For those of you who work with baseball players...
When assessing glenohumeral range of motion, are the TOTAL ranges of motion (combined IR + ER) equal? If so, and there is still a perceived increase in external rotation of the affected arm…
e.g. if the left GH joint = 110 ER + 60 IR (170 total) and the right GH joint = 90 ER + 80 IR (also 170 total)...
Then your athlete may have developed the often forgotten entity called “Humeral Retroversion”.
The reason, I’m writing this is because one of the more popular concepts in sports medicine and performance, and especially in baseball, has been to focus on posterior capsule and cuff.
This is fine but what if the posterior capsule isn’t "tight?" What if there ISN’T internal impingement? And what if the anterior structures AREN’T lax? Then maybe the athlete has actually experienced a developmental remodeling of the bone that has “twisted” the humeral shaft?
It is not uncommon for little league baseball players to develop a way to:
And if this is the case, this may actually be beneficial to the athlete. So as long as you have fully assessed your athlete, have ruled out any significant risk of injury, and have confirmed the presence of humeral retroversion (you may need to do so by CT scan but there are other ways as described above), then you can rest assured that one of the only problems he’ll have in the future is an inability to scratch his own back.
Often, there really is no reason to increase one's IR if they have sufficient functional ROM!
Humeral Retroversion is a result of the stress induced remodeling of bone in the proximal epiphysis during adolescence.