Diagnostic Imaging: Musculoskeletal Imaging: Imaging in Lameness

Question 1

What are the indications for lameness radiographs?

Answer 1

• Acute or chronic lameness
• Skeletal or joint pain
• Fracture confirmation/characterisation
• Swelling centered on bones/joints
• Monitoring/screening for inherited musculoskeletal disease
• Metabolic bone disease
• Evaluation of systemic disease

Question 2

How is the correct region to image determined?

Answer 2

• Thorough clinical exam and history
• Comprehensive orthopadeic exam
• Examination under GA/Sedation

Question 3

What is geometric distortion?

Answer 3

• Occurs if structure is towards edge of collimated area
• Or not truly parallel to the film/detector
• Tight collimation can help

Question 4

What are the limitations to lameness radiographs?

Answer 4

• Oblique projections can create apparent artefactual lesions
• Poor soft tissue contrast resolution

Artefact from not straight radiograph- MAC line

Question 5

What is serial radiography used for?

Answer 5

• Monitor progression of disease
• Show diseases radiographically occult in their early stages
• Assess dynamic component of disease
• Can be useful if diagnosis is uncertain

Question 6

What are the radiographic rontgen signs?

Answer 6

1. Number
2. Size
3. Shape
4. Location
5. Opacity

Consider that the lesions is possibly: artefact, normal, superimposed shadow

Question 7

What should be specifically assessed about bones and joints in musculoskeletal cases?

Answer 7

Bones
* Alignment, shape, length
* Periosteal reaction/cortical lysis/defects
* Endosteal/medullary changes
* Physes

Joints
* Swelling/effusion
* Subchondral bone
* Periarticular changes

Soft tissue
* Swelling/loss

Question 8

What can cause reduced size of soft tissues?

Answer 8

Atrophy
* Chronic lameness
* Neurogenic
* Fibrosis/scarring

Weight loss

Question 9

What can cause increased size of soft tissues?

Answer 9

Focally
* Trauma
* Abscess/seroma
* Granuloma
* Neoplasia

Diffuse
* Oedema
* Cellulitis/vasculitis
* Diffuse neoplasia

Question 10

What can a reduction in opacity of bones mean?

Answer 10

• May be artefactual
• 30-60% mineral loss is required to be appreciated
• Minimum 7 days to be apparent
• Focal loss easier to detect

Question 11

How can focal bone loss (lysis) be described?

Answer 11

• Geographic
• Moth-eaten
• Permeative

Question 12

Periosteal reaction can be inactive/benign to active/aggressive

How can it be described from benign to active?

Answer 12

• Smooth
• Rough
• Brush border
• Pallisading
• Spicular
• Sunburst
• Amorphous

Top- smooth- benign 2nd- brush border 3rd- interuped, spicular Bottom- amorphus

Question 13

What are these different arrows labelling?

Aggressive lesion

Answer 13

Top- Bottom
* Transition zone- long
* Periosteal reaction- active
* Cortical integrity- destruction/expansion
* Soft tissues- swelling/mass

Question 14

How can distribution of skeletal lesions be categorised?

Answer 14

• Monostotic- one bone
• Polyostotic- multiple bones
• Focal
• Generalised
• Symmetrical
• Asymmetrical

Question 15

What is critical to assess about joints?

Answer 15

• Soft tissue swelling
• Joint ‘space’ width
• Subchondral bone opacity
• Osteophyte/enthesophytes
• Periarticular mineralisation

Question 16

What may a joint effusion not be indistinguishable from?

Answer 16

Joint effusion may not be distinguishable from periarticular swelling

Other then stifle- adjacent fat

Question 17

What are the differentials for subchondral defects at joints?

Answer 17

• Osteochondrosis
• Aseptic necrosis (femoral head)
• Septic arthritis
• Erosive arthritis (carpus/tarsus)
• Soft tissue neoplasia
• Trauma (avulsions)
• Osseous cyst like lesions
• Osteoarthritis (only very severe)

Question 18

What are the two following subchondral defects?

Answer 18

Left- erosive arthritis
Right- Avulsion fracture- pulled of origin of Cranual cruciate ligament

Question 19

What presents on a radiograph with osteoarthritis?

Answer 19

• Soft tissue swelling/effusion
• Periarticular new bone at predictable sites
• Subchondal sclerosis
• Narrowed joint space
• Look for the primary disease process

Question 20

What is the difference between an osteophyte and an enthesophyte?

Answer 20

Both are types of periarticular bone
* Osteophyte is in the joint capsule
* Enthesophyte is in the ligament

Question 21

What do these images show?

Answer 21

Mineralised bodies
* Commonly seen
* Normal- sesamoids, accessory centres of ossification

Question 22

What are the predilection sites for osteochondrosis?

Answer 22

1. Caudal aspect humeral head
2. Medial part humeral condyle
3. Lateral femoral condyle
4. Medial trochlear ridge talus

Question 23

What are the predilection sites for osteosarcomas?

Answer 23

1. Proximal humerus
2. Distal radius/ulna
3. Distal femur
4. Proximal tibia

Question 24

How can ultrasound be used to image and help diagnosis of lameness?

Answer 24

• Use linear (high frequency) probe
• Muscles, tendons and ligaments can be visualised clearly
• Bone surface is well depicted

Question 25

What are the key soft tissue structures surrounding the shoulder that can be visualised?

Answer 25

• Biceps tendon and sheath (craniomedial)
• Supraspinatus and infraspinatus muscles and tendons (lateral/craniolateral)

Question 26

What can be ultrasound imaged at the tarsus?

Answer 26

Calcaneal tendon
* Gastrocnemius
* Superficial digital flexor
* Conjoined/common calcaneal (bicep femoris, semintendinosus and gracilis)

Question 27

How is the right imaging modality selected?

Answer 27

• Radiographs usually initially

Question 28

How is an image examined?

Answer 28

1. Correct region radiographed
2. Well-positioned, reproducible
3. Adequate number/orthogonal
4. Free from significant artefacts
5. Awareness of limitations

Question 29

Label the epiphysis, diaphysis and metaphysis

Answer 29

Top- epiphysis
Middle- diaphysis
Bottom- metaphysis