology (posterosuperior labrum involvement).
Treatment
•Nonoperative
oAvoid aggravating activity
oPhysical therapy for up to 6 months and posterior capsular stretching with sleeper stretches
oDo therapy to strengthen the rotator cuff
oMajority of patients will improve with nonoperative treatment
•Operative
oWhen nonoperative treatment fails
oArthroscopic debridement or repair of the labrum plus debridement of the undersurface of the rotator cuff lesions. Repair the cuff if tear is greater than 50%
oPosterior capsular release in patient with GIRD if conservative treatment fails.
What is sleeper stretch?
Sleeper stretch is a posterior capsular stretch performed with internal rotation stretch exercise at 90 degrees abduction with scapular stabilization.
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