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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,

1:49

and that one are going to come together to form the superficial MCL,

1:56

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

3:30

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

4:31

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,

4:51

the superficial MCL or SMCL,

4:54

contiguous with this other superficial structure, the POL,

4:58

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.

5:14

And this is a common site where the MPFL will rupture, fail, or tear.