The Knee Joint Flashcards
1
Q
Where degrees of freedom in the tibio femoral joint?
A
2 degrees of freedom
Flex / ext
IR / ER
2
Q
What are the defining features of the medial condyle?
A
Larger & more distal
3
Q
What are the defining features of the lateral condyle?
A
Smaller; more in line with femoral shaft
Projects more anterior
4
Q
Where is the intecondylar notch/femoral sulcus
A
5
Q
Which lip of the patella is larger?
A
Lateral lip is larger than the medial
6
Q
What is the angle of the tibial plateaus?
A
7-10°
7
Q
Which tibial plateau is longer?
A
Medial longer vs. lateral (AP)
8
Q
What is the shape of the tibial plateau?
A
Shape concave
9
Q
What do the inter-CON DY LAR tubercles do in the knee joint?
A
Engage in notch in full extension
Bony stability
10
Q
What is considered normal physiologic valgus of knee?
A
Norm = 170°- 175°
11
Q
What does physiologic valgus allow?
A
Allows equal loading in both compartments
12
Q
What is genu valgus?
A
“knock knees”
< 170
13
Q
What are the consequences of genu valgus?
A
Compressive forces on lateral side of knee and tensile forces on medial side
14
Q
What is genu varus?
A
“bow legs”
> 180°
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
16
Q
What is the function of the knee joint capsule?
A
Restricts joint motion and provides proprioception
17
Q
What is the close packed position of the joint capsule of the knee?
A
Full extension
18
Q
What position of the knee allows the most volume in the joint capsule?
A
Semi flexed position
19
Q
What are the posterior attachment to the joint capsule of the knee?
A
Condyles
20
Q
What are the anterior/inferior attachments of the joint capsule of the knee?
A
Retinaculum
Patellar tendon
21
Q
What is the superior attachment of the capsule of the knee?
A
Quadriceps tendon
22
Q
What is the composition of the capsule of the knee?
A
Fibrous layer
Synovial layer
23
Q
What does the synovial layer of the knee joint capsule due posteriorly?
A
it folds inward to surround cruciates
24
Q
What are plicae? And how many are there?
A
Embryologic remnants of synovial septae
Potentially 4
Inferior, superior, medial, lateral
25
What is the anterior fibrous layer of the joint capsule also known as?
Extensor retinaculum
26
What are the Medial retinacular fibers?
MPFL & Medial patelleotibial ligament
27
What are the lateral retinacular fibers?
LPFL & lateral patelleotibial ligament
28
What is the lateral layer of the joint capsule reinforced by?
Reinforced by LCL, ITB and lateral patellar retinacular fibers
29
What is the medial side of the joint capsule reinforced by?
Reinforced by MCL, medial patellar retinacular fibers
30
What is the posterior medial corner of the fibrous layer of the joint capsule of the knee made of?
31
Where are the following?
32
What is the posterior lateral corner of the fibrous layer of the joint capsule of the knee made of?
33
Where are the following?
34
What does the posterior medial corner & posterior lateral corner of the knee capsule resist respectively?
Resist hyperextension and valgus and varus stresses respectively
35
What are the attachments of the IT band?
Attaches to the tibia via the iliotibial band and the patella via the patellofemoral ligament
36
What are the functions of the IT band?
Support anterolateral knee
With knee flexion, assists ACL in resisting anterior tibial translation
37
What cushions the IT band deeper to the tendon?
Fat pad rather than a bursa
can become inflamed and agitated leading to IT band syndrome
38
How many portions does the medial collateral ligament have?
Two portion superficial and deep
39
What is the primary restraint of the MCL
Valgus (0° & 25°)
60% at 0 and 80% at 25
Lateral rotation of tibia
40
What is the secondary restraint of the MCL?
ant tibial trans
41
Which of the four distinct ligaments of the knee has the greatest capacity for healing?
MCL, highly vascular
42
What is the primary restraint of the lateral collateral ligament?
Primary restraint
Varus (0° & 25°)
55% at 0 and 70% at 25 degrees
43
Which ligament is extra capsular in the knee?
LCL
44
What is the secondary restraint of the LCL?
Lateral rotation of tibia
45
What are the attachments of the ACL?
