This is Brent of the Brookbush Institute and in this video we're going to go
over a special test for the knee, specifically for the LCL and MCL. These
are the valgus and varus stress tests. I'm going to have my friend Melissa come
out, she's going to help me demonstrate. Now these valgus and varus stress tests
are supposed to try to side bend the knee, and you can imagine if I try
to side bend the knee, when I side bend it the side farthest away is going to open
up and of course that's what these ligaments are supposed to prevent. So if
we start with the valgus stress test. The valgus stress test is trying to push
her knee this way which means her medial or inside knee would open up during side
bending. If I can actually make her knee open up, something's wrong with her MCL,
that's what her MCL is supposed to be preventing her from doing. So I'm
going to get a nice lock on her lower leg here to do this test, and the
reason being is, number one - I want to stabilize the tibia so I'm going to get
this hand around her tibia close to her knee, but I also want to
stabilize the foot to try to control for tibial internal and external rotation,
otherwise when I go to press I end up with all of this stuff, her knee
just flops around on me. So I want to get a nice lock that way and
then I'm going to use this hand on her femur and I'm going to push this way while
bending her tibia towards me to try to open up her medial knee, and I can
feel that because if you notice, this thumb is right over the joint line.
So I'm going to go like this, I can't get it to open up but I'm also going to ask -did that
hurt? That actually hurt her a little bit. So although I can't gape her knee we are
positive for maybe some MCL strain or at least some MCL pain here. But we're not
done yet, we also have to do this test at 30-degrees and here's where you better
make sure you have good lock on her tibia, because when you go to press, this
is where you get all sorts of like this stuff -which is hip internal rotation.
I need to make sure I'm locked so that I'm still trying
side bend her knee, how does that feel? That's still pain too. Okay so we
have pain both in full extension and pain at 30-degrees. Now why did I do
it at full extension and 30-degrees, well it ends up that when you're fully
extended your strap like PCL at the back of the knee is totally taut, which holds
your tibia plateau against your femoral condyles pretty tightly, and since those
are two flat-ish surfaces it is possible that without an MCL your PCL by itself
will keep your knee from gaping because you have two flat surfaces being pressed
against each other. So if I was to get her medial knee to open up here
there's actually a good chance that we don't only have MCL injury, we might have
PCL as well. Whereas if we're here, it's probably not
here, like let's say we get negative here but positive here then it's probably MCL
only. Now she has pain in both and no opening that actually doesn't tell us
much more than it's probably MCL, it could be PCL, it doesn't seem like
anything's ruptured. That's what we get from that and I hope you follow the
logic there. So now let's flip this test around for the LCL and do our varus
stress test. So what I'm actually going to do is I'm going to sit down on the table,
I'm now going to lock her tibia on my other arm here. I have the same setup as
I had on this arm, and now I'm going to push the femur this way into a knees
bow out side bending. I'm going to put this thumb over her joint line and I get no
opening up, that joint line isn't moving at all. But again if my
goal was to test the LCL I know in this position that her PCL could be giving us
a false negative result, right her PCL is holding her knee together even though
she might not have an LCL, so what am I going to do? 30-degrees, put a little
slack in that PCL, make sure I have a good lock because I
don't want rotation to mix up my test, and make sure I'm just doing side
bending. How did those feel? Alright so those are fine, that's fine. So she's
definitely negative for any LCL issues.
She is positive for some MCL issues though, so that gives us a little
indication of some of the stuff that Melissa might have done. Now since she
doesn't look like she has a rupture we might start with some physical therapy,
and see if we can improve her symptoms before I would send her out for any sort
of imaging or physician's diagnostic assessment. So just to review
real quick, make sure on both of these you lock, make sure you're doing 0
and 30 because at 0-degrees our PCL can fool us. This way varus, lock, pushing
out this way, 0-degrees and 30-degrees because PCL can fool us. So if
you have any questions whatsoever let me know, just leave a question in the
comments box below.