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Hello, and welcome to Noon Conference, hosted by Modality.

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Noon Conference connects the global radiology community through free, live

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educational webinars that are accessible for all and is an opportunity to learn

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alongside top radiologists from around the world.

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Today, we are honored to welcome Dr.

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Rajesh Chawla for a lecture entitled Ultrasound Anatomy of Knee Joint

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with Common Pathologies. Dr. Chawla is the consultant and director

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at Th- Thane Ultrasound Center, and his primary clinical

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interest and expertise include various ultrasound interventions, including

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fetal interventions and pain management procedures, ultrasound contrast and

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elastography, and MSK ultrasound.

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At the end of the lecture, please join him in a Q&A session where he will address

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questions you may have on today's topic.

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Please remember to use that Q&A feature to submit your questions so we can get to

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as many as we can before our time is up.

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With that, we're ready to begin today's lecture. Dr.

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Chawla, please take it from here.

0:58

Thank you. Good morning, everyone.

1:00

Um, so, uh, today's topic is on knee

1:03

ultrasound, and I'm going to be focusing on the ultrasound

1:07

anatomy and the scanning techniques.

1:09

And of course, after that, we'll be having a look at the common

1:13

pathologies that we encounter in our day-to-day

1:16

practice. Uh, so first of all, thank you for having me over here

1:20

again, and it's always a pleasure being on this platform.

1:24

Right. So... Right. So when we talk about

1:28

scanning the knee, we are typically looking at scanning this knee

1:31

with something like a twelve to fourteen megahertz linear

1:34

transducer. Uh, nowadays, we have these newer

1:38

transducers, you know, ranging up to eighteen and even twenty

1:41

megahertz, um, which are quite good.

1:44

One thing we need to remember is, of course, we use a broad

1:47

footprint transducer linear probe to begin with, but

1:51

at times you may have some challenges, uh, when you have maybe

1:55

a lot of joint effusion or hemarthrosis, where you may need a

1:59

curvilinear probe to have a quick look at the joint as well.

2:03

So in a nutshell, we need to generally use the high-frequency

2:07

transducers, but we need to be flexible as to what we are

2:10

using. So when we are looking

2:14

at the knee joint on ultrasound, we tend

2:18

to compartmentalize these, uh, the joint, depending

2:22

upon the requi-- the, uh, expected pathology or

2:26

the expected symptoms or the presenting symptoms of that particular

2:29

patient. So for the convenience of looking at these

2:33

structures, we're going to be dividing the knee into compartments, so it'll just

2:37

make our scanning that much a little bit easier.

2:41

Another thing is, whenever we are looking at MSK

2:45

scanning, it's always a good idea to have a checklist in

2:49

your mind as to what structures and in what way you

2:53

would look at those structures so that you're not missing out on anything

2:57

major. So let's begin with the anterior

3:01

compartment of the knee. And again, when it comes to MSK

3:05

ultrasound, oh, the patient positioning plays a very, very

3:09

important role, right? So for looking at the anterior

3:13

compartment of the knee, you want the knee to be in

3:17

about a twenty or a thirty-degree flexion.

3:20

And to achieve this, what we do is keep a pillow or a

3:23

roll under the knee joint. That really helps to

3:27

extend the quadriceps as well as the patellar tendon, and that

3:30

makes our scanning easier. So coming back to our

3:34

checklist for the anterior compartment, we are going to be looking at the

3:38

quadriceps tendon, we're going to be looking at the suprapatellar

3:42

joint recess, the patellar tendon, and we'll have a look at

3:46

the medial patellar retinaculum as well.

3:50

Now, another important thing is whenever we are doing any

3:54

form of MSK ultrasound, we need to keep in mind the

3:57

bony landmarks, right? If we jump to soft tissue

4:01

structures, there's a good chance that we may kind of end up losing our

4:04

bearings, not knowing what structures we are looking at.

4:08

So identifying the bony landmarks and beginning your scan with the

4:11

bony landmark is very important. So as far as the

4:15

anterior compartment is concerned, the bony landmark that we have is

4:19

this nice patella. So the moment you place your transducer

4:23

on the patella, you see this nice structure,

4:27

which is hyperechoic, which is the cortex you are looking at, followed

4:31

by shadowing distally. So you know that, you know, you,

4:35

you-- this is going to be kind of your lighthouse to the

4:38

knee. So once you identify the patella,

4:42

we move the probe into the suprapatellar

4:45

region, right? And we're starting with the long axis.

4:49

So we move our probe from the patella to the suprapatellar

4:53

region, and what we expect to find over here is the

4:56

quadriceps tendon, right? So this over here is

5:00

the quadriceps tendon, which appears as this

5:04

linear fibrillar structure. The inferior

5:08

portion over here is the superior edge of the patella, the

5:11

superior pole of the patella, rather, as we can identify over

5:15

here. Now, if you look a little closely to this quadriceps

5:19

tendon, we can actually identify the different

5:23

layers of the quadriceps tendon as well.

5:26

So the superficial layer over here is formed by the rectus

5:30

femoris. You have a middle layer, which is formed by the vastus

5:34

medialis and the lateralis, and you have the deep

5:38

layer, which is formed by the vastus intermedius muscle.

5:42

Right? So when we are looking at tears of the quadriceps

5:45

tendon, we can potentially even look at which

5:49

area or which region or which fibers are getting

5:53

torn.

5:56

So this, again, is the quadriceps tendon, and there

6:00

are two other important things that we need to look over here, which are the

6:04

fat pads. So this triangular echogenic

6:08

area, which is sitting-... below the quadriceps tendon

6:11

and superior to the patella over here is the suprapatellar fat

6:15

pad. And again, this echogenic area, which is sitting

6:19

anterior to the femur over here, is the pre-femoral

6:23

fat pad. And in between this, you see this

6:26

hypoechoic area, which is generally not filled with

6:30

too much fluid. You may see a minimal, minuscule amount of

6:34

fluid over here. This is the suprapatellar

6:37

recess. Okay? So identify the quadriceps

6:40

tendon. We go to the superior pole of the patella, you have the

6:44

suprapatellar fat pad. Anterior to the femur, you have the

6:48

pre-femoral fat pad, and sitting in between these two is the

6:51

suprapatellar recess. And at times, this recess

6:55

may be very small, but, uh, if there's distension of fluid, you'll

6:59

be able to see it quite easily. Now, once we're done

7:03

with the superior margin, we go to the inferior

7:07

aspect of the patella. And as we move inferior to the

7:11

patella, again, in the longitudinal plane, what we are able to

7:15

identify over here is that this linear, um,

7:18

fibrillar kind of a structure which is sitting over here is your patellar

7:22

tendon, right? And sitting below that, you have another

7:26

fat pad, which is over here, which is the Hofuas fat pad.

