Knee

Question 1

What is the angle of the knee on its lateral side?

Answer 1

170°-175°

Question 2

The normal alignment of the knee is referred to as genu ____

Answer 2

valgum

Question 3

If the frontal plane angle of the knee is less than 170° it is called excessive genu ____, or “knock-knee”.

Answer 3

valgum

Question 4

If the frontal plane angle of the knee is greater than 180° it is called genu ____, or “bow-leg”.

Answer 4

varum

Question 5

2 joints of the knee

Answer 5

tibiofemoral joint and patellofemoral joint

Question 6

Describe the articulation at the tibiofemoral joint

Answer 6

Articulations between large, convex femoral condyles and nearly flat, smaller tibial condyles

Question 7

What portion of the menisci are attached to the tibia?

Answer 7

The anterior and posterior horns

Question 8

What attaches the external edges of each meniscus to the tibia?

Answer 8

coronary (or meniscotibial) ligaments

Question 9

The medial and lateral menisci are attached anteriorly by what ligament?

Answer 9

the slender transverse ligament

Question 10

What muscles attach to the medial meniscus?

Answer 10

• Quadriceps

- Semimembranosus

Question 11

What muscles attach to the lateral meniscus?

Answer 11

• Quadriceps
• Semimembranosus
• Popliteus

Question 12

Where is blood supply to the menisci greatest?

Answer 12

near the peripheral (external) border

Question 13

Describe the shape of the medial and lateral meniscus

Answer 13

• Medial meniscus has oval shape

- Lateral meniscus has more circular shape

Question 14

Complete lateral meniscectomy increases peak contact pressures at knee by __%

Answer 14

230%

Question 15

What is the MOI for a meniscus tear?

Answer 15

forceful axial rotation of femoral condyles over partially flexed and weight-bearing knee

Question 16

Medial meniscus injured ____ as frequently as lateral meniscus

Answer 16

twice

Question 17

What is the MOI for a medial meniscus tear?

Answer 17

axial rotation and external valgus force applied to lateral aspect of knee

Question 18

How many degress of freedom does the tibiofemoral joint have? What are they?

Answer 18

2

• Flexion and extension
• Internal and external rotation

Question 19

Frontal plane motion at the knee occurs passively and is limited to _° - _°.

Answer 19

6° - 7°

Question 20

From the tibial-on-femoral perspective which bone is stationary? Which is stationary from the femoral-on-tibial perspective

Answer 20

femur

tibia

Question 21

The migrating path of the ML axis of rotation for flexion and extension of the knee is called what?

Answer 21

the “evolute”

Question 22

What are the 2 biomechanical and clinical implications of the migrating ML axis of rotation?

Answer 22

1) alters the length of the internal moment arm of the flexor and extensor muscles of the knee
2) external devices that attach to knee (goniometer) rotate about a fixed axis of rotation which means they may rotate in a dissimilar arc than the leg

Question 23

From a tibial-on-femoral perspective, external rotation of the knee occurs by ____ rotation of the tibia

Answer 23

external

Motion is the same

Question 24

From a femoral-on-tibial perspective, external rotation of the knee occurs by ____ rotation of the femur

Answer 24

internal

Motion is opposite

Question 25

Generally, freedom of axial rotation _____ with greater knee flexion

Answer 25

increases

Question 26

A knee that is flexed to 90° can perform about __°-__° of total axial rotation

Answer 26

40°-45°

Question 27

_____ rotation range of motion generally exceeds _____ rotation by ratio of about 2 : 1

Answer 27

external | internal

Question 28

From a tibial-on-femoral perspective the tibia rolls ____ and slides ____ during extension

Answer 28

anteriorly anteriorly In the same direction as the movement

Question 29

From a femoral-on-tibial perspective the femur rolls ____ and slides ____ during extension

Answer 29

anteriorly (same direction as the movement) | posteriorly

Question 30

In order to fully extend the knee about __° of external rotation is required. What is this called?

Answer 30

10° “Screw-Home”Rotation of Knee

Question 31

What characteristic of the medial femoral condyle helps direct tibia to its externally rotated and locked position

Answer 31

The fact that it is curved

Question 32

For a knee that is fully extended to be unlocked, the joint must first _____ rotate.

Answer 32

internally

Question 33

Which muscle internally rotates (unlocks) the knee?

Answer 33

popliteus

Question 34

Once the knee is flexed, arthrokinematics of internal and external rotation involve primarily what motion between the menisci and articular surfaces.

Answer 34

spin

Question 35

What are the functions of the MCL?

Answer 35

1. Resists valgus (abduction) 2. Resists knee extension 3. Resists extremes of axial rotation (especially knee external rotation)

Question 36

What are the functions of the LCL?

Answer 36

1. Resists varus (adduction) 2. Resists knee extension 3. Resists extremes of axial rotation

Question 37

What are the functions of the ACL?

Answer 37

1. Most fibers resist extension (either excessive anterior translation of tibia, posterior translation of femur, or a combination thereof) 2. Resists extremes of varus, valgus, and axial rotation

Question 38

What are the functions of the PCL?

Answer 38

1. Most fibers resist knee flexion (either excessive posterior translation of tibia or anterior translation of femur, or a combination thereof) 2. Resists extremes of varus, valgus, and axial rotation

Question 39

How do approximately 70% of ACL injuries occur?

Answer 39

through non-contact or minimal contact

Question 40

What does the Sartorius muscle do at the hip and knee?

Answer 40

- Hip flexion, external rotation, and abduction | - Knee flexion and internal rotation

Question 41

What does the Gracilis muscle do at the hip and knee?

Answer 41

- Hip flexion and adduction | - Knee flexion and internal rotation

Question 42

What does the quadriceps femoris muscle do at the hip and knee?

Answer 42

- Hip flexion | - Knee extension

Question 43

What does the popliteus muscle do at the knee?

Answer 43

flexion and internal rotation

Question 44

What does the semimembranosus muscle do at the hip and knee?

Answer 44

- Hip extension | - Knee flexion and internal rotation

Question 45

What does the semitendinosus muscle do at the hip and knee?

Answer 45

- Hip extension | - Knee flexion and internal rotation

Question 46

What does the short head of the biceps femoris muscle do at the knee?

Answer 46

flexion and external rotation

Question 47

What does the long head of the biceps femoris muscle do at the hip and knee?

Answer 47

- Hip extension | - Knee flexion and external rotation

Question 48

What does the gastrocnemius muscle do at the knee and ankle?

Answer 48

- Knee flexion | - Ankle plantar flexion

Question 49

What does the plantaris muscle do at the knee and ankle?

Answer 49

- Knee flexion | - Ankle plantar flexion