AP/PA/Lateral
For an AP Knee where is the central ray directed?
to a point 1/2 inch inferior to the patellar apex
How many different methods are used for the intercondylar fossa, and can you name them?
3 methods:
1. Homblad
2. Camp-Coventry
3. Beclere
For the oblique knees, how is the central ray directed?
Same as an AP knee, 1/2 inferior to the patellar apex
3-5 degrees caudad (for thin pelvis less than 19 cm)
3-5 degrees cephalad (for thick pelvis over 24cm)
perp (for normal pevlis 19-24 cm)
What is the superior border of the patella named?
the base
For the merchant method what SID is recommended?
A 6 foot SID (2 meters)
For a lateral knee (mediolateral projection) how flexed is the patient's knee supposed to be?
20 - 30 degrees
For the Homblad method Intercondylar Fossa how is the patient positioned, what runs parallel with the long axis of the IR, and how is the central ray directed
With the knee flexed 70 degrees from full extension
with the tib-fib running parallel with the IR
the central ray is perp
For oblique knees how far do you rotate the patient's extremity?
45 degrees
Why would the patella be imaged in a PA projection?
to lower OID and improve spatial resolution
For the Settegast method, how is the central ray typically angled?
15-20 degrees towards the IR depending on the patients body position
How do you angle for a PA knee when the foot is extended?
5-7 degrees caudad to exit a point 1/2 an inch inferior to the patellar apex
For the Camp-Coventry Method of the intercondylar fossa how is the patient positioned, what part runs parallel with the IR, and how is the central ray directed?
The patient is prone with the foot propped up on a support
the femur runs parallel to the long axis of the IR
The central ray is directed to the popliteal fossa matching the angle of the tib-fib
What is seen on the lateral oblique of the knee
the fibula superimposed over the lateral half of the tibia, the medial condyles of the of femora and the tibia, tibia plateaus
How is the patient positioned for the PA projection of the patella?
the heel needs to be rotated 5-10 degrees laterally
How is the patient positioned and how is the central ray directed for the Hughston method?
The tib-fib forms a 50-60 degree angle from the table and the CR is angled 45 degrees cephalad
For a mediolateral knee, how is the central ray directed? why?
5-7 degrees cephalad 1 inch distal to the medial epicondyle.
Because the medial condyle lies 5-7 degrees lower than the lateral condyle.
In the Beclere method of the intercondylar fossa how is the patient positioned?
How is the central ray directed?
The long axis of the femur is angled 60 degrees to the long axis of the tibia
The central ray is angled to enter the knee joint 1/2 inch below the patellar apex, perp to the long axis of the lower leg
What is shown on the medial oblique projection of the knee?
Lateral condyles of the femur and the tibia, the posterior tibia, both tibial plateaus
How is the patient positioned for the lateral projection of the patella (mediolateral)?
with the affected knee flexed 5-10 degrees with the femoral epicondyles superimposed and the patella perpendicular to the IR
How many methods exist for tangential projection of the Patella and Patellofemoral joint and what are their names?
3 methods
1. Hughston
2. Merchant
3. Settegast
How is the central ray directed for a AP knee when the patients pelvis is thin (less than 19 cm)? when their pelvis is thick (more than 24 cm)? when their pelvis is average (19 - 24 cm)?
3-5 degrees caudad
3-5 degrees cephalad
perp
Which method is the only AP projection for the intercondylar fossa?
The Beclere method
Which oblique of the knee shows the tibiofibular joint?
the medial oblique
List the 4 ligaments
Posterior Cruciate Ligament (PCL)
Anterior Cruciate Ligament (ACL)
Tibial Collateral Ligament (TCL)
Fibular Collateral Ligament (FCL)
Which method is preferred for the tangential projection of the patella and patellofemoral?
The Merchant method because the central ray is going away from the patients body