CM-Musculoskeletal Radiology

Question 1

What are the 7 things that can be viewed on plain film?

Answer 1

1. cortex
2. trabeculae
3. Joint space
4. joint fluid
5. muscles and fat
6. soft tissue gas
7. foreign objects

Question 2

How does the look of fat and fluid look different on the plain film?

Answer 2

Fat is darker gray and fluid is a lighter grey.

This helps identify effusions

Question 3

What 4 things are radiographs not able to see? What would you do instead?

Answer 3

1. complex bone anatomy (overlapping joints)- CT
2. marrow edema for early bone infection/tumor- MRI
3. fine soft tissue detail : MRI
4. metabolic activity : PET/ NM

Question 4

What is a Colles fracture?
Which bone is fractured?
It is seen most frequently in people with what?

Answer 4

The fracture you get when you fall on an outstretched wrist.
It is fracture of the distal radius with dorsal displacement of the wrist/hand

Seen in people with osteoporosis

Question 5

what 3 things do you need to do to get a good radiographic exam?

Answer 5

1. get at least 2 orthogonal planes (one view is no views)
2. use proper technique (kV, mAs)
3. ensure good patient positioning:
   - centering the body part of interest
   - true AP, lateral, one or more standard oblique

Question 6

What is kV and mAs for radiography technique?

Answer 6

kV determines contrast. Less kV = more contrast

mAs determines density. too much mAs = overexposed film

Question 7

Describe the 3 steps in systematically reading musculoskeletal radiographs.

Answer 7

1. check the bone
   - alignment (normal shape)
   - periosteum (should be invisible, if calcified= tumor or fracture)
   - cortex (smooth/uniform around the bone)
   - cancellous bone (uniform/orderly in metaphysis)
2. check the joint
   - alignment (articulated bones centered to each other)
   - joint space (uniform and wide enough for cartilage)
3. check the soft tissue
   - edema (swelling)
   - effusion (displaced articular fat pads or fluid levels)

Question 8

How should the periosteum look on a normal radiograph?

Answer 8

It should be invisible.

If it is calcified, it is a sign of fracture or malignancy

Question 9

What is the difference between a complete and incomplete fracture?
Who is more likely to get an incomplete fracture?

Answer 9

Complete goes from cortex to cortex.
Incomplete does not cross from cortex to cortex. Children are more likely to get incomplete fractures because their bones are more elastic.

Question 10

What is the difference between a simple and comminuted fracture?

Answer 10

Simple = 2 bone pieces
Comminuted = 3 or more separate fragments of bone

Question 11

What is the difference between closed and open fracture?

Answer 11

If the hematoma around the fracture communicates with the outside world, it is open (also called compound fracture)
This appears as gas tracking down the fracture.

Question 12

What is an impacted fracture?

What is an overriding/overlapping fracture?

Answer 12

Impacted: the bones fragments are driven together.
Overriding: fragments of long bone lie side by side

Question 13

What is angulation?

What is rotation?

Answer 13

A: You can describe something as apex lateral or medial angulation of the distal fragment. It is description given to the break

R: the bone turns after it breaks. most serious misalignment and toughest to see

Question 14

What are the 5 signs of fracture on plain fillm?

Answer 14

1. disrupted cortex
2. disrupted trabeculae
3. soft tissue swelling
4. fat plane displacement
5. hemarthrosis/lipohemarthrosis

Question 15

If the elbow fat pad is displaced after trauma, how should you treat the situation?

Answer 15

Treat it as an occult radial head fracture until proven otherwise.

Question 16

When a fracture is present in the ulna or radius, what should you look for?

Answer 16

They form a ring, so if a fracture is in one, you should pay attention to the elbow and wrist joints which can also be points of failure.

Question 17

What is Galeazzi fracture?

Answer 17

fracture of the radius above the wrist combined with dislocation of the distal ulna.

Question 18

What is the normal height of a vertebral body?

What can cause compression fractures with loss of height?

Answer 18

Somewhere between the heights of the one above and below.

Axial loads and flexion injuries can cause compression fractures with loss of height of anterior parts of the vertebral body.

Question 19

When examining the spine, you note compression of the anterior parts of the vertebrae. What are the 2 most likely causes?

Answer 19

Compression fracture by:

1. axial load
2. flexion injury

Question 20

What is the loss of anterior and posterior body height of vertebrae indicative of?

Answer 20

a burst fracture with potential retropulsion of fragments into the spinal canal

Question 21

How does the ring structure of the pelvis affect its fracture pattern?

Answer 21

The pelvis tends to break in two places when it breaks

Question 22

A subtle ________ fracture is often overlooked as the second fracture in the pelvic ring. Look carefully at the _____________ of the ________ whenever the pelvis is disrupted elsewhere. They should be intact and symmetric.

Answer 22

Sacral fracture- look at the arcuate lines of the sacrum which should be symmetric and intact

Question 23

What is a knee lipohemarthrosis usually indicative of?

Answer 23

an occult tibial plateau

Question 24

When looking at ankle fractures, what is the difference between eversion and inversion fractures?

Answer 24

Eversion- fracture of the fibula above the ankle joint line with avulsion of the middle malleolus

Inversion- avulsion of the lateral malleolus

Question 25

What is a Lisfranc fracture?

Answer 25

Lateral displacement of the metatarsels relative to the midfoot.

Question 26

What are the typical target joints of OA? How does it look on the radiograph?

Answer 26

DIPs, base of thumb metacarpal

1. narrow joint space
2. irregular
3. sclerosis of bone increased bone to compensate for cartilage loss
4. osteophytes/subchondrocytes
5. increased joint fluit due to inflammation
6. “loose bodies” cartilage/bone that branches off synovium

Question 27

What are the features of RA seen on the radiograph?

Answer 27

1. joint space narrowing
   2 marginal erosions
2. osteopenia
3. LACK of osteophytes/sclerosis compared to OA

Question 28

What are the radiographic features of psoriatic arthritis?

Answer 28

1. erosion of interphalangeal joints

2 “pencil in cup”

Question 29

What are the radiographic features of septic arthritis?

Answer 29

1. monoarthritis
2. joint space narrowing (after early widening)
3. joint fluid
4. periarticular osteopenia
5. loss of subchondral bone plate
6. loss of bone due to osteomyelitis

Question 30

What do most bone tumors do to bone? How does this show up on radiograph?

Answer 30

They are lytic (esp. multiple myeloma and most metastases)

The radiograph will show lucent areas of cortical desctruction. Bone may even appear absent in areas.

Question 31

How does the appearance of a multiple myeloma lytic lesion differ from a metastatic lytic lesion?

Answer 31

MM: well-defined, non sclerotic lesions that appear “punched out”

Mets: ill-defined, “moth-eaten” lytic spaces

Question 32

If a metastatic cancer is osteoblastic (like prostate cancer) how will it appear on radiograph?

Answer 32

large focal areas of density (sclerosis)

Question 33

What two cancers have metastases to the bone that are a mix of lytic and blastic?

Answer 33

prostate and breast

Question 34

What are the radiographic features of osteosarcoma?

Answer 34

1. start at the medullary cavity in dia/metaphysis
2. permeative cortical destruction
3. soft tissue mass **
4. tumor “new bone”
5. periosteal reaction - lifted off

Question 35

How does the periosteum usually appear on radiograph?

What does it look like in tumor or infection?

Answer 35

It is usually invisible but in tumor or infection it will be lifted off the bone and will attempt to repair damage by forming a new layer of cortex.

sometimes you will see a “sunburst pattern”