The knee joint Flashcards

1
Q

What joints make up the knee

A
  • tibiofemoral

- patellofemoral

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2
Q

Tibiofemoral joint

A

technical knee joint (flex/ext)

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3
Q

Patellofemoral joint

A

articulation between patella and femur (gliding)

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4
Q

Functions of the knee joint

A
  • transmits loads (that go from low extension or up from the ground)
  • participates in motion
  • aids in conservation of momentum (when you can’t efficiently walk you need to use other energy-using forces to gain motion)
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5
Q

ROM in sagittal plane of tibiofemoral joint

A

0 - 140 deg of flexion

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6
Q

ROM in transverse plane of tibiofemoral joint

A

full extension: 0 degrees (b/c lig and capsules should be tight

@ 90 deg knee flexion:
ER= 45 deg
IR = 30 deg

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7
Q

ROM in frontal plane of tibiofemoral joint

A

full extension = 0 deg

30 deg flexion = a few degrees only

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8
Q

Degrees of freedom of knee

A

TWO

  • flex/ext in sagittal plane (predominant motion)
  • IR/ER in transverse plane
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9
Q

Functional ROM of knee

A

0 - 117 degrees

range needed to do ADLs

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10
Q

Anatomy of tibiofemoral joint

A
  • Double condyloid joint (one surface convex & one surface concave)
  • 2 articulating surfaces: Medial & lateral
  • Composed of two bones: femur & tibia
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11
Q

Anatomy of femur

A
  • 2 condyles (articulating surfaces) separated by intercondylar fossa/notch
  • notch becomes shallow –> PATELLAR GROOVE
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12
Q

Medial condyle of femur

A
  • is 2/3 inches longer anterior-posterior

- extends further distally

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13
Q

Anatomy of tibia

A
  • 2 condyles separated by intercondylar tubercles
  • medial condyle = 50% larger
  • 2 articular disks = menisci
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14
Q

Knee Menisci

A
  • Dynamic (as opposed to static) structures

- assymmetric, wedge-shaped, fibrocartilagenous disk-like structures

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15
Q

area of menisci susceptible to tears

A
  • “horns”

- open ends

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16
Q

vascularization of menisci is located

A

only in the periphery (poor)

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17
Q

Medial knee menisci

A
  • semi-circular or c-shaped
  • attaches to MCL
  • more firmly attached
  • less mobile – doesn’t give as much, therefore susceptible to injury
  • MEDIAL = MORE likely to get hurt
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18
Q

Lateral Menisci

A
  • 80% of a ring (O-shaped)

- more loosely attached to tibia - less susceptible to injury

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19
Q

Functions of menisci

A

1) distribute and absorb force (joint reaction)
2) enhance joint congruency
3) enhance arthrokinematics
4) aids in nutrition & lubrication

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20
Q

Meniscus tears - symptoms

A
  • knee pain
  • swelling
  • tenderness
  • popping/clicking
  • limited motion (could be caused by structure interfering with gliding)
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21
Q

debridement

A

go in, take away pieces & clean it up

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22
Q

central meniscus tear

A

debride pieces torn

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23
Q

outer periphery meniscus tear

A
  • debride if small tear

- repair if large tear

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24
Q

post operative treatment – debridement (meniscus)

A
  • walking in 1 - 2 days

- full activity in 4 weeks

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25
Q

IMMEDIATE post op repair - meniscus

A
  • knee immobilizer/brace
  • flexion to 60 deg
  • WBAT (weight bearing as tolerated) with knee locked in extension
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26
Q

1 month post op repair - meniscus

A
  • continue with brace but not in extension

- ROM greater than 60 deg – let person go beyond 60

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27
Q

3 - 4 months post op repair - meniscus

A

return to activities

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28
Q

normal tibiofemoral alignment

A

185 - 190 degrees (slight valgus)

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29
Q

genu valgum

A

greater than 195 degrees
knock knee – knees stick together

increase compressive forces laterally
increase tensile forces medially

30
Q

genu varum

A

less than 180 degrees
bow legged – knees spread apart

increase compressive forces medially
increase tensile forces laterally

31
Q

Q angle

A

(quadriceps angle) – supine

  • more clinical
  • midpoint of patella to the tibial tuberoisty
32
Q

normal q angle for males

A

less than 10 deg

33
Q

normal q angle for females

A

less than 16 deg because females have a wider pelvis

34
Q

pathological q angle

A

greater than 20 deg

causes the patella to track incorrectly
this is b/c the quads pull obliquely, causing patella to move laterally

35
Q

AOR moves as knee moves through ROM…. this is typical of what type of motion???

