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Shoulder Special Test: Infraspinatus and Internal Rotation Resistance Strength Test (IRRST) Tests

The Infraspinatus and Internal Rotation Resistance Strength Test (IRRST) Tests are a series of tests used to evaluate the strength of the shoulder abductors and internal rotators, specifically the infraspinatus and other rotator cuff muscles.The tests involve the patient actively performing shoulder abduction against resistance from the clinician or an external force. The ability of the patient to resist external rotation of the shoulder is also assessed in different variations of the test.

Transcript

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This is Brent of the Brookbush Institute, and in
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...blank
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this video we're going to go over two special,
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or orthopedic tests for the shoulder
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that are indicative of either
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impingement or rotator cuff damage. I'm
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going to have my friend, Melissa, come out.
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She's going to help me demonstrate these
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tests. The reason we've paired these
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tests is I think you're going to find
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they look very similar to the Kendall
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manual muscle tests we've gone over in
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previous videos. The first one is
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actually called the Internal Rotation
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Resisted Strength Test. I'm going to have
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Melissa go ahead and bring her shoulder
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into 90 degrees, her elbow in 90
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degrees of flexion, and her wrist is
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going to be in neutral. I'm going to
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brace her elbow a little bit here. I'm
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going to go ahead and put my hand behind
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her hand and have her press back into my
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hand to externally rotate the shoulder.
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I'm not going to try to overpower her. I'm
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just going to match her strength. Press
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as hard as you can, Come on, come on.
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Alight, you don't have to actually egg
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people on, but you do want to take mental
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note of how strong she is in external
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rotation. Now, I'm going to do the same in
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internal rotation. Alright, go ahead and
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press into my hand. Good. Good. And what I
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want to note is: Are they about equal? If
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internal rotation is weaker than
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external rotation, that is indicative of
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either a rotator cuff problem or
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impingement. Of course, the other sign
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that we always go back to is- go ahead
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and press in- "Does this replicate the
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symptoms you were talking about?" Always
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remember to ask that question. So,
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pain and/or weakness in internal
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rotation when compared to external
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rotation is a positive result for that
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test. Now, the other test we're going to
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do looks exactly like the manual muscle
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test for external rotation. I'm going to go ahead and
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brace her elbow hit a little bit here. I
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want to make sure I show her what I'm
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doing, what we want her to do. So, "Go ahead
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and turn your hand out this way." Because
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what you'll find is if you guys go, "Just
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press out," people tend to do that old
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school like deltoid machine thing. We
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want to test external
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rotation here. So, "Go ahead and externally
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rotate. Does that hurt? Does that provoke
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the symptoms you're talking about?"
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So, if it's pain or if I know some
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real significant weakness she may be- "Go
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ahead press out"- if she just gives way under
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a little bit of pressure, that's a
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positive sign for this test. Alright,
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guys, so, we have two tests here. We have
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the Internal Rotation Resisted Strength
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Test, and then we have the Infraspinatus,
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or External Rotation Resistance Test.
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Both of these tests can be used for
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either rotator cuffs or impingement. We
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do have to keep in mind that these
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probably should be used within testing
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clusters, because what I'm about to tell
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you is going to be a little confusing.
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These tests actually have higher
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specificity than some of the other tests
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we've already talked about, like the Neer,
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or the Hawkins Kennedy, or the Yocum, or
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even the Supine Impingement Test.
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These tests tend to be more specific
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than sensitive, which makes absolutely no
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sense to me. We have tests that-
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obviously, if they're testing for
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impingement, why are we rotating and
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testing the strength of our rotator cuff?
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So, this is already bringing in more
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diagnosis, making it a more specific test.
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Ah, fun with research. Guys, if you weren't
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confused about specificity and
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sensitivity before, you probably are now.
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That's okay, because sometimes it
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doesn't work out mathematically as it
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should. Let's start thinking through this
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logically though. Obviously, moving,
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resisting, resistance- using our strength
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in this position- for somebody with
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shoulder impingement is not going to
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feel very good. We already have
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some external rotation and some
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abduction that's probably already
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starting to compress on some of those
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subacromial tissues. In this position,
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external rotation, if somebody has pain
