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Flashcards in knee Deck (50)
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1

Movement between 2 objects can be categorized into which 3 groups? Which 2 are seen in the knee joint?

Slide/glide: single point on one surface contacts multiple points on another
Roll/rock: multiple points on one surface contact multiple points on another
Spin: single point on one surface rotates on a single point on another
At knee: slide and roll

2

What are the 3 degrees of freedom at the knee joint?

Abduction/adduction
Flexion/extension
Internal/external rotation

3

True or false: the knee is a hinge joint

False - there are no hinge joints in the body. The axis of rotation changes as the joint moves

4

Which 2 joints are contained within the knee complex?

Tibiofemoral
Patellofemoral

5

The differences in shape and orientation of the femoral condyles are important for what mechanism?

Screw home

6

Which is larger: the articulating surface of the medial or lateral condyle?

Medial (50% larger)

7

The articular cartilage is thicker on the (femur/tibia)

Tibia (x3)

8

What structure greatly enhances the articular congruence of between the spherical femoral condyles and the flat tibial plateaus?

Menisci

9

Which meniscus is C shaped? Which is more circular?

C: medial
Circular: lateral

10

Name the 5 structures attached to the medial meniscus

ACL
MCL
Semimembranosus tendon
Coronary lig
Transverse lig

11

Name the 4 structures attached to the lateral meniscus

Popliteal tendon
PCL
Transverse lig
Coronary lig
NOT LCL (outside jt capsule)

12

What is the normal tibiofemoral angle?

185-190deg

13

How do you measure the mechanical axis of the lower limb? Why is this useful? What is a normal measurement?

From centre of head of femur to centre of talus

Shows weight distribution over knee (should pass through centre of knee)

Normal: 3deg from vertical

14

What is the threshold measurement for genu valgum? For genu varum?

Valgum: >195deg
Varum: <180deg

15

What changes are typically seen in the knee and foot joints in individuals with coxa vara?

Genu valgum
Supination of subtalar joint and transverse tarsal joint

16

In which direction is the knee most unstable? What limits this motion?

Flexion
Joint capsule + associated ligaments

17

In which knee position is the MCL most important in resisting valgus stress: flexion or extension?

Flexion (because other structures are lax in this position)

18

Other than resisting valgus stress, what other 2 jobs does the MCL have in limiting knee motion?

Limits lateral rotation of tibia
Limits anterior displacement of tibia (espec when ACL absent/ruptured)

19

Other than resisting varus stress, what other 2 jobs does the LCL have in limiting knee motion?

Limits lateral rotation of tibia (espec at 35deg of flexion)
Limits posterior displacement of tibia

20

True or false: the IT band is taut in knee extension and slack in knee flexion

False - consistently taut regardless of hip and knee position

21

Which knee ligament does the IT band assist? How?

ACL
Forms a sling behind lateral femoral condyle with the biceps femoris and vastus lateralus to hold the femur anteriorly

22

What kind of collagen makes up the ACL and PCL?

Composed of Type I Collagen, separated by Type III collagen fibrils

23

In which knee position is the ACL lax?

30degrees of flexion

24

Other than anterior translation, what motions does the ACL resist?

Medial rotation (ACL twists around PCL)
Lateral rotation (ACL is stretched over lateral femoral condyle)

25

In which knee position is the PCL most lax?

75-90deg flexion

26

The oblique popliteal ligament is created by the tendinous expansion of which muscle?

Semimembranosus

27

Which 2 ligaments reinforce the posterior aspect of the knee joint capsule? What direction of force does each resist?

Oblique popliteal ligament: valgus stress
Arcuate popliteal ligament: varus stress

Both resist hyperextension

28

When the knee is in extension, which direction does the synovial fluid go to? Why?

Anterior - posterior capsule and ligaments are taught which compresses the gastroc and sub-popliteal bursae, shifting the fluid anterior

29

In which position is the suprapatellar bursa the least compressed? Why?

In extension, the suprapatellar bursa is compressed by posterior structures moving the fluid anterior

In flexion, the suprapatellar bursa is compressed by the tension in the anterior structures, shifting the fluid posterior

During a semi-flexed position, the synovial fluid is under the least amount of tension

30

Which 2 knee bursae are located within the capsule? Which 3 are outside the knee capsule?

Inside: gastroc and suprapatellar
Outside: pre-patellar, subcutaneous infrapatellar, deep infrapatellar

31

How is the axis of flexion/extension oriented in the knee? What effect does this have on the alignment of the femur and tibia?

Lower on medial side (oblique angle)
Causes tibia to sit medial to the femur during flexion

32

Passive knee flexion is _____ when the hip is flexed and _____ when the knee is extended

130-140deg
120deg

33

Match the ADL with the amount of knee flexion required:

1. Normal gait
2. Climbing stairs
3. Sitting in chair

a. 80deg
b. 90 deg
c. 60deg

1 - c
2 - a
3 - b

34

What is the close-packed position of the knee?

Full extension

35

In which knee position is there the greatest tibial rotation range?

90degrees flexion

36

What is the total possible tibial rotation? How much is lateral rotation and how much is medial rotation?

60-70deg total
Lat: 0-40deg
Med: 0-30deg

37

In open-chain tibial rotation, which tibial condyle moves most: medial or lateral?

Lateral (posteriorly for lateral rotation, anteriorly for medial rotation)

Medial acts as pivot point

38

How can you isolate soleus from gastroc in terms of plantar flexion?

Stand on toes and slightly flex knee (causes active insufficiency)

39

What is one of the key functions of gastrocnemius during gait?

Prevents knee joint hyperextension

40

In which position are the hamstrings actively insufficienct?

Hip extension
Knee flexion

41

Dr. Ross does not believe that popliteus is actually for unlocking the knee joint. What function does he believe it serves?

Moving the meniscus out of the way during unlocking.

42

What 3 functions do the quads serve during the gait cycle?

Decelerate flexion of knee during early swing

Straighten knee during end of swing

Keep knee from flexing when ground rxn force is posterior to the knee

43

]What is the screw home mechanism of the knee? How does it work?

Helps keep knee stable by causing joint surfaces to be more tightly packed as cruciate ligs wind around each other

Occurs when tibia is externally rotated relative to femur

44

At what point in gait does the screw home mechanism unlock? What does the tibia do to facilitate this?

20 degrees of flexion
Tibia rotates internally

45

The pressure on the patellofemoral joint is determined through the combined forces of which 4 structures?

Quad tendon
Patellar lig
Medial and lateral retinacula
IT band

46

In the patellofemoral joint, increasing flexion causes the weight-bearing portion to shift from the _______ pole to the _______ pole

Inferior
Superior

47

A patient reports that they have patellofemoral pain only on full extension of the knee. Which part of the patellofemoral joint is most likely affected?

Odd facet

48

A patient reports that they have patellofemoral pain only on full flexion of the knee. Which part of the patellofemoral joint is most likely affected?

Superior pole

49

Why is it important to avoiding having a bike seat too low?

Knee is in more flexed position. Decreases moment arm, requiring greater quad strength and increasing patellar compression

50

What important role do the superior and inferior tibiofibular joints play in ankle biomechanics?

Allows ankle mortise joint to be adjustable. Important because the anterior aspect of the talus is wider than the posterior aspect. Allows for full plantar and dorsiflexion without compromising joint stability.