Biomechanics of Knee Flashcards

1
Q

Type of Joint

A

Modified hinge Synovial
2 degrees of freedom

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2
Q

joint articulations of knee joint

A

femorotibial
Pallelofemoral

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3
Q

How is the femur aligned?

A

oblique angle inferiorly and medially from proximal to distal

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4
Q

Angle b/w lateral aspect of femur and tibia is approximately

A

170-175
Due to the size and shape of evenly distributed b/w the medial and lateral surfaces of knee joint

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5
Q

Genu Valgus Knock knees

A

Decreased angle at lateral aspect
Less than 170

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6
Q

Genu Varus bow leg

A

Increased angle at the lateral aspect of the knee
greater than 180

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7
Q

Excessive genu valgum can increase load on which aspect

A

Lateral

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8
Q

Excessive genu varus can increase load on which aspect

A

medial

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9
Q

How can it affect pateloofemoral alingment

A

As patella sits in the midline of longitudinal axis of rotation of the lower limb

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10
Q

Q angle meaning

A

oblique angle of femur when quads pulls patella superiorly and small degree laterally

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11
Q

How is q angle determined

A

line running from central patella to ASIS

line intersecting the tibial tuberosity and middle patella

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12
Q

Average Q angle

A

13-15

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13
Q

factors that influence q angle therefore patella position

A

sex, females 3-4 increase due to wider pelvis

Excessive genu valgum

tibial torsion

Foot mechanics

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14
Q

Knee Flexion how many degrees

A

140

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15
Q

Extension

A

5-10

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16
Q

Tibial and Femoral Osetokinematics

A

direction of knee rotation is the same as knee rotation as the tibia

17
Q

Femoral on tibial knee

A

Direction of knee rotation is opposite to the motion of the moving femru

18
Q

Flexion: femoral on tibial arthokinematics

A

femoral Condyles roll posterioly and slide anteriroly
ACL and menisci help ensure that conact is maintain

19
Q

Extension femoral-tibial

A

femoral condyles roll anteriorly and slide posteriorly
tension of PCL and menisci help facilitate

20
Q

Flexion tibial on femoral

A

tibia rolls and glides posteriorly on femoral condyles

21
Q

extension tibial on femoral

A

tibia rolls and glides anteriorly on femoral condyles

22
Q

Screw Home Mechanism its purpose

A

to result in maximus congruence of the joint surfaces, ligaments are taught and menisci tightly interposed whcihc means reduced requiremnt for muscle contraction

23
Q

Locking of the knee relies on 3 factors

A

Shape of femoral condyles, passive tension of acl slight lateral pull of quadriceps

Contraction of popliteus muscle

24
Q

Locking/unlocking (Tibial-on-Femoral)
Open Chain

A

During T-F extension as tibia moves 30 degrees of flexion into fully extended. ACL lateral pull of quads creates external rotation of the tibia

To unlock, Popliteus internally rotates the tibia to unlock knee

25
Q

Locking/Unlocking of Knee (Femoral-Tibial)
Closed Chain

A

during F-T extension, knee moves from 30 degrees flexion to fully extended position the shape of the femoral condyles and tension of ACL ligament produce slight Medial rotation

To unlock, poplitues externallyy rotates

26
Q

Role of Patella

A

Articulates with the intercondylar groove of the femur
Work as an anatomical pulley and mechanism to reduce friction b/w quadriceps and femoral condyles

27
Q

Role of Patella regarding Moment arm

A

Patella displaces tendon of the quadriceps anteriorly which increased the moment arm of the knee extensor mechanism

28
Q

Patellofemoral Joint Forces

A

deep squat increases moment arm therefore greater force whihc reaches a maxiums to 60-90 degrees

29
Q

Patellofemoral Pain Syndrome

A

Less congruent joint

May be exacerbated due to imbalance in medial and lateral forces of patella

30
Q

ACL limits

A

Knee extension
Anterior translation of tibia on femur
Posterior translation of femur on tibia

31
Q

ACL Injury Vectors

A

Hyperextension
Rotation
Valgus Force

32
Q

PCL limits

A

Knee flexion
Posterior translation of tibia on femur

33
Q

PCL injury Vectors

A

Hyperflexion
Posterior translation

34
Q

MCL resists

A

Valgus
extension

35
Q

MCL Injury Vectors

A

Valgus
Hyperextension

36
Q

LCL Resists

A

Varus
Extension

37
Q

LCL Injury Vectors

A

Varus
Hyperextenstion