Knee Joint Flashcards

1
Q

How many joints share the capsule at the knee joint?

A

2

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2
Q

What are the two articulations of the knee joint?

A

Femur with tibia = tibiofemoral

Femur with patella = patellofemoral

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3
Q

What is the largest sesamoid bone in the body?

A

Patella

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4
Q

Why is the knee a modified hinge joint?

A

Have rotation when flexed, unlike normal hinge joint which only flexes and extends

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5
Q

What movement is required to flex the knee?

A

Rotation

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6
Q

What is the range of movement of the knee joint?

A

Relatively large

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7
Q

What is a close packed position?

A

Articular surfaces meet each other to greatest extent

Ligaments tight

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8
Q

What is the close packed position of the knee?

A

Extension

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9
Q

What is the loose packed position of the knee?

A

Midway through flexion

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10
Q

Why is the stability of the knee joint not from the bones?

A

Mismatch of shapes of articular surfaces: rounded femoral condyle articulating with flat tibial plateau

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11
Q

What gives the knee joint its stability?

A

Strong ligaments reinforcing capsule

Muscles attaching at joint

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12
Q

What is the notch between the femoral condyles?

A

Intercondylar notch

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13
Q

What is the nick in the intercondylar notch for?

A

Indentation of anterior cruciate ligament

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14
Q

What can cause erosion of the anterior cruciate ligament?

A

Narrow intercondylar groove (nick in intercondylar notch)

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15
Q

Which femoral condyle is longer, and by how much?

A

Medial femoral condyle longer by 1 cm

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16
Q

Which femoral condyle is wider?

A

Lateral femoral condyle

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17
Q

What action is the position of the anterior cruciate ligament very important for?

A

Hyperextension at knee > stand upright

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18
Q

Which femoral condyle bears the most weight, and what proportion is it?

A

Medial femoral condyle bears 75% of weight

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19
Q

Which femoral condyle undergoes more osteoarthritic changes?

A

Medial femoral condyle

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20
Q

With a valgus deviation, what is the change in weight bearing at the knee?

A

Lateral femoral condyle bears more weight than normal

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21
Q

What covers the tibial plateau in the medial and lateral aspects?

A

Articular cartilage

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22
Q

What covers the margins of the tibial plateau?

A

Menisci

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23
Q

What are the menisci made of?

A

Fibrocartilage

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24
Q

What do the menisci in the knee joint do?

A

Support femoral condyles

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25
Q

From anterior to posterior, what attaches to the central, raised part of the tibial plateau?

A
Anterior horn of medial meniscus
Anterior cruciate ligament medially, Anterior horn of lateral meniscus laterally
Posterior horn of lateral meniscus
Posterior horn of medial meniscus
Posterior cruciate ligament
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26
Q

What is the femoral attachment of the anterior cruciate ligament?

A

Lateral aspect of lateral femoral condyle

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27
Q

What is the femoral attachment of the posterior cruciate ligament?

A

Medial femoral condyle

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28
Q

What is the shape of the cruciate ligaments from the front?

A

Cross

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29
Q

What 3 pairs of non-muscular structures support the capsule at the knee joint?

A

Anterior and posterior cruciate ligaments
Medial and collateral ligaments
Medial and lateral menisci

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30
Q

When are the structural supports at the knee especially susceptible to injury?

A

In flexion and rotation

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31
Q

What is the extent of the capsule in the knee?

A

Runs around knee
Surrounds patellofemoral joint
Passes behind femoral condyles and tibial plateau

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32
Q

What lines the capsule?

A

Synovial membrane

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33
Q

What is the extent of the synovial membrane at the knee?

A

Doesn’t line everything

Passes to sides of posterior cruciate ligament then passes around and in front of anterior cruciate ligament

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34
Q

What is the relationship of the cruciate ligaments with the capsule and the synovial membrane?

A

Intracapsular by extrasynovial

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35
Q

How do you tell the medial and lateral menisci apart?

A

Medial meniscus more open, with horns further apart

Lateral meniscus more circular, with horns closer together

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36
Q

Why is the anterior cruciate ligament associated with considerable bleeding when it tears, when it is relatively avascular?

A

Because of intimate association with synovial membrane

Blood mostly coming from tears to membrane

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37
Q

What is haemarthrosis?

A

Bleeding because of tear in synovial membrane

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38
Q

What is effusion?

A

Production of extra synovial fluid

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39
Q

What is the relationship between the capsule and the medial collateral ligament?

A

Medial collateral ligament essentially merges with medial aspect of capsule

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40
Q

What is the relationship between the capsule and the lateral collateral ligament?

A

Lateral collateral ligament somewhat detached from capsule

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41
Q

What reinforces the knee joint anteriorly?

A

Patellar tendon/ligament

Medial patellar retinaculum

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42
Q

From which muscles does the medial patellar retinaculum arise?

