Knee and Patella Flashcards
When the femur is vertical, the medial condyle is ______ than the lateral condyle.
Lower
About a __ to __ degree difference exists between the two condyles.
5 to 7
Adductor tubercle is located
above the medial epicondyle
Patella Structures
Superior edge is called the base.
Pointed inferior surface is the apex.
Posterior surface has 2 articular facets
When the leg is straightened the patella can move slightly over the…
Patellar surface
When the knee is flexed the patella is locked in front of the _____ _______ by the ________ ________
Knee joint; quadriceps tendon
Knee Articulations(joints)
Femorotibial Joint
•Synovial Hinge
Patellofemoral Joint
•Synovial Gliding
Proximal Tibiofibular Joint
•Synovial Gliding
Stabilizing structures of the knee
Collateral Ligaments
•Medial
•Lateral
Cruciate Ligaments
•Anterior (ACL)
•Posterior (PCL)
Lateral and Medial menisci provide…
stability and shock absorption
Knee IR size and SID
IR: 10x12 LW
SID: 40 inches
Knee AP: IR, Position, CR, Collimation
IR: 10x12 LW
Position: Supine
•Femoral condyles parallel to IR
CR:
•Entering 1/2” inferior to patellar apex
Angle variable (ASIS to TT)
-If <19 cm: 3-5º caudal
-If 19-24 cm: perpendicular
-If >24 cm: 3-5º cephalic
Collimation: 1” on sides
Knee AP Evaluation Criteria
-Knee fully extended
-Entire knee without rotation
•Femoral condyles symmetric and tibia intercondylar eminence centered
•Slight superimposition of the fibular head if the tibia is normal
•Patella completely superimposed on the femur
-Open femorotibial joint space, interspaces of equal width on both sides if the knee is normal
Knee AP Oblique Medial Rotation IR, Position, CR, Collimation
IR: 10x12 LW
Position: Medial rotation
•Rotate affected side 45º
CR:
•Entering 1/2” inferior to patellar apex
•Angle variable (ASIS to TT)
-If <19 cm: 3-5º caudal
-If 19-24 cm: perpendicular
-If >24 cm: 3-5º cephalic
Collimation: 1” on sides
Knee AP Oblique Medial Rotation Evaluation Criteria
-Tibia/Fibula separated
-Lateral condyles of femur and tibia
-Both tibial plateaus
-Patella projecting beyond medial side of femoral condyle
-Open knee joint
Knee AP Oblique Lateral Rotation IR, Position, CR, Collimation
IR: 10x12 LW
Position: Lateral rotation
•Rotate affected side 45º
CR:
•Entering 1/2” inferior to patellar apex
•Angle variable (ASIS to TT)
-If <19 cm: 3-5º caudal
-If 19-24 cm: perpendicular
-If >24 cm: 3-5º cephalic
Collimation: 1” on sides
Knee AP Oblique Lateral Rotation Evaluation Criteria
-Medial femoral and tibial condyles
-Both tibial plateaus
-Fibula superimposed over the lateral half of the tibia
-Patella projecting beyond lateral side of femoral condyle
-Open knee joint
Knee Lateral IR, Position, CR, Collimation
IR: 10x12 LW
Position: Mediolateral
•Turn on affected side
•Knee flexed 20-30º
•Epicondyles and patella ⟂ to IR
CR:
•Entering 1” distal to medial epicondyle
•Angle: 5-7º cephalic
Collimation: 1” anterior to patella
For Knee Lateral why is CR entering 1” distal to medial epicondyle?
Prevents joint space from being obscured by magnified medial condyle
Knee Lateral Evaluation Criteria
-Knee flexed 20 to 30º in true lateral
-Femoral condyles superimposed
-Fibular head and tibia slightly superimposed
-Patella in a lateral profile
-Open patellofemoral joint
-Open joint space between femoral condyles and tibia
If the anterior surface of medial condyle is closer to the patella there is…
Over-rotation toward the IR
If the anterior surface of medial condyle is farther from the patella there is…
Under-rotation away from the IR
Patella Tangential (Settegast method) Cr and Collimation
CR: depends on degree of flexion (Typically 15 to 20 degrees Perpendicular to the joint space between the patella and femur)
Collimation: 4x4
What if patient can’t bend knee that much for the tangential(settegast) view?
Do the Hughston method
Patella Tangential (Merchant Method) IR, Position, CR
-IR: 14x17 CW
-SID: 72”
-Position:
•Supine with both knees flexed off table
•Elevate knees 2” to place femurs parallel with table
•Knees flexed 40º
•IR placed 1 foot distal to patella
-CR: perpendicular to IR at 30º caudal angle midway between patellae at patellofemoral joint
