Ultrasound of the Knee - Extraarticular Knee - SD

Introduction to Knee Ultrasonography

Greetings everyone and welcome to the knee module
of ultrasonography of the musculoskeletal system.

When you look at the knee, you could actually
break it into two parts, the extra articular portion
of the knee and that of the intraarticular portion.

Let's look at the extra articular portion,
but first telling you that the ultrasonography
of the knee involves evaluation of the tendons,
the ligaments, the bursa,
and as you could see on netter's cross-sectional imaging,
the multiple bursa around the knee,
you appreciate the super patella recess,
which itself is known as the super patella bursa
and that is the window to the knee.

As you could see that it communicates throughout the rest
of the knee, and as you go to the front
of the patella, you have the per patella bursa.

Further down, a little bit more inferior.
You have the infra patella burse,
the superficial one in front of the patella tendon
and the deep infra patella bursa just posterior
to the patellar tendon behind the knee.

Of course, you over here you see a supracondylar type
of bursa, but even more important,
although not shown here on another storing, is going
to be the baker cyst, which will include
as the intra articular portion of the knee.

After getting to know the bursa, we're going
to be looking at the signia further on.

And last but not least, of course,
for the intraarticular portion of the knee,
we're looking at the cartilage today with the extended field
of view of ultrasound.

You can appreciate the fidelity
of ultrasound gray scale imaging
to the known sectional anatomy presented by netter.

Starting from the top, you see the multipennate structure
of the distal quadriceps muscle
merging itself into the Musculo Tendonous Union
or junction into the febrile pattern
of the distal quadriceps tendon
to the bone acoustic landmark of the patella, back again
to a fibrile pattern of the patella tendon
and inserting into the bone acoustic landmark
of the tibial tuberosity.

The great scale imaging shows you a bit
of the penate structure
of the quadriceps muscle at the muscular tendon Tendonous
junction into the filar pattern
of the distal quadriceps tendon
into the bone acoustic landmark of the patella
and back into fibular pattern known as the patella tendon
and into its final insertion into the anterior tubial
tuberosity behind the patella region.

You'll notice the triangular S patella fat pad
separated from the premal fat pad by a small amount
of fluid, physiological fluid in the S patella recess,
much like what we see in Dr.
Netter, throwing from the S patella fat pad
to the premal fat pad to a tad bit of fluid
in the super patella recess below the patella, right
behind the patella tendon,
you have half a fat pad again showing the complete
resolution that we can appreciate between Dr.
Netter's throwing and our gray scale imaging.

If you look at the the long axis view with an extended field
of view, you can also catch the portion of the knee
and thigh in a short axis view.

Here you could note on the gray scale imaging the equivalent
counterpart of Dr.
Netter's drawing. First, the bone acoustic landmark
of the circumferential femur.

Here you can see it on Dr.
Netter's drawing around the femur in a short axis view
because it's short axis view,
then you can expect a Tite pattern
of muscle is the VAs intermediates to the medial aspect.

You have the AVAs media Alis,
and then you have the EVAs lateralis.

Dr. Netter's drawing shows a little whiteish tendon
because the rectus femoral is represented more
as a tendon in comparison that we chose a level
where we're showing muscle of the rectus femoral.

Regional Approach to Knee Ultrasonography

Another way to look at ultrasonography in a modular approach
is to look at the regions.

Here you have the anterior knee, the medial knee,
and the lateral knee.

This will entail all the extra-articular structures.

Later on will include the posterior knee,
which includes most of the intraarticular structures,
including the posterior horns
of the menisci and baker cysts.

Anterior Knee Structures

Let's start again on the extra-articular structures
of the knee with an anterior approach.

Looking at the quadriceps tendon with a quadriceps tendon,
putting the transducer in a long axis view,
identifying the bone acoustic landmark at the base
of the patella, then we should be able to duplicate exactly
what the cross-sectional anatomy wants to show us.

Here you see the mon acoustic landmark of the base
of the patella, the fbri pattern of the quadriceps tendon,
the super patella fat pad,
and you also appreciate the femoral condyle
with highline cartilage
and an imperceptible S patella recess.

When afflicted with some lesions,
the quadriceps tendon ordinarily will start
with some degenerative changes
or acute traumatic changes of tendinosis
here in a long axis view.

In an extended field of view, you appreciate that
as the quadricep stand
and inserts into the base of the patella,
you've lost the fibrile pattern that you were expecting,
but not all of it because here you see only the anterior
portion shows this thickened fusiform hypo genicity
of the distal quadricep tendon
representing the rectus fems portion of the tendon.

And if you go a little bit more posterior, you begin
to see the fiar pattern of the fastest intermediate.

