0:00

Let's move now to the patellar tendon.

0:03

So the patellar tendon technically is not really a tendon.

0:06

It could also be considered a ligament

0:08

because it's going from bone, uh, bone to bone.

0:11

But I'll use the term patellar tendon.

0:14

Um, it can be lax in the extended position.

0:17

So it's quite commonly you'll see these little magic angle,

0:21

uh, artifacts, uh, related, uh, to the, uh, tendon.

0:25

So just be aware of those. They're normal finding.

0:28

They will disappear as you go to a more long T two, uh,

0:33

longer t uh, sequence.

0:35

And they're quite common here

0:36

because the knee is extended during the mr.

0:40

And so the patella tendon, uh, tends to be, uh, lax

0:45

like the quadriceps.

0:46

We will frequently see tendinopathy, uh, in this area.

0:49

This patient has partial tearing with the high grade POF

0:53

of the quadriceps from the upper, uh, patella, uh,

0:56

and a lot of tendinosis, uh, in the, uh, patellar tendon,

1:01

showing you the typical findings of thickening.

1:03

And as I mentioned, uh, earlier, uh, this again,

1:07

like the quadriceps does have a tendency to be angioplastic

1:12

and can be painful even when you're not seeing a lot

1:15

of fluid on your T two weighted, uh, images.

1:19

So you, you wanna mention, uh, the, uh, the tendinosis.

1:23

Now I want to just show you this

1:25

'cause it looks kind of like tendinosis.

1:27

It's more extensive in this example, but this is gout

1:30

and this is gouty deposition within the patellar tendon.

1:34

And it can be very small and maybe focal.

1:37

I don't really see great bone erosion here.

1:40

Probably some erosion right in this area has developed

1:43

'cause there's some bone marrow edema, uh, in that area.

1:46

Um, but you can certainly see, uh, well-defined

1:50

or better erosions than, than in this case.

1:53

But it's a nice example showing you

1:55

how the diffuse involvement,

1:57

certainly some erosive disease at the tibial tuberosity

2:01

where the cortex looks irregular

2:02

and there's more intense, uh, bone marrow edema.

2:05

So gout loves the extensive mechanism,

2:08

and this is from the same patient where he has

2:11

aranon bursitis with hyperdense tophaceous material,

2:16

a little bit of which is calcified.

2:19

And again, that sort of surface blistering para articular

2:22

erosion, that's very characteristic of gout.

2:26

Now, in terms of partial tears, uh, they are most common

2:31

on the articular side

2:33

of the tendon near its patellar insertion.

2:36

They can certainly occur distally.

2:37

We'll often see that in patients

2:39

with Osgood slaughter disease, for example.

2:42

Uh, this patient has some findings suggesting sending Larsen

2:45

with bone proliferation.

2:47

But this is the place

2:48

that you wanna focus when you're looking for a partial tear,

2:51

is the undersurface fibers near the patellar tendon.

2:56

So this type of tearing has been referred to

2:58

as a jumper's knee.

3:00

Uh, it may be quite focal

3:01

as we see in this example over here.

3:04

And if you're going quickly, the tear

3:07

may be just on one slice on your sagittal images

3:10

because the tears are often sag oriented

3:12

and they're quite easy to overlook.

3:14

So really focus in on that area.

3:17

And I like to look on my axial images as well,

3:21

because the sagittal nature of the tear,

3:23

you can often calculate its depth better on your images,

3:28

uh, that are axial.

3:30

Um, this is thought to be due to

3:32

tensile stresses at the undersurface of the patella.

3:36

And because of the fiber lengths being different,

3:39

the shorter fibers in the back,

3:41

the tensile stresses are actually higher in the

3:44

posterior fibers.

3:45

It's also been suggested that a prominent peaked lower pole,

3:50

as we see in this example, can lead

3:52

to direct impingement on the posterior fibers leading

3:56

to this characteristic, uh, pattern of a jumper's knee.

4:00

Now in a, in a complete tear, you can see in this patient

4:04

that we have the opposite of patella Baja.

4:08

We have patella alta with superior migration.

4:11

And as a rough rule, um, again,

4:14

you can use those measurements, none of which I really like.

4:16

It's a rough rule you can use as measurement

4:19

of seven centimeters from the tibial tubercle

4:22

and, uh, on mr, we can see the tear, uh, directly, uh,

4:26

in this example with the background of tendinosis.

4:30

Now what we see in children is quite different.

4:32

In children, you can get a number

4:34

of different, uh, injuries.

4:36

This is a, what's known as a patella sleeve injury,

4:40

which is an avulsion of bone

4:42

and periosteum from the patella.

4:45

Uh, it's a, it's a equivalent to a complete tear

4:48

of the patella tendon,

4:50

but it occurs at the periosteum and bone.

4:52

I do not have an mr example of this

4:55

because we do not do pediatrics, uh, at our, uh, facility.

4:59

I will show you Mrs.

5:01

On some of the more common abnormalities.

5:04

This is syn Larsen, which is a more chronic condition

5:07

with ossification, irregularities

5:10

and marrow edema thought to be due

5:12

to repetitive excess traction at the patella.

5:15

We see this usually in our young athletes, uh,

5:18

who are involved, uh, in, in sports,

5:21

and it's really the pediatric equivalent of, uh, the adult,

5:26

uh, jumpers knee.

5:27

And at the other end we have Osgood Slaughter disease.

5:31

In this case, it's really mild.

5:33

We have marrow edema without boning changes. This is common.

5:37

You don't usually need to get an MR for this.

5:40

It's diagnosed clinically, uh,

5:42

with the focal tibial tuberosity pain

5:44

and, uh, during the period of rapid growth.

5:49

But it can go on to form obstacles

5:51

and, uh, that don't unite.

5:53

It can then be associated with chronic problems

5:57

Of the patellar tendon, which can be torn.

6:00

This one looks pretty intact,

6:01

but the patient does have bursitis.

6:03

But you do run into all kinds of issues here.

6:06

Patient still has edema

6:08

and they can be symptomatic well into adulthood once you

6:11

start getting these displaced, uh, ossicles.

6:14

So this can persist, um, as a symptomatic, uh,

6:19

abnormality into into adulthood.