Knee

Question 1

Three articulations of the knee joint

Answer 1

• Medial femorotibial
• Lateral femorotibial
• femoropatellar

Question 2

Movements at the knee

Answer 2

Extension
Flexion
- some lost when the hip is extended due to loss of tension on hamstrings.
Rotation
- can only occur when the knee is flexed and the collateral ligaments are relaxed

Question 3

Locking of the knee

Answer 3

Medial rotation of the femur on the tibia as the joint approaches full extension.

A very stable position so thigh muscles can relax

Question 4

Unlocking the knee

Answer 4

Popliteus laterally rotates the femur to unlock the knee

Question 5

Why is the knee joint incongruent?

Answer 5

Tibial plateau - the surface of the tibia above the condyle a is flat and thus a poor fit for the round femoral condyles.

Tibial plateaus are deepened by the menisci

Question 6

Extension of knee

Answer 6

Most congruent + most stable position.

Question 7

Flexion of the knee

Answer 7

Least congruence + less stable position

Question 8

What are the menisci?

Answer 8

Two C-shaped wedges of cartilage

Thicker at the external margins

External edges attach to the fibrous capsule of the joint

Medial meniscus is firmly attached to the tibial collateral ligament

Question 9

Functions of the menisci

Answer 9

• Increase joint congruence
• Distribute weight evenly
• Shock absorption
• Assist in locking mechanism

Question 10

What aids the stability knee?

Answer 10

• Intra-articular ligaments
  > the anterior and posterior cruciate ligaments
• Extra-articular ligaments
  Both prevent rotation during extension of the knee = stability while standing
  > the fibular collateral ligament
  ~ prevents ADduction of the leg at the knee
  > tibial collateral ligament
  ~ prevents ABduction of the leg at the knee
  Surrounding muscles
  Menisci

Question 11

Posterior Cruciate Ligament

Answer 11

Posterior intercondylar region of the tibia
–> travelling superolaterally –>
Medial femoral condyle

Question 12

Anterior cruciate ligament (ACL)

Answer 12

Anterior intercondylar region of the tibia
–> superoposteriorly –> lateral femoral condyle

The ACL is weaker than the PCL

Question 13

PCL function

Answer 13

• Prevents posterior displacement of the tibia on the femur
• Prevents hyperflexion
• Main stabiliser of the flexed knee when weight bearing
  > eg walking down hill

Question 14

PCL injury

Answer 14

PCL can be damaged when landing on the tibial tuberosity with the knee flexed

Question 15

ACL function

Answer 15

• Prevents anterior displacement of the tibia on the femur

- Prevents hyperextension

Question 16

ACL injury

Answer 16

ACL injury when the knee is hyperextended or force applied anteriorly

Question 17

Tibial (medial) collateral ligament

Answer 17

• wide flat ligament on the medial side of the joint
• Medial epicondyle of femur –> medial surface of the tibia
• attaches to the medial meniscus
• prevents ABduction of the leg at the knee

Question 18

Fibular (lateral) collateral ligament

Answer 18

• Cord like band, NOT attached to lateral meniscus
• Lateral epicondyle of the femur –> depression on the lateral surface of the fibular head
• Prevents ADduction of the leg at the knee

Question 19

Muscles that stabilise the knee

Answer 19

- Quadriceps 
 > building up the quads through physio and/or exercise can compensate for ligament damage and avoid surgery. 
- Hamstrings (posterior thigh)
- Sartorius
- Gracilis
- Iliotibial tract

Question 20

Bursae of the knee

Answer 20

Suprapatella bursa
Prepatella bursa
Infrapatella bursa
(Semimembranosus bursa)

Question 21

Bones of the knee joint

Answer 21

• Distal femur
• Proximal tibia
• Patella

(Fibula is NOT associated with the knee joint!!!)