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Today we are honored to welcome Dr.

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Anjali Bajaj for a lecture entitled Imaging

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of the Lower Extremity Stress Injuries.

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Dr. Bajaj is currently an assistant professor

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of radiology at University of Arkansas for medical sciences.

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She completed radiology residency in 2017

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and fellowship in MSK Imaging and body MRI, both at UAMS.

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Her areas of interest include sarcoma

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and sports injuries imaging.

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At the end of the lecture, please join her in a q

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and a session where she will address questions you

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may have on today's topic.

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Please remember to use that q

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and a feature to submit your questions so we can get to

0:58

as many as we can before our time is up.

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

1:03

Bajaj, please take it from here.

1:06

Uh, thank you Ashley for the introduction.

1:08

Uh, hello everyone. Uh, have a good day.

1:11

Uh, my name is Gaan Lee.

1:12

I'm one of the M MSS K radiologists from Little Rock,

1:15

Arkansas, and today I'm going to be talking on imaging

1:18

of lower extremity stress injuries

1:20

and elite, uh, performers, which includes athletes

1:23

and even military recruits.

1:26

So in the next, uh, 50 minutes

1:28

or so, we are going to try to learn what are stress injuries

1:32

and how do these occur?

1:34

What are some of the characteristic imaging features

1:37

of various lower extremity stress injuries?

1:39

How can we easily diagnose them

1:41

and even learn about their grading

1:44

and how it affects management?

1:46

So let's move on. Um, so what are stress injuries?

1:49

Stress injuries are overuse injuries

1:51

of bone resulting from repetitive mechanical stress.

1:54

So when a normal healthy bone is subjective

1:57

to excessive stress, it overwhelms its capacity to repair

2:01

and heal, and it eventually cracks starts

2:04

by developing a micro crack that progresses

2:06

to a complete fracture.

2:07

And these injuries are

2:08

of significant concern in sports medicine,

2:10

especially in high performing populations like athletes

2:14

and military recruits engaged in repetitive high

2:17

impact activities.

2:21

So in college athletes, the incidence rates varies from 0.5

2:24

to 20% annually,

2:25

and the highest rates are seen in track and field athletes.

2:28

Uh, it's a high proportion of cases.

2:30

One of the most common injuries, uh, sports injuries

2:33

that we see in our practice

2:35

among military recruits undergoing basic training,

2:37

stress fractures are reported in up to 20% of men

2:40

and 40% of the men,

2:41

depending upon their training regimen and duration.

2:44

And the importance is these injuries lead to weeks to months

2:48

of rest and rehab.

2:50

This disrupts their training

2:51

and often leads to missed sessions.

2:53

Major competitions for athletes,

2:55

and if they have a severe injury, they may just lose out

2:57

of a competition or a game completely.

3:00

For military recruits,

3:01

that training disruption can even mean

3:03

disqualification from survey.

3:04

So that's a huge impact on somebody's career who are

3:08

that young, um, in their life.

3:11

So, um, stress injuries are basically of two types.

3:14

Um, first one is a fatigue fracture where, uh, it's, uh,

3:19

caused by abnormal stress on a normal healthy bone.

3:23

And this is what is common in athletes

3:24

and military recruits.

3:26

And this is the focus of today's topic.

3:28

The other form of stress injury,

3:30

which is an insufficiency fracture, which happens on, uh,

3:33

uh, from normal stress on an abnormal bone,

3:36

is commonly seen in osteoporotic or weak bone.

3:39

We will not be discussing this, uh, today.

3:42

So fatigue fractures are further, uh,

3:45

characterized into high risk injuries

3:47

and low risk injuries based on their location.

3:50

If they are in an area which is relatively avascular

3:53

or subjected to high tensile forces,

3:56

these injuries have high likelihood of progression

3:58

to complete fractures

3:59

and complications such as non-union and AV n.

4:02

So these are termed as high risk injuries

4:04

and low risk injuries tend to heal eventfully

4:07

and can be managed conservatively.

4:10

So stress fractures in lower extremities can involve any

4:13

bone, uh, in the pelvis.

4:15

They commonly involve the pubic bone

4:16

and sacrum and the extremity.

4:18

They can be seen along femur neck,

4:21

femur shaft tibia is the most common site of stress.

4:24

Lower extremity stress injuries classically seen along the

4:27

postal cortex in the distal third,

4:29

but occasionally you can see injuries along the

4:31

anterior cortex as well.

4:33

Um, occasionally we can see stress injuries along the fibula

4:37

within the patella, along the malli

4:39

of the tibia within several tarsal bones.

4:42

Metatarsals, again, are one

4:43

of the other common stress injuries, uh,

4:45

in the lower extremity that we get to see,

4:47

and occasionally even in the sesamoid.

4:49

So pretty much any bone can be affected by it.

4:53

The side of stress fracture will vary from sport to sport.

4:56

For example, track

4:57

and field athletes are more predisposed

4:59

to have navicular fractures.

5:00

These are one of the most common fractures

5:01

that we see in track and field athletes, followed by tibia

5:04

and metatarsal fractures and distance runners.

5:07

We see tib build fractures, any long bone fractures,

5:10

sacro pelvic fractures because of torsion

5:13

and femoral shaft fractures.

5:15

And dancers, probably

5:17

because of the way the foot is landed on the crown.

5:20

Uh, metatarsal fractures are very common

5:22

and military recruits, calcan

5:24

and metatarsal fractures are very common.

5:28

So based on, uh, where they're located,

5:30

if they're on the compressive side of the bone,

5:32

that the fracture gets compressed on weight bearing, um,

5:36

these are low risk, uh, fractures because they heal well

5:39

and can be managed conservatively.

5:41

On the other hand, if the fractures are on the tensile side

5:45

of the bone, they're subjected to excessive tensile uh,

5:48

forces, or they're located in a relatively

5:51

avascular area of the bone.

5:53

Those are high risk fractures.

5:54

These are, uh, they need to be managed aggressively.

5:58

Uh, they often require surgical fixation,

6:00

otherwise they won't heal well.

6:02

And these are some of the common locations listed for each.

6:06

So let's, uh, take a few minutes

6:08

to understand the risk factors, um, that, um,

6:11

predispose somebody to develop these, um, stress injuries

6:15

so they can be divided into biological factors

6:17

and biomechanical factors.

6:19

So let's look at the biological factors first.

6:22

So females have higher incidence of stress injuries

6:25

as compared to males.

6:26

It's just because of their build.

6:28

They have a narrow bone structure,

6:29

they have lower muscle mass

6:30

and have more hormonal fluctuations

6:32

that vary the bone mineralization.

6:35

And there's something known as female athlete tried.

6:38

It's a health issue in women athletes that we get to see,

6:41

which is characterized by disordered eating.

6:43

That eventually results in mens menstrual dysfunction, uh,

6:46

in conjunction with accessive activity

6:49

and eventually low bone mineral density.

6:52

Uh, it basically occurs when these athletes are burning more

6:55

calories than than they consume, leading

6:57

to energy deficiency

6:58

and hormonal changes that affect their menstrual cycle.

7:02

And eventually, bone health, low dietary factors such

7:06

as calcium and vitamin D deficiency will lead

7:09

to poor bone health

7:10

and bone mineral density, increasing the risk

7:13

for distress injuries.

7:14

There's something in, uh, known

7:16

as relative energy deficiency in sports medicine,

7:20

which is again, uh, similar to female athlete triad.

7:23

Basically, when the energy intake is chronically lower than

7:27

energy expenditure, the bone remodeling slows,

7:30

resulting in a very weak bone prone to injury.

7:34

And also low energy state, uh, affects, uh,

7:38

the estrogen and testosterone pro uh, production.

7:41

And both these hormonal hormones are anabolic to bone.

7:45

So deficiency of these hormones are decreased production

7:48

leads to something known, uh,

7:49

something like secondary osteoporosis

7:51

or osteopenia increasing the risk for stress injuries.

7:54

Uh, growth spurts can also be a window of relative weakness

7:58

because the growing is, uh,

7:59

the bone is growing at a faster rate than than

8:02

than it can be mineralized.

8:03

So it creates a window of relative weakness

8:06

and transient osteopenia

8:08

and increased risk of stress injuries in that phase.