A

Vastus medialis

Vastus lateralis

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43
Q

What reinforces the knee joint laterally?

A

Popliteus
Biceps femoris
Iliotibial band

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44
Q

What reinforces the knee joint medially?

A

Pes anserius tendons

  • Sartorius
  • Gracilis
  • Semitendinosus
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45
Q

What reinforces the knee joint posteriorly?

A

Oblique popliteal ligament

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46
Q

From what does the oblique popliteal ligament arise?

A

Semimembranosus

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47
Q

How does the lateral patellar retinaculum change the position of the patella?

A

Drags it laterally

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48
Q

Can the muscular reinforcements of the knee cover for damage to the cruciate ligaments?

A

Yes

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49
Q

What is the collective name for the muscular reinforcements of the knee?

A

Secondary restraints

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50
Q

How do you remember the muscle insertions of the pes anserinus from superior to inferior?

A
Say = sartorius
Grace = gracilis
Before = bursa
Tea = semitendinosus
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51
Q

What does the anterior cruciate ligament do?

A

Primary stabiliser in the A-P direction

Limits forward displacment of tibia on femur

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52
Q

When is the anterior cruciate ligament taut?

A

Extension

Full flexion

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53
Q

What is the loose packed position of the anterior cruciate ligament?

A

Semi-flexion

54
Q

What are the two bands of fibres in the anterior cruciate ligament?

A

Anteromedial - most taut in extension

Posterolateral - most taut in complete flexion

55
Q

What is the role of the anterior cruciate ligament when it tightens in the last 15-20 degrees of extension?

A

Axis for rotation during terminal extension

56
Q

What does the anterior cruciate ligament allow during extension?

A

Medial rotation on fixed tibia

Limits backwards movement of lateral condyle

57
Q

What can a person with a tear in their anterior cruciate ligament not do?

A

Properly lock joint > unstable in full extension

58
Q

What sound is often heard with an injury to the anterior cruciate ligament?

A

Pop sound

59
Q

When does injury to the anterior cruciate ligament occur?

A

Lateral rotation

Involves extension on weight-bearing leg

60
Q

How much thicker is the posterior cruciate ligament than the anterior cruciate ligament?

A

2x

61
Q

What is a common variant that reinforces the posterior cruciate ligament?

A

Meniscofemoral ligaments

62
Q

What does the posterior cruciate ligament do?

A

Limits posterior displacement of tibia in knee flexion

63
Q

When is the posterior cruciate ligament prone to injury?

A

Fall on flexed knee

64
Q

What is the course of the popliteus muscle?

A

Runs across back of joint
Passes under lateral collateral ligament
Attaches to outside of lateral femoral condyle

65
Q

What does the popliteus do?

A

Rotates femur laterally on fixed tibia

66
Q

What is the role of the popliteus in unlocking the knee joint?

A

Contraction allows knee joint to flex to do other activities

67
Q

Describe the superficial part of the collateral ligament?

A

Long, flat band

68
Q

What is the relationship of the medial collateral ligament and the capsule and medial meniscus?

A

Deep part blends with capsule and attaches to medial meniscus

69
Q

When is the medial collateral ligament taut?

A

Extension

70
Q

When is the medial collateral ligament slack?

A

Flexion

71
Q

What does the medial collateral ligament do?

A

Resist valgus forces and lateral rotation of tibia

72
Q

What does the medial collateral ligament do when the anterior cruciate ligament is damaged?

A

Secondary restrain - limits anterior displacement of tibia

73
Q

What is the unhappy triad?

A

Injury to all

  • Anterior cruciate ligament
  • Medial collateral ligament
  • Medial meniscus
74
Q

What separates the lateral collateral ligament from the lateral meniscus?

A

Popliteus tendon

75
Q

What does the lateral collateral ligament do?

A

Resist varus forces

76
Q

Which collateral ligament is more often injured?

A

Medial collateral ligament

77
Q

What are the attachments of the lateral collateral ligament?

A

Lateral femoral condyle

Fibula

78
Q

What is the shape of the menisci in the knee?

A

Wedge shaped

79
Q

What are the functions of the menisci in the knee?

A

Shock absorb
Weight distribution
Separates joint into 2 cavities

80
Q

With which structure do the menisci move in rotation?

A

Femur

81
Q

By how much do the menisci increase area of contact?

A

1/3

82
Q

Are the menisci within the synovial cavity or extrasynovial?

A

Within synovial cavity, but only bony attachments have covring

83
Q

Which meniscus is more often injured, and why?

A

Medial meniscus, because

  • Longer
  • Horns further apart
  • Less mobile
84
Q

What kind of injuries can occur to the medial meniscus?

A

Nipped

Torn

85
Q

What does an injury to the medial meniscus contribute to?

A

Locked knee

86
Q

What happens if the menisci are completely removed?

