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Biomechanics Exam 1 > Knee > Flashcards

Knee Flashcards

1
Q

Knee joint is a ——axial joint with ——-degrees of freedom.

A

biaxial

2

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2
Q

Knee joint has 2 articulations

A

Tibiofemoral articulation

Patellofemoral articulation

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3
Q

Knee joint is what type of joint?

this is a test question

A

Ginglymus joint (a joint that allows movement in but one plane, forward and backward, as does a door hinge) A hinge joint`

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4
Q

Does fibula contribute in the knee joint?

A

NO

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5
Q

Sagittal plane motion provided by an axis

A

which passes through the femoral condyles located parallel to the frontal and transverse planes

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6
Q

What allows the knee to be aligned so that purely sagittal plane motion occurs?

A

changes in angle of inclination

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7
Q

The varus attitude of the femur is balanced by

A

the longer/larger medial femoral condyle to put the axis of the joint parallel to the transverse plane

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8
Q

Axes of the knee

A

The axis providing sagittal plane motion
The anatomical axis of the femur and tibia
The mechanical axis of the knee

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9
Q

The anatomic axes of the femur and tibia are their ———axes

A

Longitudinal

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10
Q

Longitudinal axes of femur and tibia form an angle of

A

185º-190º (5-10 degrees off of vertical)

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11
Q

The tibia is relatively———–on the femur

A

Abducted

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12
Q

tibia has a physiological valgus of

A

5-10º

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13
Q

Mechanical axis (weight-bearing line) of the knee joint normally passes

A

through the centers of the knee , hip and ankle joints

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14
Q

Mechanical axis forms an angle of ~

A

3º from the vertical

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15
Q

The mechanical axis represents the line through which

A

ground reactive forces passes

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16
Q

what happens if frontal plane angulation at the knee increases ( genu varum or genu valgum

A

The mechanical axis will no longer pass through the center of the knee joint

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17
Q

What does the mechanical axis represent?

A

It represents the path for ground reactive forces

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18
Q

if the mechanical axis falls medial to the knee , the condition is called

A

Genu Varum

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19
Q

In genu Varum, compressive forces will be ————– and ————-

A

increased medially

decreased laterally

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20
Q

If the mechanical axis falls laterally to the knee joint, it is called

A

Genu valgum

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21
Q

in Genu valgum

A

compressive forces will be increased laterally and decreased medially

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22
Q

A change in the mechanical axis of the knee will cause

A

a change in the ground reactive forces (external moment) across the knee.

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23
Q

constant overloading on the increased compression side of the knee may lead to

A

articular cartilage damage
increased frontal plane deformity
increased overload

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24
Q

foot orthoses changes

A

the mechanical axis

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25
Q

external moment examples

A

GRF
Gravity
Momentum

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26
Q

internal moment examples

A

muscles
ligaments
bony limitation

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27
Q

GRF causing ———————and the body responding with ————

A

External abduction moment

Internal adduction moment

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28
Q

Requirements for Knee joint function

A
  1. Great mobility

2. Stability

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29
Q

Knee joint flexibility is provided by

A
  • Anatomical structure of the knee

- The instant axis of rotation of the tibiofemoral articulation

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30
Q

The change in location of instant axis of rotation is a result of

A

combination of gliding and rolling

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31
Q

Flexion of the knee from full extension to 25º flexion is purely——-

A

rolling

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32
Q

Flexion beyond 25º requires

A

Anterior gliding

posterior rolling of the femur on the tibia to prevent the femur from falling off the tibia posteriorly

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33
Q

the gliding motion during knee FLEXION is facilitated by

A

ACL

menisci

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34
Q

Knee EXTENSION is facilitated by

A

PCL

Menisci

35
Q

As the knee flexes , the femur

A

slides forward on the tibia

36
Q

What is the normal max motion of the tibiofemoral articulation in the sagittal plane?

A

140º of flexion

5-10º of extension (hyperextension)

37
Q

Hyperextension greater than———is generally considered genu recurvatum

A

10º

38
Q

minimum requirements for Sagittal plane knee motion in gait

A

60º of knee flexion ( on level ground)

39
Q

minimum requirements for Sagittal plane knee motion in stair climbing

A

80º of knee flexion

40
Q

minimum requirements for Sagittal plane knee motion in sitting

A

90º of knee flexion

41
Q

In stance phase of the gait, the greatest amount of force is on

A

the medial plateau

42
Q

In swing phase of the gait, the greatest amount of force is on

A

the lateral plateau

43
Q

which one is larger? medial or lateral plateau?