7:30

Now, keep in mind, whenever we are looking at any of these tendons,

7:34

whether it is a patellar tendon or whether it is the quadriceps tendon, we

7:38

need to evaluate them in the long axis as well as the short

7:42

axis. So once you move your probe in the longitudinal

7:45

plane, you not only move and translate the

7:49

probe from left to right to cover the entire tendon in the longitudinal

7:53

plane, but you also look at these tendons in short axis

7:57

to identify any pathologies.

8:01

Well, so once we're done with the major tendons, we move to the next

8:05

important structure over here, which is the prepatellar bursa.

8:09

Now, normally, the prepatellar bursa is not

8:12

distended, right? So you will not see any fluid, which

8:16

is over here. But in cases of bursitis, of course, it's quite easy

8:20

to identify the fluid over here. Now, whenever we are looking

8:24

at these fluids, especially in these superficial bursa like the prepatellar

8:28

bursa, it's very important that we scan this

8:32

area with very minimal pressure. If you apply too much of

8:36

pressure over here, you're going to be displacing the fluid, and you will

8:40

not be able to identify the presence of

8:42

bursitis. The other important

8:46

bursa which come up over here are the superficial

8:50

and the deep

8:52

infrapatellar bursa. Okay? So for that, again, a

8:55

landmark is going to be the patellar tendon.

8:58

This is the insertion of the patellar tendon onto the tibia,

9:02

and just superior or anterior, rather, to the patellar

9:05

tendon, we see the superficial infrapatellar bursa, and

9:10

deep to the patellar tendon over here, we have the

9:13

deep, uh, infrapatellar bursa.

9:18

So whenever we do identify any pathologies, especially involving

9:22

those of the quadriceps tendon or the patellar tendon, it may be a good idea to

9:26

get a good panoramic view. This is, uh, quite

9:30

easily acquired with, especially our newer machines, and it gives

9:34

a good idea of the relation of the distinct structures and

9:37

pathologies. Now, moving on to the actual

9:41

view in the suprapatellar region, what we want to identify is

9:45

this hyperechoic cortex of the femoral

9:48

trochlea, and sitting above that, this hypoechoic

9:52

area is the cartilage. Right? So normally, you see a

9:56

nice, thick cartilage, something like this, right?

9:59

But if you do have a degenerative process, you may end up

10:03

identifying thinning of the carti- cartilage or any

10:07

defects over here as well. Now,

10:11

moving on to the other structure in the anterior compartment, which

10:15

is the medial patellar retinaculum.

10:17

Now, the medial patellar retinaculum extends from the patella to the

10:21

femur, and what we need to do is scan.

10:24

We need to-- To scan this, we need to probe, move our probe a little more

10:28

medially, as we are seeing over here, and at the same time, we

10:32

push the patella towards the probe.

10:34

Now, as we push the patella towards the probe, not only is the structure

10:38

more evident, we also end up identifying the

10:42

hypoechoic cartilage, which is sitting on the medial aspect of the

10:46

patella. And again, you will be able to identify if there is

10:49

any thinning of the cartilage over here or any defects in the

10:53

cartilage.

10:55

Now, when it comes to the anterior cruciate ligament, the

10:59

ultrasound is not the modality of choice,

11:03

I would say. Right? Of course, so if you're suspecting injuries to the

11:07

ACL or the PCL, it may be a good idea to do an MRI as

11:10

well. But having said that, we can very well

11:14

identify the tibial attachment of the anterior cruciate

11:17

ligament. So this is how the tibial attachment of the

11:21

anterior cruciate ligament looks.

11:23

It is this kind of a nice, thick, fibrillar, hyperechoic

11:27

structure, as we can see over here.

11:29

And to identify this, we need to rotate the

11:33

probe from a long axis or a short

11:36

axis, right, in, in, in the direction of the

11:40

fibers of the anterior cruciate ligament.

11:42

So once we rotate this probe, we are able to

11:46

identify this anterior cruciate ligament much

11:49

better. So we covered the more important

11:53

compartment, which is the, uh, anterior compartment.

11:57

We'll move on to the medial compartment now.

12:00

And for the medial compartment, the-- this is the position that we

12:04

end up giving. So we ask the patient to do an external rotation

12:08

with about twenty, thirty degree of flexion.

12:11

And again, if you place a pillow or a pad underneath the, uh,

12:15

knee, it helps to support the knee, and it makes your

12:18

imaging slightly easier.... So as far as the medial

12:22

compartment is concerned, we are going to be looking at the medial collateral

12:26

ligament and, of course, the pes anserine

12:29

tendons. Now, remember what I said

12:33

previously, we need to identify the bony landmarks.

12:36

And for the bony landmarks on the medial side, we're gonna be looking at the

12:40

femur and the tibia. And the moment we look at the femur

12:44

and the tibia, we see this triangular hyperechoic

12:48

structure, which is sitting over here, which is the medial

12:51

meniscus. Right? So once we identify these structures,

12:55

we know where and what we should be looking at.

12:59

Now, as far as the medial collateral ligament is concerned, this

13:03

is seen more superficial to the medial meniscus.

13:06

It connects, goes all the way from the femur to the

13:09

tibia, right? And it has two components: you have superficial

13:13

component, and you have a deep component.

13:16

Now, the superficial component is actually quite long.

13:19

It goes almost seven centimeters in length, and it

13:23

goes way down onto the tibia. So when

13:27

you're trying to identify the medial collateral ligament, you're

13:31

not just looking at this view. You need to trace the medial,

13:35

uh, medial collateral ligament all the way down towards its

13:39

insertion onto the tibia. And then you have the deeper

13:43

component as well, where the fibers fuse with the

13:46

superficial part of the medial meniscus.

13:49

So you have a meniscofemoral component, and you have a

13:53

meniscotibial component. So at this level, it's not really

13:57

always possible to differentiate the fibers

14:00

from the medial meniscus because these fibers almost fuse

14:04

with each other.

14:07

And the other important

14:10

structure in the medial side or on the medial side is the

14:13

pes anserine complex. Now, this pes anserine complex is a

14:17

combination of different tendons, right?

14:20

So which is semi, uh... I'm sorry, the sartorius

14:24

muscle, you have the gracilis tendon, and you have the

14:28

semitendinosus tendon. So all these insert

14:32

onto the medial aspect of the tibia, right?