8:11

Other factors include some people may have a

8:14

genetic predisposition.

8:16

Thyroid parathyroid disorders can affect calcium

8:18

balance in the blood.

8:20

Um, smoking and alcohol make somebody calcium

8:23

and vitamin D de deficient.

8:24

Um, so all these can affect bone mineralization.

8:28

So all these factors, um, make the bone osteopenic

8:32

and, um, such bone, um, such a bone is at an increased risk

8:36

to develop stress injuries.

8:38

Now, moving on to another

8:39

important category of risk factors.

8:41

The biomechanical factors,

8:43

which are also equally important in these athletes

8:46

and military recruits,

8:47

and the most important being their training pattern.

8:50

Like if they have a sudden change in the training volume

8:53

or training intensity puts a lot of stress on the bone

8:57

and the repair capacity of the, uh, bone,

9:00

uh, gets overwhelmed.

9:02

Any change, sudden change in equipment, uh,

9:05

changing in a training surface

9:07

or footwear like switching from playing on grass

9:10

to playing on concrete or sudden change in footwear.

9:13

All these will alter ground reaction forces

9:17

and increase load on the bone.

9:19

Um, other characteristics, bone and muscle characteristics.

9:23

Thinner bones, bones,

9:24

which have inherently low mineral density are more subjected

9:28

to stress response.

9:30

Um, atomic factors like some people have a little bit

9:34

of leg leg length discrepancy, lean mass foot type,

9:39

like a cvis type of a foot

9:40

or a flat foot, smaller calf cross-sectional areas.

9:43

These also can affect, um, the bone mineralization

9:47

and a repair mechanisms

9:48

and can predispose the people, uh,

9:50

the athletes to have stress injuries.

9:53

So identifying and addressing these risk factors is

9:56

important in preventing injury progression

9:58

and guiding both imaging and managing decisions.

10:03

Oh, I'm sorry. So how do these, uh, injuries happen?

10:06

So when a normally mineralized healthy bone is subjected

10:10

to excessive load, um,

10:13

from high impact forces from activities such as running,

10:16

jumping, intense field sports,

10:19

this cumulative mechanical load exceeds the bone's ability

10:23

to remodel and repair, and bone develops these micro cracks.

10:27

And when there are micro cracks in the bone,

10:29

the body repair, uh, mechanism sets in.

10:32

Uh, there is osteoclast accumulation at the

10:35

micro crack site.

10:37

Uh, there is a little bit of bone resorption,

10:39

but it is quickly followed by osteoblast activation.

10:42

There is new bone formation, there's bone deposition,

10:46

bone mineralizes remodels,

10:48

and it is back to the healthy staff.

10:51

But what happens in athletes and military recruits

10:54

because of repetitive ongoing high impact activities,

10:58

the bone doesn't have enough time

11:00

to repair these micro cracks adequately

11:02

before a new round of stress comes in.

11:05

So over time, these micro cracks progress

11:08

to over stress fractures.

11:09

So this is what happens, and that's

11:11

how these stress injuries develop.

11:12

And it's important to know

11:14

because we get to see the imaging, uh, part of it where it,

11:19

the stress injury will progress from just marrow edema

11:22

to some intracortical changes

11:23

and eventually to a discreet fracture line.

11:27

So these often present with vague, um, uh,

11:31

poorly localized pain, uh, that worsens with activity.

11:35

Clinical red flags for high risk stress injuries, uh,

11:38

include persistent pain at rest

11:40

or at night pain that worsens despite rest.

11:44

High risk anatomical areas like femoral navicular,

11:47

anterior tibial cortex.

11:49

So, um, when somebody presents with these symptoms, um, have

11:53

to be cognizant and try to pick up these injuries early.

11:58

So when do we order imaging?

12:00

Um, um, when the pain persists for more than one

12:03

to two weeks, despite adequate rest?

12:05

There's a high clinical suspicion if in high risk areas

12:08

involved, and sometimes we just do imaging

12:11

as a baseline evaluation to decide to return to play

12:15

or military duty clearance.

12:18

So what are the some of the imaging modalities

12:20

that we can use to evaluate these, uh, injuries?

12:23

Obviously radiographs are the first test done in such cases,

12:26

but they're extremely, um, less sensitive,

12:30

especially in the early phases of the disease.

12:32

But they do have an important role in follow up to see

12:36

how the changes progress.

12:38

MRI is the imaging modality of choice for this.

12:41

It's a gold standard. It's extremely sensitive.

12:44

It can easily localize the area of abnormality.

12:47

It not just helps in making us, uh,

12:49

helps us in making the diagnosis,

12:51

but also create the severity of the injury.

12:54

And creating the severity of the injury is important, um,

12:58

that decides the, uh, how these injuries will be managed.

13:02

CT has a limited role, particularly, uh,

13:04

when somebody's interested.

13:05

The surgeon is interested in knowing if there's truly a

13:09

fracture line, how extensive that fracture line

13:11

to no more cortical details is when CT is ordered.

13:14

So navicular fractures are some, is one entity

13:16

where CT is often per performed to determine

13:20

or delineate the fracture line well.

13:22

And to decide on the management bone scans

13:25

have an historic use.

13:27

They used to be used earlier

13:28

before, uh, wider availability of mr.

13:31

Uh, but they're, uh, they're highly sensitive,

13:34

but they have low specificity.

13:36

Any abnormality will show

13:37

as increased activity on bone scan.

13:40

Ultrasound has an extremely limited role.

13:42

It can occasionally be performed in clinic

13:45

for superficial injuries like distal fibrillary pain

13:48

and wanna look at periosteal reaction associated

13:50

with the stress fracture, but otherwise,

13:52

or some ultrasound guided procedures.

13:54

Other than that, uh,

13:55

doesn't have much role in in imaging of stress injuries.

13:58

So, uh, general imaging appearance

14:01

of stress injuries in a long bone.

14:03

Uh, the first, uh, the earliest sign of stress injury, uh,

14:08

in a long bone is, uh, appearance of periosteal edema.

14:11

So, um, you see localized periosteal edema at a classic site

14:15

known for, um, developing these stress injuries.

14:19

That will be the first sign, then it progresses

14:21

to endo edema.

14:23

So then you have periosteal

14:24

and non Indo edema injury progresses.

14:27

Uh, the forces increase, um,

14:30

or it's not picked up early in these stages,

14:33

this injury will progress to developing those

14:35

increase in micro cracks,

14:37

and those will start showing up

14:38

as intracortical changes on mr

14:40

and eventually it progresses to a discrete fracture line.

14:43

So even though when the fracture line is small

14:45

and incomplete, it's still a high grade stress entry,

14:48

we really need to pick up these early at a stage

14:51

where they're just at the stage of per osteo endo edema,

14:55

then they have better prognosis and better recovery rates.

15:00

One of the most common, uh, grading scheme, um, um, used

15:04

for these, uh, stress injuries

15:05

and long bones is MR based classification, which is proposed

15:09

by Fredrickson, uh, with, um, a later modified by joki,

15:14

uh, is the most commonly used, uh, severity grading system

15:18

for stress injuries of long bones

15:20

where grade zero is normal bone no changes,

15:22

grade one when we just see periosteal edema on

15:25

fluid sensitive sequences.

15:26

Grade two is when we see periosteal and endo edema

15:30

and fluid sensitive sequences.

15:32

Grade three is when you see those changes even on

15:35

a T one weighted sequence.

15:37

And grade four is when it develops intracortical changes,

15:40

which is further subdivided into four A

15:42

and four B, where four A you just have

15:45

ill-defined intracortical changes.

15:47

And four B is when you have a discrete fracture line.

15:50

So let's look at individual sites of lower extremity,

15:53

uh, stress injuries.

15:54

Uh, we can start from the top.

15:57

Uh, sacral stress injuries,

15:59

these are more common in long distance runners,

16:02

military recruits, female athletes.

16:04

Uh, these are often overlooked because again,

16:06

because of the non-specific presentation, they present

16:09

with low back pain

16:10

and then people start thinking of lumbar pathology

16:13

or with hip pain, then you're thinking of, um,

16:15

hip pathology.

16:17

It is also often clinically

16:19

and imaging wise confused with sacroiliitis

16:21

because again, that's an important cause

16:22

of low back pain in young individuals.