A

Medial plateau is 50% larger and has cartilage 3X thicker than the lateral plateau

44
Q

Hip and ankle position will effect sagittal plane knee RANGE OF MOTION in

A

OKC

45
Q

Hip and ankle position will effect KNEE FUNCTION in

A

CKC

46
Q

Transverse plane knee motion occurs via 2 separate mechanisms :

A
  • true transverse plane knee motion

- the screw-home mechanism

47
Q

How much true transverse plane knee motion occurs depends on

A

sagittal plane position of the knee

48
Q

Fully extended knee

A

has no transverse plane motion due to interlocking mechanism between femoral and tibial condyles

49
Q

When there is no transverse plane motion due to interlocking mechanism between femoral and tibial condyles this represents

A

closed-packed or locked position of the knee joint and the knee ligaments

50
Q

When the knee is flexed at 90º, the ligaments are

A

lax

51
Q

When the knee is flexed at 90º. external rotation may be as high as

A

45º

52
Q

When the knee is flexed at 90º, internal rotation may be as high as

A

30º

53
Q

As the knee moves further away from 90º in the direction of extension/flexion the amount of transverse plane motion available

A

decreases

54
Q

Screw-Home mechanism occurs as a result of

A

The medial condyle being 1.7 cm longer than the lateral condyle which allows for spiral like motion to occur

55
Q

in Screw-Home mechanism, what you see is

A

The tibia appears to externally rotate on the femur with knee extension

56
Q

in Screw-Home mechanism, what actually happens is

A

the femur internally rotates relative to the tibia

this is most notable during the last 5º of knee extension

57
Q

Screw-Home mechanism is a ———plane motion

A

Transverse

58
Q

Screw-Home mechanism occurs with knees in what position ?

A

occurs with knee extension brings the knee into its closed packed position with menisci tightly interposed and the ligaments taut

59
Q

Screw-Home mechanism benefits?

A

provides increased stability for the knee joint in the extended position

60
Q

The Screw-Home mechanism sometimes referred to as

A

the automatic rotation of the knees

61
Q

Axial or transverse plane rotations occure ———-from screw home mechanism

A

Separate

62
Q

motion of the knees in this plane considered insignificant

A

Frontal plane

63
Q

when the knee is flexed to about 30º we get the greatest—————–motion

A

frontal plane knee motion

postion most vulnerable to frontal plane injury

64
Q

frontal plane injury and anterior-posteior displacement are considered to be the result of

A

joint incongruity and variable amounts of ligamentous laxity

65
Q

stability of the knee is primarily provided by soft tissue structures

A

menisci

ligaments

66
Q

menisci increase

A

concavities of the tibial surfaces upon which the femoral condyles sit

67
Q

menisci act to improve

A

joint congruity for a joint whose bony structure is relatively incongruous

68
Q

menisci reduce

A

friction

69
Q

menisci distribute

A

weight bearing forces

70
Q

Ligaments resist or control

A
  • Excessive knee extension
  • Varus or Valgus stresses at the knee
  • Anterior or posterior displacement of the tibia beneath the femur
  • medial or lateral rotation of tibia beneath the femur
  • combinations of A/P displacements and rotations of the tibia (rotatory stablization )
71
Q

When the knee is FULLY EXTENDED which articular facets of the femur articulate with the patella ?

A

Both medial and lateral articular facets

72
Q

When the knee flexes past 90º which articular facets of the femur articulate with the patella?

A

Only the medial facet articulates with the patella

73
Q

Patella helps to improve lever arm of

A

the quadriceps femoris

74
Q

absent patella

A

decreased strength from the quads b/c you lost some of the lever arms

75
Q

patella aids in Knee

A

Extension

76
Q

How does the patella help in knee extension?

A

by lengthening the lever arm of the quadriceps femoris

77
Q

Patella allows for better distribution of

A

compression stresses on the femur by increasing the contact between the patella and femur

78
Q

Increased knee flexion will increase

A

the force of the quadriceps contraction

79
Q

increase in the force of the quadriceps contraction

A

increases the force on the patellofemoral joint

80
Q

patella as it glides in the intercondylar area adjusts

A

the angle of insertion of the quadriceps femoris into the tibia to conform the long axis of the leg

81
Q

Q-angle

A

represents the angle of the pull of the quadriceps femoris- a vertical line from ASIS to the border of patella to the tibial tuberosity

82
Q

Q-angle is involved with what deformities?

A

Patella femoral pain syndrome

tracking syndrome

83
Q

Increased Q-angle can cause

A

dislocation of the patella

84
Q

Increased Q-angle is more common in female or male?

A

Female

Biomechanics Exam 1 (12 decks)

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