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EDKP-206 > Lecture 8 - Biomechanics of the Knee (part 1) > Flashcards

Lecture 8 - Biomechanics of the Knee (part 1) Flashcards

1
Q

What are the 2 joints of the knee?

A

tibiofemoral and patellofemoral

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2
Q

What 3 bones comprises the knee?

A
  1. femur (distal) (medial + lateral condyle)
  2. tibia (proximal)
  3. patella
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3
Q

Which condyles of the femur articular with the tibia?

A

the medial and lateral condyles

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4
Q

Which condyle is bigger?

A

the medial condyle

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5
Q

What surface articulates with the patella?

A

the patellar surface

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6
Q

What surface prevents lateral patella dislocation?

A

the patellar surface

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7
Q

What kind of slope does the tibial plateau have?

A

posterior

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8
Q

What kind of area does the medial tibial plateau have?

A

large

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9
Q

What kind of shape is the medial tibial plateau?

A

concave but relatively flat

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10
Q

What kind of shape is the lateral tibial plateau?

A

concave in medial-lateral direction, flatter than medial plateau

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11
Q

Which bone is the largest sesamoid?

A

the patella

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12
Q

What are the 3 functions of the patella?

A
  • Protects quadriceps from excessive friction
    during knee flexion
  • Increases angle of application of quadriceps
  • Increases moment arm of the quadriceps tendon
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13
Q

What would happen if the patella was removed?

A

can reduce the quadriceps moment arm by 33-70% with the knee extended and the moment generated by the muscle may be reduced up to 40%

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14
Q

Which 3 bones demonstrate trabecular bone organization?

A

distal femur, proximal tibia, and patella

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15
Q

Which cartilage is the thickest in the body?

A

articular cartilage

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16
Q

The articular cartilage helps improve congruity between which 2 joints’ articulating surfaces?

A

the patellofemoral and tibiofemoral joints

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17
Q

What does the articular cartilage increase?

A

area of contact

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18
Q

What are the 4 noncontractile supporting structures?

A
  • Articularcapsule
  • Collateralligaments
  • Cruciateligaments
  • Accessoryligaments
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19
Q

What are the 4 articular structures of the knee?

A
  1. trabecular bone
  2. articular cartilage
  3. menisci
  4. noncontractile supporting structures
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20
Q

What shape of the fibrocartilage discs?

A

wedged

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21
Q

Where are fibrocartilage discs located?

A

between the femur and tibia

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22
Q

What blood supply is found in the fibrocartilage disks?

A

peripheral blood supply

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23
Q

What are the 3 functions of the menisci?

A
  • Enhancejointlubrication
  • Protect underlying articular cartilage
  • Increase contact area between tibia and femur (~doubles the surface contact area) and thus decreases stress
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24
Q

What are the 2 collateral ligaments?

A

medial and lateral

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25
Q

What does the MCL stabilize against?

A

valgus directed
(abductor) force

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26
Q

Which collateral ligament is most commonly injured?

A

MCL

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27
Q

What does the LCL stabilize against?

A

varus directed (adductor) force

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28
Q

What are the 2 cruciate ligaments?

A

anterior and posterior

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29
Q

What does the ACL resist?

A

anterior glide of tibia

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30
Q

What does the ACL limit?

A

extension ROM with menisci

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31
Q

What kind of stabilization does the ACL have?

A

frontal and transverse plane stabilization

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32
Q

What does the PCL resist?

A

posterior glide of tibia, rotation, varus and valgus

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33
Q

What stabilization does the PCL have?

A

frontal and transverse plane stabilization

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34
Q

What rotation does the PCL limit?

A

lateral tibial rotation with LCL

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35
Q

What are the 2 flexors of the knee?

A

hamstrings and popliteus

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36
Q

What are the 3 medial rotators of the knee?

A

sartorius, gracilis, pes anserinus

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37
Q

What are the 4 extensors of the knee?

A

rectus femoris, vestus intermedius/lateralis/medialis

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38
Q

What is the lateral rotator of the knee?

A

tensor fasciae latae

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39
Q

What is the alignment of the knee joint affected by?

A
  • Foot, ankle, and hip alignment
  • Muscle imbalances
  • Abnormal loads on joint
40
Q

What are the 2 frontal plane alignments of the knee joint?

A

varus and valgrus

41
Q

What is the saggital plane alignment of the knee joint?

A

180 degrees

42
Q

What is the transverse plane alignment of the knee joint?

A

0 degrees

43
Q

What is varus sometimes referred to?

A

bow leg

44
Q

Where is the line found in varus cases?

A

between proximal and distal joints passes medial to the center of the knee

45
Q

Where does varus increase force across?

A

the medial tibiofemoral compartment

46
Q

Where is the line found in valgus cases?

A

between proximal and distal joints and passes lateral to the center of the knee

47
Q

Where does valgus increase fore across?

