ARRT Lower Extremity Procedures 2 — Questions and Answers
Question 1: Which projection of the knee best demonstrates the fibular head free of superimposition over the tibia?
- AP projection
- Lateral projection
- Medial oblique projection (Correct answer)
- PA axial projection
Correct answer: Medial oblique projection
The medial oblique (internal rotation) projection of the knee projects the fibular head free of tibial superimposition.
Question 2: For a lateral projection of the ankle, the patient's foot should be dorsiflexed to approximately what angle to place the long axis of the foot perpendicular to the leg?
- 45 degrees
- 60 degrees
- 90 degrees (Correct answer)
- 120 degrees
Correct answer: 90 degrees
Dorsiflexing the foot to 90 degrees (a right angle to the leg) ensures a true lateral ankle projection without distortion.
Question 3: The AP axial projection of the foot (Béclère method) is used primarily to demonstrate which structure?
- Subtalar joint
- Sesamoid bones of the great toe (Correct answer)
- Tarsometatarsal joints
- Calcaneus
Correct answer: Sesamoid bones of the great toe
The Béclère method uses a tangential projection to visualize the sesamoid bones beneath the first metatarsophalangeal joint.
Question 4: When performing a bilateral weight-bearing AP projection of the knees for alignment assessment, the central ray is directed to:
- The tibial plateau at 0 degrees
- A point 1 inch below the apex of the patella at 5-7 degrees caudad (Correct answer)
- The mid-patella at 10 degrees cephalad
- The joint space at 15 degrees caudad
Correct answer: A point 1 inch below the apex of the patella at 5-7 degrees caudad
For weight-bearing knee alignment, the CR is angled 5–7 degrees caudad directed to 1 inch below the patellar apex to open the joint space.
Question 5: For the lateral projection of the calcaneus, the central ray is directed:
- Perpendicular to the IR at the level of the ankle mortise
- 1 inch distal to the medial malleolus
- To the mid-calcaneus perpendicular to the IR (Correct answer)
- To the sustentaculum tali at 40 degrees cephalad
Correct answer: To the mid-calcaneus perpendicular to the IR
For the calcaneus lateral, the CR is perpendicular to the IR directed to the mid-calcaneus to avoid distortion.
Question 6: Which projection of the hip demonstrates the femoral neck without foreshortening in a patient who cannot rotate their leg?
- AP projection with 15 degrees internal rotation
- Lateral (frog-leg) projection
- Axiolateral inferosuperior (Danelius-Miller) projection (Correct answer)
- PA oblique (Hsieh method)
Correct answer: Axiolateral inferosuperior (Danelius-Miller) projection
The axiolateral inferosuperior (Danelius-Miller) projection allows imaging of the femoral neck in true profile when leg rotation is contraindicated.
Question 7: The tunnel (intercondylar fossa) projection of the knee is performed with the knee flexed approximately how many degrees?
- 20-30 degrees
- 40-45 degrees (Correct answer)
- 60-70 degrees
- 90 degrees
Correct answer: 40-45 degrees
The tunnel (Camp-Coventry or Holmblad) projection requires 40–45 degrees of knee flexion to open the intercondylar fossa.
ARRT Lower Extremity Procedures 2
Which projection of the knee best demonstrates the fibular head free of superimposition over the tibia?