Knee Joint Flashcards
(131 cards)
1
Q
How many joints share the capsule at the knee joint?
A
2
2
Q
What are the two articulations of the knee joint?
A
Femur with tibia = tibiofemoral
Femur with patella = patellofemoral
3
Q
What is the largest sesamoid bone in the body?
A
Patella
4
Q
Why is the knee a modified hinge joint?
A
Have rotation when flexed, unlike normal hinge joint which only flexes and extends
5
Q
What movement is required to flex the knee?
A
Rotation
6
Q
What is the range of movement of the knee joint?
A
Relatively large
7
Q
What is a close packed position?
A
Articular surfaces meet each other to greatest extent
Ligaments tight
8
Q
What is the close packed position of the knee?
A
Extension
9
Q
What is the loose packed position of the knee?
A
Midway through flexion
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
11
Q
What gives the knee joint its stability?
A
Strong ligaments reinforcing capsule
Muscles attaching at joint
12
Q
What is the notch between the femoral condyles?
A
Intercondylar notch
13
Q
What is the nick in the intercondylar notch for?
A
Indentation of anterior cruciate ligament
14
Q
What can cause erosion of the anterior cruciate ligament?
A
Narrow intercondylar groove (nick in intercondylar notch)
15
Q
Which femoral condyle is longer, and by how much?
A
Medial femoral condyle longer by 1 cm
16
Q
Which femoral condyle is wider?
A
Lateral femoral condyle
17
Q
What action is the position of the anterior cruciate ligament very important for?
A
Hyperextension at knee > stand upright
18
Q
Which femoral condyle bears the most weight, and what proportion is it?
A
Medial femoral condyle bears 75% of weight
19
Q
Which femoral condyle undergoes more osteoarthritic changes?
A
Medial femoral condyle
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
21
Q
What covers the tibial plateau in the medial and lateral aspects?
A
Articular cartilage
22
Q
What covers the margins of the tibial plateau?
A
Menisci
23
Q
What are the menisci made of?
A
Fibrocartilage
24
Q
What do the menisci in the knee joint do?
A
Support femoral condyles
25
From anterior to posterior, what attaches to the central, raised part of the tibial plateau?
```
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
```
26
What is the femoral attachment of the anterior cruciate ligament?
Lateral aspect of lateral femoral condyle
27
What is the femoral attachment of the posterior cruciate ligament?
Medial femoral condyle
28
What is the shape of the cruciate ligaments from the front?
Cross
29
What 3 pairs of non-muscular structures support the capsule at the knee joint?
Anterior and posterior cruciate ligaments
Medial and collateral ligaments
Medial and lateral menisci
30
When are the structural supports at the knee especially susceptible to injury?
In flexion and rotation
31
What is the extent of the capsule in the knee?
Runs around knee
Surrounds patellofemoral joint
Passes behind femoral condyles and tibial plateau
32
What lines the capsule?
Synovial membrane
33
What is the extent of the synovial membrane at the knee?
Doesn't line everything
| Passes to sides of posterior cruciate ligament then passes around and in front of anterior cruciate ligament
34
What is the relationship of the cruciate ligaments with the capsule and the synovial membrane?
Intracapsular by extrasynovial
35
How do you tell the medial and lateral menisci apart?
Medial meniscus more open, with horns further apart
| Lateral meniscus more circular, with horns closer together
36
Why is the anterior cruciate ligament associated with considerable bleeding when it tears, when it is relatively avascular?
Because of intimate association with synovial membrane
| Blood mostly coming from tears to membrane
37
What is haemarthrosis?
Bleeding because of tear in synovial membrane
38
What is effusion?
Production of extra synovial fluid
39
What is the relationship between the capsule and the medial collateral ligament?
Medial collateral ligament essentially merges with medial aspect of capsule
40
What is the relationship between the capsule and the lateral collateral ligament?
Lateral collateral ligament somewhat detached from capsule
41
What reinforces the knee joint anteriorly?
Patellar tendon/ligament
| Medial patellar retinaculum
42
From which muscles does the medial patellar retinaculum arise?
Vastus medialis
| Vastus lateralis
43
What reinforces the knee joint laterally?
