Bony Adaptation of the Shoulder in Baseball Pitchers

It is well known that the glenohumeral joint (shoulder joint) goes through changes in throwing shoulder of baseball pitchers. A change in its range of motion (ROM), know as glenohumeral internal rotation deficit (GIRD), is very common in baseball pitchers. GIRD is when pitchers lose internal rotation (IR) motion and gain external rotation (ER) motion and a total arch of motion (IR + ER) is considerably less than that of the non-throwing shoulder. According to a study, a loss of more than 5 degrees of total ROM increases a risk of shoulder injury in baseball pitchers. This change in ROM may be due to soft tissue adaptation or/and bony adaptation that shoulder goes through after repetitive stress placed on the joint. Known bony adaptations are humeral head retroversion where humeral head (the ball part of ball and socket shoulder joint, a part of upper arm bone), after repetitive torsional force from pitching, turns backwards compared to the other shoulder and glenoid retroversion where glenoid fossa (socket part of the shoulder joint, a part of scapula) shifts backwards. In most shoulders, the glenohumeral joint is aligned about 30 degrees anteriorly instead of facing straight to the side. However, in the throwing shoulders of baseball pitchers that have gone through this adaptation, the alignment of the joint is slightly shifted backwards. Importance of these adaptations, which likely happens before bones complete its growing process (physis closure), is that it may be a protective mechanism of the shoulder against repetitive stress and possible injury such as SLAP tear according to several studies. 

       Will baseball pitchers whose shoulder has gone through this bony adaptation be at less risk of SLAP tear in the future?! Is it better to start pitching when they are younger that later to prevent SLAP tear?! There are many more questions to be answered.