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Lachman's and Anterior Draw

Lachman's and Anterior Draw is a test used to assess the integrity of the anterior cruciate ligament (ACL) in the knee joint. It is performed by having the patient lying on their back with their leg bent at 90 degrees, with the examiner's hands under the thigh and shin, applying an anterior and posterior force on the knee joint, respectively. The resulting movement of the knee is assessed for evidence of anterior tibial translation, a hallmark sign of an

Transcript

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