14:36

And what you do end up getting is this kind of a

14:39

keys-feet pattern, which is the reason why it's called as pes anserine

14:43

tendon. And sometimes, again, differentiating these tendons at

14:47

the insertion can be quite challenging.

14:50

So how do we identify these tendons?

14:52

Remember, when we start looking at the, uh,

14:56

medial, uh, collateral ligament, we traced our medial

15:00

collateral ligament all the way down, which is, again, what we are doing over

15:04

here, tracing the medial collateral ligament here.

15:06

And as we move towards the distal part of the attachment

15:10

towards the tibia, we move the probe slightly

15:14

anteriorly. So we move the probe all the way down to

15:17

trace the inferior aspect of the attachment of the medial

15:21

meniscus, and we direct the probe anteriorly.

15:25

And the moment we do that, we are able to see

15:29

this, uh, structure where you are looking

15:33

at the medial collateral ligament here, and you can see these

15:37

ovoid kind of structures, the tendons which are coming up over

15:40

here, which is the pes anserine complex, the pes

15:44

anserine tendons. And the more important thing is that you at

15:47

times may get bursitis at this level, and you will see

15:51

fluid between these pes anserine, uh, tendons

15:55

and the medial collateral ligament.

15:57

So this is the site you look out for the pes anserine

16:01

bursa. So moving on to the

16:05

lateral compartment, and positioning of the lateral compartment, very

16:09

similar to what we did with the medial side, only I generally

16:13

ask the patient to turn on to the other side.

16:16

So, and with the knee in a little bit of flexion, uh, we give

16:20

a pillow between the two knees. Again, that makes the patient

16:23

comfortable, and the slight flexion position makes your

16:27

scanning easier as well. So as far

16:31

as the lateral compartment is concerned, we are trying to look for

16:35

the iliotibial band and the lateral collateral

16:38

ligament. Now, for identifying the iliotibial

16:42

band, we need to know the insertion of the iliotibial

16:46

band, and that is onto the gerdy's tubercle of the

16:50

tibia. Right? So the bony landmarks that we are going to be

16:54

identifying over here is the femur.

16:57

You have the gerdy's tubercle. Between these two, you have the

17:00

lateral meniscus. Right?

17:04

So for identifying the gerdy's tubercle, we need to

17:07

translate the probe slightly more anteriorly.

17:11

So we keep one edge of the probe on the lower end

17:15

of the femur, and we translate the probe little more

17:18

anteriorly at its inferior end in order to identify

17:22

the gerdy's tubercle. And once you identify the gerdy's tubercle,

17:26

we can see the structure which is inserting onto the gerdy's

17:29

tubercle. This is your iliotibial

17:33

band. And if you observe a little closely

17:36

towards, uh, the, uh, femoral, uh, aspect of

17:40

this image, you see this another tendon, which is

17:43

coming in the short axis, and this is your popliteus

17:47

tendon. Right? So in this image, we have been able to identify the

17:51

lateral meniscus. We've been able to identify the gerdy's tubercle

17:55

with the insertion of the iliotibial band.

17:59

Now, as far as the lateral collateral ligament is concerned,

18:02

this inserts onto the fibula. So we need to translate

18:07

our probe from a little more anterior approach towards

18:10

a posterior approach. So we keep the bony landmarks of the

18:14

femur and the fibula in view, and we can see this

18:18

fibular structure, which is connecting these two bony

18:22

landmarks, and this is your lateral collateral

18:25

ligament.... Okay? Now, normally what happens is

18:29

when you're looking at the lateral collateral ligament, you'll always see this kind

18:33

of a wavy pattern, which is coming up onto the lateral

18:36

collateral ligament. So we need to be careful before we

18:40

say that there is a tear over here. A varus force will help

18:44

you to

18:45

strengthen this ligament, tighten this ligament, and you'll be able to identify the

18:49

ligament a little bit better.

18:53

So again, uh, the bony landmarks on the lateral aspect, you

18:57

have the femur in view. We have the, um, the

19:00

Gerdy's tubercle of the tibia, and this will help you to

19:04

identify the, um, uh, iliotibial

19:07

band. And once you translate the probe a little more

19:11

posteriorly and you go onto the fibular head, you are

19:14

able to identify the lateral collateral ligament.

19:19

So I want you to just take a notice of how the

19:23

probe is positioned. You can see that here it's more anteriorly

19:27

positioned, whereas for the lateral collat- la- lateral

19:31

ligament, we translate the probe a little more posterior.

19:36

Now, coming to the posterior compartment, it's relatively

19:39

easier to scan. All we need to do is keep the patient in a

19:43

prone position with, of course, the knee extended.

19:47

And we are going to be looking at the posteromedial tendons, we're

19:51

gonna be looking at the biceps femoris, we'll be looking at the

19:54

common, uh, peroneal nerve,

19:57

and we'll have a quick look at the neurovascular bundle as well.

20:02

So coming to the posteromedial tendons over here, there are

20:06

three tendons that we are looking at.

20:08

We are looking at the sartorius, we are looking at the gracilis, and we are

20:12

looking at the semitendinosus. So we already discussed the

20:15

insertion of these tendons when they formed the pes anserine

20:19

tendons. Right? Now, at this level, on the posteromedial

20:23

aspect of the calf, we are predominantly looking at the

20:27

muscle belly or maybe the myotendinous

20:30

junction. So again, from medial to

20:34

lateral, we have the semi, um, uh, the

20:38

sartorius, the gracilis, and the semitendinosus.

20:42

So again, as we start translating the probe from

20:46

the posteromedial aspect, and we start going more towards

20:50

the medial or the anteromedial aspect, you see that

20:53

the muscles have changed into the myotendinous junction.

20:57

In fact, at this level, for the gracilis as well as the semitendinosus, we are

21:01

seeing predominantly the tendons over here.

21:04

And the other important structure which comes up over here is the

21:08

semimembranosus tendon. So in the same

21:12

plane as you identify the

21:14

semitendinosus, uh, uh, tendon, you

21:18

see a structure which is sitting below it, which is the

21:21

semimembr- semimembranosus muscle and the

21:25

tendon. So on the contrary, when you

21:28

have a challenge identifying the semitendinosus, what we

21:32

in fact do is try and identify the semimembranosus

21:36

and look at this kind of a structure, which is a cherry-on-top appearance

21:40

for the semitendinosus, that helps you to identify the

21:44

semitendinosus quite easily. And as we go a little

21:48

bit onto the medial aspect, we are again at the--

21:51

somewhere at the level of the medial femoral condyle, and we move

21:55

towards the popliteal fossa, we are able to identify the

21:59

medial head of the gastrocnemius.

