Knee Biomechanics Flashcards

1
Q

What is the size of the posterior tibial slope

A

9 degrees inferiorly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the closed pack position of the knee

A

Extension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the normal range of knee flexion with hip flexion

A

130-140

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the normal knee flexion with hip extension

A

120

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the only quadriceps muscle to cross the hip

A

Rectus femoris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How much knee flexion is needed for level surface gait

A

60-68

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How much knee flexion is needed for ascending stairs

A

80

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How much knee flexion is needed for descending stairs

A

90

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How much knee flexion is needed for sit stand sit transfer

A

90

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How much knee flexion is needed to tie a shoe

A

106

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How much knee flexion is needed for full squat to floor

A

150-160

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is normal range of knee extension

A

5-10 hyperextension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the AAOS normal range for knee flexion

A

10-0-135

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which meniscal horn tears are more effected while descending stairs

A

Posterior horns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which meniscal horn tears are more effected while ascending stairs

A

Anterior horns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How can your knee flex to 150-160 during a deep squat if the normal range is 135

A

Due to the super incumbent body weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Are the femoral condyles concave or convex

A

Convex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Is the tibial plateau concave or convex

A

Concave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which side of the tibial plateau is more concave and which is flat/slightly convex

A

Lateral is flat/slightly convex

Medial is more concave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the arthrokinematics of OKC knee extension

A

Concave tibial plateau moving on convex femoral condyles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which way do the mensci translate during OKC knee motions

A

The same direction of the roll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which way if the patella drawn during OKC knee extension

A

Superiorly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the patella moving superiorly do to the menisci

A

Pulls them anteriorl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does the patella pull the menisci anteriorly

A

Due to the attachment of the coronary ligaments from patella to the anterior horns of the mensci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which way are the menisci drawn during OKC knee flexon

A

Posteriorly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What cause the menisci to be drawn posteriorly during OKC knee flexion

A

Attachment of the semimebranosus and popliteus to the posterior horns of the menisci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Which menisci do the semimembranosus and popliteus attache to

A

Semimembranosus: medial meniscus
Popliteus: lateral meniscus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the function of the popliteus

A

Initiate flexion of the knee

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does the popliteus act like

A

Anconeus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the functions of the menisci (3)

A
  1. Increases tibial plateau radius of curvature
  2. Reduces tibiofemoral friction
  3. Attenuates tibiofemoral compression loads
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How much of the menisci are red zone and white zone

A

Red: 1/3
White: 2/3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Which compartment of the knee has more surface area

A

Medial compartment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the arthrokinematics of CKC knee flexion

A

Convex femur on concave tibia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the roll and slide with CKC knee flexion

A

Posterior roll and anterior glide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What happens at 15 degrees of knee flexion

A

Medial compartment posterior roll begins to be accompanied by a small amount of anterior slide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Why is there anterior slide on the medial compartment during knee flexion at 15 degrees

A

Due to the larger surface area resulting in more ground to cover

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

How do you name rotation of the knee

A

Based on the tibia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What type of knee rotation occurs with CKC knee flexion

A

Internal rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What type of knee rotation occurs with CKC knee extension

A

External rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What happens at 25 degrees of CKC knee flexion

A

Lateral compartment posterior roll begins to be accompanied by anterior glide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What happens at mid ROM CKC knee flexion

A

Equal amounts of posterior roll and anterior glide in both compartments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What happens at late ROM CKC knee flexion

A

Greater anterior glide than posterior roll in both compartments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What happens at end ROM CKC knee flexion

A

All anterior femoral glide in both compartments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

When is the angle of inclination of the ACL the greatest

A

Full knee extension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the main function of the ACL

A

Convert roll into slide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What happens to the inclination of the ACL as knee flexion increases

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Is the ACL in a better position to create anterior glide of the femur on the tibia in full knee extension or knee flexion and why

A

Knee flexion due to decreased angle of inclination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What position is the ACL most vulnerable to being torn full knee extension or knee flexion

A

Knee flexion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What happens to the ACL at end ROM extension

A

The midsubstance of the ACL comes in contact with the femoral intercondylar shelf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is another name for the intercondylar shelf

A

Notch of Grant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What does the contact point with the notch of Grant do to the ACL

A

Acts as a fulcrum to tension load the ACL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

True or False:

