Knee and Patella Flashcards
(43 cards)
Knee - AP projection
supine with leg fully extended
- toes up
femoral condyles parallel to IR
- may require 5 internal rotation
CP: 1/2 inch below patellar apex
CR: Variable
AP Knee CR angles based on hip height measurments
18 cm and below - 5 caudad
19-24 cm - perpendicular
25 cm and above - 5 cephalad
what is the other way you can determine angle of the AP knee?
match tube angle to the tibia and reduce CR angle by 5 degrees
Knee - AP evaluation criteria
open femorotibial joint space
no rotation
- femoral condyles symmetrical
- slight superimposition of fibular with tibia
- petal superimposed on femur
Knee - PA projection
Patient is prone with top of toes on table
femoral condyles parallel to IR
CR: perpendicular
CP: Exit 1/2 inch below apex
Marker face down
Knee - PA evaluation criteria
open femorotibial joint space
no rotation
- femoral condyles symmetrical
- slight superimposition of fibular with tibia
- petal superimposed on femur
Knee - AP Medial Oblique projection
rotate entire leg 45
- elevate hip at affected side
- may need to use sponge
CR: Variable
CP: 1/2 inch below apex
Knee - AP Medial Oblique evaluation criteria
open proximal tib/fib joint
both tibial plateaus
lateral femoral/tibial condyles
medial border of patella
open knee
Knee - AP Lateral Oblique projection
rotate entire leg 45
- elevate unaffected hip
- may need sponge
CR: variable
CP: 1/2 inch below apex of patella
If doing a knee series of AP, AP medial oblique and AP lateral oblique, what order should you complete the images?
AP, AP lateral oblique then AP medial oblique, as the medial oblique will change the CR angle much more than the lateral (may not change at all)
Knee - AP lateral oblique evaluation criteria
medial femoral and tibial condyles
tibial plateaus
open knee joint
lateral border of patella
fibula superimposed with lateral half of tibia
Knee - PA internal and external oblique
patient prone, full leg rotated
CR: perpendicular
Marker: face down
Knee - Lateral projection
mediolateral
affected knee bent 20-30
- maximum of 10 if patellar injury
- pretend patellar injury is not a risk for practical exam
femoral condyles superimposed
CR: 5-7 cephalad
CP: 1 inch below medial condyle
Knee - lateral evaluation criteria
femoral condyles superimposed
open femerotibial joint space
open patellafemoral joint space
fibular head slightly superimposed with tibia
How to tell if a knee is under rotated?
locate adductor tubercle of medial condyle
more superimposition of tibia and fibula
how to tell if a knee is over rotated?
locate smooth posterior surface of lateral condyle
less superimposition of tibia and fibula
Knee - Trauma cross table lateral projection
lateromedial
demonstrates fat/fluid levels
- lipohemarthrosis
turn detector so grid lines are going vertical
marker - face down
bring the leg in 5-7 degrees
CR: horizontal
CP: 1 inch distal to lateral epicondyle
What does varus mean?
towards midline
What does valgus mean?
away from the midline
What does erect imaging of the knee demonstrate?
progression of arthritis
joint space narrowing
varus and valgus deformities
Knees - AP standing projection
Bilateral, weight bearing
- no shoes
True AP - condyle parallel to the IR
CP: 1/2 an inch below the apex of the patella
CR: 5 caudad for average patient - perpendicular for larger patients
Marker: L and R and up arrow
Knee - PA standing projection
weight bearing
Legs flexed 45
- toes level to the IR
- knees against the Bucky
be careful shielding is not blocking your image
CP: Exit 1/2 inch below apex
CR: 10 caudad
Marker: facedown with arrow up
Knee - PA standing evaluation criteria
both knees without rotation
tibial plateaus in profile
intercondylar fossae visible
What is joint mince?
loose bodies in the intercondylar joint space
