Lower Leg, Knee, and Patella Positioning (RAD 1101)

Leg - AP Projection

Explain how the patient should be positioned for an AP projection of the leg.

1. Supine with leg extended

Explain how the patient's body part should be positioned for an AP projection of the leg.

1. Leg in true AP position (toes up)

2. Foot is dorsiflexed to 90 degrees

3. Femoral condyles parallel to the IR

When taking an AP projection of the leg, the leg is in true ______ position meaning the toes are up

AP

When taking an AP projection of the leg, the foot is dorsiflexed to ______ degrees

90 degrees

When taking an AP projection of the leg, the femoral condyles are ________ to the IR

parallel

When taking an AP projection of the leg, the CR is _________ to the IR

perpendicular

When taking an AP projection of the leg, the CR is at the _________ of the leg

midpoint

NOTE: When taking an AP projection of the leg, the IR is typically ______________ to the person's leg in order to get the entire leg

diagonal (or caddy cornered)

NOTE: When taking an AP projection of the leg, the SID is typically increased to about ________ rather than kept at 40" SID otherwise you may clip your ankle and knee joints

50"

The structures shown in an AP projection of the leg are the....

- entire tibia and fibula (fibula is posterior and lateral to the tibia)

- both knee and ankle joints included

When meeting criteria for an AP projection of the leg, what should be met?

- The long axis of the leg should be in alignment with the long axis of the IR

- Ankle and knee joint open

- Distal fibula superimposed over tibia

- Slight overlap of proximal head of fibula over tibia

When meeting criteria for an AP projection of the leg, the ______ axis of the leg should be in alignment with the ______ axis of the IR

long; long

When meeting criteria for an AP projection of the leg, the ankle and knee joints are ________

open

When meeting criteria for an AP projection of the leg, what part of the lower leg is superimposed over the tibia?

distal fibula

When meeting criteria for an AP projection of the leg, what part of the lower leg is slightly overlapped over the tibia?

proximal head of the tibia

Leg - Lateral Projection

Explain how the patient should be positioned for a lateral projection of the leg.

1. Lateral recumbent

Explain how the patient's body part should be positioned for a lateral projection of the leg.

1. Turned toward affected side

2. Patella perpendicular to the IR

3. Femoral condyles superimposed

4. Malleoli superimposed

5. Knee flexed 20-30 degrees

When taking a lateral projection of the leg, the leg is turned toward the _______ ______

affected side

When taking a lateral projection of the leg, the patella is ________ to the IR

perpendicular

When taking a lateral projection of the leg, what parts of the leg are superimposed?

femoral condyles and malleoli

When taking a lateral projection of the leg, the knee is flexed _____ to ______ degrees

20 to 30 degrees

When taking a lateral projection of the leg, the CR is _________ to the IR

perpendicular

When taking a lateral projection of the leg, the CR is at the __________ of the leg

midpoint

NOTE: If the patient is unable to turn for a lateral projection of the leg, what are you able to do?

obtain by doing a cross-table lateral a with horizontal beam which will require 2 separate XTL's (cross-table laterals)

The structures shown in a lateral projection of the leg are the....

- entire tibia and fibula superimposed

- both knee and ankle joints included

When meeting criteria for a lateral projection of the leg, what should be met?

- The long axis of the leg should be in alignment with the long axis of the IR

- Ankle and knee joint open

- Distal fibula lying over posterior half of tibia

- Slight overlap of the proximal head of fibula over tibia

When meeting criteria for a lateral projection of the leg, the ________ axis of the leg should be in alignment with the _______ axis of the IR

long; long

When meeting criteria for a lateral projection of the leg, the knee and ankle joints are ______

open

When meeting criteria for a lateral projection of the leg, the distal fibula lies over what part of the leg?

posterior half of the tibia

When meeting criteria for a lateral projection of the leg, what part of the lower leg has slight overlap over the tibia?

proximal head of the fibula

What is the error in this lateral leg X-ray? How should it be corrected?

Leg is rotated. The head of the fibula is separated from the tibia and the distal fibula is too posterior. To correct, roll patella away to the IR (backward rotation of the leg).

What is the error in this lateral leg X-ray? How should it be corrected?

Leg is rotated. The head of the fibula is too superimposed over the tibia and the distal fibula is too anterior. To correct, roll patella toward the IR (forward rotation of the leg)

Artifact in Lateral Leg X-ray

Patient in a cast as the white circle is a quarter

Knee - AP Projection

Explain how the patient should be positioned for an AP projection of the knee.

1. Supine; leg extended

Explain how the patient's body part should be positioned for an AP projection of the knee.