Anteromedial tibia to posteromedial LFC
46
What is the primary restraint of the ACL
Anterior tibial translation
Hyperextension
Rotary stability
47
Which ligament tension guides the arthrokinematics of the knee?
Anterior crusade ligament (ACL)
48
What is the ACL loaded with that play a protective role?
mechanoreceptors
49
What muscles place stress on the ACL?
quadriceps muscles
50
What is the most common ACL mechanism of injury?
Strong activation of the quad over a slightly flexed knee
Valgus collapse
Excessive ER of the tibia
51
What is another ACL mechanism of injury?
Hyperextension of the knee
52
What are the attachments of the posterior cruciate ligament?
Posterior tibia to medial femoral condyle
53
What increases tension in the PCL?
Tension increases with greater amounts of knee flexion
54
What is the primary restraint of the PCL?
Posterior tibial translation at ALL angles of flexion
55
What muscle group places stress on the PCL?
Hamstring muscles
56
Were the common ways the PCL is injured?
fall on flexed knee or “dashboard injury”
57
What is the composition of the menisci?
Fibrocartilage discs
58
What is the function of the knee menisci?
Improve congruence
friction
Shock absorption
Up to 50-70% of load
(Altered with alignment)
Distribution of forces
59
What are the common stabilizing structures of the menisci?
Transverse ligament
coronary ligaments
Patellomensical ligament
60
What are the unique attachments of the medial meniscus?
MCL
semimembranosus tendon
anterior cruciate ligament
61
What is the shape of the medial meniscus?
C shaped
62
How mobile is the medial meniscus compared to the lateral meniscus?
The medial is less mobile
63
Was the shape of the lateral meniscus?
More round & more mobile
64
Attachments of the lateral meniscus?
Popliteus
PCL & femoral condyle via meniscofemoral ligament
65
What part of the menisci are innervated?
Outer one third
66
What part of the menisci are vascularized?
Outer one third
67
What is the function of the bursae in the knee?
Lubrication, cushion
68
What are the three isolated bursae in the knee?
prepatellar, infrapatellar, deep infrapatellar bursa
69
What are the three bursae in the knee that are continuous with the synovial lining?
Subpopliteal, Gastrocnemius, Suprapatellar
70
What is the common total range of motion in the knee?
Total ROM: 5-0-140
71
What is Genu recurvatum?
> 5° hyperextension
72
What are the AK's of flexion and extension at the knee
73
What is the ratio of internal to extra rotation at the knee?
External > Internal rotation (2:1)
74
What are the AK's of internal and external rotation at the knee?
75
“Screw home mechanism” or “locking mechanism” of knee?
Obligatory rotation of the femur or tibia occurring with end range extension and early flexion of the knee
76
What are the factors of the locking mechanism of the name?
Shape of medial femoral condyle**
Passive tension in ACL
Lateral pull of quadriceps muscle
77
What is the open chain locking mechanism?
Lateral Rotation of tibia on femur
78
What is open chain unlocking mechanism?
(initiated by poplitues m)
Open chain: MR of tibia on femur
79
What is the relative difference between open chain and close chain unlocking?
Unlocking relative motions are opposite in close chain
80
What is what is the length tension relationship between lower extremity muscles?
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
What is passive insufficiency of the hip?
Limitation range of motion when the muscle groups are stretched over both joints only the one tested for range of motion
82
What is active insufficiency of the HIP?
Force production sub optimal when muscles are not lengthened over one joint segment and shortened over the other
83
How do the menisci move in knee flexion?
Posterior Roll
84
How do the menisci move in knee extension
Anterior roll
85
What contributes to posterior roll in the menisci?
Semimembranosus & Popliteus
86
What contributes to anterior roll in the menisci?
Lateral – meniscofemoral ligament
Medial – anterior capsular fibers
87
How do the menisci move and lateral medial rotation??
Menisci move with femoral condyles
88
What muscles make up the quadriceps?
Rectus femoris (2 joint)
Vastus intermedius
Vastus lateralis
Vastus medialis
Vastus medialis obliqus (VMO)- fiber attach to patella at 50-55 deg
89
What does the Articularis genu do and where is it?
Deep to VL and VI; tenses capsule w/ extension
90
What produces the majority of the extensor torque?
