1. Trauma: Knee/Tibia/Fibula Flashcards
Segond Fracture
This is a fracture of the Lateral Tibial Plateau {common distractor is medial tibia).
Internal Rotation = ACL tear (75%)
Reverse Segond Fracture:
This is a fracture of the Medial Tibial Plateau.
External rotation = PCL tear = Medial meniscus injury
Arcuate Sign
This is an avulsion of proximal fibula (insertion of arcuate ligament complex).
The thing to know is that 90% are associated with cruciate ligament injury (usually PCL)
Deep Intercondylar Notch Sign
This is a depression of the lateral femoral condyle (terminal sulcus) that occurs secondary to an impaction injury.
This is associated with ACL tears.
Composed o f two bundles (anteromedial & posterolateral). The tibial attachment is thicker than the femoral attachment.
Both the ACL and PCL are intra-articular and extrasynovial.
ACL
The strongest ligament in the knee (you don’t want a posterior dislocation of your knee resulting in dissection of your popliteal artery).
PCL
fibers are laced into the joint capsule at the level of the joint, with connection to the medial meniscus.
This is an Extra-articular Structure
MCL
Unlike the ACL and PCL, the MCL is an extra-articular structure.
Formed by the biceps femoris tendon and the LCL.
Conjoint Tendon
ACL & PCL
extrasynovial and intra- articular.
The synovium folds around the ligaments.
This is why a torn ACL won’t heal on its own (usually).
The PCL and Patellar tendon may have foci of intermediate signal intensity on sagittal images with short echo time (TE) sequences where the tendon forms an angle of 55 degrees with the main magnetic field {magic anglephenomenon).
Magic Angle: You see it on short TE sequences (Tl, PD, GRE). It goes away on T2
ACL Tear are associated with
Segond Fracturc (lateral tibial plateau) and tibial spine avulsion
ACL Angle lesser than
Blumensaat’s Line
O’donoghue’s Unhappy Triad:
ACL Tear
MCL Tear
Medial Meniscal Tear
Classic Kissing Contusion Pattern in ACL tear
The lateral femoral condyle (sulcus terminals) bangs into the posterior lateral tibial plateau. This is 95% specific in adults.
The association of an osteochondral injury at the impaction site is highly testable
Ortho Physical Exam Finding suggesting ACL Tear.
Anterior Drawer Sign
ACL Mucoid Degeneration
ACL Mucoid Degeneration
This can mimic acute or chronic partial tear of the ACL. There will be no secondary signs o f injury (contusion etc..).
It predisposes to ACL ganglion cysts, and they are usually seen together.
The T2/STIR = “celery stalk” because of the striated look.
The Tl buzzword is “drumstick” because it looks like a drum stick.
ACL Mucoid Degeneration
ACLcanberepairedwithtwoprimarymethods
1:Usingthemiddleone-thirdofthe patellar tendon, with the patella bone plug attached to one end and tibial bone plug attached at the other.
Method 2: Using a graft made of the semitendinosus or gracilis tendon, or both.
Tibial Tunnel in ACL repair
Should parallel the roof of the femoral intercondylar notch.
Too Steep = Impinged by femur on extension.
Too Flat = Lax & won’t provide stability.
Too Far Anterior (“Intersection with Blumensaat line”) = Can lead to pinching at the anterior inferior intercondylar roof
Buzzword “Roof Impingement.”
Femoral Tunnel in ACL repair =
Maintains Isometry. Tibial Tunnel = Roof Impingement.
“Arthrofibrosis”
Can be focal or diffuse (focal is more common).
The focal form is the so called “Cyclops” lesion - so named because of its arthroscopic appearance. It’s gonna be a low signal mass-like scar in Hoffa’s fat pad. It’s bad because it limits extension.
“palpable audible clunk”
“Arthrofibrosis”
Posterior Lateral Corner (PLC)
The most complicated anatomy in the entire body.
“edema in the fibular head.”
very common cause ofACL reconstruction failure
Missed PLC injury
the strongest ligament in the knee.
PCL