Knee Flashcards
(27 cards)
Which guidelines are best for evaluating radiographs for acute knee injuries?
Ottawa and Pittsburgh
What makes Ottawa and Pittsburgh “the best?”
Excellent sensitivity for identifying fractures by applying simple predictive parameters
When should radiographs be ordered after a trauma to the knee?
- Joint effusion after direct blow or fall
- Inability to walk without limping
- Palpable tenderness over patella or fibular head
- Inability to flex knee to 90
When shouldn’t radiographs be ordered?
If patient had a twisting injury but is able to walk and no effusion present
What do meniscal tears present with?
Intermittent clicking and eventually chronic blocking or loading of knee joint motion
Effusion
Pain
What is the standard modality for evaluating meniscal tears?
MRI, menisci seen as LOW signal intensity (dark) with HIGH signal intensity (bright) tear that extends to the surface
In what direction are meniscal tears most common?
Vertically
What are longitudinal extensions from vertical tears called?
Bucket handle tears
What direction of meniscal tears is most common in older individuals?
horizontal
How does a patient present who injured a collateral ligament?
After an acute episode with pain, joint effusion, instability upon examination with ligamentous stress testing
Which collateral ligament is more commonly injured?
Medial, often associated with tears of joint capsule and medial meniscus
Which structures are injured in O’Donoghue’s terrible triad?
MCL, MM, ACL
Which imaging technique is best for looking at collateral ligamentous injuries?
MRI T2-weighted, discontinuity of low-signal intensity ligament best seen on coronal image
How many ACL injuries occur per year?
200,000
How much more are women prone to ACL injuries than men?
8 times more
What is the MOI for PCL injuries?
external forces that strike anterior aspect of knee, as in dashboard injuries
What is the MOI for ACL injuries?
non-contact forces that place great valgus and rotary stresses on the knee, as when athlete suddenly decelerates, turns and hears “pop” of rupture
What is dynamic lower extremity valgus force?
Combination of motions and rotations at all 3 LE joints
Ex: hip ADD/IR, knee ABD, tibial ER/anterior translation, ankle eversion
What imaging should be used to view cruciate ligament injuries?
Radiographs required to evaluate an avulsion fracture
Sagittal MRI best to demonstrate cruciates
What are the routine radiographs for the knee?
AP, lateral, PA axial (tunnel) and tangenital view of patellofemoral joint (sunrise)
When are CT used?
degree of fragmentation or depression of articular surfaces, pre-op planning
When are MRIs used?
injuries to articular cartilage, menisci, cruciate and collateral ligaments, soft tissue
What are bone scans used?
Occult or subtle fractures, stress fractures, injury to articular cartilage (great sensitivity, inexact location)
Which portion of proximal tibia is most involved in a fracture?
Tibial plateau, usually lateral