A

lateral tibiofemoral compartment

48
Q

What is valgus sometimes referred to?

A

knock-knee

49
Q

Where is the mechanical axis found?

A

femoral head to ankle

50
Q

Where is the anatomical axis found?

A

femoral head to knee

51
Q

What are the 2 axes of the lower limb?

A

mechanical and anatomical axis

52
Q

What knee alignment can newborns/young children exhibit?

A

genu varum

53
Q

What is genu varum?

A

varus alignment that goes away by 3-4 years of age

54
Q

What is genu recurvatum?

A

knee hyperextension

55
Q

What does genu recurvatum result from?

A

muscle imbalances at the ankle or knee

56
Q

What does genu recurvatum apply increased stress to?

A

ACL and posterior knee structures

57
Q

Which two structures are aligned so tranverse axes of proximal tibia and distal femur are parallel in knee extension?

A

tibial plateaus and femoral condyles

58
Q

What is knee OA equal to?

A

5 degrees tibial version

59
Q

How many lines make up the Q-angle?

A

2

60
Q

Where is line 1 of the Q-angle?

A

ASIS to patella center

61
Q

Where is line 2 of the Q-angle?

A

tibial tubercle to patella center

62
Q

Increased Q angle is considered a risk factor for…

A
  • Patellofemoral pain (PFP)
  • Patellar subluxation and dislocation
  • Knee OA
  • Overuse injuries, etc.
63
Q

What increases with the Q angle?

A

the lateral pull of quadriceps on patella

64
Q

What is the stability of the lateral pull of quadriceps on patella enhanced by?

A
  • lateral femoral condyle
  • medial extensor retinaculum
  • vastus medialis
65
Q

How many degrees of freedom does the knee have?

A

6

66
Q

What plane is the normal ROM of the knee?

A

saggital

67
Q

What does ROM change with?

A

age

68
Q

What is uncommon with ROM?

A

hyperextension ROM

69
Q

What are the 2 kinetic chains?

A

closed and open

70
Q

What does movement of one joint cause in a closed chain?

A

causes the other joints in the chain to move in a predictable manner

71
Q

What is an example of a closed chain?

A

rising from a chair or doing a push up

72
Q

What does movement of one joint cause in an open chain?

A

it is independent of other joints in the chain

73
Q

What is an example of an open chain?

A

swing phase of gait or bicep curls

74
Q

In a closed chain, the segment furthest from the body is ___.

A

fixed/stationary

75
Q

In an open chain, the segment furthest from the body is ___ and ___ fixed to an object.

A

free, not

76
Q

What does moment arm of the trunk weight increase with?

A

increasing knee flexion

77
Q

What makes pure rolling motion of the tibiofemoral joint possible?

A

the more articular surface on the femoral side of the knee joint

78
Q

What is pure rolling?

A

every point of contact on one surface has a unique point of contact on other surface

79
Q

What does the relative motion between the tibia and femur depend on?

A

which parts are in contact

80
Q

What two surface shapes directly impact the relative motion of the tibiofemoral joint?

A

the femoral and tibial articular surface shapes

81
Q

What surfaces contribute to 3-D movement of the femur and tibia during knee flexion and extension?

A

tibiofemoral joint surfaces

82
Q

What does the tibiofemoral motion not adhere strictly to?

A

the concave-convex rule

83
Q

When a convex joint surface is moving, roll and glide occurs in the ___ direction; when a concave joint surface is moving, the roll and glide occurs in the ___ direction.

A

opposite, same

84
Q

When is the rate of rotation the greatest?

A

at the end of extension between 30 degrees of flexion and complete extension

85
Q

During flexion, as the femur rolls into ___, it rotates ___ with respect to the tibia.

A

flexion, laterally

86
Q

The femur rotates ___ as it rolls into extension.

A

medially

87
Q

Contact between the femur and tibia migrates…

A
  • Posteriorly on the tibia during flexion
  • Anteriorly on the tibia during extension
88
Q

Posterior translation of the femur on the tibia during ___.

A

flexion

89
Q

Anterior translation of the femur on the tibia during ___.

A

extension

90
Q

What does the patellofemoral motion depend on?

A

knee position

91
Q

In extension, the patella is ___.

A

moveable

92
Q

Translation of the patella during knee flexion is ___ cm distal glide with knee flexion.

A

5-7

93
Q

What action does the patella do during knee flexion?

A

rotates and tilts laterally until at least 90 degrees of knee flexion

94
Q

What happens during contact ACL injuries?

A
  • Footplanted
  • Femur driven posterior
  • Rotation
95
Q

What happens during non-contact ACL injuries?

A
  • Landing, deceleration, pivoting/cutting
  • Knee/hip in extension+valgus
  • Quadriceps overload

EDKP-206 (16 decks)

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