The Knee Flashcards
What type of joint is the knee?
A modified hinge joint.
What are the two articulations within the knee joint?
Patellofemoral and tibiofemoral joints.
What structures provide static and dynamic stability to the knee?
Capsule, ligaments (MCL, LCL, ACL, PCL), and musculotendinous support.
Why is the patella important?
It improves the leverage of the quadriceps, increasing the efficiency of knee extension.
What is the largest sesamoid bone in the body?
The patella.
When does the patella become visible on X-rays?
After infancy, as it is initially cartilaginous.
What does a non-flat tibial plateau surface on X-ray indicate?
A tibial condyle fracture, often from a fall.
What is genu valgum?
Knock knees – legs angle inward.
What is genu varum?
Bow-legged appearance – legs angle outward.
Where is the MCL located?
On the medial side, attached to the medial meniscus.
What forces does the MCL resist?
Valgus (inward) forces.
How is the MCL tested?
Apply valgus stress while stabilizing the thigh.
Where is the LCL located?
Lateral knee, connecting femur to fibula
What forces does the LCL resist?
Varus (outward) forces.
How is the LCL tested?
Apply varus stress by pushing the lower leg medially.
Why are they called cruciate ligaments?
They cross each other inside the knee like a cross.
Are cruciate ligaments intra- or extra-synovial?
Intra-capsular but extra-synovial.
When is the ACL tightest?
In extension.
What does the ACL prevent?
Posterior displacement of the femur on the tibia.
How is ACL rupture tested?
Lachman or anterior drawer test.
When is the PCL tightest?
In flexion.
What does the PCL prevent?
Anterior displacement of the femur on the tibia.
Common causes of PCL rupture?
Dashboard injury or falling on a bent knee.
What is the function of the menisci?
Increase congruence, stability, and weight distribution.