16:25

So we need to really know how these look different

16:28

or present differently from sacroiliitis.

16:31

Uh, but for all the risk factors that we discussed,

16:34

these are strongly associated with low energy states,

16:37

vitamin D deficiency

16:38

and pelvic biomechanics like limb length discrepancy

16:42

and sacro joint dysfunction Imaging, uh,

16:46

radio crafts are almost always normal.

16:47

It's very tough to pick up a sacral fracture on radio crafts

16:51

because of its complex anatomy overlap with bubble gas

16:54

and so on and so forth.

16:56

Um, MRI will be the gold standard

16:58

and can pick up the earliest stress response,

17:01

which is just in the form of mar edema.

17:03

In the sacral ala.

17:05

When the injury is more advanced,

17:06

we can see a discreet linear fracture line.

17:10

And the imaging hallmark

17:11

for this injury is you get a longitudinally oriented

17:15

fracture line in the anterior part of the sacral ala

17:17

paralleling the sacral LEA joint.

17:19

And that's how we differentiate it from sacroiliitis,

17:22

which is more common on the iliac side of the bone

17:24

'cause of the thicker cartilage on that side.

17:26

So remember, uh, longitudinal fracture line, uh,

17:29

along the anterior sacral Lela paralleling the side joint

17:32

surface, that's an imaging hallmark for a stress reaction.

17:35

Bone scans, again, historically used will show increased

17:38

uptake in the area of sacral, uh, ct when again,

17:42

if you wanna evaluate the fracture line better.

17:44

And also in older patients,

17:46

if they wanna rule out sacral insufficiency fracture,

17:48

cts more commonly used.

17:50

So an example here, uh, a young athlete presented

17:53

with right pelvic discomfort on fluid sensitive sequences.

17:56

We can see that, uh, geographic area

17:58

of marrow edema in the right sacral lala corresponding

18:01

hyperintensity on T one VA images were very small

18:04

fracture line along the anterior cortex

18:06

and then surrounding marrow edema.

18:08

So these, again, given the location, the distribution

18:11

of the marrow edema

18:12

and the presence of the fracture line along the anterior

18:15

cortex, it's it's highly suggestive

18:17

of a stress reaction given patient's history

18:19

that they're an athlete.

18:20

Um, this patient, these are low risk injuries,

18:23

and, uh, patient improved with conservative therapies.

18:26

So, um, since these are low risk injuries,

18:28

conservative treatment is almost always successful

18:31

with activity modification, protected weight bearing,

18:34

and then gradual pain guided return to sports.

18:37

Typical healing time is six to 12 weeks for these injuries.

18:41

And it's also important

18:42

to address the underlying risk factors that we discussed.

18:45

Um, that's an always an important part of management

18:47

of these stress injuries.

18:49

Often, uh, not, um, managed surgically until un, until,

18:54

unless we suspect a pathologic fracture.

18:56

So moving on to pubic cre, my stress injuries.

18:59

Um, these are seen in distance runners, military recruits,

19:02

soccer players, again 'cause of torsion, pelvic torsion,

19:05

and, uh, especially in females.

19:08

Um, this may present with, uh, groin pain.

19:12

And we know that groin pain in an athlete, um, has,

19:15

it's an umbrella term that includes, uh,

19:18

multiple theologies such as sitis, pubis,

19:20

the upper neurosis train,

19:22

and sometimes it can be just a

19:24

stress reaction in the pubic bones.

19:27

These are also associated with biomechanical asymmetry,

19:30

hip adductor overuse

19:31

because that's where the adductors, uh, attach

19:34

and low energy states.

19:35

In females, um, in pubic bone,

19:37

the stress reaction is more commonly seen along the inferior

19:40

ramus, uh, um, as compared to the superior ramus.

19:43

And occasionally it can be even seen in the body

19:46

of the pubic, uh, pubic bone parallel to the synthesis.

19:49

And this often coexists with ost prostitis pubis making, uh,

19:54

diagnosis challenging sometimes.

19:55

So what are the imaging features?

19:57

Uh, radiographs again, can be normal,

19:59

but along the inferior pubic c Remus, if there's a fracture

20:01

that has developed callous, you can see a localized area

20:04

of thickening, uh, sclerosis irregularity along

20:07

that inferior Remus.

20:09

Mr again can show earliest imaging features in the form

20:12

of marrow edema, pero edema,

20:14

there'll be surrounding soft tissue edema as well.

20:17

And in advanced cases, a discrete fracture line.

20:20

And, um, when things are confusing on Mr,

20:23

you really don't see a fracture line.

20:24

A CT may be performed to delineate the fracture line better.

20:28

There are no specific, um, uh, grading scheme for, uh,

20:32

this type of an injury.

20:34

Um, so pubic, uh, stress injuries are,

20:38

as we already discussed,

20:40

that they're more common along the inferior ramus at the

20:42

junction of the inferior and rami, and it's

20:45

because of the repeated tenile forces from the attachment

20:48

of the adductor magnus.

20:49

So this is an area of high stress,

20:51

and that's why an area good

20:53

for developing a stress response.

20:55

It's a young female track, uh, athlete

20:58

who participates in high jump

20:59

and hurdle race, so can imagine the amount of force, um,

21:04

and use of adductors in these cases.

21:06

Um, they presented with persistent right hip

21:08

and pelvic pain radiographs, you do,

21:11

you do not see a discrete fracture line,

21:12

but we do see some asymmetry along the inferior aus,

21:15

some localized sclerosis.

21:17

And Mr again makes the diagnosis very easy

21:19

where you see a fracture along the inferior aus

21:22

with a lot of callous formation.

21:24

So it's like a subacute or a repetitive entry.

21:28

So we see mar edema,

21:29

callous formation fracture along the inferior pubic Remus at

21:32

the junction of Remus initial tuberosity.

21:35

Now this is an example of stress response in the pubic bone.

21:38

This is a, again, a young, uh, tennis player that presented

21:41

with hip pain with high clinical suspicion

21:44

for s sports hernia, given the area of the abnormality.

21:47

And Amar shows asymmetric mar edema in the left pubic bone.

21:50

Um, it's compatible with, um,

21:53

stress response given patient's presentation and history.

21:58

Uh, one thing to note in this case is,

22:00

is a skeletally immature patient.

22:01

So what the symmetric findings

22:03

that we are seeing is just in complete fusion

22:06

of the hypothesis and should not be

22:08

confused for a fracture line.

22:09

Uh, the clue is that these are bilateral symmetric findings,

22:13

the age of the patient at the biggest clue,

22:15

and on the right there is no edema associated with it.

22:19

So, um, when you see mar edema

22:21

and a linear sclerotic fracture line within the pubic bone

22:24

in an athlete or a military recruit, you need to think

22:27

of a stress reaction.

22:29

How are these managed? Again, uh, similar principles

22:32

that lower risk in, uh, it's a low risk area.

22:35

Uh, it typically heals well with conservative management.

22:37

That includes activity modification.

22:39

Sometimes when there is associated sitis pubis

22:42

anti-inflammatories may help

22:44

and a lot of pelvic stabilization exercises, um,

22:48

individuals have to avoid aggravating activities like

22:50

cutting and twisting that again, um,

22:53

exert extort forces on the pelvis,

22:55

and that should be for six to eight weeks.

22:57

Um, physical therapy helps to address pelvic asymmetry

23:00

and adductor tightness and gradual return to sport in, um,

23:04

six to 12 weeks, depending upon the

23:06

severity and pain resolution.

23:09

Moving on to femoral neck stress injuries,

23:11

these are more common in military recruits.

23:13

Long distance runners, again, female athletes

23:15

with low energy states.

23:17

This accounts for 11% of all stress fractures and runners

23:21

and in femoral neck, one, one important factor

23:23

to consider is to determine, uh,

23:25

whether it's located on the medial side of the neck

23:28

or the lateral side of the neck.

23:30

The medial side of the neck is the compressive side.

23:32

It's under compressive stress.

23:34

Um, um, so it's, it's a low risk area

23:36

and it heals well with conservative treatment

23:39

as fracture parts are pressed together with weight bearing

23:43

the fractures on the lateral side, on the other hand, high,

23:46

high risk because they are under tenile strength.

23:49

So, um, they're at a higher risk for progression

23:52

to complete fracture and avascular necrosis.