22:02

Now, keep in mind that when you are in a plane where you're looking at the

22:05

semimembranosus and the medial head of the gastrocnemius, you may not

22:09

see both the tendons or the muscles nicely because there may be some

22:13

amount of anisotropy. So you may need to tilt your probe

22:17

a little bit and maybe angulate it to have a look at this

22:21

area better. And the importance of this area lies

22:25

in identifying what we call as the Baker's cyst, right?

22:29

So which typically lies between the medial head of the gastrocnemius and the

22:33

semimembranosus tendon. The

22:37

other structure which, uh, we'll go on to the

22:40

posterolateral aspect is the biceps femoris,

22:44

right? So the biceps femoris inserts again onto the

22:48

fibular head, right? And for looking at

22:52

the biceps femoris, what we can do is move on to the fibular

22:56

head. We look at this insertion of this tendon

22:59

posteriorly. So the short and the long head of the biceps combine

23:03

to give this appearance, and you can identify the,

23:07

uh, insertion of the tendon on the fibular

23:10

head.

23:12

Uh, if you have a little bit of a challenge identifying this, you can

23:16

also ask the patient to flex his knee.

23:18

Once you flex the knee, you can almost palpate the biceps femoris

23:22

on, on the posterolateral aspect, and you can palpate the muscle and the

23:26

tendon in order to identify this tendon a little more

23:30

easily. Now, when we are looking at the fibular head, keep in

23:33

mind that, you know, the, the fibular head is very

23:37

small. So identifying these insertions may be

23:41

challenging when you're not very accustomed to looking at it.

23:45

But of course, the more you practice it, the more easily you will be

23:49

able to identify the structures.

23:53

Now, as far as the neurovascular bundle is concerned, again, which is

23:57

something which is very important. Why?

23:59

Because you're looking at the popliteal artery and the popliteal

24:02

vein, and we need to keep in mind that some of these

24:06

popliteal fossa pains or, uh, swellings

24:10

can actually be involvement of the popliteal vein as

24:14

well. So when you're looking at abnormalities in the

24:17

posterior, uh, aspect of the knee, just

24:21

remember to have a look at the neurovascular bundle as

24:25

well, the popliteal vein, as well as the nerves.

24:29

So as far as the nerves are concerned-...

24:32

what we are looking at on the posterolateral aspect is the common

24:36

peroneal or the fibular nerve. And this is a bifurcation,

24:40

this- sorry, this arises, uh, from the sciatic nerve,

24:45

right? So

24:46

when we try to identify the common peroneal nerve, I

24:50

usually go all the way high up into the popliteal

24:53

fossa to identify the sciatic nerve.

24:57

And the sciatic nerve is relatively easier to identify. Why?

25:00

Because it travels along the popliteal artery, and you will see

25:04

this as this thick nerve. So you see this kind of an

25:08

appearance where you have these multiple fascicular,

25:12

uh, um, uh, um, fascicular appearance.

25:15

You can see these, uh, the nerve very well and identify it over

25:18

here. And once you trace it down, you can see the bifurcation of the

25:22

nerve. So the one which is going along the tibial vessel,

25:26

uh, along the popliteal vessel is the tibial nerve, whereas the one

25:30

which bifurcates and comes a little more superficially into the fascia

25:34

over here, this is your common peroneal nerve.

25:38

And again, this is important to identify because we do end up picking up a

25:42

lot of pathologies of the fibular nerve or the common peroneal

25:46

nerve.

25:48

Uh, so the common peroneal nerve winds along the head of the

25:52

fibula, and this is where it has a chance to get damaged

25:56

if there is a fracture of the head of

25:59

fibula. And this is the place where we end up picking up

26:03

these abnormalities of the common peroneal nerve.

26:07

And the common peroneal nerve can further, further splits into a

26:11

deep and a superficial branch, which can also be quite

26:14

easily traced on the ultrasound. So the advantage of

26:18

ultrasound is that you are able to do a dynamic scan, you can

26:22

trace the nerves, and you can identify these smaller

26:25

branches, and you can really identify pathologies

26:29

even coming up along these small branches as well.

26:34

Now, similar to what we said with the anterior cruciate ligament, posterior

26:38

cruciate ligament, we can identify the tibial attachment

26:42

over here, and, uh, the, we may not be able to

26:45

really identify the entire extent of the post- posterior cruciate

26:49

ligament. But if you do end up picking up a large

26:53

hematoma or you do end up picking a, seeing haemarthrosis in this

26:57

area, uh, keep in mind, you could potentially be looking at

27:01

a posterior cruciate ligament injury.

27:03

And in these cases, again, probably an MRI will be

27:07

helpful to identify the pathologies.

27:11

So having gone over the anatomy of the knee

27:15

joint, we'll quickly see some of the common pathologies that we

27:19

encounter in our day-to-day practice and how we put ultrasound

27:23

to use. So again, ultrasound is quite

27:26

useful because of its dynamic nature.

27:29

We have very high resolution. Some of these, uh,

27:33

newer, um, you know, higher frequency transducers can

27:37

actually make, um, it quite easy to identify these small

27:41

branches of the nerves or some of the pathologies and giving you

27:45

excellent resolution. So, uh, for the sake of

27:49

simplicity, we are just going to classify these pathologies similar to what we

27:52

did with our anatomy based on the compartments.

27:56

So first, coming to the anterior compartment, and we

28:00

talked about the quadriceps tendon.

28:02

So tendinosis in the quadriceps tendon, like anywhere

28:06

else, is going to appear, uh, uh, with a focally

28:10

thickened or hypoechoic tendon, and you may have a partial

28:14

tear where you have, may have a small disruption of the tendon,

28:18

and these are invariably associated with some

28:21

degrees of hematoma. So if you do end up picking up

28:24

hematomas, if somewhere close to the tendon, watch the tendon

28:28

out properly for the presence of any tear.

28:31

And again, you have to look at the entire length and width of the

28:35

tendon and make sure you're scanning from left to right in, in

28:39

order to cover the entire tendon. The

28:43

patellar tendon, again, is something which is commonly involved,

28:47

especially when you have, uh, you know, these athletes, they come

28:51

with anterior, um, uh, anterior knee joint

28:54

pain. Or if you have tendinosis of the patellar tendon,

28:58

similarly, you'll see a quite a thickened and a hypoechoic

29:01

tendon. If this thickness generally crosses about four to five millimeters,

29:06

you're looking at an abnormal tendon, and at times you may be

29:09

able to identify small clefts or even tears within this

29:13

tendon. If you are at times unsure whether this

29:16

tendon is definitely thickened or no, it may be a good idea to quickly

29:20

have a look at the contralateral side as well.

