All right, so having done that, let's move on
to some specific etiologies of shoulder pain
and we're going to start with the rotator cuff.
As I mentioned earlier, the rotator cuff is
consist of four muscles, the SITS muscles, S-I-T-S
and so we'll start with the
subscapularis here, the infraspinatus here,
the teres minor down here, and then the
supraspinatus, so S-I-T-S, the SITS muscles.
And for the purposes of the physical exam,
we take the teres minor and the infraspinatus
and we group them together
as one because essentially
they're performing the
same muscular action.
In fact, shown on this model here,
this is the posterior view of the scapula.
Here is the infraspinatus and the
teres minor and you can see that
they're largely doing the same thing.
There are some very subtle physical exam
findings that can help to tease them apart,
but they're not particularly relevant here.
And there, our supraspinatus, is there, and
our subscapularis is this very large muscle
that is anterior to the scapula or deep to the
scapula, which is why it's called the subscapularis.
So let's start off by testing the supraspinatus.
We're going to test essentially
three groups of muscles.
We're going to start with the supraspinatus.
And the way I'm going to do that is I'm just going to
ask you, Shayla to lift your arm up over your head.
So having done that, I'm going to
just have you slowly lower your arm.
And what I would ask the patient to do
is to pay attention to where is it painful
as you're lowering your shoulder.
If the patient has poor, active range of
motion, then of course, I would do this myself.
I would lift her shoulder all the way up
and then I would have her slowly lower it
as best she could.
And what I'm looking for
something called the 'painful arc'.
Patients who have specifically disease of
the supraspinatus will have the most pain
between 120 and 60 degrees.
And that's because it's actually in
that position where the supraspinatus
is doing the most work of stabilizing
the humeral head in the glenoid fossa.
When we think about the real mover and
shaker of getting your shoulder up in the air,
it's not the supraspinatus, it's your deltoid
muscle, that big giant muscle that's wrapping around
your humeral head.
It also inserts more distally so it has more
torque, more force that it can apply to the shoulder.
So the supraspinatus is not designed
to really move your shoulder around.
It's to stabilize it in place.
And when your arm is in this position, there's a
lot of work required for that supraspinatus muscle.
In fact, the entire rotator cuff to
hold the humeral head position
while the deltoid and you can see
she's got some big deltoids here,
are trying to pull her arm out of its socket, the
supraspinatus, doing the work of keeping it there.
So that's called the painful arc when a
patient feels reasonably well up here,
starts to get pain here, the pain continues until
you get to around here where things start to relax.
A patient who has a supraspinatus tear may,
in fact, start up here and they start to lower it
and then that discomfort kicks in
so badly that they drop their arm.
That's called the 'drop arm sign'.
The last thing I'll mention about
that test, since we're showing it,
is that if a patient has the worst pain
up here, this is also testing the AC joint.
So a person with acromioclavicular
disease will have pain
when the shoulder is all
the way up at 180 degrees.
because as you might imagine, if I lift
up this shoulder, I'm pinching this joint
once I get up to a certain extreme level of shoulder abduction as well.
All right, so that was the test for
supraspinatus injury, most often tendinopathy.
But there's actually a really specific test
to look for a supraspinatus tear,
and it's called the external rotation lag test.
It turns out the same test is effective for
assessing an infraspinatus tear as well.
So I will demonstrate it now.
So what I do is I take the patient's arm.
We're going to externally
rotate to the kind of hard stop,
or I can feel that this is kind of
the extreme of her range of motion.
And then I'm going to have you do
Shayla is I'm going to let go of your wrist,
but I want you to actively keep
your arm in this position after I let go.
And you note that I'm holding
her elbow in one position.
I don't want her to cheat
and bring her arm forward.
I wanted to keep her elbow here.
And I want you to keep your
wrist in this position after I let go.
3, 2, 1...
So she was able to easily do that.
But in this position, she's activating the stabilizing
force of her supraspinatus and her infraspinatus.
If one of those muscles was torn,
she would lag inwards like that.
And that's why it's called the external
rotation lag test.
Very useful test.
So those are the tests for the supraspinatus
and it moves us into the infraspinatus.
I already showed you the
test for a tear of infraspinatus
and I'm going to show you a test for
just tendinopathy of the infraspinatus.
The infraspinatus again and the
teres minor, the two of them combined
are responsible for externally rotating.
You can sort of see here that if these two
muscles were to contract, they would rotate
my humeral head outward like this.
So in order to test that, I'm going to
basically resist her efforts at externally rotating.
So I just want to keep your elbow tucked in
and just rotate out and I'm going to resist you
So just that test, if she has significant
weakness on one side versus the other
or if this action reproduces the
pain that she's been reporting,
that test of resisted external rotation
would support an infraspinatus tendinopathy,
a disease of the infraspinatus.
All right, time to move
on to the subscapularis.
This is the anterior muscle
on the humeral head.
This big meaty muscle here
that lines the inside of the scapula.
When this muscle contracts, you're going to
move, your humeral head is going to rotate in.
So this is your primary
muscle for internal rotation.
And first thing I'm going to do is show you the
test for a tear of the subscapularis
since that muscle's
responsible for internal rotation.
If I take her arm to the extreme of internal
rotation, to where I sort of feel, again,
a hard end point, she can't
internally rotate any more than this.
I'm now going to ask you to hold your
wrist here when I let go, just like we did
in the other direction before.
So I'm going to sort of hold her
elbow in position while I do this.
On the count of three,
I let go of your wrist
3,2,1... and she's able to do that.
There was a tiny little bit of lag there,
but not enough that I'd be concerned.
And in contrast, if a person did not have
a strong subscapularis, or if it was torn,
that wrist would lag inwards.
And that would be a confirmation
that the person has or likely
is to have a subscapularis tear.
And then we're going to do a test
for subscapularis tendinopathy.
To be clear, there's tendinopathy,
which is a strained, unhappy tendon,
and then there's a torn tendon.
And we're always trying to distinguish between
those two because a torn tendon can be repaired.
A tendon that is just strained or
has a little bit of some micro tears in it,
just need some physical
therapy and a little bit of time.
So there's a big difference in
how we'd manage those two things.
So we look for a tear already for
tendinopathy of the subscapularis tendon.
We're going to do what's
called the 'belly-off test'.
Put your hand on your belly, please Shayla.
I'm just going to keep your
hand there for the moment.
I'm going to bring your elbow
kind of awkwardly forward.
It always feels weird to do this test.
And then I'm going to let go of your hand and I want
you to keep your hand on your belly after I release it
So the fact that she can keep her hand
on her belly tells me that her subscapularis
again, this muscle is strong enough to
keep her humerus fully internally rotated.
And one last test to go over to
assess the rotator cuff very quickly,
is something called the 'lateral Jobe
test' and the utility of this test is that
it essentially tests the entire rotator cuff.
And if it's normal, it makes your
likelihood of a rotator cuff tear much less.
So, I'll demonstrate that really quickly.
Just bring your arm out to the side like
this and just resist me as I push down.
If that doesn't cause the patient
have significant pain or if there's no
asymmetric weakness on
one side versus the other,
your likelihood of a rotator
cuff tear is certainly less.