Deficits in the shoulder’s ability to rotate both internally and externally occur in patients with shoulder pain all of the time. Today we will be talking about internal rotation deficits. This is clinically referred to as “GIRD” (Glenohumeral Internal Rotational Deficit).
The following photos illustrate how GIRD presents. Note that with the patient’s attempt to bring the hand down to the floor, either the hand stops well before the normal range (pic #1), or the shoulder picks up off the floor to compensate for the movement of the hand (pic#2).
This phenomenon is seen frequently in overhead throwing athletes such as baseball pitchers and volleyball servers (which is a different topic of discussion).
Why does this happen to normal folks like us?
One plausible theory has to do with how the head of the humerus (the ball) fits into the glenoid fossa (the socket) of the shoulder joint. The unfortunate truth is that with most of us, the ball portion of the shoulder rests a bit too forward in the socket.
This may occur because of what we spend most of our time doing, namely sitting at a desk and reaching forward to operate a mouse pad or a keyboard. This forward reaching movement can draw the head of the humerus forward, and over time the body accommodates to this position to make us more efficient.
The muscles, ligaments, and capsule of the shoulder can become stiff posteriorly because the shoulder never rests back into the socket. We will also often see a more lax anterior portion of the shoulder because the humerus bone is resting in a forward position and stretching against the anterior structures.
Stay with me here.
In order for the shoulder to rotate inward, it needs to be able to glide back into the socket. If the head of the humerus is always sitting forward, the backwards glide is stiff.
How do we deal with this?
We need to slowly “un-stiffen” the back portion of the shoulder and encourage normal mechanical motion of the humerus. There are many manual things that can be done to encourage the posterior glide of the humerus such as massage to the posterior muscles of the shoulder and capsular stretching. A physical therapist can show you how these are done in a single visit. There are also exercises that you can start doing to encourage the correct gliding.
The following exercise is a good starting point in addressing GIRD. Pay particular attention to the towel placements in the video. They are incredibly important because they serve to block the head of the humerus from lurching forward.
It is also a good idea to strengthen other muscles that support the shoulder and the shoulder blade if they are weak. Once again, a quick assessment done by a professional can point you in the right direction.
If you have struggled with shoulder pain and notice that your shoulder will not rotate internally as in the photos, it is entirely possible that this deficit in rotation may be contributing to your problem.
Image credits: Top photo © WavebreakmediaMicro/Fotolia