So this region
or segment is relatively preserved
on short axis view.

You again, confirm
and build your confidence to the fact
that it is a focal affliction of the rectus femoral portion
that's affected because
of the effusive form hypo coic thickening in comparison
to the relatively preserved bristle pattern
of the vasts intermedius.

And behind it is the equally
or almost as hyper coic fat of the premal fat pad
of the femur when you have a tear.

The fibrile pattern's completely disrupted.

Here you see in a long axis view
where you were expecting some fibular patterns,
a hypo coic cleft transecting,
all the way from the bone acoustic landmark of the femur
to well above the bone acoustic landmark of the base
of the patella, representing fluid tracking
through the supra patella recess across the tear
of the quarry substandard into the pre femoral portion.

Note the relatively preserved S patella fat pad.

This is on long axis view and on short axis view.

Now you begin to realize the fact
that the hyper coic tendon is now being torn away from its
muscle junction by a high coic cleft of hematoma
and fluid cutting clearly
from the super patella recess all the way
to the skin surface.

The most commonly affected portion in the patients
that we have in our institution includes the
quadratus portion of the Ssus medias.

So this is the first region that most
of us would like to take a PA.

Let me show you first in long axis view a normal tendon
of the distal quadriceps.

Here you see the penate structure of the muscle,
and as it joins the fibrile pattern of the tendon,
you have the muscular tendon as junction note, the clear
and pristine fibrile pattern of the distal quadricep tendon
as it inserts on the base of the patella.

Behind that, you have the triangle
of the supra patella fat pad
and the peripheral fat pad with a moderate amount
of S patella effusion.

But if you look at a torn quadriceps tendon, you'll notice
that you no longer can appreciate that fiber pattern.

Instead, where you have a measurable gap
of a discontinuous quadricep tendon tear, you could see
that there is a herniation off the skin into that gap.

This is actually more like a clinical sign
that the clinicians would appreciate in the er as imagers,
we see the proximal stump of the torn quadricep tendon
and the distal stump
of the quadriceps tendon resulting in a downward
displacement of the patella known as patella baja,
and it's now exposing almost the entire convexity
of the femoral condyle.

Knowing musculoskeletal ultrasound
and MRI gives a lot of people healthy respect
of the baseline radiographs of most of these patients.

Note that on the lateral radiograph of the knee,
the left knee, a quadriceps tendon tear is easily suspected
because of the sup patella effusion.

Then you have a disruption of the patella silhouette
and a widening of the soft tissue outline
on the external portion of the knee.

But immediately on ultrasound, you can appreciate the fact
that you can identify immediately a measurable gap usually
filled with hematoma
and identify the proximal stump from the distal stump.

This is a classical example wherein you note that the tears
of the distal quadriceps tendon usually will involve one
or two centimeters right above the patella.

Now the long, from the long axis view going
to the short axis view, note that now you have a separation
of the tendon from the musculo tendonous junction
and also clearly you can appreciate the hematoma collecting
and separating the two stumps in a cross-section view.

Let's move from the distal quadricep tendon
to the patella tendon.

If the knee is more extended than flexed,
you will create some anisotropy of the patella tendon.

You'll appreciate
that there is some hypo echogenicity in the infra patella
portion of the tendon,
and also as it inserts into the anterior tibial tuberosity,
simply have your patient flex his knee a little bit more
and the same patient as you can appreciate here.

Now we see throughout its entire extent
the homogenous fibular pattern of a normal patellar tendon.

The most common lesion that most
of us would see would be a jumper's knee,
which is degenerative
or overuse disease of the proximal portion
of the patella tendon.

As it leaves the apex of the patella in MRI,
you may see increased intensity adjacent to the apex
of the patella While ultrasound
and remember that we are looking for
that fibrile pattern instead in its place we see this
fusiform hypo coic thickening of the tendon
and loss of the fibrillar pattern.

What's interesting about the jumper's knee
is more often than not,
if you look again at the same patient on short axis view,
you appreciate the fact
that you'll see this nodular thickening centric in this case
to the medial portion of the knee and or patella tendon,
and that this does not involve the entire patella tendon.

The other thing that you'd also appreciate is
that the inflammatory
or degenerative changes
of this disease will now extend into HFAs fat pad.

So patella tendinosis,
after you've identified it,
take a closer look at what's happening
because well within the substance of the patella tendon,
you begin to note that there is lakes
or Es being created,
representing now true inter substance partial thickness
tears or mucoid degeneration.

The other thing you'll notice is that
because of its proximity to bone and bone is an active organ
and it likes to react to violent instances.

Note that what used to be a crisp bone acoustic landmark
of the apex of the patella in this patient with chronic
jumper's knee now shows some cortical irregularity.