Constant rubbing of the ACL on the notch of Grant can lead to an ACL tear

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Where does the ACL insert on the femur

A

Medial aspect of lateral femoral condyle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Where does the ACL run

A

Anteromedial to posterolateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Do we want ligaments to have small or large angles of inclination

A

Small angles of inclination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What are the 2 bands of the ACL

A
  1. Anteromedial band (AMB)

2. Posterolateral band (PLB)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

When is the AMB of the ACL most taut

A

Greater degrees of flexion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

When is the PLB of the ACL most taut

A

Greater degrees of extension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is isometricity

A

Some portion of a ligament is taut in all varying degrees of osteokinematic motion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

True or False:

The ACL has isometricity

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

At what amount of knee flexion are both bands of the ACL not particularly tensed

A

30 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the lack of tension at 30 degrees good for

A

Testing the integrity of the ACL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Why is there great tension in both bands of the ACL during hyperextension of the knee

A

The ACL is hitting the Notch of Grant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

When is the angle of inclination of the PCL the greatest

A

Full flexion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Where does the PCL insert on the femur

A

Lateral aspect of medial femoral condyle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Where does the PCL run

A

Posterolateral to anteromedial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

How many bundles does the PCL have

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Do the bundles of the PCL have different or the same function

A

Same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What happens to the angle of inclination of the PCL during knee extension

A

Decreases

70
Q

What is the function of the PCL

A

Convert anterior roll of the femur into posterior glide of the femur

71
Q

What does the ACL prevent in the OKC

A

Anterior translation of the tibia on the femur

72
Q

What does the ACL prevent in the CKC

A

Posterior translation of the femur on the tibia

73
Q

What does the PCL prevent in the OKC

A

Posterior translation of the tibia on the femur

74
Q

What does the PCL prevent in the CKC

A

Anterior translation of the femur on the tibia

75
Q

Are transverse plane motions at the knee passive or active motions

A

Passive only

76
Q

How much lateral/external rotation occurs at the knee at 90 degrees of knee flexion

A

40

77
Q

How much medial/internal rotation occurs at the knee at 90 degrees of knee flexion

A

30

78
Q

Does the amount of knee rotation increase or decrease with greater knee flexion/extension

A

Decreases

79
Q

Where does the longitudinal axis run for the knee

A

Medial to the medial tibial intercondylar tubercle

80
Q

What does the location of the longitudinal axis of the knee result in

A

Greater excursion laterally than medially during rotation

81
Q

What check rein IR of the knee

A

The cruciates

82
Q

What check rein ER of the knee

A

The collaterals

83
Q

Do the cruciates physically wind around each other

A

Yes

84
Q

Do the collaterals physically wind around each other

A

No the wind around one another in space

85
Q

What motions tear the collaterals more often and why

A

Varus and valgus motions due to the ligaments being in the frontal plane

86
Q

What plane does the lateral femoral condyle lie in

A

Sagittal plane

87
Q

Which condyle of the femur has a large A-P dimension

A

Lateral femoral condyle

88
Q

What does the greater amount of A-P dimension of the lateral condyle provide

A

Buttress for the patella to help prevent lateral dislocations

89
Q

What plane does the medial femoral condyle lie in

A

Oblique to the sagittal plane

90
Q

What femoral condyle has greater surface area

A

Medial femoral condyle

91
Q

What is the screw home mechanism of the knee

A

Obligatory ER of the tibia with terminal 20-30 degrees of knee extension

92
Q

What is a negative Helfet test

A

ER of the tibia in knee extension

93
Q

What are the 2 things that contribute to the screw home mechanism

A
  1. Femoral condyle surface area contribution

2. Cruciate contribution

94
Q

What type of ACL/PCL tears would you not see a positive Helfet test

A

Grade 1 because there is no tearing of fibers

95
Q

What is a positive Helfet test

A

No ER of the tibia in knee extension

96
Q

What does a positive Helfet test look like

A

Tibial tuberosity and patella are still in line with one another during knee extension

97
Q

What type of ACL/PCL tears are you able to see a positive Helfet test

A

Grade 2 and 3

98
Q

What contributes more to the screw home mechanism of the knee the femoral condyle surface area or the cruciate ligaments

A

Cruciate ligaments

99
Q

How do the ACL and PCL contribute to the screw home mechanism during knee extension

A

During extension the ACL and PCL wind up on each other becoming tighter and they unwind to relieve some of the tension

