MSK: Trauma and Overuse, Knee/Tibia/Fibula Flashcards
Reverse segond fracture, recommend MRI to look for PCL tear and/or medial meniscus injury
Note: Fracture of the medial tibial plateau.
Segond fracture, recommend MRI to look for ACL tear
Note: Fracture of the lateral tibial plateau.
A segond fracture is a fracture of the…
Lateral tibial plateau
Note: A reverse segond fracture involves the medial tibial plateau.
Segond fractures are associated with…
ACL tear (75%)
Note: Recommend an MRI if you see one.
What is usually the mechanism of injury for this fracture?
Segond fractures typically occur during internal rotation
Reverse segond fractures are associated with…
- PCL tear
- Medial meniscus injury
What is usually the mechanism of injury for this fracture?
Reverse segond fractures usually occur during external rotation
Avulsion fracture of the proximal fibula (at the insertion site of the arcuate ligament complex), recommend MRI to look for ACL/PCL tear
Note: This is the “arcuate sign”.
This type of fracture is associated with…
ACL or PCL injury (90%)
Note: This is the “arcuate sign” (proximal fibula avulsion fracture at the insertion of the arcuate ligament complex).
Lateral femoral notch sign (AKA deep intercondylar notch sign), recommend MRI to look for an ACL tear
Note: Depression fracture of the lateral femoral condyle (terminal sulcus) that occurs due to an impaction injury and is associated with ACL tears.
The lateral femoral notch sign is associated with…
ACL tears
What are the components of the anterior cruciate ligament?
- Anteromedial bundle
- Posterolateral bundle
What is the strongest ligament of the knee?
The PCL
Note: This is good because it prevents posterior dislocations of the knee (which could result in dissection of the popliteal artery).
The IT band inserts on…
Gerdy’s tubercle (on the lateral tibia)
Is the ACL intraarticular?
The ACL is intraarticular, but extrasynovial
Note: The synovium folds around the ligament (which is how you can have a torn ACL even with an intact synovium). This is also why a torn ACL rarely heals on its own.
Is the PCL intraarticular
The PCL is intraarticular, but extrasynovial (like the ACL)
Is the MCL intraarticular?
The MCL is extraarticular
Note: MCL fibers are interlaced with the joint capsule.
MCL fibers interlace with the…
Knee joint capsule and medial meniscus
Merging of the _______ and the ______ creates the conjoint tendon of the knee, which inserts on the fibula head
- Biceps femoris tendon
- Lateral collateral ligament
Can you have an ACL tear without disrupting the synovium?
Yes, the ACL is intraartciular but extrasynovial
Magic angle artifact
Note: This occurs when the tendon/ligament forms a 55 degree angle with the main magnetic field (only on short TE sequences).
At what angle does the magic angle artifact happen?
55 degrees to the main magnetic field
What sequence can you check to ensure a lesion is due to magic angle artifact?
T2
Note: Magic angle artifact is not present on long TE sequences (e.g. T2).
Magic angle artifact can be seen on what sequences?
Short TE sequences (e.g. T1, proton density, GRE)
Note: It is not present on T2 (long TE sequence).