Popliteus
Biceps femoris
Iliotibial band
44
What reinforces the knee joint medially?
Pes anserius tendons
- Sartorius
- Gracilis
- Semitendinosus
45
What reinforces the knee joint posteriorly?
Oblique popliteal ligament
46
From what does the oblique popliteal ligament arise?
Semimembranosus
47
How does the lateral patellar retinaculum change the position of the patella?
Drags it laterally
48
Can the muscular reinforcements of the knee cover for damage to the cruciate ligaments?
Yes
49
What is the collective name for the muscular reinforcements of the knee?
Secondary restraints
50
How do you remember the muscle insertions of the pes anserinus from superior to inferior?
```
Say = sartorius
Grace = gracilis
Before = bursa
Tea = semitendinosus
```
51
What does the anterior cruciate ligament do?
Primary stabiliser in the A-P direction
| Limits forward displacment of tibia on femur
52
When is the anterior cruciate ligament taut?
Extension
| Full flexion
53
What is the loose packed position of the anterior cruciate ligament?
Semi-flexion
54
What are the two bands of fibres in the anterior cruciate ligament?
Anteromedial - most taut in extension
| Posterolateral - most taut in complete flexion
55
What is the role of the anterior cruciate ligament when it tightens in the last 15-20 degrees of extension?
Axis for rotation during terminal extension
56
What does the anterior cruciate ligament allow during extension?
Medial rotation on fixed tibia
| Limits backwards movement of lateral condyle
57
What can a person with a tear in their anterior cruciate ligament not do?
Properly lock joint > unstable in full extension
58
What sound is often heard with an injury to the anterior cruciate ligament?
Pop sound
59
When does injury to the anterior cruciate ligament occur?
Lateral rotation
| Involves extension on weight-bearing leg
60
How much thicker is the posterior cruciate ligament than the anterior cruciate ligament?
2x
61
What is a common variant that reinforces the posterior cruciate ligament?
Meniscofemoral ligaments
62
What does the posterior cruciate ligament do?
Limits posterior displacement of tibia in knee flexion
63
When is the posterior cruciate ligament prone to injury?
Fall on flexed knee
64
What is the course of the popliteus muscle?
Runs across back of joint
Passes under lateral collateral ligament
Attaches to outside of lateral femoral condyle
65
What does the popliteus do?
Rotates femur laterally on fixed tibia
66
What is the role of the popliteus in unlocking the knee joint?
Contraction allows knee joint to flex to do other activities
67
Describe the superficial part of the collateral ligament?
Long, flat band
68
What is the relationship of the medial collateral ligament and the capsule and medial meniscus?
Deep part blends with capsule and attaches to medial meniscus
69
When is the medial collateral ligament taut?
Extension
70
When is the medial collateral ligament slack?
Flexion
71
What does the medial collateral ligament do?
Resist valgus forces and lateral rotation of tibia
72
What does the medial collateral ligament do when the anterior cruciate ligament is damaged?
Secondary restrain - limits anterior displacement of tibia
73
What is the unhappy triad?
Injury to all
- Anterior cruciate ligament
- Medial collateral ligament
- Medial meniscus
74
What separates the lateral collateral ligament from the lateral meniscus?
Popliteus tendon
75
What does the lateral collateral ligament do?
Resist varus forces
76
Which collateral ligament is more often injured?
Medial collateral ligament
77
What are the attachments of the lateral collateral ligament?
Lateral femoral condyle
| Fibula
78
What is the shape of the menisci in the knee?
Wedge shaped
79
What are the functions of the menisci in the knee?
Shock absorb
Weight distribution
Separates joint into 2 cavities
80
With which structure do the menisci move in rotation?
Femur
81
By how much do the menisci increase area of contact?
1/3
82
Are the menisci within the synovial cavity or extrasynovial?
Within synovial cavity, but only bony attachments have covring
83
Which meniscus is more often injured, and why?
Medial meniscus, because
- Longer
- Horns further apart
- Less mobile
84
What kind of injuries can occur to the medial meniscus?
Nipped
| Torn
85
What does an injury to the medial meniscus contribute to?
Locked knee
86
What happens if the menisci are completely removed?
Increased incidence of osteoarthritis
87
What are the two zones of the menisci, as defined by their blood supply?
