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
PCL Tear
A tear is actually uncommon (unless you just won’t tap to that knee bar), it’s more likely to stretch and appear thickened ( > 7 mm).
If you see a PCL Tear
- look at the popliteal flow void.
If the knee dislocated posterior = vascular compromise
Any kind of history that suggests posterior knee dislocation should prompt
ngiogram to studv the popliteal artery.
Meniscal Anatomy
Meniscal Healing
The Central “white zone”
Avasular = wont heal
The Peripheral “Red Zone”
Vascular = might heal
Radial Tear
Bad because they cause “loss of hoop strength.”
Can lead to extrusion, early OA etc.
Flap Tear (Parrot Beak)
- Radial Tear that Changes Direction into the longitudinal direction
Longitudinal Tear
- Can be vertical or horizontal (or mixed oblique patterns)
- Defined by a long extension in the axial direction
- Vertical Types can flip (bucket- handle)
Horizontal Cleavage Tear
- Pure cleavage tears extend to the apex
- Associated with Meniscal Cysts
- Most common In posterior horn of the medial meniscus
Radial Tears: There are 3 classic Signs - two of which are usually present.
Discoid Meniscus
This is a nomial variant of the lateral meniscus that is prone to tear.
It’s not C-shapcd, but instead shaped like a disc. In other words, it’s too big (too many bowties!).
Pediatric patians + meniscal tear =
Think of Discoid Meniscus
Bow Ties ” If shown on sagittal they have to show you 3 or more “bow ties” / double triangles.
Discoid Meniscus
Normal Meniscus vs Discoid Meniscus
Normal meniscus will have 2 bowtie shapes in the sagittal plane - assuming 3mm slices with 1mm gap-
Discoid Meniscus will have 3 or more bowties
If shown on coronal they need to show you a meniscus stretching into the notch. (Transverse length >15 mm on midline coronal = diagnostic).
-Extending into Notch
Bucket Handle Tear
This is a tom meniscus (usually medial - 80%) vertical longitudinal sub-type, that flips medially to lie anterior to the PCL.
Bucket Handle Tear
“Double PCL Sign”
The appearance of a double PCL can only occur in the setting of an intact ACL,
Bucket Handle Tear
Meniscal Cysts
Most often seen near the lateral meniscus and are often associated with horizontal cleavage tears.
Meniscal Ossicle
Trauma / developmental = focal ossification of the posterior horn of the medial meniscus
Assoc = Radial Root tears
Bakers Cyst
Occurs between the semimeinbranosus (Sm) and the
m edial head ofthe gastroc (Mg)
Meniscocapsular Separation:
The idea is that the deepest layer of the MCL complex (capsular ligament) is relatively weak and is the first to tear.
This deep tearing may result in the separation of the meniscus and the MCL
Meniscofemoral Ligaments
There are 2
Wrisber, Humphry = which can be mimics o f meniscal tears.
from the posterior horn of the lateral meniscus and cross around the PCL
The one that crosses anterior is Humphrey (white arrow)
The one that crosses posterior is Wrisberg (black arrow)
Wrisberg is in the back ( “humping Humphry ”)* You could also remember that “H” comes before “W” in the alphabet.
Meniscal Flounce
This an uncommon finding of a “ruffled” appearance of the meniscus that mimics a tear. It’s NOT associated with an increased incidence of tear - but can look like one, if you don’t have any idea what one looks like.
Patella Dislocation
Patella Dislocation
usually LATERAL because of the shape o f the patella and femur.
Associated tear of the MPFL (medial patellar femoral ligament)
Associated with “Trochlear Dysplasia ” - the trochlea is too fiat.
Tibial tuberosity transfer is done to treat patellar instability. If you see screws in the proximal tibia - that is what happen (probably).
Bipartite Patella vs Fracture
This is an anatomy variant where the patella doesn’t totally fuse.
Normally the thing fuses by age 12 - so don’t call this in an 8 year old.
location — upper lateral corner
Patella Alta/Baja
The patella will move up or down in certain traumatic situations. If the quadricep tendon tears you will get unopposed pull from the patellar tendon resulting in a low patella (Baja). If the patella tendon tears you will get unopposed quadriceps tendon pull resulting in a high patella (Alta).
The “classic” association with patellar tendon tear (Alta)
Systemic Lupus Erythematosis
“Bilateralpatellar tendon rupture ”
is a buzzword for chronic steroids.
Prepatellar Bursitis
Fat Impingement Syndrome
Jumpers Knee
Tibial Plateau Fracture
This injury most commonly occurs from axial loading (falling and landing on a straight leg)
The lateral plateau is way more common than the media
Schatzker classificaiton of teh TIbial Plateau fracture
type 2 is the most common (split and depressed
lateral plateau).
Pilon Fracture (Tibial plafond fracture)
axial loading, with the talus being driven into the tibial plafon
The fracture is characterized by comminution and articular impaction. About 75% of the time you are going to have fracture of the distal fibula.
Tibial Shaft Fracture
This is the most common long bone fracture.
tibia is one of the slowest healing bones in the body (10 weeks).
Tiliaux Fractures
This a Salter-Harris 3, through the anterolateral aspect o f the distal tibial epiphysis.
Triplane Fracture
This is a Salter-Harris 4, with a vertical component through the epiphysis, horizontal component through the physis, and oblique through the metaphysis.
Maisonneuve Fracture:
This is an unstable fracture involving the medial tibial malleolus and/or disruption of tlie distal tibiofibular syndesmosis.
ankle with the widened mortis, and “next step? ” get you to ask for the proximal fibula - which
will show the fracture of the proximal fibular shaft.
The fracture does not extend into the hindfoot
