The Knee Joint Flashcards

1
Q

Where degrees of freedom in the tibio femoral joint?

A

2 degrees of freedom
Flex / ext
IR / ER

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2
Q

What are the defining features of the medial condyle?

A

Larger & more distal

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3
Q

What are the defining features of the lateral condyle?

A

Smaller; more in line with femoral shaft
Projects more anterior

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4
Q

Where is the intecondylar notch/femoral sulcus

A
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5
Q

Which lip of the patella is larger?

A

Lateral lip is larger than the medial

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6
Q

What is the angle of the tibial plateaus?

A

7-10°

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7
Q

Which tibial plateau is longer?

A

Medial longer vs. lateral (AP)

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8
Q

What is the shape of the tibial plateau?

A

Shape  concave

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9
Q

What do the inter-CON DY LAR tubercles do in the knee joint?

A

Engage in notch in full extension
Bony stability

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10
Q

What is considered normal physiologic valgus of knee?

A

Norm = 170°- 175°

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11
Q

What does physiologic valgus allow?

A

Allows equal loading in both compartments

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12
Q

What is genu valgus?

A

“knock knees”
< 170

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13
Q

What are the consequences of genu valgus?

A

Compressive forces on lateral side of knee and tensile forces on medial side

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14
Q

What is genu varus?

A

“bow legs”
> 180°

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15
Q

What are the consequences of genu varus?

A

Compressive forces on the medial side of the knee and tensile forces on the lateral aspect

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16
Q

What is the function of the knee joint capsule?

A

Restricts joint motion and provides proprioception

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17
Q

What is the close packed position of the joint capsule of the knee?

A

Full extension

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18
Q

What position of the knee allows the most volume in the joint capsule?

A

Semi flexed position

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19
Q

What are the posterior attachment to the joint capsule of the knee?

A

Condyles

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20
Q

What are the anterior/inferior attachments of the joint capsule of the knee?

A

Retinaculum
Patellar tendon

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21
Q

What is the superior attachment of the capsule of the knee?

A

Quadriceps tendon

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22
Q

What is the composition of the capsule of the knee?

A

Fibrous layer
Synovial layer

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23
Q

What does the synovial layer of the knee joint capsule due posteriorly?

A

it folds inward to surround cruciates

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24
Q

What are plicae? And how many are there?

A

Embryologic remnants of synovial septae
Potentially 4
Inferior, superior, medial, lateral

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25
Q

What is the anterior fibrous layer of the joint capsule also known as?

A

Extensor retinaculum

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26
Q

What are the Medial retinacular fibers?

A

MPFL & Medial patelleotibial ligament

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27
Q

What are the lateral retinacular fibers?

A

LPFL & lateral patelleotibial ligament

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28
Q

What is the lateral layer of the joint capsule reinforced by?

A

Reinforced by LCL, ITB and lateral patellar retinacular fibers

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29
Q

What is the medial side of the joint capsule reinforced by?

A

Reinforced by MCL, medial patellar retinacular fibers

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30
Q

What is the posterior medial corner of the fibrous layer of the joint capsule of the knee made of?

A
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31
Q

Where are the following?

A
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32
Q

What is the posterior lateral corner of the fibrous layer of the joint capsule of the knee made of?

A
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33
Q

Where are the following?

A
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34
Q

What does the posterior medial corner & posterior lateral corner of the knee capsule resist respectively?

A

Resist hyperextension and valgus and varus stresses respectively

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35
Q

What are the attachments of the IT band?

A

Attaches to the tibia via the iliotibial band and the patella via the patellofemoral ligament

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36
Q

What are the functions of the IT band?

A

Support anterolateral knee
With knee flexion, assists ACL in resisting anterior tibial translation

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37
Q

What cushions the IT band deeper to the tendon?

A

Fat pad rather than a bursa
can become inflamed and agitated leading to IT band syndrome

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38
Q

How many portions does the medial collateral ligament have?

A

Two portion superficial and deep

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39
Q

What is the primary restraint of the MCL

A

Valgus (0° & 25°)
60% at 0 and 80% at 25
Lateral rotation of tibia

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40
Q

What is the secondary restraint of the MCL?

A

ant tibial trans

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41
Q

Which of the four distinct ligaments of the knee has the greatest capacity for healing?

A

MCL, highly vascular

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42
Q

What is the primary restraint of the lateral collateral ligament?

A

Primary restraint
Varus (0° & 25°)
55% at 0 and 70% at 25 degrees

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43
Q

Which ligament is extra capsular in the knee?

A

LCL

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44
Q

What is the secondary restraint of the LCL?

A

Lateral rotation of tibia

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45
Q

What are the attachments of the ACL?

A

Anteromedial tibia to posteromedial LFC

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46
Q

What is the primary restraint of the ACL

A

Anterior tibial translation
Hyperextension
Rotary stability

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47
Q

Which ligament tension guides the arthrokinematics of the knee?

