Knee quiz

Question 1

What is the locking mechanism of the knee and what unlocks it?

Answer 1

Achieves closed pack position at full extension
Brought about by automatic rotation between femur and tibia in last 30 degrees of extension
Knee needs to flex to unlock

Question 2

To what extent do the menisci have blood and neve supplies?

Answer 2

The peripheral borders of the meniscus have the greatest blood supply in youth
In later life we rely on nutrition from synovial fluid
The outer thirds of the menisci have a few non-myelinated fibres

Question 3

What are the differences between the ACL and PCL?

Answer 3

ACL provides 86% of anterior restraint of the tibia upon the femur and 30% of medial displacement
PCL is shorter but has twice the strength in tension than the ACL
PCL provides 94% of posterior restraint of the tibia upon the femur and 36% of lateral displacement

Question 4

What is the Q angle?

Answer 4

Q angle is a line from the centre of the ASIS to the centre of the patella, and a 2nd line from the centre of the patella to the tibial tuberosity
Normally 10-14 in males and 15-17 in females
Angle of 18 or above suggests patella tracking dysfunction, subluxating patella, increased femoral anteversion or increased tibial torsion

Question 5

What do sartorious, gracilis and semitendinosus have in common?

Answer 5

Distal tendons of all three insert to upper medial surface of tibia
Known as Pes Anserinus