W5- Knee Reviewing Radiologic Images

Question 1

What are some common views used for the knee? (6)

Answer 1

• AP
• Lateral
• PA axial “tunnel” view of intercondylar fossa
• Tangential view of patella
• WB posterioanterior axial view of intercondylar fossa
• Oblique

Question 2

What are some things we can see in a AP view of the knee? (7)

Answer 2

• Femur/tibia long axis alignment
• Overlap of medial fibular head and tibia
• equal joint space distance
• Patella (just above joint line)
• Intercondylar tubercles
• Femoral condyles
• Tibial condyles

Question 3

Where should the apex of the patella be in regards to the joint line?

Answer 3

Directly above joint line but not overlapping it.

Question 4

What are some things we can see in a Lateral view of the knee? (4)

Answer 4

• Overlapping femoral condyles (medial lower)
• Fabella
• Patellar positioning (alta/baja)
• Patellar length

Question 5

How is a lateral view of the knee taken and what position is the knee in?

Answer 5

View taken from medial to lateral with knee in slight flexion. Central ray angles 4-7 degrees upward.

Question 6

In a lateral view of the knee, does the medial or lateral femoral condyle go more inferior?

Answer 6

medial femoral condyle

Question 7

What is a sesamoid bone that is embedded in the lateral head of the gastrocnemius muscle and often articulates directly with the lateral femoral condyle? Is it normal?

Answer 7

Fabella, yes (in 1/5 images of the knee)

Question 8

What are some things we can see in the PA Axial “tunnel” view of the knee? (6)

Answer 8

• intercondylar fossa
• medial/lateral intercondylar noth of tibia
• joint spaces
• intercondylar tubercles (avulsion possible w/ cruciate tear)
• free floating bodies
• femoral/tibial condyles

Question 9

What is the “tunnel” view best at looking at?

Answer 9

intercondylar fossa

Question 10

What are some things we can see with a Tangential view of the patella?

Answer 10

• patellofemoral joint
• relation of patella to distal femur
• patellar subluxations
• spatial relationships (patellar subluxations, Sulcus angle, Congruence angle)

Question 11

What is the Tangential view best utilized for?

Answer 11

looking at the patellofemoral joint

Question 12

• What is the Sulcus Angle? Normal?

- What is the Congruence Angle? Normal?

Answer 12

• Sulcus Angle (138) = The angle is formed by the trochlear opening of the knee, measuring the angle between the medial and lateral facets.
• Congruence Angle (-6) = Line bisecting the sulcus angle and line drawn from the median ridge of the patella to the deepest point of the intercondylar sulcus

Question 13

With the congruence angle, a measurement of ___ degrees or more is associated with what?

Answer 13

16 degrees or more associated with lateral subluxation

Question 14

What is typically the first study utilized for bony and soft tissue abnormalities of the knee?

Answer 14

X-rays

Question 15

General Indications for CT of the Knee. (5)

Answer 15

• Severe trauma
• Fracture alignment/displacement
• Loose bodies within joint
• Tibial plateau depression Fx
• Health conditions typically viewed with MRI, if MRI contraindicated

Question 16

• A ______ Fx can be a telltale sign of a ACL tear.

- What is this?

Answer 16

• Segond Fx

- Avulsion fracture of the knee that involves the lateral aspect of the tibial plateau. (75% of ACLs)

Question 17

General Indications for MRI of the Knee. (15)

Answer 17

• Meniscal lesions
• Ligament abnormalities
• Extensor mechanism abnormalities
• Osteochondral lesions
• Articular cartilage abnormalities
• Loose bodies
• Synovial disorders
• Marrow abnormalities
• Muscle & tendon disorders
• IT band syndromes
• Neoplasm
• Infections
• Congenital/ developmental conditions
• Vascular conditions
• Neurologic conditions
• Staging Disease (inflammatory arthropathies, bone/soft tissue tumor, fx/dislocations)