A

Anterior crusade ligament (ACL)

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48
Q

What is the ACL loaded with that play a protective role?

A

mechanoreceptors

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49
Q

What muscles place stress on the ACL?

A

quadriceps muscles

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50
Q

What is the most common ACL mechanism of injury?

A

Strong activation of the quad over a slightly flexed knee
Valgus collapse
Excessive ER of the tibia

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51
Q

What is another ACL mechanism of injury?

A

Hyperextension of the knee

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52
Q

What are the attachments of the posterior cruciate ligament?

A

Posterior tibia to medial femoral condyle

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53
Q

What increases tension in the PCL?

A

Tension increases with greater amounts of knee flexion

54
Q

What is the primary restraint of the PCL?

A

Posterior tibial translation at ALL angles of flexion

55
Q

What muscle group places stress on the PCL?

A

Hamstring muscles

56
Q

Were the common ways the PCL is injured?

A

fall on flexed knee or “dashboard injury”

57
Q

What is the composition of the menisci?

A

Fibrocartilage discs

58
Q

What is the function of the knee menisci?

A

Improve congruence
 friction
Shock absorption
Up to 50-70% of load
(Altered with alignment)
Distribution of forces

59
Q

What are the common stabilizing structures of the menisci?

A

Transverse ligament
coronary ligaments
Patellomensical ligament

60
Q

What are the unique attachments of the medial meniscus?

A

MCL
semimembranosus tendon
anterior cruciate ligament

61
Q

What is the shape of the medial meniscus?

A

C shaped

62
Q

How mobile is the medial meniscus compared to the lateral meniscus?

A

The medial is less mobile

63
Q

Was the shape of the lateral meniscus?

A

More round & more mobile

64
Q

Attachments of the lateral meniscus?

A

Popliteus
PCL & femoral condyle via meniscofemoral ligament

65
Q

What part of the menisci are innervated?

A

Outer one third

66
Q

What part of the menisci are vascularized?

A

Outer one third

67
Q

What is the function of the bursae in the knee?

A

Lubrication, cushion

68
Q

What are the three isolated bursae in the knee?

A

prepatellar, infrapatellar, deep infrapatellar bursa

69
Q

What are the three bursae in the knee that are continuous with the synovial lining?

A

Subpopliteal, Gastrocnemius, Suprapatellar

70
Q

What is the common total range of motion in the knee?

A

Total ROM: 5-0-140

71
Q

What is Genu recurvatum?

A

> 5° hyperextension

72
Q

What are the AK’s of flexion and extension at the knee

A
73
Q

What is the ratio of internal to extra rotation at the knee?

A

External > Internal rotation (2:1)

74
Q

What are the AK’s of internal and external rotation at the knee?

A
75
Q

“Screw home mechanism” or “locking mechanism” of knee?

A

Obligatory rotation of the femur or tibia occurring with end range extension and early flexion of the knee

76
Q

What are the factors of the locking mechanism of the name?

A

Shape of medial femoral condyle**
Passive tension in ACL
Lateral pull of quadriceps muscle

77
Q

What is the open chain locking mechanism?

A

Lateral Rotation of tibia on femur

78
Q

What is open chain unlocking mechanism?

A

(initiated by poplitues m)
Open chain: MR of tibia on femur

79
Q

What is the relative difference between open chain and close chain unlocking?

A

Unlocking relative motions are opposite in close chain

80
Q

What is what is the length tension relationship between lower extremity muscles?

A

Force production affected by position of hip for 2 joint muscles: hamstrings and rectus femoris
Best when lengthened over one and shortened over one

81
Q

What is passive insufficiency of the hip?

A

Limitation range of motion when the muscle groups are stretched over both joints only the one tested for range of motion

82
Q

What is active insufficiency of the HIP?

A

Force production sub optimal when muscles are not lengthened over one joint segment and shortened over the other

83
Q

How do the menisci move in knee flexion?

A

Posterior Roll

84
Q

How do the menisci move in knee extension

A

Anterior roll

85
Q

What contributes to posterior roll in the menisci?

A

Semimembranosus & Popliteus

86
Q

What contributes to anterior roll in the menisci?

A

Lateral – meniscofemoral ligament
Medial – anterior capsular fibers

87
Q

How do the menisci move and lateral medial rotation??

A

Menisci move with femoral condyles

88
Q

What muscles make up the quadriceps?

A

Rectus femoris (2 joint)
Vastus intermedius
Vastus lateralis
Vastus medialis
Vastus medialis obliqus (VMO)- fiber attach to patella at 50-55 deg

89
Q

What does the Articularis genu do and where is it?

A

Deep to VL and VI; tenses capsule w/ extension

90
Q

What produces the majority of the extensor torque?

A

Vasti produce 80% of knee extensor torque

91
Q

What is the extensor mechanism?

A

Quad muscle + patella + patellar tendon

92
Q

What is the torque ratio for extensors over flexors of the knee?

