Interactive Transcript
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Let's look at the secrets of the medial patellar stabilization,
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comparing that and using a diagrammatic vignette
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that addresses the same subject, the MPFL.
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So we start out with an axial projection in the upper
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aspect of the patella along its medial edge.
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And we have a somewhat fibrillated structure right here,
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and one that's a little bit thicker right underneath it.
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And these are part of the medial retinaculum,
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also known as the fascia layer in the orthopedic literature,
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unfortunately called the deep fascia layer,
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even though it's pretty superficial.
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Now, right underneath here is a condensed,
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slightly thicker and longer and more confluent structure.
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And this is the medial patellofemoral ligament.
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It's coming off right in this location along the medial edge of the patella.
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Now let's track them back.
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Now I'm going to mark them three layers just for emphasis.
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So here's one layer that's very, very thin,
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and there's some little fibrillated areas superficial to it.
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Then I've got another layer that's a little bit thicker right here.
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That's also a fascia layer.
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And then I've got the MPFL,
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the medial patellofemoral ligament, right there.
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And then underneath that, believe it or not,
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is another layer that's coming up from the meniscus called the MPML,
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which has a lesser role in stabilization, but still some role.
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So now let's scroll these backwards and see what they do.
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I'm going to go up high for a minute just to show
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you the vastus medialis oblique and its tendon,
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which contributes somewhat to the medial patellar stabilization,
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but not much.
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As we move down further inferiorly these structures that I've pointed to,
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this one especially,
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and that one are going to come together to form the superficial MCL,
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or SMCL, also known as the superficial crus.
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This structure underneath is the MPML.
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So let's keep following the crus back posteriorly and it is
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the superficial layer of the medial collateral ligament.
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Right underneath it is the more globular but much shorter
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from front to back tibial collateral ligament.
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The superficial MCL rides over top of the tibial collateral ligament.
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It has been contributed to by the MPFL.
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And these all meet right here, the MPFL, the SMCL,
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and the tibial collateral ligament, or TCL, as a unique global train station.
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Then, as we move more posteriorly,
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the superficial MCL continues over top of the tibial collateral ligament.
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And right underneath it, I'm going to make it a little bigger,
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is the posterior oblique ligament or POL.
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So it goes superficial MCL,
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POL, cortex of the femur.
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So the MPFL, and to a lesser extent, the MPML,
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are the major stabilizers of the patella
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and keep it from dislocating laterally.
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By the way, there is a lateral patellofemoral ligament,
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but that will be a story for another day.
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We do see the lateral retinaculum and I'll comment on it only.
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Now, if we look in the sagittal,
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we cannot see the ligament because it's too thin and our
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slices aren't thin enough to catch it on foss.
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But it starts here and it goes posteriorly.
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I'm even going to draw it as a line as if it were present.
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It goes along this direction
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and it inserts somewhere between the adductor tubercle.
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Let's get the adductor tubercle right there.
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Here's the adductor magnus.
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Here's the tubercle and the medial epicondyle of the femur,
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which we really can't see unless we go all the way out to the side.
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So right about here is where the MPFL will insert.
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So if we draw it with our mind's eye,
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it'll have a course that looks something like this from the
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free edge of the patella right to about this location.
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And then, as we said in our diagrammatic demonstration,
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it meets the tibial collateral ligament, which is underneath, it's pretty short.
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And over top of the tibial collateral ligament is going to be the superficial
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MCL which has a very vertical course and has both a proximal
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and a very distal femoral insertion.
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And then another structure over top of that,
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which I'll draw in brown,
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is a more triangular structure in the back with a more oblique course.
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The triangle is pointed posteriorly, and that's the POL.
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So we've got deeper, the tibial collateral ligament, more superficial,
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the superficial MCL or SMCL,
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contiguous with this other superficial structure, the POL,
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and they come up to meet the MPFL at our all-encompassing global train
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station right here. So when you have a patellofemoral dislocation,
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there's a lot more going on than you might imagine.
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All these structures meeting.
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And this is a common site where the MPFL will rupture, fail, or tear.
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