29:23

One of the advantages of ultrasound, and you can make a

29:26

comparison to try and identify if this tendon definitely

29:30

is pathological.

29:33

At times, you may get calcific tendonitis involving the patellar tendon,

29:37

where you get these hydroxyapatite crystal deposits within the

29:41

tendon. So you see these as hyperechoic foci,

29:45

generally with shadowing in, uh, later

29:48

stages. Uh, patellar tendon tear, again, more

29:51

common towards the inferior pole of the patella, and you may,

29:56

uh, end up picking this as a small fluid

30:00

next to the patellar tendon. If you look a little more closely, you will see that

30:03

there's some disruption of the fibers over here.

30:06

So this indeed was a partial tear, and in case you

30:10

do have a full-thickness tear, there are good chances of there being a

30:13

hematoma. But keep in mind that you may have a proximal

30:17

retraction of the patella. So if you see a patella which is

30:21

displaced, try and look at the patellar tendon to

30:24

identify any tear. Osgood-Schlatter

30:27

disease, not very commonly seen, but yes, you can see it

30:31

in adolescent athletes, where you see a fragmentation

30:35

of the tibial tuberosity. So you will see this irregular

30:39

appearance at the level of the tibial tuberosity.

30:42

You may end up picking up thickening of the patellar tendon as well, and you

30:46

may end up seeing soft tissue edema....

30:48

patellar fracture is rare, but this generally involves the

30:52

superficial cortex of the patella.

30:54

So what you see is a disruption in the superior cortex

30:58

of the patella, as you can see over here.

31:01

There's some amount of fluid over here, and you are able to see

31:05

this deformity, and you can, of course, compare it to the other

31:09

side. So here you are able to identify this kind of a step-up

31:12

or a step-off deformity. And the other

31:16

important thing is that the patellar tendon typically appears

31:20

wavy. So again, if you do identify a patellar tendon which is

31:24

wavy but everything is normal, have a look at the patella.

31:27

You may be looking at some pathology sitting up over

31:30

there. And this may-- this, it needs to be differentiated

31:34

from a bipartite patella, which may be an anatomical

31:38

variation.

31:41

Joint effusions is what we see most commonly in, uh, a

31:45

knee joint, where you have extension of the,

31:48

of, uh, joint recess by fluid. So you see

31:52

this fluid between the pre-femoral fat pad and the

31:56

suprapatellar fat pad. So you see this fluid separating

32:00

these two fat pads, and any fluid which is more than two millimeters

32:04

is generally considered as pathological.

32:07

Now, at times, you may miss out, um, on

32:11

small amount of fluids if you are looking at the knee in extension.

32:15

So if you give a little bit of flexion, you will see this fluid filling up

32:19

better. So again, if you're suspecting effusions, make a point

32:23

to do a little bit of a flexion extension in order to identify

32:27

these small fluids. Another important point

32:31

again, if you scan with too much of pressure, there's a chance that you may

32:35

miss out on, uh, the, uh, fluid. You may end up

32:38

displacing the fluid. So scan with gentle pressure, scan

32:42

the entire, uh, joint space in longitudinal as well

32:46

as in transverse, and you also go to the medial as

32:50

well as the lateral recesses because this is again, somewhere

32:54

where the fluid may accumulate. So identifying small amounts

32:58

of fluid in the medial or the lateral recesses is actually

33:02

easier.

33:04

So the joint effusions can be simple or complex.

33:08

Complex is typically when you have these kind of echoes which are sitting within

33:12

the joint fluid, and it can be actually difficult to

33:15

differentiate, um, uh, when you see complex fluid from a

33:19

septic joint, from a non-septic joint, and the only way you may get this answer

33:23

is doing an aspiration.

33:26

The other thing is when you see complex fluid, you want

33:30

to differentiate this from synovitis.

33:32

So what helps over here is the color Doppler.

33:35

So synovitis will generally appear as a hypoechoic

33:39

area with a lot of vascularity, and this will help you to

33:43

differentiate this from complex fluid.

33:47

So remember I mentioned about the presence of haemarthrosis,

33:51

and when you do have haemarthrosis, you are looking at

33:55

a joint which is more difficult to image, and you may want to

33:59

shift to your curvilinear probes or something with a higher- or even your

34:03

linear probes with a, uh, higher frequency, uh, I'm sorry, a lower

34:07

frequency, to get that penetration, to get that depth, to look at these

34:11

internal echoes. And if you do have significant

34:14

haemarthrosis, keep in mind there could potentially be an ACL

34:18

or a PCL injury. In this re-- In this case, we

34:22

are seeing a tear of the ACL. So tear of the

34:26

ACL, not very easy to identify, but we already saw

34:29

how the normal ACL looks. But if you see this kind of a

34:33

disruption or focal thickening of the ACL, keep in

34:37

mind that you're probably looking at an injury to the ACL as

34:41

well. And coming to the bursitis, we

34:45

already looked at the area of the suprapatellar bursa,

34:49

uh, and some of them have fancy names like the prepatellar bursa

34:53

is called the Housea. What you see is the presence of

34:57

fluid in the areas where you would expect a bursa.

35:01

Uh, this fluid, again, may be simple, or it may have septations or

35:05

echoes within. And if you turn on your power Doppler or color Doppler,

35:09

at times you may see this hyperemia in the periphery, and that

35:13

helps you to identify inflamed bursa.

35:16

Again, infrapatellar bursitis, you have a superficial bursitis over

35:20

here. So you can see that this is the patellar tendon.

35:23

There's fluid anterior to the patellar tendon, this is superficial

35:26

bursitis. On the contrary, the fluid over here is deep to the

35:30

tendon, so you're looking at the deep infrapatellar bursitis.

35:35

Very rarely, you may come across something like this, where you have an absent

35:39

patella or, uh, aplastic or a hypoplastic

35:43

patella. This is again, a rare condition.

35:46

This may be unilateral, bi- or bilateral, and maybe it may be

35:49

isolated or part of the knee patella syndrome.

35:52

You would typically get knee instability, muscle weakness, and you will see that

35:56

there's a gait disturbance when this child

35:58

walks. So moving on to the medial

36:02

compartment, and, uh, what we see most frequently over

36:06

here is injury to the medial collateral ligament. Right?

36:09

So how does this appear? Typically, the medial collateral ligament

36:13

is thick and hypoechoic, and this is more

36:17

frequent at the femoral attachment of the medial

36:21

collateral ligament. Generally, if this is more than six

36:25

millimeters in thickness, we are looking at a

36:29

medial collateral ligament

36:30

injury.... Now, tears, as

36:34

expected, will, uh, come up with a defect in

36:38

the medial collateral ligament, as we are seeing over here.