23:54

And if conservative treatment fails, open reduction

23:57

and internal fixation is what is performed for these cases.

24:00

Radiographs are, again, uh, often, um,

24:03

negative early in the course of the disease,

24:05

but eventually may show sclerosis

24:07

or cortical break a periosteal reaction at the site

24:10

of the stress response.

24:11

And one of the earliest radiographic signs

24:13

of this femoral neck stress fracture is what is known

24:16

as the gray cortex sign.

24:18

Uh, it's not, uh, well seen on these radiographs, uh,

24:22

where you get a focal in distinctness

24:25

or loss of cortical continuity on radio crafts.

24:28

You really have to zoom the images

24:30

to pick up the subtle findings known

24:32

as the gray cortex line is just like a focal blurring

24:34

and in distinctness

24:35

of the cortex at the site of stress response.

24:37

Again, Mr makes the diagnosis easier

24:39

where it very easily shows the marrow edema, um,

24:44

along the, uh, periosteum and osteum

24:46

and eventually intracortical changes.

24:48

And a fracture side, again, the important thing is

24:50

to determine, is it on the medial side

24:52

or on the lateral side?

24:53

In cases of femur neck, um, marrow abnormalities

24:57

as an example of a 30 5-year-old marathon runner

25:00

that presented with left hip pain

25:01

radiographs really unremarkable.

25:03

We can try to look for that gray cortex sign, uh,

25:06

along the femoral neck.

25:08

Uh, really not very well seen on these radiographs,

25:11

but again, as I said, MR makes the diagnosis very obvious,

25:14

very have this localized mar edema along the medial femoral

25:18

neck with a horizontal fracture line

25:20

that's perpendicular to the cortex.

25:22

So this patient improved with this is a low risk injury, uh,

25:25

managed with conservative treatment.

25:27

This patient improved with six weeks of rest

25:29

and partial weight bearing.

25:32

Uh, in contrast, uh,

25:33

this is a lateral femoral neck insufficiency fracture in a

25:37

patient with chronic kidney disease

25:38

and renal osteo dystrophy.

25:40

This is not a fatigue fracture, just showing it

25:42

for comparison because I didn't have a case

25:44

of a stress injury on the,

25:45

or a fatigue fracture on the lateral side.

25:47

Uh, but a nice example

25:49

of a lateral sided femoral neck fracture

25:51

and an, uh, an insufficiency fracture in a patient

25:53

who has renal osteo dystrophy.

25:56

So again, because these are high risk, uh,

25:57

this patient immediately got a hip replacement for it.

26:02

Um, there's a specific, uh,

26:03

or a separate grading, uh, system

26:05

for femoral neck stress injuries, which was given by Rohan

26:08

and canula, uh, k***y, uh, in 29, uh, 18, uh, where, uh,

26:13

low grade injuries have only end osteo edema, grade one,

26:16

when, uh, the area is less than six millimeters, uh,

26:20

or the span of the edema is less than six millimeters.

26:22

And grade two is when end osteo edema extends

26:25

for more than six millimeters into the, uh, um,

26:29

medullary cavity.

26:31

And high grade are where there's presence

26:33

of a fracture line when the fracture is less than

26:35

50% width at grade three.

26:36

If it's more than 50% of the neck width,

26:39

it's it's grade four.

26:40

So higher grade femoral neck stress injuries have

26:42

longer recovery times.

26:45

So how are these managed? Uh, obviously, uh,

26:47

tense tension sided fractures are high risk for displacement

26:51

and avian and surgical fixation is recommended,

26:53

as we saw in the example though,

26:54

that was an insufficiency fracture.

26:56

Whereas compression sided fractures can be managed

26:59

conservatively with just, um, activity modification,

27:02

protected weight bearing,

27:03

and we can serially follow them up till they get better

27:07

and are okay to resume activities.

27:09

Uh, average return to sport is three to six months, uh,

27:12

longer a surgery is required, again, because of the site

27:14

and important weight bearing area.

27:17

Moving on to femoral shaft fractures, these are, um,

27:21

primarily seen in long distance runners, um,

27:24

military recruits and athletes with high volume

27:27

repetitive impact training.

27:28

Uh, typically triathletes, again, more common in females

27:32

with low energy states.

27:34

Um, these classically happen at the junction

27:37

of proximal middle third of the femoral shaft

27:41

where mechanical loading is the greatest.

27:43

And it's because of several muscle attachments, uh,

27:46

attachment of vaus medias

27:48

and adductor brevis, uh,

27:49

that exert a lot of compressive forces.

27:51

And, uh, there's a lot of stress re redistribution

27:54

that happens at this site.

27:55

So that's a classic location

27:57

for femoral shaft stress reaction.

28:00

Uh, these injuries present

28:01

with very poorly localized high pain

28:03

that worse with activity.

28:05

So this is clinically termed as high splints, uh, compared

28:08

to shin splints in tibia.

28:11

Radiographs, again, in early stages may in normal,

28:14

but in advanced cases may show periosteal reaction,

28:17

cortical thickening or an intracortical fracture line.

28:20

This is an, um, MR image, uh, that shows localized, uh,

28:24

periosteal and endo edema, um, uh,

28:28

classically seen along the post medial cortex, um,

28:31

of the femur shaft at the junction of proximal

28:34

and middle, one third by classic appearance

28:36

for a femoral shaft stress injury.

28:39

So given that this is only, um, periosteal

28:42

and endo edema with changes seen on both T two

28:44

and T one weighted images without any, uh,

28:47

intracortical changes, this will be fredrickson, uh,

28:50

grade three injury.

28:52

Um, this classification though, it is

28:54

for tibial stress fractures can be used

28:56

for any long bone stress injuries as well.

29:01

And these are low risk injuries,

29:03

so are often managed conservatively.

29:04

This is a more advanced case of, uh, femoral, uh,

29:08

shaft stress injury where, uh, there's lot of, um,

29:11

ob obviously peral edema and a edema intracortical change.

29:14

It's a lot of localized periosteal thickening and reaction.

29:17

Mm-hmm. So this would be a, a grade four A, um,

29:20

there's no horizontal fracture line,

29:22

so this will be a f fredrickson grade

29:24

four, a stress response.

29:26

So how are these managed?

29:27

Um, again, um,

29:29

they are more commonly seen on the compression side,

29:32

the post medial aspect, which is a low risk area.

29:35

So these are managed conservatively

29:36

with activity modification and protected weight bearing.

29:39

Typical healing happens within six to eight weeks,

29:42

but occasionally, if they are on the tension side, um,

29:46

then these are high risk and may require surgical fixation.

29:51

Moving on to tibial stress injuries,

29:54

tibia is the most common location for bone stress injury,

29:57

uh, and lower extremity in both athletes

29:59

and military recruits.

30:01

It can be seen across all age groups,

30:04

but more common adolescence.

30:06

Again, uh, phases of growth support female athletes with,

30:10

uh, rapid training load or low energy states.

30:14

Um, patients present with vague localized leg pain

30:19

with symptoms that worse become worse with activities.

30:21

So this is commonly referred to as shin, uh, shin splints,

30:25

which is a clinical condition of tibial pain associated

30:28

with running this condition is also known

30:31

as medial tibial stress syndrome.

30:33

Uh, it, it's a, again, an, uh, an term

30:37

that represents a range of injuries that just, um,

30:41

vary from just localized stress edema to peros titis,

30:45

to Fran cortical fracture, uh,

30:47

along the distal two thirds of the tibia.

30:50

Now, these tibial stress fractures can be of two types.

30:53

They can be transverse

30:54

and longitudinal transfers are more common,

30:57

longitudinal are very rarely seen.

30:59

And these transfer fractures, again, can be more like,

31:02

can be on the compression side or on the TenCIS side.

31:06

It's the, uh, compression sided transfer fractures

31:09

that are most common type of, uh, tibial stress injuries.

31:13

Uh, the tension side is the anterior cortex.

31:16

Again, these are not as common as the posterior fractures.

31:20

Um, but again, if they're there,

31:21

these are high risk injuries.

31:23

Uh, these posterior transfer fractures are most commonly

31:26

seen in long distance runners.

31:27

These are classically seen along the posterial cortex

31:31

of the distal tibian.

