0:00

So, we have a 30-year-old woman

0:03

with anterior knee pain.

0:05

And in the consecutive axial images,

0:08

what first catches our attention is

0:10

lateral tilt of the patella

0:12

with respect to the femoral trochlea.

0:15

There is a slightest plastic change

0:17

of the femoral trochlea.

0:19

And as we scroll through the cartilage,

0:21

we see fissuring of the cartilage in the inferior

0:25

portion of both the medial

0:26

and lateral patellar facets.

0:28

That fissuring of the cartilage is

0:30

seen here on the sagittal images,

0:33

and it's not going all the way

0:35

to the subcondylar plate.

0:37

So, if we use the outer bridge classification

0:40

for chondromalacia,

0:42

this would be a grade two chondral injury

0:45

of the patella in the setting

0:47

of patellofemoral maltracking,

0:49

given the lateral patellar tilt.

0:52

Now checking the infrapatellar fat path,

0:54

we can see on the axial images that there is some

0:58

effacement of that fat

1:00

that translates into edema-like signal intensity

1:06

on the fluid sensitive sagittal sequence.

1:09

Edematous, when it's interposed

1:11

between the patellar tendon and

1:13

the lateral femoral condyle,

1:15

and this is the hallmark of patellar tendon

1:18

lateral femoral condylar friction syndrome.

1:21

One additional finding that has been associated

1:25

with patellofemoral maltracking

1:27

is the presence of patella alta.

1:29

And on MRI,

1:30

we can easily assess the presence of patella alta

1:34

by calculating the insall salvati ratio.

1:38

So, we measure from the top of the patella to the

1:40

bottom of the patella, and from the top of the

1:43

patellar tendon to the anterior tibial tubercle.

1:46

And if that ratio is more than 1.2,

1:49

we are facing a case of patella alta.

1:52

So, to put all this case together,

1:54

we have a patient with patella alta,

1:57

patellofemoral maltracking,

1:59

and grade two chondral injury

2:02

using the classification of outerbridge.