100
Q

What is the order of motions at the knee that effect the next

A

Sagittal plane motion creates transverse plane motion which creates frontal plane motion

101
Q

What is the anatomic or longitudinal axis of the tibiofemoral joint

A

5-10 degrees of physiologic valgus

102
Q

What creates the physiologic valgus of the knee (2)

A
  1. Coxa varum

2. Medial femoral condyle projects more distal

103
Q

Which component of the physiologic valgus occurs distally

A

Medial femoral condyle projects more distal

104
Q

Which component of the physiologic valgus occurs proximally

A

Coxa varum or proximal femoral angle of inclination

105
Q

Where does the mechanical axis of the tibiofemoral joint run

A

The weight bearing line from the center of the femoral head to superior talus center

106
Q

What does the mechanical axis of the tibiofemoral joint allow for

A

Equal weight bearing in stance of the medial and lateral tibiofemoral compartments

107
Q

Ideally where should the hip joint fall in relation to the knee joint

A

Directly over the middle of the knee

108
Q

What does increased valgus at the knee result in (3)

A
  1. Compression overload to the lateral tibiofemoral compartment
  2. Distraction overload to medial tibiofemoral compartment
  3. Tension load soft tissue on medial side
109
Q

What does decrease valgus/increased varum at the knee result in (3)

A
  1. Compression overload to the medial tibiofemoral compartment
  2. Distraction overload to the lateral tibiofemoral compartment
  3. Tension load soft tissue on the lateral side
110
Q

With IR of the knee what occurs slight valgus or varus

A

Slight valgus

111
Q

With ER of the knee what occurs slight valgus or varum

A

Slight varum

112
Q

What causes the slight valgus/varum during IR and ER of the knee

A

The 9 degree inferior and posterior slope of the tibial plateau

113
Q

If the femoral condyle sits on the posterior plateau it is considered shorter or longer

A

Shorter

114
Q

If the femoral condyle sits on the anterior plateau it is considered shorter or longer

A

Longer

115
Q

What happens to the lateral femoral condyle during ER of the knee

A

Climbs up the tibial plateau slope lengthening the lateral compartment

116
Q

What happens to the medial femoral condyle during ER of the knee

A

Falls down the tibial plateau slope shortening the medial compartment

117
Q

What happens during OKC ER to the knee in the frontal plane

A

Lengthened lateral compartment, shortened medial compartment resulting in tibiofemoral varus

118
Q

What happens during CKC ER to the knee in the frontal plane

A

Lengthened lateral compartment, shortened medial compartment resulting in tibiofemoral varus

119
Q

What happens during OKC IR to the knee in the frontal plane

A

Shortened lateral compartment, lengthened medial compartment resulting in tibiofemoral valgus

120
Q

What happens during CKC IR to the knee in the frontal plane

A

Shortened lateral compartment, lengthened medial compartment resulting in tibiofemoral valgus

121
Q

How much does the patella increase the MA of the quadriceps at 0 extension

A

31%

122
Q

How much does the patella increase the MA of the quadriceps at 90 flexion

A

13%

123
Q

Why does the patella not need to increase the MA of the quadriceps as much at 90 of flexion compared to 0 extension

A

The length tension relationship of the quadriceps is more optimal at 90 flexion

124
Q

At what angle is the length tension relationship of the quadriceps the most optimal

A

60 flexion

125
Q

What happens to the compressive force if there is no patella

A

There is no compressive force

126
Q

Which way do most patellar dislocations occur

A

Laterally

127
Q

What is the equation for torque

A

T=FxD or MA

128
Q

Someone with a patellectomy will present with what

A

Extensor lag

129
Q

What does the compressive force do to the patella

A

Stabilizes the patella in trochlea groove

130
Q

True or False:

The patella assures some compression in full extension

A

True

131
Q

Is the patella in the femoral sulcus in full extension or hyperextension

A

Nope

132
Q

What do we need to ensure stability of the patella during full extension or hyperextension

A

A compressive force

133
Q

Does the patella have an increased or decreased chance for dislocation in full extension or hyperextension

A

Increased risk

134
Q

What does it mean if you palpate the patella and it moves

A

The patient is not firing their quads therefore the line of gravity falls anterior the the axis of rotation creating an extension moment

