How to take a radiograph of a dog’s stifle

Question 1

What are the common views used for radiographs of a canine stifle?

Answer 1

Lateral
Caudo-cranial

Question 2

Describe the positioning for a lateral radiograph of the canine stifle

Answer 2

Medio-lateral projection
The limb to be radiographed is flexed 90 degrees
The upper limb is moved either:
- Cranially out of the way with a rope tie or sand bag
- Laterally out of the way with a rope tie
Pulling the leg too far cranially or laterally will tend to rotate the pelvis and thus the lower leg and stifle
Place a foam pad under the hock to ensure the tibia is parallel to the table
Use a sandbag to hold the hock in position

Question 3

Describe the collimation of a lateral radiograph of the stifle

Answer 3

The exposed area should include 50% if the femur and 50% of the tibia fibula
Collimate to include soft tissues cranial and caudal to stifle
The centre of collimation should be the stifle joint or slightly more distal (often centred at level of tibial tuberosity)
Use L / R label
In a well positioned radiograph the femoral condyles should be superimposed and not rotated

Question 4

Describe the positioning for a caudo-cranial radiograph of the canine stifle

Answer 4

The dog is put in ventral recumbency with the limb to be radiographed in extension
A sandbag on the pelvis may help maintain extension of the hip
The opposite hind limb is lifted laterally by a sandbag so that the affected limb can be held in a non-rotated position
Aim to rotate the limb so that the patella is in the midline

Question 5

Describe the centering and collimation of a caudo-cranial radiograph of the stifle

Answer 5

Centre at the middle of the stifle joint
Collimate to include the distal 50% of the femur and proximal 50% of the tibia / fibula
Collimate to include the lateral and medial soft tissues
Use L/R label
A well positioned radiograph has the femoral condyles of equal size with the patella in the midline (no limb rotation)
Centring on the middle of the joint means there is good visualisation of the joint space

Question 6

What are the challenges when taking a cranio-caudal radiograph of the stifle?

Answer 6

The cranio-caudal view can result in magnification distortion as it is difficult to get the stifle close to the table
It may also be more difficult to take a radiograph without rotation as it is difficult to hold the limb slightly rotated (femur needs to be rotated medially)

Question 7

What is this pathology?

Answer 7

Question 8

What is this pathology?

Answer 8

Cranial movement of the tibia with cranial cruciate ligament rupture (progressive worsening from A to D) (i.e. traumatic)

Question 9

Identify the pathologies here

Answer 9

Chronic stifle arthrosis (i.e. degenerative [could be secondary to traumatic]):
- Lots of new bone (osteophytes)
- Joint effusion
- underlying cause often not evident

Question 10

Identify this pathology

Answer 10

Osteochondrosis (i.e. developmental):
- Radiolucent defect with surrounding sclerosis
- Could be seen years later as chronic arthrosis