Tuesday, May 11, 2010

Robbing Peter to pay Paul

The Effect of Posterosuperior Rotator Cuff Tears and Biceps Loading on Glenohumeral Translation- Su, Budoff et al/ Arthroscopy May '10.

The long biceps tendon is one of the shoulder's backup systems to control GH instability. Tendinitis is usually a warning that the tendon is becoming a primary stabilizer.

A pretty simple study; they cut fibers of the subscapularis, supraspinatus, and infraspinatus to different degrees and combinations. Then mesured the amount of anterior/superior translation of the humeral head in the glenoid with and without biceps loading. The long head biceps tendon reduced humeral head translation up to 53%!.

Relocating the tendon from the scapula to the humerus is often a surgical treatment that increases shoulder instability; which is a precoursor to rotator cuff tendinitis.


JH said...


I wonder what they would find by changing the angle of the humerus in flexion or abduction? When we have our athletes perform any type of biceps strengthening we have them do it with arms at or above shoudler height for the very reason of shoulder stability.

Joe Przytula said...

Good point- the arm motion studied was uniplanar/directional. May well have been greater translation once you start tossing more stuff into the picture.