A

Produce torque 2/3 > knee flexors

93
Q

How does the external moment arm change in open chain knee extension?

A

External moment arm increases from 90-0 degrees

94
Q

Why do clinicians often select close chain exercises following knee surgery or injury?

A

increasing anterior shear stress placed on the tibia during open chain knee extension in the last 45 degrees

95
Q

How does the external moment arm change during close chain knee extension?

A

External moment arm decreases from 90-0 degrees

96
Q

At what degrees of flexion is the max knee extension torque?

A

occurs between 45-70 degrees of knee flexion (usually say 60 degrees

97
Q

To what extent is torque production decrease towards full extension of the knee?

A

50-70% reduction as knee approaches full extension

98
Q

What are the knee flexors and rotators?

A

Hamstrings (Semimebranosus, Semitendinosus, Biceps femoris), Sartorius, Gracilis, Gastrocnemius, popliteus

99
Q

What is the secondary action of the semitendinosus, semimembranosus, gracilis, sartorius, & popliteus?

A

IR of tibia

100
Q

What is the secondary action of the biceps femoris?

A

ER of tibia

101
Q

What is the Pes Anserine?

A

Common attachment for sartorius, gracilis and semitendinosus

102
Q

What is the synergistic function of the muscles that attach to the pes anserine?

A

3 muscles function synergistically to resist valgus forces at knee; also IR tibia

103
Q

When is the best moment arm for the gastrocnemius to participate in knee flexion?

A

When the knee is extended fully

104
Q

What is the action of the popliteus muscle

A

MR of tibia
Posterior pull on lateral meniscus

105
Q

What are the attachments of the popliteus muscle?

A

LFC to posterior medial tibia

106
Q

What is the retropatellar surface covered with?

A

articular cartridge

107
Q

What are the facets of the patella?

A

Medial, lateral, odd, superior and inferior

108
Q

And what direction is the normal pull of the patella?

A

B/c of normal physiologic valgus at the knee and larger CSA of vastus lateralis, action lines of quad and patellar tendon result in net lateral pull on patella

109
Q

What is the Q angle?

A

Two lines drawn to measures
Line from ASIS to mid patella
Line from mid patella to tibial tuberosity

110
Q

What is a normal Q angle?

A

10° to 15°

111
Q

What happens with the Q angle greater than 20°

A

Structural malalignment

112
Q

What is the general motion of the patella with flexion?

A

0-30° medial & inferior

113
Q

What is the general motion of the patella with extension?

A

Superior lateral with knee extension

114
Q

What are some possible alterations the alignment of the patella and in trochlear groove?

A

Femoral rotation (anteversion)
Genu valgus
Can be dynamic or static

115
Q

What are the passive stabilizers of the patella femoral joint?

A

Bony geometry / architecture
Ligaments

116
Q

What are the dynamic stabilizers of the patella femoral joint?

A

Muscles

117
Q

What is the bony static stabilizer of the PF joint?

A

Lateral lip of femoral sulcus

118
Q

What are the soft tissue static stabilizers of the PF joint?

A

Patellar tendon, quadriceps tendon, extensor retinaculum/joint capsule
Lateral PF ligament (LPFL)
Medial PF ligament (MPFL)
60% of stability

119
Q

What is the contact of the patella at 0° of flexion?

A

above groove

120
Q

What is the contact of the Patel lead 20° of flexion?

A

enters trochlear groove; 1st part contacted- inferior pole

121
Q

What is the contact of the patella at 45° of flexion?

A

 mid-pole-medial and lateral facets

122
Q

What is the contact of the patella at 90° of flexion?

A

 superior facet

123
Q

What is the contact of the patella at 135° of flexion?

A

odd facet; patella lodged in intercondylar groove

124
Q

What causes “train problems” at the knee joint?

A

Quad weakness
ITB/flexibility
Alignment issues

125
Q

What can cause “track problems” at the knee joint?

A

Hip weakness

126
Q

What is less contact area on the patella cause?

A

More stress (stress equal force divided by area)

127
Q

What is a joint reaction force?

A

Resultant force (or contact force) created when two or more forces causes contact between joint surfaces

128
Q

What causes the joint reaction at the PF joint?

A

Quadriceps!

129
Q

How does the joint reaction force change at the patella joint?

A

Knee joint angle
Quad force

130
Q

What causes Patellofemoral Joint Dysfunction

AKA Patellofemoral Pain Syndrome (PFPS)

A

Abnormally high contact forces (we already discussed the many reasons) + High Joint reaction forces (created by high quad forces)

131
Q

How should we select open kinetic chain versus close kinetic chain exercises for the knee?

A

If CKC exercises are less painful than OKC, then stick with CKC
If OKC is selected, knee extension from 90º-40º is often used
With CKC exercises (squats, leg press, etc), initiate activity in lower ranges of knee flexion (0-30º, progress to 0-60º)