Knee Locking Mechanism

Question 1

Why is it important?

Answer 1

For muscle energy efficiency

Question 2

What initiates the unlocking?

Answer 2

Popliteus laterally rotates the femur on a fixed tibia

Question 3

Knee is locked

Answer 3

Closed pack position
Full extension
Maximum joint congruency
Centre of gravity is anterior to the knee joint

Question 4

Sitting to standing

Answer 4

Femoral condyles roll anteriorlly over tibial condyles
Femoral condyles glide posterially over tibial condyles to stop from rolling off
Lateral femoral condyles movement stops first
Femur medially rotates around lateral condyle to complete the movement

Question 5

Standing to sitting

Answer 5

Unlocking the knee joint from a closed pack position
Popliteus unlocks the knee
As we begin to flex the knee rotates laterally on the tibia and femoral condyles roll posteriorly on the tibial condyles
Glide anteriorly on the tibial condyles to stop them rolling off the back