Jumper's knee is again the fusiform hypo coic enlargement
of the proximal portion of the patellar tendon.

And on short axis view, as noted in you see that it is more
or less eccentrically affecting and not the entire tendon.

What is important with these individuals is
to confirm indeed that it is hypervascular with the
neovascularization of this overuse syndrome in this
individual's and confirmed on power doppler.

In this case, the
adolescent equivalent
to jumper's knee is known ASC sending Larson
and Johanson disease.

If you look at the upper left hand image
with the radiographs, you'll notice that there is a
cortical disruption,
cortical disruption at the apex of the patella.

This is not a fracture here in a 16-year-old Norwegian boy
in Oslo, Norway.

The first image we actually encountered was the ultrasound
image where you see that there is a fissure
or fragmentation of the apex of the patella
and fusiform hypo coic thickening
of the proximal patella tendon.

Because this was a very promising varsity athlete,
of course, we went ahead and asked for an MRI.

Here you could see the increase intensity of the
proximal patella tendon adjacent to the apex of the patella
with mild signal changes involving the cortical portions
of the patella.

Patella tendon rupture usually will occur almost just like
the quadriceps tendon about one
or two centimeters from the patella.

Note that on the MRI image,
you'll have increased signal intensity
of the proximal portion of the patella accompanied
by slackening or even telescoping of the tear.

On ultrasound, you have lost all the fi pattern.

You have a measurable distal stump from the proximal stump,
which is at near at the apex of the patella.

An artifact, which is the refractory artifact,
helps us a lot with ultrasound
because this identifies the edge of the stu.

Likewise, on ultrasound, it was easier
to identify the high level echo representing the heterotopic
ossification in this individual's.

In comparison to the MRI, which was a tad more difficult
and retrospectively identified
after we've done the ultrasound as a signal void within the
distal stu of the tendon,

A discontinuous patellar tendon will have a measurable
gap in its place.

You'll have a hypo coic hematoma one more time.

The edge of the proximal
and distal stumps have this refractory type of artifact
that will help you identify a true tear in these tendons.

The short axis view of course, clearly now shows that
what we expected to see as a bristle pattern
of a tendon is almost occupied completely
by this hypo coic hematoma with some fluid trickling
around the anterior portion of the patella.

It's not uncommon to have a diffused patella tendon tear.

Notice that the entire berro pattern is disrupted
and well within it you'll have longitudinal creation
or separations of the fibers.

In addition, you can appreciate that indeed is a tear
because there is some herniation
of hoffa's fat pad into the posterior portion
as the tendon decompensates
and the distal stump again allows more of the fat
to herniate into this defect.

Same patient now on MRI.

A little bit more difficult to appreciate the distal portion
of the affliction because of the lack
of increased signal intensity,
but again, the change in contour helps for the confirmation.

Likewise, on the fluid sensitive actual images
here at the patella distribution, you'll see the
complete inter substance changes
afflicting this diffuse patella tendon tear.

Bursae of the Anterior Knee

The burse are very important and they're vir virtual spaces.

The prep tailor bursa, if you're not careful,
might be completely a face merely by the weight
of your transducer.

Here you see the bone acoustic landmark
and a virtual space of the per patella bursa.

As you go further out now here in an illustration, notice
that it is eccentric towards the apex of the patella.

On radiographs, you'll see the soft tissue swelling
overlying the patella.

On ultrasound definitively, you begin
to appreciate the distended bursa
and that of the synovial lining of the bursa.

So when you have pre patella bursitis,
aside from identifying the fluid,
take a look at what's happening to the nuvia.

The synovitis accompanying the perella bursitis in this
patient in long axis view
and in short axis view tell us
that there is not only the proative proliferative changes
of bursitis or the nuvia,
but also the dirty subcutaneous fat.

As you can appreciate it in somebody
with gouty arthritis disease
and gouty bursitis,

this is a great case
to illustrate why sometimes in the ER it's very difficult
to identify if the patella tendon is intact
because of the overwhelming soft tissue swelling.

As you can see here, here in Hema bursitis,
not only is the superficial infra patella bursa distended
with uncomplicated fluid,
but also it tracks all the way
to the prep patella bursa itself.

But clearly you can appreciate
that it's all extra articular subcutaneous
and does not affect the intact patella tendon.

Sometimes you'll get
to see a deep infra patella bursitis right
behind the patella tendon.

Here you see the fibular patterns
of the distal patella tendon
and behind it a extended sac
of the deep infra patella bursa, distal patella tendinosis
probably in younger individuals, better appreciated
as an ostrich slaughter's disease.