A

curvilinear

36
Q

spin

A
pure rotation (top)
axis of rotation is fixed
37
Q

glide/slide

A

skid

pure translation & no rotation

38
Q

roll

A

ball/wheel

translation & rotation (curvilinear)

39
Q

convex on stable concave surface

A

convex surface slides in opposite direction as motion of bony lever

40
Q

concave on stable convex surface

A

concave surface slides in same direction as motion of bony lever

41
Q

arthrokinematics of tibiofemoral joint in a standing position

A

flexed & stable tibia

42
Q

0 to 25 degrees flexion of tibiofemoral joint (arthrokinematics)

A

primarily roll

43
Q

beyond 25 degrees flexion of tibiofemoral joint (arthrokinematics)

A

anterior gliding of femur along with a roll = pure spin

44
Q

in arthrokinematics of the tibiofemoral joint, why is there gliding with a roll???

(in greater than 25 deg flexion)

A

b/c gliding offsets the posterior displacement that would occur if rolling occurred alone

45
Q

how does the meniscus contribute to the anterior glide of the tibiofemoral joint

A

b/c it is wedge shaped

46
Q

screw-home/locking mechanism

A

tibial ER during the last 30 degrees of knee extension (this is b/c the medial condyle is longer)
greatest during the final 5 degrees
b/c of asymmetry of the femoral condyles

47
Q

screw-home/locking mechanism with full knee extension

A
  • tibial tubercles are lodged in intercondylar notch
  • menisci tightly interposed between femur & tibia
  • ligaments taut
48
Q

passive stabilizers of the tibiofemoral joint

A
  • joint capsule
  • LCL
  • MCL
  • ACL
  • PCL
  • Iliotibial band
49
Q

MCL

A
  • posteromedial femur –> anterior tibia
  • blends with capsule
  • attaches to medial meniscus
  • resists valgus stressers
50
Q

LCL

A

lateral femur –> fibula head
- resists varus stressers

note kick on the outside of the knee hurts the MCL bc the LCL compresses

51
Q

ACL

A

posteromedial aspect of the lateral femoral condyle –> anterior intercondylar region of the tibia

  • resists anterior tibial translation & IR of tibia
52
Q

ACL injury

A
  • flexion with femoral ER (ACL winds around PCL)

- flexion with femoral IR (ACL winds around lateral femoral condyle)

53
Q

PCL

A

anterolateral surface of medial femoral condyle –> posterior intercondylar region of the tibia

  • primary restraint to posterior tibial translation
  • hyperextension is a common mechanism of injury
54
Q

ITB

A
  • fascia from TFL, gluteus maximus, & medius
  • attaches to linea aspera of femur and lateral tubercle of tibia
  • gives rise to iliopatellar band –> patella tracking problems
  • reinforces anterolateral aspect of knee

*** tight ITB can cause patella to track incorrectly

55
Q

patella functions:

A
  • aids in extension by increasing moment arm
  • —–***** this has the greatest effect at 20-40 degrees flexion
  • allows for wider distribution of contact forces, causing decreased pressure and friction between quad tendon & femur
  • protection
56
Q

anatomy of patella

A
  • triangular-shaped
  • largest sesamoid bone
  • least congruent joint
  • 3 facets
57
Q

with knee flexion the patella translates ________ & ___________

A

caudally & medial to lateral

58
Q

full knee ________ —> sinks into femoral trochlea

A

flexion

59
Q

patella also ____ (vertical axis) and ______ (anterior-posterior axis)

A

tilts; rotates

60
Q

failure of patella to slide tilt or rotate properly can lead to:

A
  • restricted patellar femoral ROM
  • restricted knee ROM
  • Patellar femoral tracking problems –> pain –> tissue damage
  • patellar femoral instability –> subluxation & dislocation (usually laterally)
61
Q

subluxation

A

partial dislocation

62
Q

medial/lateral stabilizers of patella

A

medial patellar retinacula –> vastus medialis

lateral patellar retinacula –> vastus lateralis

63
Q

superiorly/inferiorly

A

patellar tendon (ligament) quadriceps tendon

64
Q

abnormal lateral forces on patella:

A
  • vastus lateralis (pull too hard on knee)

- ITB (tight iliotibial band)

65
Q

IN TERMS OF ABNORMAL FORCES ON PATELLA, anything that increases the obliquity (laterally) of the pull could cause

A
  • excessive lateral compression

- subluxation &/or dislocation laterally

66
Q

Excessive lateral oblique pull

A
  • weakness of VMO
  • excessive genu valgum (incr Q angle)
  • excessive femoral anteversion
  • tight lateral retinaculum/loose medial retinaculum
  • tight ITB
  • diminished height of lateral femoral lip
67
Q

other factors affecting patella alignment & tracking

A
  • status of gluteal muscles
  • position of tibial tuberosity
  • mechanics of feet
68
Q

specific problems with vastus medialis obliqus

A
  • barely reaches top of patella

- fibers run more vertical than oblique

69
Q

extensors of knee

A

QUADICEPS

  • vastus medialis (oblique and lateralis)
  • vastus lateralis
  • vastus intermedius
  • recuts femoris
70
Q

flexors of knee

A

hamstrings

  • lateral (ER tibia) – biceps femoris (short/long)
  • Medial (IR tibia) – semimembranosus, semitendinosus

popliteus
gracillis
sartorious

71
Q

other musculature of knee

A

gastrocs