Shoulder GIRD: Mechanical Imbalance from Internal Rotation Loss

  • March 17, 2022
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  • Shoulder
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  • Dr. J. Winslow Alford

Over the years of helping people recover from shoulder surgery and injuries, I’ve noticed an under emphasis on regaining symmetric internal rotation of the shoulder joint, which is key to achieving healthy balanced shoulder mechanics. On a very basic level, this is measured by our ability to raise our thumb behind our back up to our shoulder blade (scapula).

Most of what we do with our shoulders places our hand in front of us where we can see our hand. Unless we have an itch, need to attach a bra strap, or get handcuffed, we humans don’t put our hand up behind our backs very often. Normal shoulder internal rotation should allow us to touch the middle of our shoulder blades. If we cannot lift our injured arm above our belt line, the ball (humeral head) of the ball and socket joint rides off center in the socket (glenoid).

Glenohumeral internal rotation deficit of the right shoulder (GIRD)

This imbalance causes a dynamic imbalance of the rotator cuff function, leading to inflammation of the rotator cuff tendons, bicep-labral complex, and capsule. This imbalance, like a “shimmy” on a wheel, can perpetuate the inflammation which caused the tight painful joint, and can also cause structural damage to the lining of the shoulder joint (labrum) and to our shoulder tendons. To maintain the ability to achieve normal thumb height posteriorly, we need to stretch our shoulder capsule by gently forcing our shoulders to raise our thumb into that position in the middle of our back. This is tough love: a balance of pushing and recovery.

Normal rotator cuff function depends on balanced strength, neuromuscular dynamic control, and balanced joint tension of the glenohumeral joint. Asymmetry will push the humeral head off its ideal axis of rotation and place the rotator cuff tendons at a mechanical disadvantage, even in the midrange, as they try to apply a dynamically balanced, force-coupled control of the humeral head position. In throwing athletes, particularly baseball pitchers, internal rotation loss can lead to poor compensatory scapular mechanics (dyskinesis), which can further perpetuate the problem (1).

Whether we are recovering from a minor strain, a major shoulder injury or surgery, it’s important to work to regain this “thumb height” posteriorly. When our thumbs reach to an equal level, the injured shoulder is achieving symmetric balanced mechanics equivalent to our uninjured shoulder. Regaining this flexibility does not happen overnight and cannot be done for you; you must do it yourself. It takes personal ownership of a methodical stretching regimen to regain lost internal rotation. Like anything, the simpler a routine is, the more likely you are to stick with it.

One easy method of regaining internal rotation is to spend one minute, every day without fail, stretching your thumb up behind your back with a non-elastic strap. This could be your daily use of a bath towel or dog leash. Think of it part of daily maintenance like brushing your teeth – towel stretch at least once a day, without fail, for a full minute.

Drop your towel behind your back and hold on with the recovering hand. With your good arm, gently lift the hand of your injured arm into a position that feels tight but not excruciating.  Hold this for 1 minute (a quick count to 10 will not help). If you do this every day for a month or so, what was difficult initially will become easier. Although initially sore from this hard work, your shoulder will regain more normal balanced mechanics and feel much better. You’ll get out of this what you put into it - keep it simple and routine.

Towel Stretch part 1: Hold the towel with a firm grip but relax your injured/recovering shoulder. In this photo, the right shoulder will receive the stretching treatment.

Towel Stretch, part 2: Use your good arm to gently lift your recovering arm into a tight but not excruciating position. The goal is to be equal to the uninvolved shoulder. Usually the mid-scapular area. Hold for 1 full minute. Repeat at least once but optimally, twice a day.

Improved glenohumeral mechanics, with almost equal thumb heights posteriorly.


1. Stephen S Burkhart, Craig D Morgan, W Ben Kibler. The disabled throwing shoulder: spectrum of pathology Part I: pathoanatomy and biomechanics, Arthroscopy 2003 Apr;19(4):404-20.

Photos: (courtesy of SD Allen Photography Studios)

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  • physical therapy
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