31:32

That's how sometimes we identify these, um,

31:36

injuries is when you have localized periosteal indo edema

31:40

along the post medial cortex of the distant tibia.

31:43

It's a li, uh, low risk zone, often managed conservatively.

31:46

And one of the hypothesis,

31:48

like why is this a common location, uh,

31:50

or tibia, is a common location for stress responses

31:53

because of a broader attachment of sous

31:55

and repeated contraction leads to traction perio sitis.

32:00

Um, the tensions, uh,

32:03

cited transfer fractures happen along the anterior cortex.

32:06

These are more commonly seen in jumpers, again,

32:07

because of, um, excessive force on the anterior cortex.

32:11

And anterior cortex is the tensile side.

32:14

It's a high risk side, excuse me,

32:18

and has a high propensity for non-union

32:20

and progression to complete fracture.

32:23

Uh, the third type, uh, tibial fractures,

32:25

which is a rare type, are longitudinal fractures, only 10%

32:29

of all table stress fractures.

32:30

These are associated with more marginal forces,

32:32

and it presents as a vertical fracture line

32:34

along the table shaft.

32:36

I can show you examples of all.

32:39

Uh, so imaging findings, radiographs, again, um,

32:41

early phases could be normal.

32:43

And when an advanced injuries can they show, um, uh,

32:47

localized, uh, perote reaction, cortical changes

32:50

and osteosclerosis, uh,

32:52

or a loosen fracture line in the cortex.

32:54

Uh, but obviously the radiographic findings typically lack

32:57

behind the symptoms, uh,

33:00

the high risk fractures along the anterior cortex

33:02

because they're high risk.

33:04

Uh, that, uh, horizontal fracture line in the anterior

33:06

cortex is also known as the dreaded black line.

33:10

And these are, because these are high risk,

33:11

they're associated with poor healing.

33:13

So whenever you see this, it's, it's not a good sign

33:16

that this patient has, um, high risk injury

33:20

that should be aggressively managed.

33:23

And for longitudinal fractures,

33:24

plain radiographs are relatively insensitive

33:27

for detecting those fractures because, just

33:28

because of the orientation, because these are longitudinally

33:31

oriented, um, they are not tangential to the extra beam

33:36

and they're not picked up the long radiograph.

33:38

So you often need CT and MR to delineate that fracture line.

33:41

And even if you see a longitudinally running linear luine,

33:46

the tib shaft can be mistaken

33:48

for a normal, uh, nutrient for.

33:51

So one has to be, uh, cognizant of that.

33:54

And if it's an athlete, they're hurting.

33:56

And you see something like this,

33:58

and there's a subtle hint in the form

33:59

of periosteal reaction, think of a stress reaction

34:02

and not a, just a normal nutrient for emina.

34:06

So, uh, how are these, uh, tibial stress injuries graded?

34:09

We have already talked about f fredrickson gradin,

34:11

which is the most common grading, uh, severity grading used

34:14

for these kind of injuries.

34:16

Um, I can just quickly go over these

34:18

because this is really important.

34:19

Any long bone stress fracture, we make a diagnosis on MR

34:22

by picking up thesal and industrial edema.

34:25

And the second most important thing as a radiologist

34:27

that we need to do is

34:28

to do severity grading based on this frederickson

34:31

classification so that they can be adequately managed.

34:34

The management depends on what grade of injury an athlete

34:37

or a military recruit is having.

34:39

So grade zero is, uh, normal bone with no edema, uh, at all.

34:43

Grade one is when there's only periosteal edema.

34:46

Grade two is when it's, uh, periosteal

34:48

and industrial edema seen on fluid sensitive sequences only

34:52

grade three when these changes are seen on a T one

34:54

weighted sequence as well.

34:56

And grade four changes are

34:58

when they're intracortical changes.

35:00

If they're ill-defined, it's four A.

35:02

If there's a discreet fracture line, it's four B.

35:06

This is an example of, um,

35:11

I think that's, sorry I put a femoral stress,

35:13

but that's why I was like, where is the fibula here?

35:16

So, uh, that's an example of a grade two injury

35:19

where you have periosteal and industrial edema.

35:24

Um, this is an example

35:26

of more advanced stress injury along the post medial cortex

35:29

of the, the distal tibia, where you have periosteal edema

35:33

and osteo edema.

35:34

With some intracortical changes.

35:36

There's cortical thickening.

35:37

So this will be a grade four, a stress response,

35:40

no horizontal fracture line is seen.

35:43

Another example here

35:45

where you have localized edema in the proximal tibial shaft

35:48

and cross-section imaging,

35:49

you can see perusal edema and a osteo edema.

35:52

Lot of intracortical changes.

35:54

Um, so this will be a grade four injury.

35:59

In this example, you have a nice discreet, um,

36:02

horizontal fracture line that's perpendicular to the cortex.

36:05

So this will be the highest severity grade four B

36:08

by fredrickson classification.

36:12

Another example of grade four B injury again,

36:15

and this is more in the proximal tibia, uh, I can see that,

36:19

um, uh, an incomplete fracture line

36:21

with surround a callous formation with surrounding, uh,

36:25

marrow edema and periosteal edema.

36:28

So, uh, the distal one third is the most common side,

36:31

but if you see injuries in the proximal tibia,

36:34

consider metabolic sources of injury

36:36

or that the patient has a relatively low energy state when

36:39

it happens in the proximal tibia.

36:41

'cause not a very, uh, usual site

36:43

for a tibial stress response.

36:46

Now, um, um, we talked about this, um, the high risk, uh,

36:51

part of the tibial stress injuries

36:53

that happen along the anterior cortex.

36:55

These are seen in athletes that perform jumping

36:57

and leaping activities,

36:59

and the anterior cortex is the tensile side of the tibia.

37:02

So these are high risk injuries.

37:03

Uh, and these are also areas of low vascularity

37:06

because of less muscle bulk covering the anterior part

37:09

of the tibia, and they have higher propensity for non-union

37:13

and progression to complete fractures.

37:14

And on radiographs, those horizontal intracortical fracture

37:17

lines, you call them as dreaded black line.

37:19

Again, whenever you have this, it's not a good sign.

37:23

Okay, so another rare form of tibial stress, uh, reaction,

37:27

which is a longitudinal fracture.

37:29

You've seen the radiographs earlier,

37:31

but, uh, this is the MR in that case where you can see a lot

37:35

of, so this was obviously a nutrient for MI,

37:37

you don't expect any marrow changes,

37:39

but this was a stress injury.

37:41

You can see a lot of periosteal industrial edema,

37:43

and you can appreciate that localized cortical thickening.

37:46

The, the intracortical fracture line on the axial images

37:50

and periosteal reaction on those, uh, coronal images.

37:53

And this, because it's an, uh, uh, it has a fracture line.

37:56

This was fixed surgically with an intermittent.

37:59

You can see the fracture line again on post-op images.

38:03

So how are tib stress injuries managed?

38:05

Uh, kind of, uh, have an idea that the low risk ones,

38:09

which are along the postmen cortex,

38:11

are managed conservatively with activity modification.

38:14

They take about four to eight weeks, uh, to return

38:17

to full activity when these are lower grade injuries.

38:20

If it's a high risk injury along the anterior cortex will

38:22

often require a prolonged nod weight bearing phase.

38:26

And if it doesn't respond to conservative management,

38:28

it can go for surgical fixation

38:31

and you can do a follow-up bone scan for monitoring.

38:35

So moving on to fibrillary stress injuries.

38:38

Um, these are overall less common,

38:40

but majority of them occur in runners and jumpers.

38:43

And it's not just compression,

38:44

but also, uh, torsional forces and muscle contraction acting

38:48

and resulting in these fractures and a cava type of foot.

38:51

As a risk factor for developing fibular stress fractures,

38:55

the most common site is the distal fibula, just proximal

38:58

to the inferior syndesmosis.

38:59

So knowing the, uh, classic location is important,

39:01

that just, uh, makes it easier to make the diagnosis.

39:05

But sometimes, uh,

39:06

occasionally proximal fibular stress

39:08

fractures have been reported as well.

39:10

They typically present with, uh, lateral lower leg pain

39:13

that increases with activity.

39:15

That's an example here,

39:16

a young female dancer presented with leg pain.