1. Leg in true AP position

2. Center 1/2" (1 cm) distal to the apex of the patella

3. Femoral condyles parallel to the IR

When positioning a patient's body part for an AP projection of the knee, the leg should be in true ______ position

AP

When positioning a patient's body part for an AP projection of the knee, you should center 1/2" (1 cm) distal to the ______ of the patella

apex

When positioning a patient's body part for an AP projection of the knee, the femoral condyles are ________ to the IR

parallel

When taking an AP projection of the knee, the CR is _______ (1 cm) ________ to what?

1/2 inch distal (below) to the patellar apex

For an asthenic (thin, frail build) patient, you should place the CR ______ degrees _________ if the ASIS to tabletop is < _______ cm in an AP projection of the knee

3-5 degrees caudad; 19

For a sthenic (common physical build and body shape) patient, you should place the CR __________ if the ASIS to tabletop is _______ cm in an AP projection of the knee

perpendicular; 19-24

For a hypersthenic (massive, heavy build) patient, you should place the CR ______ degrees _________ if the ASIS to tabletop is > _______ cm in an AP projection of the knee

3-5 degrees cephalad; 24

NOTE: The CR is parallel to the ________ ________ in an AP projection of the knee

tibial plateau

The structures shown in an AP projection of the knee are the....

- knee joint

- distal femur

- proximal tibia and fibula

When meeting criteria for an AP projection of the knee, what should be met?

- The femoral condyles should be symmetrical

- The intercondylar eminences should be centered within the intercondyloid fossa

- The head of the fibula should overlap the tibia by approximately 1/4 inch

- The patella should be seen in the center of the femur

- The knee joint should be opened

- The intercondyloid fossa should be partially seen with the knee fully extended

When meeting criteria for an AP projection of the knee, the femoral condyles should be _____________

symmetrical

When meeting criteria for an AP projection of the knee, what is centered within the intercondyloid fossa?

intercondylar eminences

When meeting criteria for an AP projection of the knee, how much should the head of the fibula overlap the tibia?

by approximately 1/4 inch

When meeting criteria for an AP projection of the knee, where is the patella seen in relation to the femur?

patella is seen in the center of the femur

When meeting criteria for an AP projection of the knee, the knee joint should be ___________

opened

When meeting criteria for an AP projection of the knee, what should be partially seen when the knee is fully extended?

intercondyloid fossa

What is the error in this AP knee X-ray? How should it be corrected?

Medial or internally rotated which causes the lateral condyle to appear larger, intercondyloid fossa will be distorted, and there will be less overlapping of the fibular head and the tibia. To correct, externally rotate the leg.

What is the error in this AP knee X-ray? How should it be corrected?

Knee is laterally or externally rotated which this will cause the medial condyle to appear larger, the intercondyloid fossa will be distorted, and there will be more superimposition of the fibula and tibia. To correct, internally rotate the leg.

What is the error in this AP knee X-ray? How should it be corrected?

Knee not fully extended which causes intercondyloid fossa to be opened too much and the femur is distorted. Knee is internally rotated as the fibula is too lateral. To correct, extend the entire leg and rotate the knee externally.

Knee - Lateral Projection

Explain how the patient should be positioned for a lateral projection of the knee.

1. Lateral recumbent

Explain how the patient's body part should be positioned for a lateral projection of the knee.

1. Knee flexed 20-30 degrees

2. Patella is perpendicular to the IR

3. Femoral condyles are perpendicular to the IR

When taking a lateral projection of the knee, the CR is _______ degrees ________ through the knee joint

5-7 degrees cephalad

For the lateral projection of the knee, why is the CR angled 5-7 degrees cephalad?

Due to a magnified medial femoral condyle, plus it is at a lower level than the lateral femoral condyle

When taking a lateral projection of the knee, the CR is centered _______ _______ to the medial femoral epicondyle

1" distal

NOTE: If the patient is unable to turn into the lateral position for a lateral knee projection like in cases of trauma, a _______ ________ ________ may be obtained

cross table lateral (XTL)

The structures shown in a lateral projection of the knee are the....

- knee joint

- femoropatellar joint

- patella in profile

- superimposed femoral condyles

- proximal tibia and fibula

- shows posterior and anterior displacement of fractures

When meeting criteria for a lateral projection of the knee, what should be met?

