Knee Flashcards
What 4 things should be assessed when viewing the knee from an AP projection?
- Patellar Apex at level of joint line
- Joint space heights
- Tibiofemoral alignment
- Parallel to tibial plateau
Why is the medial femoral condyle magnified in a lateral view of the knee?
- Farther from plate
How long should the patellar tendon be when viewing the knee from a lateral projection?
- Equal to the length of the patella + or - 20 %
How should the intracondylar notch of the femur be shaped?
- Like a U
What may be found within the joint as seen through the PA tunnel view of the knee?
- Loose bodies
- Joint space narrowing
What is the sunrise view of the knee?
Tangential view of patella
What can be assessed using the joint space of the patella femoral joint?
- Cartilage thickness
What are 3 measures of the sulcus and congruence of the patellafemoral joint?
- Sulcus angle
- Congruence Angle
- Patellar Tilt
What is the sulcus angle? What is normal?
- Lines formed between deepest point of groove and highest point of each femoral condyle
- Normally 138 degrees + or - 6
What is the congruence angle? What is normal? What is a lateral sublux?
- Line bisects sulcus angle
- Line between apex of sulcus angle and most posterior point on the patella
- Normally - 6 degrees
- Lateral sublux: + 16 degrees
What is patellar tilt?
- Line connecting medial and lateral edges of patella
- Line a horizontal
- Normal: < 5 degrees
What is the specificity, sensitivity, and accuracy of the patellar tilt measurement?
Spec: 92 %
Sens: 85 %
Accuracy: 89 %
In a fracture of the tibial plateau, although the actual fracture may be difficult to see, what is indicative of a fracture?
- Abnormal fat and blood within capsule
How will a bucket handle tear appear on imaging?
- Space in meniscus with surrounding tissue intact
How will a horizontal/ vertical meniscal tear appear on imaging?
- Horizontal/ vertical line through dark meniscal space
On what imaging is an ACL best visualized?
- T1 MRI
What makes the a full visualization of the ACL difficult in a normal lateral view?
- Medial course of ligament
How should the ACL be shaped?
- Ruler straight with a very slight convex shape inferiorly
What is a Segond fracture? What is it associated with?
- Fracture of lateral tibial plateau
- Internal derrangement of knee, most commonly the ACL
What is the Blumensaat angle? What is normal/ abnormal? What is a normal angle?
- Line running parallel to posterior surface of femur
- Line running course of ACL
- If the apex points superiorly, it is normal
- If apex points inferiorly, it is abnormal
- Normally - 13 degrees
What is the anterior tibial line? What is normal?
- View knee sagitally
- Vertical line from posterior margin of tibia
- Should not cut through posterior horn of lateral meniscus
How will an acute torn ACL appear on MRI?
- Hemmorrhage in intracondylar notch area
- Bone bruises often seen in T2
What 3 secondary effects are usually needed to identify a chronic partial ACL tear?
- Segond fracture
- Bone bruise
- Hemorrhage
How are Blumensaat line angles shaped in a partial ACL tear?
- Can be normal
Since partial ACLs are difficult to visualize, what is the result?
False negative reports
How is a normal PCL shaped?
- Deep black structure from posterior tibia to the middle of the femur
How can a torn PCL present on images?
- Disrupted or enlarged in T1
How is a torn MCL visualized?
- Edema and joint effusion
What other structures is the LCL associated with?
- Arcuate ligament
- Fabellofibular ligament
- Popliteus tendon
- Biceps femoris tendon
- Conjoined tendon
What should the patella be aligned with in an AP projection of the knee?
- With the joint line
What is the Pittsburgh knee rule?
- History of blunt trauma AND < 12 yo >50 yo OR Can't walk 4 WB steps
Is the pittsburgh knee test sensitive or specific?
Sensitive
What is the Ottawa knee rule?
- History of trauma AND any of the following: - Tenderness at fibular head - Isolated tenderness of the patella - Inability to flex knee 90 degrees - Inability to walk 4 steps immediately AND in clinic