39:19

What we see on MR is, again, uh, localized periosteal

39:23

and industrial edema with localized cortical thickening.

39:26

Um, so this is a, this is a low risk area,

39:29

so managed conservatively,

39:30

and this patient recovered with conservative treatment

39:32

with rest, rehab, and a boat for six weeks.

39:38

So again, uh, these are low risk injuries.

39:40

They're often managed conservatively

39:42

and will rarely require surgical fixation.

39:45

Moving on to some other specific sites, uh, another site

39:48

that we don't get to see very frequently, uh,

39:52

but it's a known, uh, site

39:54

for stress injuries along the medial ulu.

39:57

This type of injury seen in track

39:58

and field athletes, BA basketball players, gymnasts,

40:02

and military recruits.

40:03

Uh, it occurs because of repetitive axial loading.

40:06

Very similar mechanism as to pylon fracture, like that's

40:10

how the plaform is affected.

40:12

Um, this along with foot inversion

40:14

and valgus stress, that puts a lot

40:16

of stress on the medial side of the plaform.

40:20

Uh, this presents with medial ankle pain, which is gradual

40:22

and onset worse with activity relief

40:24

by less all classic symptoms of a stress reaction.

40:27

But this location is a high risk location

40:29

because it doesn't heal well, radiographs may be negative,

40:34

but the classic imaging finding that you get

40:35

with these stress fractures is a vertically oriented

40:38

fracture line at the junction of the pho

40:40

and the medial milus.

40:41

So whenever with that suggestive history

40:43

that somebody's an athlete didn't have an acute traumatic

40:46

event, because otherwise you can think

40:48

of those post-traumatic ME ankle injuries.

40:50

But if there's an athlete, no acute traumatic event, just

40:54

progressive pain that will, um, worsens with activity,

40:59

and you see this kind of an imaging appearance,

41:01

uh, it's a stress reaction.

41:03

And again, um, x-rays, uh,

41:06

or radiographs show advanced changes when there's

41:09

already a fracture line.

41:10

But these injuries can be picked up in their earlier stage

41:12

with Mr, where MR can pick up localized mar edema at

41:16

that site, which will be the lowest grade of the injury.

41:19

And you start seeing a fracture line

41:21

that's a higher grade injury.

41:22

And once there's a fracture,

41:23

it'll often always be fixed surgically.

41:29

So this case, again, as you can, as we said,

41:31

it's a high risk injury, if there there is a fracture line,

41:34

the only treatment is surgical fixation.

41:35

And that's what this, um, patient underwent a screw fixation

41:39

of that medial ular fracture.

41:41

Um, how are these managed?

41:43

Uh, again, again, think we already addressed this.

41:46

Um, like if this, a low grade injury with just marrow edema,

41:49

that site, you can manage it conservatively

41:52

with not weight bearing immobilization for a couple weeks.

41:55

But if it's a fracture, if it's an elite athlete, um, it's,

42:00

there's any form of displacement, then there's no choice

42:02

but to, uh, do surgical fixation

42:06

and they can only return

42:07

to sport when they are clinically pain free.

42:09

And imaging shows fracture healing.

42:13

Moving on to another site, um, which is the calcaneus, uh,

42:16

we get to see insufficiency fractures

42:19

also a lot in this location.

42:20

But if it's a young athlete with normal bone mineralization,

42:23

that's going to be a stress fracture.

42:24

These are common end runners,

42:26

military recruits and basketball players.

42:28

Again, due to repeat repetitive axial loading,

42:30

it typically occurs in the posterior calcaneus near the

42:33

insertion of the calcaneus.

42:34

Again and again, the classic imaging feature is a fracture

42:37

line that's parallel to the posterior cortex,

42:39

but it, it can happen in the, in the body

42:42

or the anterior calcaneus as well.

42:44

Um, it presents with heel pain

42:46

and, uh, that gets worsened by impact and relieve with rest.

42:49

And again, if there's heel pain, we clinically think

42:52

of couple things, um, um, that includes plantar fasciitis,

42:56

at least end neuropathy, retrocalcaneal bursitis,

42:58

and, uh, stress response.

42:59

So often imaging is performed to differentiate

43:03

what is the cost for heeled pain in an athlete

43:05

or a military recruit.

43:07

These are low grade, uh, low risk injuries.

43:09

So they heal, uh, favorably,

43:11

which is conservative management.

43:13

This is an example of a young military

43:15

recruit with ankle pain.

43:17

Um, they had osteopenia for some metabolic reasons,

43:20

and you can see the bones look osteopenic,

43:22

and they had this subtle, uh, um,

43:25

linear sclerosis in the body

43:27

of the calcaneus along the superior cortex.

43:30

Um, but, um, it, it's subtle, it can get missed,

43:34

but it's an important finding that should be picked up

43:36

because this can represent a stress reaction

43:38

or this does represent a stress reaction.

43:40

But Mr makes it obvious where we see a very nice discrete,

43:45

um, low incomplete, uh, fracture line in the,

43:48

in the calcaneus.

43:51

Um, so radiographs can be normal,

43:53

but they can, uh, reveal such kind of sclerosis

43:56

or linear sclerosis is, are typically,

43:58

if it's in the posterior calcaneus, you have to think

44:00

of stress reaction.

44:02

So ing to the posterior cortex is an

44:04

important imaging feature.

44:06

And sometimes, um, CT may be performed to again,

44:08

delineate the fracture line.

44:10

In chronic and indeterminate cases,

44:12

they're often managed conservatively

44:14

because these are low risk injuries.

44:16

Uh, just rested out from impact activities

44:19

for four to six weeks.

44:20

Protected weight bearing, um, have

44:23

to address training errors because a lot of them will be

44:25

because of sudden increase in training, um, um, volume,

44:30

um, mileage

44:31

and change in footwear, uh, change in training surfaces.

44:34

So you have to address all those issues, uh,

44:37

or the, the sports medicine has to address those issues

44:40

and they can return to activity once they're pain free.

44:45

Moving on to another important, uh, stress injury,

44:48

which is of the navicular.

44:49

Now this is the most common stress injury that we get

44:52

to see in a track and field athletes.

44:54

It can also be seen in basketball players,

44:57

jumpers, military recruits.

44:58

Um, these are typically seen in young male athletes.

45:01

Um, again, it can be seen in females,

45:04

but more with patients who have low energy states

45:07

or biomechanical abnormalities like a type of a foot.

45:10

These are often underdiagnosed

45:12

because they present with a very vague midfoot pain.

45:15

And you really need a high index of suspicion

45:17

to think about these and order imaging

45:20

and pick them up early.

45:21

It's important to pick these injuries early

45:23

because it's an high risk area

45:25

and will go into non-union, if not picked on time

45:28

and managed appropriately.

45:31

This fracture is seen in the central third of the navicular

45:34

because this is in relatively avascular zone.

45:37

And another, um, important, um, aspect of this,

45:41

the imaging appearance of this fracture is the fracture

45:43

starts from the dorsal cortex,

45:44

runs in a sagittal plane towards the body of the navicular

45:48

and towards the plantar cortex.

45:49

So it's a very characteristic orientation, um,

45:52

that when it's present, you know,

45:53

it's a stress response like as shown in this case.

45:56

Uh, you see a fracture line, uh,

45:58

that starts from the dorsal cortex

46:00

and then progresses in a sagittal plane towards

46:02

the plantar cortex.

46:04

It may not go straight, it may go oblique,

46:06

but it eventually starts from one cortex

46:08

and ends to the other, other cortex.

46:11

There's a separate, uh, CT classification scheme

46:13

for this injuries because, uh,

46:15

often CT is performed in these fractures

46:17

to better delineate the fracture line

46:19

because it's the extent of the fracture line

46:21

that decides management in these cases.

46:23

So there is this weird point, uh, five type where, um, um,

46:28

you only see just MA edema in the navicular.

46:31

Type one is when there's a fracture

46:33

that has started in the dorsal cortex,

46:34

but has really not progressed

46:36

into the body of the navicular.

46:37

So these lower grade injuries are managed conservatively

46:40

with immobilization, strict non-weight bearing

46:42

for six weeks, and then gradual pro progression.

46:46

And then the higher grade injuries, uh,

46:48

is type two when fracture extends to the mid body.

46:50

And type three is when it extends to the other cortex.