Outer 1/3 has blood supply = red zone
| Inner 2/3 avascular = white zone
88
What is a bursa?
Sac with small amount of fluid in it
89
What can happen to bursa with irritation?
Fluid inside can increase
90
Where is the quadriceps/suprapatellar bursa?
In knee joint, deep to quadriceps muscle
91
What is the largest bursa in the body?
Quadriceps bursa
92
What is the superior extent of the suprapatellar bursa?
Hand's breadth above tibiofemoral joint
93
Does the suprapatellar bursa communicate with the knee joint?
Yes
94
Where can an effusion at the knee joint expand into?
Suprapatellar bursa
95
How can the extent of the effusion into the suprapatellar bursa be estimated?
Pressing down on bursa to push fluid back into joint cavity
96
What is a baker's cyst?
Bursa deep to popliteus becomes fibrous
97
Where are there bursae in the knee?
Wherever
- Ligaments attach
- Large tendon sliding over bone
98
Where is the prepatellar bursa?
Superficial to patella
99
Where are the superficial and deep infrapatellar bursae?
Inferior to patella
100
Which bursae are non-communicating with the knee joint?
Prepatellar
Superficial infrapatellar
Deep infrapatellar
101
Can non-communicating bursae still become irritated?
Yes
102
What is the relationship between the synovial membrane and bursae at the knee joint?
Lines communicating bursae
103
What part of the cruciate ligaments does the synovial membrane conver?
Front
104
What are plicae?
Fringes/folds of synovial membrane
105
Where are there plicae in the knee joint?
Medially and laterally
106
What is the relationship between the synovial membrane and infrapatellar fat pad?
Synovial membrane sits on top of infrapatellar fat pad
107
Where is the patellofemoral joint?
In front of femur
108
What is the surface of the femur that articulates with the patella called?
Patellar surface
109
Where does the quadriceps tendon attach?
Upper aspect of patella
110
How does the patella move across the femur?
Slides up and down and rotates to some extent in grooved part of femur
111
What is the quadriceps' action on the patella?
Pulls patella up in extension
| Pushes patella down in flexion
112
Where is the groove in which the patella moves across the femur?
Between lateral and medial femoral condyles
113
Which articular surface of the patella is larger: lateral or medial?
Lateral
114
What is a bipartite patella?
Two ossification centres of patella don't merge
| Looks like fracture on x-ray
115
What structures maintain the normal alignment of the patellofemoral joint?
Vastus medialis
Medial patellar retinaculum
Raised lip on lateral femoral condyle
116
In which direction does the patella rotate during extension?
Medially
117
What happens if the raised lip of the lateral femoral condyle is diminished in size/absent?
Tendency for patella to slide laterally
118
In which direction do the fibres of vastus medialis approach the patella?
Come towards medial aspect
| Move almost horizontally - that's why this section of muscle sometimes called vastus medialis oblique
119
What does the vastus medialis do in relation to the patella?
Helps keep it in place when moving from flexion to extension
120
What is the medial patellar retinaculum an extension of?
Vastus medialis to medial aspect of patella
121
Why is the medial patellar retinaculum a static structure?
Ligamentous
122
What acts upon the medial patellar retinaculum?
Vastus medialis
123
What happens if there is a deficiency in any of the structures that maintain the normal alignment of the patella?
Tendency for patella to slide in direction of femur
124
What is the angulation between the femur and tibia called?
Quadriceps (Q) angle
125
What tends to pull the patella laterally?
Quadriceps
126
What does abnormal tracking of the patella in its groove predispose you to?
Sublaxation
| Dislocation
127
What is sublaxation?
Bone partially sliding across, but not completely dislocating
128
What part of the patella articulates with the femur if there is a mechanical problem of tracking of the patella in the femoral groove?
Medial part
129
Why doesn't the medial part of the patella like to articulate?
Cartilage not very thick > wears away
130
What can a mechanical problem of tracking of the patella in the femoral groove cause?
Cartilage on medial aspect of patella wears away > contributes to arthritic changes at patellofemoral joint > chondromalacia patella
131
What is chondromalacia patella?
Softening/degeneration of cartilage at patellofemoral joint