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in this position, they're probably pretty
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far along
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in that impingement syndrome. They're
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probably really, really inflamed. Also,
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keep in mind that if we have a rotator
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cuff tear- let's say we have a
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subscapularis tear- is this going
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to hurt? Yeah, yeah that's going to hurt a
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lot. If we have a supraspinatus or an
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infraspinatus tear, is this going to
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hurt? Sure. So, how do we differentiate
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between impingement and rotator cuff tear?
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Well, we're going to have to think about
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our subjective examination, realizing
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that ruptures and tears are usually
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acute. They usually happen with some sort
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of incident that happened rapidly.
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They're usually not chronic- not that
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they can't be. If this was a
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gradual onset, I might be thinking more
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towards impingement, whereas if this was a
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sudden onset, I might be thinking more
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towards rotator cuff, or maybe if they
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had a history of rotator cuffs. And then,
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of course, we have to start adding all of
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our other test results to this. So, if
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let's say I do some other rotator cuff
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tests and they come back negative, but I
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do a bunch of impingement tests and they
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all come back positive, then these two
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tests probably help us solidify our
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impingement hypothesis, as opposed to
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solidify a rotator cuff hypothesis. Now,
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how would I use this? Of course, I would
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use this within a testing cluster, and I
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would be looking for the concordant
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sign, which I keep talking to you guys
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about. You want to find your quick tests.
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We're all short on time. So, as you're
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going through your tests and find the one that
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immediately provokes their symptoms, man,
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you want to make note of that, because
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when they come to the next time, that's
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the one you're going to go back to. You're
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not going to go through your whole
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battery of tests again. You're going to
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go back to that one provocative test, and
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then that's the one you're going to keep
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going back to as you test different
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interventions. So, maybe I want to release
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a few things and then see how that works,
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test my hypothesis. Maybe I then want
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to activate a few things, test my
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hypothesis. Maybe I want to try something a
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little bit more outside of the box,
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although I know us movement
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professionals think in this way. Maybe I
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want to try some thoracic spine
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mobilization or manipulation, thinking
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that maybe scapular dyskinesis is
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contributing to shoulder instability and
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see if that improves. Well, I now have-
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let's say this is her concordant sign-
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I now have a quick test that I can
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keep coming back to after each
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intervention. We are going to be talking
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about those testing clusters in
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future videos. Please stay tuned. Let me
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give you guys a quick review here of
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these two tests. I hope you guys will
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keep watching. So, starting with the
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Internal Rotation Resistance Test: I'm
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going to go ahead and bring her arm up
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to 90 degrees of abduction, elbow 90
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degrees of flexion, and wrist neutral. The big
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sign on this test is internal rotation
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weaker than external rotation. That
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should make sense to you guys from a
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kinesiology standpoint. Your internal
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rotators are much bigger and stronger. So,
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if your internal rotation rotators are
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testing weaker than your external
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rotators, that's an issue. We go ahead and
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test external rotation first. Alright,
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that feels pretty strong. We test internal
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rotation. That's also pretty strong, so that's a
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negative test, unless it happened to- "Did
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that provoke your symptoms?" Oh, it did
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provoke her symptoms. Well, then that's a
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positive, actually. That's still a
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positive test. I want to remember
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that for my future quick tests. Again, the
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External Rotation Test looks exactly
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like that Kendall MMT. I'm going to go
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ahead and brace her elbow here a
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little bit, hold her elbow and make sure she's
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not doing the old-school deltoid
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exercise here. Go ahead and press out
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in external rotation. She's very, very
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strong, so I'm not getting any indication
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there. "Does that provoke your symptoms?"
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Yes, oh, that provokes her symptoms, so we
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have some some serious issues here
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having to do with either impingement or
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rotator cuff, and I need to continue
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testing. Guys, I hope you will continue to
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learn your assessments. If you're not
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assessing, your guessing. Step up your
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assessment game
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and continue watching these videos