Knee

Question 1

What is different about the medial femoral condyle?

Answer 1

medial condyle extends farther distally and laterally and has a larger articular surface

Question 2

Screw home mechanism

Answer 2

movement caused by the size of the condyles and how they interact with the tibia during extension

Question 3

What is different about the lateral femoral condyle?

Answer 3

lateral condyle projects farther anteriorly, has a trochlea, and an intercondylar notch where the cruciate ligaments fit in

Question 4

On the tibia, which articular side is larger?

Answer 4

Medial tibial condyle is larger, corresponding with the larger femoral condyle size.

Question 5

Patella

Answer 5

lateral articular surface is larger

Question 6

Is the tibiofemoral joint a good fit?

Answer 6

No, it has poor congruence.

Question 7

Does the patellofemoral joint have a good fit?

Answer 7

Yes, good congruence, better in flexion

Question 8

Joint capsule

Answer 8

fibrous sleeve, as inner synovial lining. It is reinforced by ligaments for stability.

Question 9

In what movement is the joint capsule taut posteriorly? Why is this good?

Answer 9

Full extension. This will prevent hyperextension.

Question 10

In what movement is the joint capsule taut anteriorly? Why is this good?

Answer 10

Flexion. This will prevent translation of the femur anteriorly when flexed.

Question 11

Synovium: does it contain the cruciate ligaments?

Answer 11

No, they are outside the membrane (extra-synovial), and this cannot be nourished by the synovial fluid, thus leading to poor healing.

Question 12

4 anterior knee bursa in descending order:

Answer 12

1. suprapatellar (just deep to quadriceps tendon)
2. prepatellar (found between skin and patella)
3. deep infrapatellar (found between patellar ligament and tibia)
4. subcutaneous infrapatellar (between skin and patella tendon)

Question 13

Bursa function

Answer 13

reduce frictional and compressional stresses

Question 14

4 posterior knee bursa:

Answer 14

1. two gastoc bursa (found under medial and lateral gastroc heads)
2. popliteus bursa (found under popliteus muscle)
3. semimebmranosis tendon bursa (found under the distal tendon of the semimembranosis)

Question 15

Why do we have menisci?

Answer 15

to improve the boney fit. They are wedge shaped, taller at the edges.

Question 16

Does the meniscus have good vascularization?

Answer 16

At the edges, yes, but at the center, no. So if damaged, the edges may be able to heal themselves, but the center will not.

Question 17

Where do the menisci attach?

Answer 17

they are c-shaped, and have many ligaments coming off of them. They form horns at the intercondylar eminence, creating the intercondylar ligament.

Question 18

Menisci ligaments: 4 types

Answer 18

1. coronary: on the periphery of the menisci, attach the menisci to the tibia.
2. transverse: attaches the anterior meniscus to the anterior meniscus (runs across eminence)
3. intercondylar: attaches meniscal horns to intercondylar eminence.
4. meniscofemoral: attaches the posterior horn of lateral meniscus to medial femoral condyle.

Question 19

What is the purpose of the menisci ligaments?

Answer 19

To stabilize the fibrocartilage pads

Question 20

What’s special about the medial meniscus?

Answer 20

it has additional attachments to the joint capsule and MCL, thus not as free floating

Question 21

Describe meniscal movement (1) during flexion and (2) during extension.

Answer 21

1. moves posteriorly

2. moves anteriorly

Question 22

Stability of the knee (and joint capsule) depends on:

Answer 22

1. collateral ligaments
2. cruciate ligaments
3. capsular ligaments
4. muscles/tendons

Question 23

Extensor mechanism

Answer 23

provides anterior stability, prevents femur from sliding anteriorly. Includes: quads, quad tendon, patella, and patella ligament.

Question 24

Patellar retinaculum

Answer 24

fibrous bands that extend from quad tendon and patellar ligament and broaden the extensor mechanism medially and laterally. Support the joint anteriorly.

Question 25

MCL

Answer 25

capsular ligament, from medial epicondyle to medial tibia, joins with the capsule and medial meniscus. Really is just a thickening of the joint capsule.

Question 26

What force does the MCL resist? How is it loaded?

Answer 26

resists tensile forces and valgus stress. If there is a force acting laterally in the knee, causing the femur to move medially and the tibia to move laterally, this is a valgus load.

Question 27

LCL

Answer 27

extracapsular ligament, from lateral femoral condyle to fibular head, under the biceps femoris attachment.

Question 28

What stress does the LCL resist?

Answer 28

resists varus stress, when there is a blow medially, causing the femur to move laterally and the tibia to move medially.

Question 29

IT Band

Answer 29

formed by TFL and inserts into lateral tibial condyle. Reinforces the knee laterally, resists varus loading.

Question 30

Dynamic ligament

Answer 30

muscle tendon unit that, when active, acts as a ligament to support the joint.