Vasti produce 80% of knee extensor torque
91
What is the extensor mechanism?
Quad muscle + patella + patellar tendon
92
What is the torque ratio for extensors over flexors of the knee?
Produce torque 2/3 > knee flexors
93
How does the external moment arm change in open chain knee extension?
External moment arm increases from 90-0 degrees
94
Why do clinicians often select close chain exercises following knee surgery or injury?
increasing anterior shear stress placed on the tibia during open chain knee extension in the last 45 degrees
95
How does the external moment arm change during close chain knee extension?
External moment arm decreases from 90-0 degrees
96
At what degrees of flexion is the max knee extension torque?
occurs between 45-70 degrees of knee flexion (usually say 60 degrees
97
To what extent is torque production decrease towards full extension of the knee?
50-70% reduction as knee approaches full extension
98
What are the knee flexors and rotators?
Hamstrings (Semimebranosus, Semitendinosus, Biceps femoris), Sartorius, Gracilis, Gastrocnemius, popliteus
99
What is the secondary action of the semitendinosus, semimembranosus, gracilis, sartorius, & popliteus?
IR of tibia
100
What is the secondary action of the biceps femoris?
ER of tibia
101
What is the Pes Anserine?
Common attachment for sartorius, gracilis and semitendinosus
102
What is the synergistic function of the muscles that attach to the pes anserine?
3 muscles function synergistically to resist valgus forces at knee; also IR tibia
103
When is the best moment arm for the gastrocnemius to participate in knee flexion?
When the knee is extended fully
104
What is the action of the popliteus muscle
MR of tibia
Posterior pull on lateral meniscus
105
What are the attachments of the popliteus muscle?
LFC to posterior medial tibia
106
What is the retropatellar surface covered with?
articular cartridge
107
What are the facets of the patella?
Medial, lateral, odd, superior and inferior
108
And what direction is the normal pull of the patella?
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
What is the Q angle?
Two lines drawn to measures
Line from ASIS to mid patella
Line from mid patella to tibial tuberosity
110
What is a normal Q angle?
10° to 15°
111
What happens with the Q angle greater than 20°
Structural malalignment
112
What is the general motion of the patella with flexion?
0-30° medial & inferior
113
What is the general motion of the patella with extension?
Superior lateral with knee extension
114
What are some possible alterations the alignment of the patella and in trochlear groove?
Femoral rotation (anteversion)
Genu valgus
Can be dynamic or static
115
What are the passive stabilizers of the patella femoral joint?
Bony geometry / architecture
Ligaments
116
What are the dynamic stabilizers of the patella femoral joint?
Muscles
117
What is the bony static stabilizer of the PF joint?
Lateral lip of femoral sulcus
118
What are the soft tissue static stabilizers of the PF joint?
Patellar tendon, quadriceps tendon, extensor retinaculum/joint capsule
Lateral PF ligament (LPFL)
Medial PF ligament (MPFL)
60% of stability
119
What is the contact of the patella at 0° of flexion?
above groove
120
What is the contact of the Patel lead 20° of flexion?
enters trochlear groove; 1st part contacted- inferior pole
121
What is the contact of the patella at 45° of flexion?
mid-pole-medial and lateral facets
122
What is the contact of the patella at 90° of flexion?
superior facet
123
What is the contact of the patella at 135° of flexion?
odd facet; patella lodged in intercondylar groove
124
What causes "train problems" at the knee joint?
Quad weakness
ITB/flexibility
Alignment issues
125
What can cause "track problems" at the knee joint?
Hip weakness
126
What is less contact area on the patella cause?
More stress (stress equal force divided by area)
127
What is a joint reaction force?
Resultant force (or contact force) created when two or more forces causes contact between joint surfaces
128
What causes the joint reaction at the PF joint?
Quadriceps!
129
How does the joint reaction force change at the patella joint?
Knee joint angle
Quad force
130
What causes Patellofemoral Joint Dysfunction
AKA Patellofemoral Pain Syndrome (PFPS)
Abnormally high contact forces (we already discussed the many reasons) + High Joint reaction forces (created by high quad forces)
131
How should we select open kinetic chain versus close kinetic chain exercises for the knee?
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)