36:41

This can again be partial or it can be complete,

36:45

and this is generally associated with significant amount of

36:49

fluid. And the challenge is, with the fluid, it may be

36:53

difficult to differentiate the ligamental thickening, and that

36:57

is where a dynamic scan can play an important role.

37:00

So we give a valgus stress to the, um, uh,

37:04

knee, and with this, if we see an opening of the joint, we

37:08

know that there's a higher chance of there being a

37:12

ligament injury. And in fact, looking at the

37:15

degree of, uh, joint space widening, we can relate it to the degree

37:20

of the injury. So grade one is anything less than five millimeters, grade two

37:24

is five to ten, or grade three is more than ten millimeters.

37:27

But again, the dynamic nature of giving a valgus

37:31

stress, uh, helps you to identify whether there's a definite

37:35

injury to the medial collateral ligament or not.

37:39

Meniscus tears, yes, the superficial, uh, portion

37:43

of the meniscus can be visualized.

37:45

If you have a tear, it will look as this focal hypoechoic

37:49

area. Sometimes it may appear like a thin slit-like

37:52

structure, uh, which is hypoechoic.

37:55

It may go onto your femoral or the tibial attachment.

37:59

But again, we are not looking at the medial

38:02

meniscus in its entirety; we are only looking at the

38:06

superficial component. Meniscal extrusion, on the other hand, we are

38:10

far more certain when there's meniscal extrusion, especially in degenerative

38:14

changes. So if you have this meniscus protruding beyond three

38:18

millimeters of the, uh, joint space, you are potentially

38:22

looking at a meniscus extrusion.

38:26

A parameniscal cyst is something which can be very easily

38:30

identified on ultrasound. Again, this may have a lobulated

38:34

appearance, this may have septations, but when you do have a

38:38

parameniscal cyst, whether it's on the medial or the lateral aspect,

38:42

try to look a little closely. At times, this can be, or

38:46

a good number of times, this may be associated with a

38:50

meniscal tear, so you will ab- be able to identify the

38:53

reason of the parameniscal cyst. We already spoke

38:57

about the pes anserine bursitis, and what you see is fluid

39:02

between the, uh, medial collateral ligament and the

39:06

pes anserine bursa. This is not a great

39:09

example, but yes, you can see that there's fluid here, and you can

39:13

see that these pes anserine tendons are lifted above.

39:17

You are seeing the medial collateral ligament a little below, uh, so you

39:21

are looking at a pes anserine bursitis.

39:25

Coming on to the lateral compartment, again, we are going to be

39:29

looking at a lateral collateral ligament injury.

39:32

So this is going to present with a thickened and a

39:35

hypoechoic, uh, appearance of the, uh, uh, lateral

39:39

collateral ligament, and invariably, it will have a wavy

39:43

appearance. But again, keep in mind that sometimes this wavy

39:46

appearance may be normal, so you give a varus force to

39:50

identify whether this is normal or abnormal.

39:54

And again, you can potentially grade the, uh, lateral collateral

39:58

ligament injury as well, depending upon the widening of the joint

40:02

space, or if you do not have, uh, a widening of the joint space,

40:06

you can potentially look at whether there's a partial or a complete

40:09

disruption of the, uh, ligament fibers and grade

40:13

the injury according. So one of the common things that we

40:17

do end up seeing nowadays is the iliotibial band friction

40:21

syndrome, and this is a common overuse injury when it

40:25

comes to the runners, where you have friction of the

40:29

iliotibial band against the lateral, uh, femoral

40:32

epicondyle, uh, giving rise to this inflammation.

40:36

So what we see on ultrasound is there may be

40:40

thickening of the band, so the band may be about more than two or three

40:44

millimeters thick, and you may end up seeing fluid, either

40:47

superficial or deep to the band. So if you do end up picking

40:51

up this kind of fluid, which may be even subtle at times,

40:55

you are potentially looking at a iliotibial band friction.

40:59

And of course, invariably, the patient will kind of point out to where

41:03

he's having the pain, and you may end up picking up that, um,

41:07

uh, fluid. But it's a good idea to scan the entire

41:10

iliotibial band all the way from the lateral aspect, from the

41:14

top to the bottom. You may end up picking up small amount of fluids

41:18

at any point along the iliotibial band.

41:23

Uh, rarely, we can come across a biceps femoris snapping,

41:27

where the biceps femoris dislocates over the

41:30

fibular head during the mo- uh, uh, the flexion of the

41:34

knee. So we see this, uh, motion triggering

41:38

the, the kind of a snapping of the biceps femoris, uh, over the fibular

41:42

head when the patient flexes his knee, and this is associated with a

41:46

click, and the patient will, uh, identify this pain

41:50

and during that motion as

41:52

well. But, uh,

41:56

as far as the lateral aspect is concerned, the common peroneal nerve

41:59

is, uh, where we see a lot of abnormalities.

42:03

We may end up picking up compressions of the common peroneal nerve, and what

42:07

happens is that the nerve proximal to the site of compression will become

42:11

thickened. Here, for example, this patient had an injury and fracture to

42:14

the neck of fibula, uh, so the-- and he subsequently came

42:18

with, uh, a foot drop, and you can see that the common

42:22

peroneal nerve proximal to the site is actually thickened.

42:25

Again, we have done a comparison to look at these subtle changes in the

42:29

nerve edema. But what again helps

42:33

over here is the dynamic nature of the ultrasound, where we are

42:37

able to trace the nerve, and we are able to pick up these

42:41

small changes in the, uh, nerve at any

42:44

level.... Uh, this was a patient where actually this patient had

42:48

a traction injury, and you can see that there's a, a thickening

42:52

of this common peroneal nerve on almost its entirety

42:56

from the, uh, origin of the sciatic nerve to it's going

43:00

on to its, uh, bifurcation. And this patient was, in fact,

43:04

on a follow-up, so we have seen a progressive improvement

43:08

of, um, the-- or rather, a reduction of the nerve thickening as

43:11

well over a period of time. But another place where ultrasound really

43:15

plays a very important role is when you have these post-operative

43:19

patients. So this, for example, is a patient who had a history of an

43:23

ACL repair, and you can see that this screw is actually

43:27

indenting the nerve, and this is what was causing the tingling

43:31

numbness on the lateral aspect of, uh, the leg for

43:35

this particular patient, right? So as far as, uh,

43:38

post-operative imaging is concerned, we get very good results.