A

Increased incidence of osteoarthritis

87
Q

What are the two zones of the menisci, as defined by their blood supply?

A

Outer 1/3 has blood supply = red zone

Inner 2/3 avascular = white zone

88
Q

What is a bursa?

A

Sac with small amount of fluid in it

89
Q

What can happen to bursa with irritation?

A

Fluid inside can increase

90
Q

Where is the quadriceps/suprapatellar bursa?

A

In knee joint, deep to quadriceps muscle

91
Q

What is the largest bursa in the body?

A

Quadriceps bursa

92
Q

What is the superior extent of the suprapatellar bursa?

A

Hand’s breadth above tibiofemoral joint

93
Q

Does the suprapatellar bursa communicate with the knee joint?

A

Yes

94
Q

Where can an effusion at the knee joint expand into?

A

Suprapatellar bursa

95
Q

How can the extent of the effusion into the suprapatellar bursa be estimated?

A

Pressing down on bursa to push fluid back into joint cavity

96
Q

What is a baker’s cyst?

A

Bursa deep to popliteus becomes fibrous

97
Q

Where are there bursae in the knee?

A

Wherever

  • Ligaments attach
  • Large tendon sliding over bone
98
Q

Where is the prepatellar bursa?

A

Superficial to patella

99
Q

Where are the superficial and deep infrapatellar bursae?

A

Inferior to patella

100
Q

Which bursae are non-communicating with the knee joint?

A

Prepatellar
Superficial infrapatellar
Deep infrapatellar

101
Q

Can non-communicating bursae still become irritated?

A

Yes

102
Q

What is the relationship between the synovial membrane and bursae at the knee joint?

A

Lines communicating bursae

103
Q

What part of the cruciate ligaments does the synovial membrane conver?

A

Front

104
Q

What are plicae?

A

Fringes/folds of synovial membrane

105
Q

Where are there plicae in the knee joint?

A

Medially and laterally

106
Q

What is the relationship between the synovial membrane and infrapatellar fat pad?

A

Synovial membrane sits on top of infrapatellar fat pad

107
Q

Where is the patellofemoral joint?

A

In front of femur

108
Q

What is the surface of the femur that articulates with the patella called?

A

Patellar surface

109
Q

Where does the quadriceps tendon attach?

A

Upper aspect of patella

110
Q

How does the patella move across the femur?

A

Slides up and down and rotates to some extent in grooved part of femur

111
Q

What is the quadriceps’ action on the patella?

A

Pulls patella up in extension

Pushes patella down in flexion

112
Q

Where is the groove in which the patella moves across the femur?

A

Between lateral and medial femoral condyles

113
Q

Which articular surface of the patella is larger: lateral or medial?

A

Lateral

114
Q

What is a bipartite patella?

A

Two ossification centres of patella don’t merge

Looks like fracture on x-ray

115
Q

What structures maintain the normal alignment of the patellofemoral joint?

A

Vastus medialis
Medial patellar retinaculum
Raised lip on lateral femoral condyle

116
Q

In which direction does the patella rotate during extension?

A

Medially

117
Q

What happens if the raised lip of the lateral femoral condyle is diminished in size/absent?

A

Tendency for patella to slide laterally

118
Q

In which direction do the fibres of vastus medialis approach the patella?

A

Come towards medial aspect

Move almost horizontally - that’s why this section of muscle sometimes called vastus medialis oblique

119
Q

What does the vastus medialis do in relation to the patella?

A

Helps keep it in place when moving from flexion to extension

120
Q

What is the medial patellar retinaculum an extension of?

A

Vastus medialis to medial aspect of patella

121
Q

Why is the medial patellar retinaculum a static structure?

A

Ligamentous

122
Q

What acts upon the medial patellar retinaculum?

A

Vastus medialis

123
Q

What happens if there is a deficiency in any of the structures that maintain the normal alignment of the patella?

A

Tendency for patella to slide in direction of femur

124
Q

What is the angulation between the femur and tibia called?

A

Quadriceps (Q) angle

125
Q

What tends to pull the patella laterally?

A

Quadriceps

126
Q

What does abnormal tracking of the patella in its groove predispose you to?

A

Sublaxation

Dislocation

127
Q

What is sublaxation?

A

Bone partially sliding across, but not completely dislocating

128
Q

What part of the patella articulates with the femur if there is a mechanical problem of tracking of the patella in the femoral groove?

A

Medial part

129
Q

Why doesn’t the medial part of the patella like to articulate?

A

Cartilage not very thick > wears away

130
Q

What can a mechanical problem of tracking of the patella in the femoral groove cause?

A

Cartilage on medial aspect of patella wears away > contributes to arthritic changes at patellofemoral joint > chondromalacia patella

131
Q

What is chondromalacia patella?

A

Softening/degeneration of cartilage at patellofemoral joint