1. Knee injury

2. This is a coronal proton density weighted image of the knee. Do you think we are in the front or back of the knee? We are in the back, you see the fibula instead of the patella. Fibula Which hamstring tendon attaches to the fibula posteriorly? This is the biceps femoris and here you see the muscle.

3. What are these low signal shock absorbers between the femur and the tibia? These are the menisci What is this low signal ligament coming off the femur? You do not see the fibular attachment of this ligament. This is the lateral collateral ligament

4. What is this ligament coming off the medial femur and attaching onto the tibia? This is the medial collateral ligament, note the attachment to the medial meniscus. On this image note the femoral attachments to the anterior (black) and posterior (white) cruciate ligaments.

5. Can you see the tibial attachment of the anterior cruciate ligament on this image? Again identify the medial collateral ligament and its meniscal attachment (arrow). This image show disruption of the medial collateral ligament from a valgus injury. Note the fiber disruption, black ligament gone, at the femoral attachment

6. Can you identify the iliotibial band and its tibial attachment?

7. Why is the cortical bone so black (arrows) and the medullary bone so bright (circle) on this imaging sequence? Remember that cortical bone is densely packed and gives almost no signal on MRI and medullary bone has fat and marrow producing elements that make it bright on T1 and proton density images.

9. What is the name of this anterior bony structure? This is the patella

10. This is a sagittal proton density weighted MRI image. Are we medial or lateral? Lateral look at the fibula. What the these 2 structures attaching to the fibula? Lateral collateral ligament Biceps femoris tendon

11. What is this low signal structure between the femur and the tibia? This is the lateral meniscus.

12. What is this grey signal material coating the tibia and the femur on both sides of the meniscus? This is the articular cartilage. Is it the same type of cartilage that makes up the menisci? No. Hyaline cartilage is articular and the menisci are made up of fibrocartilage. Note the signal differences between these cartilage types, likely related to their water content.

14. As we approach the mid knee what are these anterior tendons we see. Quadraceps tendon Patellar tendon What is the bone between them? This is the patella, you largest sesimoid bone.

15. We are now at the mid knee. What is this ligament? This is a normal anterior cruciate ligament. This is a torn ACL on a fat suppressed image. This is why this image is so black. Note the high signal (white) where the ACL is disrupted.

17. Do you see the posterior cruciate ligament on this image?

19. Look at the medial meniscus on this sagittal image in the medial compartment. Does it look normal? No. It is torn, do you see the tear? The tear is where you see high signal extending into the meniscus.