135
Q

What happens to e patellofemoral compression (PFC) as flexion increases

A

PFC increases

136
Q

How much compression does the patella experience during gait

A

0.5 x BW

137
Q

How much compression does the patella experience while ascending/descending stairs

A

3.4 x BW

138
Q

How much compression does the patella experience while squatting

A

8.8 x BW

139
Q

Where is the thickest amount of hyaline cartilage and the thickness of it

A

Retropatellar 5mm

140
Q

What happens to the patella from 90 to 120 of flexion that allows for compression to decrease a bit

A

Tilts a bit

141
Q

What happens to patellofemoral contact area as you increase knee flexion

A

Contact area increases

142
Q

When does the patella start to contact the femur

A

About 20 flexion

143
Q

When is patellofemoral contact the greatest

A

About 90 flexion

144
Q

When does the inferior facet of the patella contact the femur

A

20 knee flexion

145
Q

When does the middle facet of the patella contact the femur

A

45 knee flexion

146
Q

When does the superior facet of the patella contact the femur

A

90 knee flexion

147
Q

When does the medial/odd facet of the patella contact the femur

A

120 knee flexion

148
Q

When does the lateral facet of the patella contact the femur

A

From 20 knee flexion on

149
Q

As a person why is common to have pain on the medial side of the patella when squatting

A

Wolff’s Law, older people don’t spend too much time in the squatted position so the cartilage on the medial side of the patella becomes soft and doesn’t absorb compressive loads as well

150
Q

The patella has what shape of motion when it drops down into the sulcus as knee flexion occurs

A

C or J shape

151
Q

What is the normal length of the patellar ligament compared to the patella

A

1:1 the patellar ligament length should be the same as the patella height

152
Q

What is patella baja

A

Patellar ligament is too small

153
Q

What does patella baja result in

A

The inferior facet of the patella contacting the femur sooner which can lead to DJD over time due to increased compression

154
Q

What is patella alta

A

Patellar ligament is too long

155
Q

What does patella alta result in (2)

A
  1. Inferior facet of the patella contacts femur later leading to chondromalacia patella due to decreased compression
  2. More susceptible to patellar subluxation/dislocation
156
Q

Why does patella alta result in an increased susceptibility to patellar subluxation/dislocation

A

The patella is not in contact with another bone for a longer amount of time and there is less of a barrier on both sides of the patella

157
Q

What is one way a person can get patella baja

A

ACL reconstruction with patellar graft

158
Q

Is patella alta acquired or congenital

A

Congenital very rarely acquired

159
Q

What does the patella do for the quadriceps

A

Acts as a link to focus the divergent pull of the 4 individual quads onto one singular point at the tibial tubercle

160
Q

How does the ITB impact the patella in the frontal plane

A

It adds an additional force with the tendency to laterally or superiorly translate the patella

161
Q

Where does the ITB insert at the knee (2)

A
  1. Gerdy’s tubercle

2. Lateral side of the patella

162
Q

What can a tight ITB band result in

A

Lateral subluxation/dislocation of the patella

163
Q

How do you measure the Q angle

A

ASIS to mid point of the patella and tibial tuberosity to mid point of patella and measure the angle

164
Q

What is the normal Q angle for men and women

A

Men: 13
Women: 18

165
Q

What does the resultant force of the Q angle have a tendency to do

A

Laterally translate the patella

166
Q

What are the biomechanics that increase the Q angle (3)

A
  1. Laterally displace tibial tubercle
  2. Medially displace patella
  3. Laterally displace ASIS
167
Q

What are the 2 ways to laterally displace the tibial tubercle

A
  1. External tibial rotation

2. External tibial torsion

168
Q

What are the 2 ways to medially displace the patella

A
  1. Internal femoral rotation

2. Femoral anteversion

169
Q

Who has a more laterally displaced ASIS men or women

A

Women due to larger pelvis for birth purposes

170
Q

When does subluxation/dislocation of the patella occur (5)

A
  1. Greatest Q angle
  2. Least patellofemoral compression
  3. Greatest quad force
  4. Least patellar contact with femoral trochlea
  5. Full extension or hyperextension
171
Q

What causes the greatest quad force (2)

A
  1. Smallest quad moment arm

2. Poor length tension relationship

172
Q

Why does full extension or hyperextension increase the risk of subluxation/dislocation

A

There is no contact with the femoral trochlea