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So let's start off with the lesser metatarsal

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falange joints.

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Nice illustrations

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that really emphasize the complex interplay of all

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of the soft tissue structures, including capsule

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ligamentous structures, as well as plantar plate

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high resolution Mr.

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Image here showing the fibro cartilaginous nature

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of the plantar plate here.

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That single piece of fibrocartilage, very robust attachment

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to the proximal phalanx.

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In some cases, there can be a little normal reservoir there.

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As we follow that proximally, along that plantar surface

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of the metatarsal articular surface, we see

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that it then comes to attach in the region

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of the metatarsal head neck junction,

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that proximal attachment, much thinner of course, than

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what we see at the robust fibro cartilaginous attachment

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to the base of the proximal phalanx.

0:57

When we think about those lesser metatarsal feal joints,

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again, remember that they're withstanding the loads

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of weight bearing as well as tensile forces.

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When you're thinking about foot mechanics in general, it's

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that second metatarsal

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and metatarsal phlange joint where the primary axis of force

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and the loading of the foot occurs.

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And remember, that's when you've got normal foot alignment

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and normal foot mechanics.

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When Karen showed her cases

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before, she showed some variations with metatarsus adductus,

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and of course, that's going to change the overall mechanics

1:32

of the foot and where the primary forces occur

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with loading of the foot in general.

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The other thing that will certainly affect that is whether

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or not you've got a long second metatarsal with respect

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to the first MTP In this case.

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As you look at the weight-bearing plain thumb, you're seeing

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that hax valgus some minor degenerative changes,

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and you see again, the mass effect here on the second MTP

1:56

capsular abnormality here with that little fleck of bone.

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So always look for those changes

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as we think about what's happening at the

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forefoot and its alignment.

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So now let's look at some pathology.

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As you can imagine with these plantar plate injuries,

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they can be acute in nature

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or they can be more degenerative.

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In this case, we're looking at the second MTP.

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You can see that this is a degenerative case.

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We have reactive marrow changes, we have loss

2:25

of cartilage at the articulation.

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Here you can see where the plantar plate should be attaching

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to the base of the proximal phalanx.

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High grade tearing here,

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as we look at the long axis films really focused here

2:39

around the medial aspect of the forefoot.

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Here's your degenerative change,

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Hal valgus at the first MTP mass effect on the second MTP.

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In this case, as you look at the plantar aspect of

2:53

that second MTP, you're identifying that discontinuity

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of the plantar plate from

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The base proximal phalanx.

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Often you'll get surrounding high signal intensity

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with some inflammatory changes.

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Other associated findings per capsular fibrosis can

3:10

occur bursitis.

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Remember, you've got inter metatarsal

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between the metatarsal phlange joints

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and even ganglia can occur.

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Another example here, we're looking at a sagittal image.

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Here's your metatarsal articular surface.

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Here's the partial tearing, high grade in nature from

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that base proximal phalanx.

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As you look at the long axis film here,

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you can see the discontinuity here at the lateral aspect,

3:40

again at the second MTP common site of involvement

3:44

for plantar plate abnormalities in the forefoot.

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And a nice way to verify is to look in the short axis here,

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showing you the non-fat suppressed look at the

3:55

normal appearing capsule.

3:56

In the opposite side, you're seeing capsular abnormality

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and that discontinuity of the plantar plate.

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So we can use each of the imaging planes

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to really characterize nicely what's happening at

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that plantar plate attachment, putting that in the context

4:13

of the greater alignment at the forefoot

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and of of course, looking closely for

4:18

that when we have Hal valgus alignment at that first MTP.

4:22

So just an example of some different types

4:25

of pathology in these lesser metatarsal phal joints.

4:29

Hal valgus alignment, again here,

4:31

a focal plantar plate tear.

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You can see it right there at the lateral aspect.

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Normal appearance here when you're looking at the ligament,

4:40

similar to plantar plate.

4:42

Nice linear, low in signal intensity.

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As you look at the associated sagittal image here, you see

4:47

that nice linear low signal intensity, completely

4:51

discontinuous in nature

4:52

with a couple millimeter gap in this case.

4:56

As we look at our next sagittal image, we see that

4:59

that plantar plate tear has retraction.

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There's the torn end, maybe seven,

5:04

eight millimeters of traction.

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And the seal change is a nice secondary finding when we're

5:10

looking for these abnormalities.

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It can be low or high signal intensity within the bone.

5:17

And then moving to our high grade partial tear here,

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looking in the sagittal imaging plane,

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you see a tiny little bit of

5:24

that plantar plate still intact.

5:27

You see the retraction of the more superficial to a point,

5:32

maybe a centimeter or close to a centimeter proximally.

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And then as you look in the short axis,

5:38

playing the altered signal intensity in the region

5:40

of the plantar plate, in this case,

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high signal intensity extending to the region

5:45

of the inter metatarsal bursa

5:47

with small decompressing ganglion cyst.

5:51

So really, again, coordinating the imaging planes,

5:54

looking closely at that plantar plate,

5:57

and also looking for secondary findings, including that

6:01

surrounding inflammatory change or fibrosis

6:04

or cyst formation.