Radiologic Eval of Knee

Question 1

list radiologic views that are including during a routine exam of the knee

Answer 1

1. AP
2. Lateral
3. PA axial “tunnel” view of the intercondylar fossa
4. Tangential view of patella
5. Other
   
   1. WBing posterioanterior axial view of the intercondylar fossa
   2. oblique view

Question 2

describe the tangential view of the patellofemoral joint

Answer 2

• x-ray path superioinferior (merchant view) or inferiosuperior
• Spatial relationships
  
  • patellar subluxations
  • sulcus angle
  • congruence angle

Question 3

what is the norm for the sulcus angle?

Answer 3

138 +/- 6 degree

Question 4

what is the norm of the congruence angle?

What congruence angle would be associated with lateral subluxation?

Answer 4

-6 degree normal

+16 deg associated with lateral subluxation

Question 5

general guidelines for imaging at the knee

• what is typically the first study?*
• What is commonly used for defining complex fractures?*
• What is commonly used for defining soft tissue injuries?*
• What can be used for superficial soft tissue abnormalities?*

Answer 5

1. X-rays typically first study for suspected bony and soft tissue abnormalities
   
   1. diagnosis
   2. directs further imaging
2. CT commonly used for defining complex fractures
3. MRI commonly for defining soft tissue injuries
4. USI possibly for superficial soft tissue abnormalities

Question 6

general indications for CT of the knee

Answer 6

1. severe trauma
2. fracture alignment/displacement
3. loose bodies within joint
4. tibial plateau depression fractures
5. health conditions typically viewed with MRI when MRI is contraindicated

Question 7

what can be seen with an axial CT of the knee?

Answer 7

1. Depression/split fractures of tibial plateau
2. Segond fracture
3. Tibial tuberosity hypertrophy or fragmentation (Osgood-Schlatter’s)

Question 8

what can be seen with a sagittal CT of the knee?

Answer 8

1. position of the patella
2. fragmentation/ossification of inferior patella/patellar tendon

Question 9

what can be seen with a coronal CT of the knee? (5)

Answer 9

1. intercondylar/condylar spilt fractures involving femoral condyles
2. osteochondral lesions
3. fractures of intercondylar eminence
4. ACL avulsion
5. Segond fractures with lateral capsule sign

Question 10

list general indications for MRI of the knee

Answer 10

1. soft tissue injuries
2. staging disease
3. specific clinical scenarios

Question 11

list soft tissue indications for MRI at the knee

Answer 11

1. Meniscal lesions
2. Ligament abnormalities
3. Extensor mechanism abnormalities
4. Osteochondral lesions
5. Articular cartilage abnormalities
6. Loose bodies
7. Synovial disorders
8. Marrow abnormalities
9. Muscle and tendon disorders
10. IT band syndromes
11. Neoplasms
12. Infections
13. Congenital/developmental conditions
14. Vascular conditions
15. Neurogenic conditions

Question 12

list staging disease indications for MRI of the knee

Answer 12

1. inflammatory arthropathies
2. bone/soft tissue tumor
3. fractures/dislocations

Question 13

list specific clinical scenarios that call for MRI of the knee

Answer 13

1. prolonged, unexplained knee pain
2. acute trauma
3. mechanical symptoms
4. instability/dislocation
5. malalignment
6. following complications with knee arthropathy
7. limited/painful ROM
8. swelling/enlargement/mass
9. planned arthroscopy
10. residual/new symptoms following surgery

Question 14

what can be seen with an axial slice of a knee MRI? (9)

Answer 14

1. articular cartilage
2. patellofemoral ligament
3. patellar retinaculum
4. ACL/PCL
5. Joint effusion
6. Popliteal bursa
7. popliteus
8. pes anserine, inserting muscle/tendon
9. muscle bulk

Question 15

what can be observed with a sagittal slice of a knee MRI?

Answer 15

1. articular cartilage
2. bone marrow
3. menisci
4. ACL/PCL
5. extensor mechanism
6. Hoffa’s fat pad

Question 16

what can be observed with a coronal slice of a knee MRI?

Answer 16

1. articular cartilage
2. ACL/PCL
3. MCL/LCL
4. menisci
5. bone marrow
6. popliteus

Question 17

list different types of fractures of the distal femur

Answer 17

1. non-displaced
2. impacted
3. displaced
4. comminuted
5. condylar
6. intercondylar

Question 18

list types of tibial plateau fractures

Answer 18

1. Type I - Split
2. Type II - Split-depression
3. Type III - Central-depression
4. Type IV - Split fracture, medial plateau
5. Type V - Bicondylar fracture
6. Type VI - dissociation of metaphysis and diaphysis

Question 19

list types of chondral fractures at the knee

Answer 19

1. osteochondral body, intact articular cartilage
2. osteocartilaginous flap
3. detached osteochondral fragment
4. detached osteochondral fragment in joint

Question 20

list the Ottawa Knee Rules

Answer 20

1. age 55 or older
2. isolated tenderness of patella (no bone tenderness of knee other patella)
3. tenderness of head of fibula
4. inability to flex to 90 degrees
5. inability to bear weight both immediately and in the ED for 4 steps (unable to to transfer weight twice once each lower limb regardless of limping)

Question 21

what initial imaging is most appropriate for an adult or child greater than or equal to 5 years of age with chronic knee pain

Answer 21

radiography knee

Question 22

what next imaging procedure is most appropriate for an adult (or child greater/equal to 5) with chronic knee pain and initial knee x-rays being negative or demonstrating joint effusion?

Answer 22

MRI knee

Question 23

what next imaging procedure is most appropriate for an adult (or child greater/equal to 5) with chronic knee pain and initial knee x-rays demonstrating osteochondritis dissecans (OCD), loose bodies, or a history of cartilage or meniscal repair?

Answer 23

MRI knee

Question 24

what initial imaging procedure is most appropriate for an adult (or child aged 5 or older) who fell or had an acute twisting trauma to the knee with no focal tenderness or effusion and is able to walk?

Answer 24

No imaging required

X-rays may be appropriate but not always

Question 25

what initial imaging procedure is most appropriate for an adult (or child aged 5 or older) who fell or had an acute twisting trauma to the knee with one or more of the following: focal tenderness or effusion and inability to bear weight?

Answer 25

Radiographs of knee

Question 26

what follow-up study is most appropriate for an adult or skeletally mature child who has suffered a fall or an acute twisting trauma to the knee and no fracture was detected on radiographs but you suspect an occult fracture or internal degeneration?

Answer 26

MRI knee

Question 27

what initial imaging is most appropriate for a child up to age 5 who has an acute limp with nonlocalized symptoms and there is no concern for infection?

Answer 27

radiographs of tibia/fibula

Question 28

what initial imaging is most appropriate for a child up to age 5 with an acute limp, localized symptoms, and no concern for an infection?

Answer 28

Radiographs of LE area of interest