43:42

We are not, uh, you know, um, dependent on,

43:46

um, artifacts. So unlike MRI, where we may get

43:50

artifacts, and though we do have some, um, artifact

43:54

sequences, ultrasound can give you an answer quite

43:58

easily. Now, moving on to the posterior compartment,

44:02

what we see most commonly is the Baker's cyst, which is,

44:06

uh, uh, also referred to as the popliteal cyst, which is sitting

44:09

between the semimembranosus and the medial head of the

44:13

gastrocnemius. This can again be simple or complex.

44:17

You can have, at times, hemorrhage, you can have long-- if you have

44:21

long-standing, uh, cyst, you may have echoes, and you may even get

44:25

calcification within the Baker's cyst as

44:29

well. The more important part is

44:33

when you do have long-standing Baker's cyst, these

44:36

can at times undergo a rupture, and the rupture may be

44:40

partial or complete. Generally, you see if, if there is

44:44

a rupture, generally you see fluid, which is going along, uh, the

44:48

medial head of the gastrocnemius muscle or superficial to it.

44:52

But at times when there's complete rupture, you-- it's very

44:56

difficult to identify the cyst because the cyst kind of collapses,

45:00

right? So it's very irregular and difficult to visualize the

45:03

cyst, and what you may end up picking up is these small

45:07

pockets of fluid, which is, uh, at times superficial to the muscle

45:11

or at times even, uh, going deep to the muscle as

45:15

well. So any patient who has

45:19

posterior fossa pain, keep in mind that this could be

45:23

one of the, uh, uh, pathologies that you may be encountering.

45:29

So as far as the other pathologies that we encounter frequently, one, of

45:32

course, is the inflammatory arthritis.

45:35

We may end up picking up a thickened and hypoechoic, uh,

45:39

synovium, as we can identify over here.

45:42

And again, what helps us to differentiate this from the fluid

45:46

is the presence of this increased vascularity in

45:50

the synovium. So we are able to identify this, uh,

45:53

higher vascularity. And typically, what we use over here

45:57

nowadays is power Doppler, which is far more sensitive

46:01

for picking up the color flow.

46:05

And of course, you may have associated joint effusions as well.

46:09

Rarely, we can end up picking up a PDNS as well, where you end

46:13

up seeing these frond-like proliferations, uh, of the

46:16

synovium with, again, increase in

46:19

vascularity. Gout is something that we do

46:22

encounter even in the knee joint. You may end up picking up these

46:26

topheous deposits, which appear hyperechoic and,

46:30

uh, at times may give a modular or infiltrative

46:33

appearance, and, uh, it may, you know, almost give sometimes a

46:37

pseudotumor kind of an appearance if it infiltrates the

46:40

tendon. If, um, at times you may be able to

46:44

identify the presence of gout on the cartilage as well, so you see a double

46:48

contour sign on the cartilage, and this could be a

46:52

marker of gout. Uh,

46:55

degenerative osteoarthritis is something that we see very, very

46:59

frequently. So what we end up picking up is joint space

47:02

reduction. We see thinning of the cartilage.

47:05

You'll end up picking up osteophytes, and we already discussed about the

47:09

exclusion of the meniscus. But, uh, in some

47:13

cases, we may end up picking up loose bodies, and again, what we can do is

47:17

give a little bit of a compression onto these, uh, loose

47:21

bodies, and we'll see that they are floating in this joint

47:24

space. And, uh, this can be associated with a Baker's cyst, or

47:28

you can see these loose bodies like we saw in the Baker's cyst as well.

47:33

And again, when you're looking at, uh, posterior, uh,

47:37

pain, knee pain, keep in mind that this may not be associated with

47:41

structures of the knee. Sometimes you may have a muscle tear which is going,

47:45

uh, lower down, and one of the most frequently involved

47:49

muscles is the gastrocnemius. Uh, and depending on

47:53

the severity of the, um, uh... depending upon the degree of the

47:57

fibers' involvement, you can classify these injuries

48:01

into different grades as well. So when you're looking at a

48:04

grade one, typically you see a feathery pattern of

48:08

fluid. So this is involving about less than ten percent of the

48:12

fibers. So you see this kind of a feathery appearance of

48:16

the, um, um, at the myotendinous

48:19

junction. Uh, no significant gap or no significant

48:23

fluid. Uh, by grade two, you start identifying that there's a

48:27

visible gap with a hematoma, and now you're looking at something like a ten to

48:30

fifty percent involvement. Grade three tears are obviously much

48:34

more easily seen because you see a complete discontinuity of the muscle,

48:38

and you see this collection like what you're seeing over here between the

48:42

gastrocnemius and the soleus muscle.

48:45

Again, panoramic imaging plays an important role, whether you're looking

48:49

at a ruptured Baker's cyst like over here or you're looking at

48:52

a, uh, muscle injury, right? So it gives a good

48:56

perspective and, uh, of the lesions.

49:00

Soft tissue lesions, lipomas are what we end up picking up very, very

49:03

frequently. Nothing complicated about that....

49:06

but at times you may have a typical appearance of a lipoma, or you can

49:10

have these lesions causing compression of the nerve as

49:14

well, like we are seeing over here.

49:16

So keep that in mind if you do identify any soft tissue

49:20

lesions. And I mentioned before, one of the, uh, um,

49:24

um, mimics of knee pain is actually,

49:28

uh, uh, vein thrombosis, and this can, uh-- what we are

49:31

more worried about, of course, is the deep venous thrombosis involving the

49:35

popliteal vein. But at times you may have superficial vein thrombosis,

49:39

which can also give rise to a lot of pain and redness in the popliteal

49:43

fossa. And, uh, then keep in mind

49:46

that sometimes you just have to listen to the patient.

49:50

Uh, you may not see anything significant in the knee joint

49:53

or in, you know, in the, uh, neurovascular bundle, but you may

49:57

end up picking up just this kind of a subtle, small

50:01

neurovascular malformation like we are seeing over here.

50:04

And when you have these low flow malformations, what we do is apply

50:08

a little bit of pressure onto the probe to pick up the color flow

50:12

within these lesions.

50:15

And ultrasound plays a very important role as far as interventions is

50:19

concerned, because we are able to target the necessary area with a

50:23

significant accuracy, and, uh, we are-- because we are doing it

50:27

real time, we are reducing any risk to, uh,

50:31

risk of damage to the nerves or the vessels.

50:34

So there are different applications.

50:36

What we end up doing very commonly is aspiration of joint

50:40

effusions. Uh, we can do targeted injections to the joint or the

50:44

bursa. Uh, yeah, bigger cyst aspiration is also something that we end

50:48

up doing. But, uh, there is increased, um,

50:52

uh, interest in injecting corticosteroids and hyaluronic acid

50:55

into the joint space for degenerative conditions.