You not only appreciate the fusiform hypo coic thickening
of the distal patella tendon,
but you also begin to appreciate the fragmentation
of the apophysis.

And of course now you see the distended infra patella bursa
on long axis, readily seen,
but also on short axis, especially
for the fragmented hypotheses.

Medial and Lateral Knee Structures

We're gonna skip that part.

Okay, let's now look at the two sides.

The medial collateral ligament
and that of the lateral collateral ligament ligaments connect bone to bone,
and so from the femoral condyle to the neck of the tibia,
you connect those two points.

You begin to see the trilaminar portion
of the medial collateral ligament trilaminar
because you have a hyper coic superficial layer
and then you have a hyper coic deep
layer in between the two.

You appreciate the relatively hypo coic fibro
layer of this medial collateral ligament
over the joint line.

So this trilaminar structure stretches from the
femur to the tibia.

Likewise appreciated on netter's drawing at the bottom
of this slide,

Medial collateral ligaments are readily torn when there's
especially some valgus stress on the knee.

First, let's look at the unaffected side where you see the
intact superficial layer, the deep layer,
and the relatively hypo coic fiber aral layer.

In comparison to the affected side, notice
that there is a large collection of fluid in this case,
acute or subacute blood,
separating the superficial layer from the deep layer in
somebody with a acutely swollen medial collateral
ligament or strain.

Medial collateral ligaments like
to tear at the femoral level, as you could see here
with the disruption with this hypo coic cleft separating the
superficial layer from the deep layer, both in long axis
and in short axis

Because these are wide sheets,
they actually tear in as exact fashion.

Note here, the bone acoustic landmark of the femoral condyle
and the tibial condyle separated at the joint line
where you're expecting a trilaminar structure.

Now you have hypo coic disruption at the femoral level
and that of the et tibial level, of course,
relatively preserved in the center.

You could see some slackening off a trilaminar structure.

That's because medial collateral ligament there like to
zig zag for confirmation.

It's not uncommon from the ultrasound study to go ahead
and look at the MRI images here in the MR image.

As you can appreciate clearly that there is a disruption
of the femoral level of not only the superficial layer,
but here floating in the breeze.

Fleeing the breeze is the deep layer of the
medial collateral ligament.

Let's now jump to the tibial level on the MRI coronal image,
and you could appreciate the torn portion
of the superficial layer,
and again, blood in between this two approximating exactly
what we were appreciating on the ultrasound image.

When you have a high level echo,
this represents the heterotopic ossification
or dystrophic calcification of pellegrini theta.

On your left hand side,
you see the entire trilaminar structure
of the medial collateral ligament.

On the abnormal side, which is in the right hand part
of the slide, you'll see this high level echo
with posterior acoustic shadowing
representing the state lesion.

We'll skip the best answer arenas, okay? Mm-hmm.

The lateral collateral ligament, again is bridging
between the femoral condyle to the head of the fibula.

In a small field of view, we see this fibular pattern
of the lateral collateral ligament
as it crosses the joint line of the femur and tibia.

Netters drawing shows you clearly
that it takes off from the femoral condyle going into
the fibular head.

So with an extended field of view that one,
one can employ an ultrasound.

Here you can appreciate the fact
that the PAC fibular pattern now connects all the way
to the head of the fibula, tears
of the lateral collateral ligament like
to occur at the tibial level rather than at the femoral
level, just opposite of that
of the medial collateral ligaments.

So you'll see this hypo coic gap.

And of course, in its place you have the hematoma clearly
identifying what's going to be the distal stump from
the proximal stump.

The iliotibial band is a wide sheet of pon neurosis
that starts on the pelvic iliac crest all the way
to girdie tubercle.

So as it goes down to insert into gird tubercle,
you can place in long axis view your transducer in order
to identify the Pac fibular pattern of the idio tibial band,

iliotibial band syndrome.

Very common in long distance.

Runners and bicyclists will show
that there is some bures de novo at the level of the femur,
but also some hypo coic edema affecting the
iliotibial band proper.

If acute, you might even see some fluid
around the subcutaneous region.

Summary of Extra-Articular Knee Ultrasonography

So for the extra articular portion of the knee, remember
that ultrasound is exquisitely great
for the extensor mechanism, which includes
not only the quadriceps tendon and patella tendon,
but also the patella proper itself.

And don't forget that the extensor mechanism does include
the RET macula, both lateral and medial.

These also can be diagnosed quickly with ultrasounds
for any tears or strains.

Remember that the collateral ligaments have been shown
nicely on ultrasound
and how quickly we can diagnose using ultrasound
when we have any diseases affecting this ligaments,
especially for sports injuries and trauma.

Thank you very much for your attention.