46:53

So two cortices are involved.

46:55

Uh, the higher grade injuries are managed surgically,

46:59

and these is a high risk site, so all have

47:03

to be treated aggressively.

47:05

So in this case it was, uh,

47:06

this is the common surgical treatment for this fracture.

47:09

We do a screw fixation across that fracture site.

47:14

Again, we have already talked about these,

47:16

that non-displaced injuries,

47:17

lower grade injuries can be managed conservatively

47:20

and higher grade injuries fixed surgically may

47:23

or may not be with bone grafting.

47:27

Okay, moving on to another common, uh,

47:29

lower extremity stress injury,

47:31

which is metatarsal fractures.

47:32

These were first described

47:34

and you commonly know them as match fractures.

47:36

They were first described in military

47:38

recruits as match fractures.

47:39

Um, they're also seen in be delayed answers

47:42

and sports requiring repetitive food impact.

47:45

The common sites are, uh, second, third,

47:48

and fourth metatarsal neck and shaft.

47:50

So distill second through fourth metatarsals.

47:53

And it, they're most commonly affected

47:54

because of their, uh, immobile

47:57

or rigid position during gait or during walking.

48:00

And, but the good part is these are low risk injuries,

48:03

but there's certain metatarsal

48:04

stress injuries which are high risk.

48:06

And that's the what looks like a Jones fracture,

48:10

which is in the proximal fifth metatarsal.

48:12

Now, this is a high risk site because of poor vascularity

48:15

and poor healing potential.

48:17

These kind of injuries are again, associated

48:19

with low energy states, poor footwear,

48:21

abnormal biomechanics, and over training.

48:24

This is a nice example

48:25

of a full blood stress reaction along the second metatarsal

48:29

neck where we have, it's a grade four injury.

48:31

We have periosteal industrial edema.

48:33

We have an incomplete fracture line with gallus formation.

48:38

So, um, those are all, uh, low risk injuries.

48:41

But when it happens, um, in the proximal fifth metatarsal

48:46

or the metatarsal fifth metatarsal base, uh,

48:48

especially in zone two, it's a, it's a high risk injury

48:52

and will require surgical fixation.

48:55

There's another high risk metatarsal fracture, uh,

48:58

which again, uh, uh, it's seen, uh,

49:00

more commonly with dancers.

49:02

It's not as common

49:03

as the other metatarsal the low risk metatarsal fractures,

49:06

but can be occasionally seen.

49:08

Now this is important because this is close

49:09

to the less frank area.

49:10

It's in the proximal second metatarsal.

49:13

It should be recognized early,

49:15

and if it recognized early, it can be just treated

49:17

with four weeks of non-weight bearing immobilization.

49:21

So how are metatarsal stress fractures managed?

49:24

The low risk ones are just managed conservatively

49:27

with activity modification returned

49:29

to sports in four to six weeks.

49:31

But if it's, uh, first

49:33

or a fifth metatarsal shaft fracture, not the, uh, the

49:37

base fracture, it still can be managed conservatively

49:40

with a tall boot for six weeks.

49:42

But if it's in the base of the fifth metatarsal,

49:45

which is high risk, that will require surgical fixation

49:48

'cause it has a very high risk of non-union

49:51

and refracture, if not managed appropriately.

49:54

The last ones, uh, that we are going

49:56

to look at are the medial sesamoid stress injuries.

49:58

Again, not very common,

49:59

but we may see them, uh, seen in dancers, sprints,

50:03

basketball players, tennis players,

50:05

especially those placing repetitive stress on the four foot,

50:09

uh, playing on our, uh, turf as well.

50:12

Um, presents with gradual onset medial plant pain been, uh,

50:16

beneath the first metatarsal joint that worsens

50:19

with toe push off or extension.

50:21

Now this, that pain in that location, uh,

50:25

clinically can make you think

50:26

of several causes even on MRI imaging,

50:28

like when you have mar edema in the medial sesamoid

50:30

clinically, um, it can be a turf toe,

50:33

it can be just sesamoiditis

50:34

or it could be just pain from bipartite sesamoid.

50:38

Uh, female athletes with low energy states

50:40

and low bone density are at increased risk.

50:42

Uh, the imaging features is, uh, when you get, um,

50:45

bar edema right, it's bright on fluid sensitive sequences,

50:48

dark ated sequences, and you see a fracture line.

50:51

Now, sometimes it's not easy

50:53

to differentiate a fracture from a bipartite sesamoid.

50:56

Uh, we keep the same principles, uh,

50:59

where a fracture will have more irregular margins

51:02

and a bipartite uh,

51:04

fragments will have more smoothly corticated margins

51:07

and, um, may not be easy on mr.

51:10

Um, but if you have suggestive history

51:12

and it looks irregular, you may call it,

51:14

but you may do a CT

51:16

to further delineate the margins if they are

51:19

irregular versus smooth.

51:21

So this was a 17-year-old cross-country runner

51:24

with three weeks of medial four foot pain.

51:26

Uh, this was medial sesamoid my edema with a fracture.

51:29

Uh, this patient failed conservative treatment, so they had

51:32

to do a sesamoidectomy, um, for it,

51:35

and this patient returned to running in three months.

51:38

So early cases are managed conservatively with offloading

51:42

with stiff sho sole shoes, tan pads

51:44

or orthotics, activity modification for six

51:47

to eight weeks minimum and gradual return with, uh,

51:50

to sports with s resolution and follow up surgery.

51:54

If pain persists for more than three weeks

51:56

or these fractures go into non-union, we can do a partial

51:59

or total sesamoidectomy, um, which is reserved for elite

52:02

athletes, uh, with non-healing fractures.

52:05

And we also have to address, um, the foot biomechanics,

52:08

the low energy states,

52:09

and both all the risk factors basically associated

52:11

with stress injuries.

52:13

So let's do, we are almost getting done.

52:15

We've reviewed all the important, uh,

52:17

lower extremity stress injuries.

52:19

I'll do a quick recap just to highlight the important points

52:22

that you need to remember and that will make you, uh,

52:25

or help you make the diagnosis, um, easily.

52:29

Uh, for sacral stress injuries, look for marrow edema

52:32

and the sacral a alive, there's a fracture,

52:34

it'll be in the anterior, um, sacral

52:37

and the anterior cortex paralleling the SI joint surface.

52:41

Remember, these are low risk injuries,

52:42

so managed conservatively pubic ramus stress injuries.

52:45

These are most commonly seen along the inferior ramus

52:48

because of the adductor traction,

52:51

but occasionally they can be seen in the pubic bone

52:53

where they can mimic sitis pubis.

52:55

So make sure we know how to differentiate the two.

52:58

Again, these are low risk injuries, managed conservatively

53:01

femoral neck injuries.

53:02

One of the important things is

53:04

to know whether these are on the medial side,

53:06

which is the compressive side and are low risk,

53:08

but these are on the lateral cortex,

53:10

which is the tensile side,

53:11

and those are high risk radiographs are often normal,

53:15

but try to look for that gray cortex sign

53:17

and if it's seen, we can suggest otherwise Mr.

53:20

Um, um, can make the diagnosis very easy.

53:24

I shaft fractures, uh, these are most commonly,

53:29

again, they can be on the medial compressive side

53:32

or the lateral tensile side.

53:33

It's the medial compression side, which is the most common.

53:36

Again, these are lower risk injuries classically seen at the

53:39

junction of proximal and middle one third along the

53:42

post medial cortex.

53:43

These along the post medial cortex are the ones

53:45

that are low risk and can be managed conservatively.

53:48

Tibial stress injuries, the most common ones are the ones

53:52

that are low risk seen along the post medial cortex

53:55

of the distal tibial shaft,

53:57

but occasionally they can be seen in the proximal tibial

53:59

where you have to think of more low energy states

54:03

when they're in the anterior cortex.

54:05

They are the high risk injuries

54:07

because they're on the tensile side

54:08

and may require surgical fixation.

54:11

And also beware of this form,

54:13

which is a longitudinal fracture,

54:15

which can be completely missed thinking.

54:17

That is just a nutrient foramina, uh,

54:20

fibular stress reactions.

54:21

These are low grade injuries commonly seen in the

54:24

distal fibular shaft.

54:25

Similar imaging features at other stress fractures.