50:58

And of course, at times we end up doing something like a genicular,

51:02

uh, nerve block with a RFA or a microwave,

51:06

right? So as far as the joint aspiration is concerned, which is what we

51:10

end up doing most commonly, we try to approach from the

51:13

medial or the lateral aspect of the joint.

51:16

We avoid puncturing directly through the quadriceps.

51:19

This is an easier approach, and we place a needle

51:22

into the, uh, uh, joint for aspiration.

51:26

One of the things that I generally do is I go to the pocket, which is

51:30

more distant or deeper, aspirate the fluid from there, and

51:34

as we come out, uh, we are able to, uh, you know, aspirate the fluid, which

51:38

is more superficial. So if you're, uh, you're just able to

51:42

get a little more fluid out of that joint, and you can see that post

51:45

aspiration, in this case, that it's almost like a dry tap.

51:48

You've almost left nothing behind.

51:51

Uh, synovial biopsy is also something which can be done quite easily using our

51:55

ultrasound techniques. Uh, we routinely use a coaxial needle

51:59

with, uh, with a ten millimeter throw is what we usually

52:02

use, but this can vary depending on what pathology and how

52:06

much you are looking at. Bigger cyst aspiration,

52:10

again, um, based on under ultrasound guidance, we

52:13

puncture the cyst and, uh, uh, we try to

52:17

remove as much fluid as possible. But there can be certain

52:21

challenges over here, especially if the bigger-- uh, if this, uh,

52:25

fluid is very, very thick, can be a challenge to really aspirate

52:28

this. And if we are looking at a bigger cyst, I try to go in with a larger

52:32

needle, maybe something like a

52:35

twen-- eighteen gauge, or if required, even a sixteen gauge, if I have

52:38

clear access. I'm making sure that I'm not, you know, going anywhere close

52:42

to any nerves or vessels, um, and, and try to aspirate as much as

52:46

possible. But what we do also end up doing is injecting

52:50

steroid within the bigger cyst. That

52:54

also generally helps. And,

52:58

um, of course, a ganglion cyst can come up anywhere.

53:01

This, for example, was a ganglion cyst, which was probably communicating with

53:04

the, um, um, posterior cruciate ligament. I was not sure.

53:08

Unfortunately, there was no MR done for this case, uh, but, uh, we-- they

53:12

wanted to do an aspiration. But if you observe, this cyst already has a lot of

53:16

septae. So in fact, even after putting in the needle, we couldn't really

53:20

aspirate much, but we still went ahead with, uh, steroid

53:24

injection, and this patient did fairly well after that as

53:27

well. Uh, so that was, um, kind of a, um,

53:31

overview on, um, uh, the anatomy, ultrasound anatomy

53:35

of the knee joint and, uh, some of the common pathologies.

53:39

Of course, I think the most important aspect is, uh, getting

53:43

your, um, uh, habit of, uh, looking at the

53:47

joint on ultrasound. Once you do that, you can identify a

53:51

lot of pathologies. Uh, thank you so much.

53:55

Well, thank you so much for that lecture, Dr. Trabal.

53:57

We will open up the floor for some questions.

54:00

Yes.

54:01

Got a couple of minutes. Um, there's one in there already, if you can pop

54:05

that open. It's the Q&A box.

54:09

Okay, so please explain about genicular block indications and localization.

54:12

Okay, so for genicular blocks, normally these are

54:16

patients with, um, osteoarthritis or at times even

54:20

post, um, uh, post-uh,

54:24

surgery, right? Post TKR, they come up with refractory pain.

54:28

So I will quickly like to take you back to one

54:32

of my slides for the,

54:35

uh... Just give me a second.

54:38

Right. So when we look at the medial collateral ligament, right?

54:42

So this is, again, if you remember, your medial meniscus, you are looking at the

54:45

medial collateral ligament. As you start looking at the medial collateral

54:49

ligament, and you start coming inferiorly, can you see this neurovascular

54:53

band- bundle which is coming up over here?

54:55

This is your genicular nerve. Okay, so this is your

54:59

neurovascular bundle. So you have your artery as well as your nerve.

55:02

Maybe I think you'll see it again in this image as well.

55:06

So this will be your bony landmark for, um, the

55:10

ablation for the, uh, genicular nerve.

55:13

And of course, you have four sides, so you have, um, uh,

55:16

inferomedially, superomedially, and you can, uh, and you have that

55:20

laterally as well. Uh, so either you can do a

55:24

complete ablation or, um, uh, you know, you

55:28

can, um-... and do, um, specific,

55:32

uh, ablation of the nerve depending on, on the pain.

55:38

Okay, so another question is: How much reliable ultrasound is

55:42

as compared to MR? So I think we've gone over, um,

55:46

you know, um, uh, these, uh, things.

55:48

So if you're looking at structures like the patellar

55:52

tendon, the quadriceps tendon, you're looking at bursitis, you're looking at medial

55:55

collateral, lateral collateral, you're looking at, uh, you know, these,

55:59

um, uh, posterior fossa, um, uh,

56:03

problems, I think you have very good, um,

56:07

visualization. I think the only place where we do

56:11

end up, uh, with a little bit of challenge is the ACL and the

56:15

PCL, right? And of course, when you're looking at the articular

56:19

cartilage, unlike an MRI, you do not have the entire view because

56:23

you're looking at those specific areas for the, um, uh, cartilage

56:27

abnormalities. So that is where probably MR would,

56:30

uh, score a little bit more. But for all the superficial structures like we

56:34

saw, you know, it does very well.

56:39

So there's a question on, uh, post-op ultrasound after

56:43

metallic screw surgery. Yes, so, um, I mean,

56:47

uh, we do end up seeing a certain amount of, um, uh, post-op.

56:51

So I didn't really get the question over here, but I think this-- uh, I think,

56:55

uh, if it was with respect to the case I showed, uh, it was, it's actually

56:59

a misplaced metallic screw, which was, uh, impacting the common

57:03

peroneal nerve, uh, causing the, uh, uh, causing

57:06

the, uh, symptoms.

57:09

All right. I think,

57:11

I think you got all the questions. Thank you so much for doing this lecture and for

57:15

being here today.

57:16

Thank you.

57:16

Really appreciate it.

57:18

Thank you.

57:18

Thank you so much for everyone else for participating in this noon conference and

57:21

asking great questions. You can access the recording of today's

57:25

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57:28

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57:31

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57:35

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57:39

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