- The distal articulating surfaces of the medial and lateral femoral condyles should be superimposed, and the knee joint space should be open

- Knee flexed 20-30 degrees

- The patella should be situated proximal to the femur

- The patellofemoral joint should be open

- The tibia should be partially superimposed over the fibular head

- Patella seen in profile

When meeting criteria for a lateral projection of the knee, what parts of the knee should be superimposed?

the distal articulating surfaces of the medial and lateral femoral condyles

When meeting criteria for a lateral projection of the knee, the knee joint space should be ________

open

When meeting criteria for a lateral projection of the knee, the knee is flexed _________ degrees

20-30 degrees

When meeting criteria for a lateral projection of the knee, how should the patella be situated in relation to the femur?

proximal

When meeting criteria for a lateral projection of the knee, the patellofemoral joint should be _______

open

When meeting criteria for a lateral projection of the knee, the tibia should be ________ superimposed over the fibular head

partially

When meeting criteria for a lateral projection of the knee, the ________ is seen in profile

patella

Lateral Pediatric Knee - A pediatric patient's knee should be flexed _____ - ____ degrees

10-15 degrees

What is the error in this lateral knee X-ray? How should it be corrected?

Knee is flexed too much where the patellofemoral (between the patella and femur) joint will not be opened. To correct, flex the knee less.

What is the error in this lateral knee X-ray? How should it be corrected?

Knee is not flexed enough where the patellofemoral joint will not be opened. To correct, flex the knee more.

What is the error in this lateral knee X-ray? How should it be corrected?

The patella was situated too far from the IR (under-rotated knee). The head of the fibula is more superimposed on the tibia than normal. To correct, roll the patella closer (forward) to the IR.

If the lateral knee is positioned like this, what is the error in this lateral knee projection? How should it be corrected?

The patella was situated too far from the IR (under-rotated knee). To correct, roll the patella closer (forward) to the IR.

What is the error in this lateral knee X-ray? How should it be corrected?

The patella was situated too close to the IR (over-rotated knee). There is increased separation of the tibia and fibula. To correct, roll the patella farther away (backward) from the IR and/or angle the tube less.

If the lateral knee is positioned like this, what is the error in this lateral knee projection? How should it be corrected?

The patella was situated too close to the IR (over-rotated knee). To correct, roll the patella farther away (backward) from the IR and/or angle the tube less.

What is the error in this lateral knee X-ray? How should it be corrected?

CR was not angle cephalad. Note that medial femoral condyle obscures the knee joint space. To correct, angle the tube 5-7 degrees cephalad.

What is the error in this lateral knee X-ray? How should it be corrected?

Slight rotation as patella is too close to the IR, and clothing artifact is in the way. To correct, roll the patella away from the IR and have patient remove patients.

Case Study - Tibial Plateau Fx (Fracture)

Serious injury as it is an unstable fracture and want to make sure patient is not standing at all

Weightbearing Knees - AP Projection

Weightbearing Knees - AP Projection X-ray

Weightbearing Knees - AP Projection X-ray Diagram

Weightbearing Knees - Lateral Projection

Weight-bearing knees in the AP and lateral projections is meant for what?

For arthritis studies to show narrowing of joint space

For the weight-bearing knees in the AP and lateral projections, the CR is __________ to the IR

perpendicular

Intercondylar Fossa - "Tunnel Views"

- Rosenberg Method

- Camp-Coventry Method

- Homblad Method

- Beclere Method

What is the purpose of the Intercondylar Fossa "Tunnel Views" exams?

For arthritis studies to show narrowing of the knee joint space and ICF

For Intercondylar Fossa "Tunnel Views", one thing it is looking at is for "joint mice" in which this is when what has broken off in the joint space?

tibial spines (eminences)

Intercondylar Fossa - PA Bilateral Weightbearing Knees Projection (Rosenburg Method)

Intercondylar Fossa - PA Axial Bilateral Weightbearing Knees Projection (Rosenburg Method)

Explain how the patient should be positioned for a PA or PA Axial Bilateral Weightbearing Knees projection (Rosenburg Method) for the intercondylar fossa.

1. Upright PA with knees touching the IR

2. Patient bends (flex) their knees so that the femoral area are at a 45 degree angle

For a PA Bilateral Weightbearing Knees projection (Rosenburg Method), the CR is perpendicular to what?

perpendicular to the center of the IR and to the tibia and fibula

For a PA Axial Bilateral Weightbearing Knees projection (Rosenburg Method), the CR is angled _______ ____ degrees

caudad 10 degrees

When meeting criteria for a PA or PA Axial Bilateral Weightbearing Knees projection (Rosenburg Method) for the intercondylar fossa, what should be met?

- Both knees presented without rotation

- Knee joints centered to exposure area

- Tibial plateaus in profile

- Intercondylar fossae visible

- Soft tissue and bony trabecular

Intercondylar Fossa - PA Axial Projection (Camp-Coventry Method)

Explain how the patient should be positioned for a PA Axial projection (Camp-Coventry Method) of the intercondylar fossa.

1. Prone