54:29

Know this appearance, uh, of a stress reaction.

54:32

If you have a vertical fracture line, uh, at the junction

54:35

of the tibial pho

54:36

and the medial meles that extends proximally.

54:39

And if it's seen in an, um,

54:42

person who's involved in high impact activities, athletes,

54:45

military recruits, marathon runners, um,

54:48

and no one specific acute traumatic event.

54:51

These are stress injuries

54:52

and if it's a fracture line, it's already an advanced stage

54:55

and needs surgical fixation.

54:58

Um, sorry, calcan stress injuries.

55:00

They are, and usually in the posterior

55:02

calcaneus paralleling the cortex.

55:04

These are low risk injuries.

55:07

Navicular, they have this classic imaging appearance

55:09

where the fracture line starts in the dorsal cortex.

55:12

The fracture line is in a sagittal plane

55:15

and then can progress either straight down

55:17

or obliquely towards the plantar cortex.

55:19

This is a high risk injury.

55:21

We have to pick it up early,

55:23

and these are often managed surgically.

55:25

And this is one entity where CT is often used for

55:29

severity grading and deciding onto the ma, uh,

55:31

for deciding the management.

55:32

The F fracture fixation and also for postoperative follow-up

55:36

is where CT is often performed.

55:39

Metatarsal, uh, uh, stress fractures, again,

55:42

comes in different flavors.

55:43

Um, along these are the second most common stress injuries

55:47

of lower extremities after the tibial cortex.

55:49

Um, the second through fourth distal shafts are low risk,

55:53

but if it's in the base of the fifth metatarsal, um,

55:56

that's a high risk injury.

55:59

Medial sesamoid stress injuries are, again, high risk

56:02

and will, uh, um, don't forget to look

56:04

for those marrow changes in the sesamoids

56:06

and know how to differentiate a fracture from

56:09

a bipartite sesamoid.

56:11

So just quick take home points that, um, the,

56:15

the stress injuries present with vague pain in athletes.

56:18

So it really needs a high index of suspicion

56:21

and early detection to reduce morbidity

56:24

and prevent progression to complete fractures.

56:26

You don't want them to be out of sport for a long time.

56:29

Um, radiographs followed by Mr.

56:32

Um, are the imaging modalities of choice.

56:34

Uh, MR is the gold standard.

56:36

It makes the diagnosis very easy.

56:38

And the second most important thing is to, um,

56:41

grade the severity of these injuries,

56:43

which is gonna decide management knowledge

56:45

of early imaging findings.

56:46

The typical locations, if it's along the post medial cortex

56:49

of the proximal femur shaft, post medial cortex

56:52

of the distal tibia fibula, that navicular, you know,

56:55

those are stress injuries even though means sometimes may

56:58

not have a good clinical picture.

57:01

Uh, some injuries are

57:02

and know the injuries which are high risk based on the

57:05

location and which are low risk

57:07

because the management is very different.

57:09

And, uh, it's the grade of the stress injury

57:12

that determines treatment

57:13

and correlates, uh, with time to return to play,

57:15

which is really important in these individuals.

57:18

These are my references

57:20

and with that, I thank you all for your attention

57:23

and I'll be more than happy to take any questions at this.

57:26

Thank you so much for your lecture, Dr.

57:28

Bajaj. That was fantastic.

57:30

Thank you. We

57:31

Do have a couple questions in that q

57:33

and a box if you're able to pop that open.

57:36

So the first question, in an immature skeleton

57:38

with sports injuries, ultrasound imaging can be used

57:41

for screening early detection.

57:42

It's a low cost modality, especially sacral

57:47

apophysis, uh, pubic apophysis, et cetera.

57:50

Any experience piece. So yeah, I mean, um,

57:53

ultrasound is just because it's so operative dependent.

57:56

Um, as a radiologist we rarely get to use it.

57:59

The sports, me medicine physicians can, um, they have

58:02

that in clinic and if they're suspecting they can just like,

58:05

you know, if it's like, especially if it's a distal fibrile

58:08

fracture, which is very superficial,

58:09

they can just keep the probe

58:10

and try to look for periosteal reaction.

58:12

So that's probably one of the, that I know.

58:15

And ultrasound guided procedures is something like PRP

58:18

injections for these steroid injections for these

58:20

can be ultrasound guided, but I've really not seen them

58:23

being used for pelvic

58:24

because pelvic stuff is anyway so difficult

58:26

to see with ultrasound.

58:28

I hope that answered that question.

58:30

Next, um, how

58:32

to differentiate pubic c stress injury from issue of pubic

58:37

and chondro syndrome?

58:40

Um, I think it's more of, uh, how the,

58:44

the clinical presentation is.

58:46

And, uh, the issue of pubic

58:48

and choros is usually not in like high impact

58:52

individuals like athletes.

58:53

It's just like in a growing, um, adolescent to individual.

58:57

Um, um, but even with minor activities, they start hurting.

59:01

It's because of that disproportionate growth

59:03

and muscle, uh, growth that it, uh, results in.

59:06

But if it's, uh, um, um,

59:11

what I, if it's an athlete

59:13

or you know, where the rema have already fused

59:16

and then you start seeing a racal line

59:18

or you start seeing marrow changes

59:20

or you start seeing, um, uh, a callous formation

59:24

where it has already fused, there is no immature synosis,

59:28

then you know, it's a stress reaction.

59:29

So it's more of how the presentation is,

59:32

whether the patient is skeletally mature or not.

59:36

Uh, next question is an athletes

59:39

with early stress reactions.

59:42

How can MRI finding guide decisions about load management

59:46

and return to play timelines,

59:47

particularly when no fracture line is present?

59:50

So I think there are guidelines for, um, every, uh,

59:55

site and depending upon what grade they are

59:58

and also the, the return to play, um, not just depends on

60:02

what we see on imaging based on like

60:05

what grade it is on imaging, but also the risk.

60:07

That's why I spend good amount of time on the risk factors.

60:10

So you also have to address the risk fractures.

60:12

So if they are vitamin D calcium deficient

60:14

or low energy deficient just by, um,

60:17

and um, it's a low grade injury, just don't, you know,

60:22

make them like, uh, do activity modification

60:25

or rest them out just for six weeks.

60:29

And in the, in the same time you have to address the,

60:31

the bone mineralization, the energy part of it

60:34

and uh, make sure it also is in par.

60:37

If that's not treated, you have to extend the period of, uh,

60:40

neuroton to play for those uh, individuals.

60:45

Okay. Um, it seems

60:48

that navicular stress fractures are frequently missed

60:51

with resultant cystic change

60:52

and, uh, DJD if painful are these treated with?

60:56

So that is, uh, that is true that navicular

60:59

fractures is something that, you know, um,

61:01

though they're one of the commonest fractures

61:03

in track and field athletes.

61:05

But if you're not in a setting

61:06

where you get too many athletes,

61:08

if you see this injury once in a while

61:10

and if you're not aware of that classic imaging appearance

61:13

or yes, often it gets missed and it'll progress.

61:16

And as I said, these are high risk injuries.

61:18

They will go into non-union, it'll progress

61:21

to midfoot arthritis.

61:22

And yes, after uh, once the midfoot arthritis has set in,

61:26

one of the good treatment options is to do a fusion.

61:31

But again, I mean I think we should refer

61:32

to orthopedic literature for, uh, exact, uh,

61:35

orthopedic management of these entries.

61:39

Um, how to differentiate an m MRI shin splints

61:42

from stress fractures.

61:43

So shin splints is more of a clinical term, uh,

61:46

not a term used on imaging.

61:47

On imaging, we just use stress response, stress reaction.

61:50

If it's just marrow changes without a fracture line, um,

61:54

we just say it's stress injury or stress reaction.

61:58

But if it's a fracture, you can go ahead

62:00

and say it's a stress fracture

62:01

or best is to just put the grade like, you know,

62:05

or describe it like you just see a

62:06

fracture or you just see marrow changes.

62:10

Alright, I think you got all the questions. Dr.

62:13

Bajaj, thank you so much for sticking

62:14

around and answering those.

62:15

Yeah, it's all my pleasure. I thank you all.

62:18

Yes, thank you so much. And thank you for everyone

62:20

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62:23

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62:25

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62:29

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62:32

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62:36

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62:39

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