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Biomechanics II > Knee kinematics > Flashcards

Knee kinematics Flashcards

1
Q

what structures are included in the anterior portion of the knee capsule

A

patella and tendon

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2
Q

what muscles reinforce the anterior portion of the knee capsule

A

quads

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3
Q

what connective tissues reinforce the anterior portion of the knee capsule

A

extensions of the ITB, vastus lateralis and medius

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4
Q

what connective tissues reinforce the lateral portion of the capsule

A

LCL
lat patellar retinacular fibers
ITB

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5
Q

what muscles reinforce the lateral portion of the capsule

A

biceps femoris
tendon popliteus
lat head of gastroc

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6
Q

what connective tissue reinforces to posterior portion of the knee capsule

A

oblique popliteal lig
arcuate popliteal lig

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7
Q

what muscles reinforce the posterior portion of the knee capsule

A

popliteus
fastrocs
hamstrings

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8
Q

what connective tissue supports the posterior lateral knee capsule

A

arcuate popliteal ig
LCL
popliteofibular lig

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9
Q

what muscles support the posterior lateral capsule of the knee

A

tendon of popliteus

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10
Q

what sesamoid bone in the posterolateral capsule of the knee varies widely in humans

A

fabella

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11
Q

the anterior 1/3 of the medial capsule is reinforced by what structures

A

thin layer of fascia
medial patellar retinacular fibers

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12
Q

the middle 1/3 of the medial knee capsule is reinforced by which structures

A

medial pat retinacular fibers
superficial and deep MCL

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13
Q

the posterior 1/3 of the medial knee capsule is reinforced by which structures

A

starting neard adductor tubercle blendin with SM tendinosis expansion and posterior capsule and posterior oblique ligament

reinforced by pes anserine

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14
Q

what muscles reinforce the medial portion of the knee capsule

A

SM
SGT
pes anserine

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15
Q

describe the synovial joint of the knee

A

internal capsule lined with synovial membrane
14 bursa at inter-tissue junctions
suprapatellar and deep infrapatellar fat pads

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16
Q

describe the tibiofemoral joint

A

large convex femoral condyles and flat, smaller tibial plateuas

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17
Q

what is the function of the menisci in the tibiofemoral joints

A

menisci act as gaskets to form seats for the femoral condyles

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18
Q

where are the menisci anchored to the intercondylar region of the tibia

A

anterior/posterior horns

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19
Q

the external edge of each meniscus is attached to tibia and the capsule by ___ ligs

what are the ligs functions

A

coronary

ligs are loose and allow pivoting

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20
Q

what structure connects the anterior/posterior horns and the coronary ligaments anteriorly

A

transverse ligaments

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21
Q

what are the secondary mm that attach to the menisci

A

quads
semimembranosus
popliteus to lateral

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22
Q

what does the medial menisci attach to

A

MCL and adjacent capsule

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23
Q

what does the lateral menisci attach to

A

lateral capsule

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24
Q

what structure passes between the LCL and lateral meniscus

A

popliteus

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25
Q

what is the “red zone” of the menisci

A

the outer 1/3 of the menisci
the area of the menisci that receives blood supply

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26
Q

what arteries supply the menisci

A

genicular arteries (branches off the popliteal artery)

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27
Q

what is the “white zone” of the menisci

A

inner 2/3 of the menisci
area that is avascular

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28
Q

what is responsible for supplying nutrition to the menisci

A

synovial fluid

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29
Q

how do the menisci change during weight-bearing activities

A

meniscus deforms peripherally and creates tensile stress

30
Q

list the order of increasing stress with walking, stepping, up stairs, or cycling on the menisci

A

cycling < walking < going up stairs

31
Q

compete lateral meniscectomy increases peak contact pressure ___%

A

230%

32
Q

__% of load goes through the lateral mensici and __% goes through meniscus

A

70% in lateral
50% in medial

33
Q

what are the secondary functional considerations of the tibiofemoral joint

A

stabilizing join during motion
lubricating articular cartilage
providing proprioception
help guide arthrokinematics

34
Q

list some of the most common mechanisms of injury of the tibiofemoral joint

A

forceful, axial roation of the femoral condyles over a flexed WB knee

dislodged/folded flap can mechanically block knee motion

medial injured twice as frequently - valgus force

risk increases with ligamentous laxity and malalignment

35
Q

what is the normal range of flexion of knee flexion

A

130-150 degrees

36
Q

what is the normal range of hyperextension of the knee

A

5-10

37
Q

how does the IAR or “evolute” have biomechanical implications

A

lengthens the moment arm of flexors and extensors musculature

brace might piston - need align to the “average” axis of the lateral epicondyle

38
Q

describe the axis of axial rotation of the knee

A

longitudinal axis through tibia

39
Q

at 90 degrees of knee flexion, what is the normal range of axial rotation

A

40-45 degrees

40
Q

ER : exceeds IR

A

2:1

41
Q

how is the rotation of the tibiofemoral joint named

A

named by the position of tibial tuberosity relative to the anterior distal femur

42
Q

describe the arthrokinematics of tibia-on-femoral extension

A

tibia rolls and slides anteriorly on fenur

meniscus pulled anteriorly by quads

43
Q

describe the arthrokineamtics of femoral-on-tibia extension

A

femoral condyles roll anteriorly and slide posteriorly on tibia

quads direct the roll and stabilize the meniscus vs posterior shear of the femur

44
Q

describe “screw home”

A

full extension requires 10 degrees ER during last 30 degrees of extension

increases joint congruence/stability

open chain ER, CC femur IR

45
Q

what is “screw home” driven by

A

shape of the femoral condyle
passive tension in ACL
slight lateral pull of quads

46
Q

what motion causes the unlocking IR first

what muscle controls this

A

flexion unlocks IR first

driven by popliteus

47
Q

describe the arthrokinematics of IR/ER

A

knee must be flexed

spin between menisci and articular surfaces of tibia and femur

axial rotation of femur over tibia causes menisci to deform/compress

popliteus and semimembranosus help stabilize

48
Q

describe the superficial part of the MCL

A

well-defined parallel fibers

medial epicondyle to medial patella to medial proximal tibia

49
Q

describe the deep part of the MCL

A

slightly posterior and distal

shorter and oblique

attaches to capsule, medial meniscus, semimembranosus tendon

50
Q

describe the LCL

A

short and chord like

runs vertically from lateral epicondyle to fibular head

does not attach to adjacent meniscus

blends with biceps femoris tendon

51
Q

what structure runs between the lateral meniscus and the LCL

A

tendon of popliteus

52
Q

what is the primary function of the MCL and LCL

A

limit motion in frontal plane

53
Q

MCL resists __ force when the knee is extended

A

valgus

54
Q

LCL resists ___ force when the knee is extended

A

varus

55
Q

what is the secondary function of the LCL and MCL

A

provide general stabilizing tension

protecting against rotation extremes

56
Q

describe the blood supply to the ACL and PCL and how it affects the healing process

A

limited blood supply
slows healing process

57
Q

what is the function of the ACL and PCL

A

resist extremes of all motions

primarily resists AP shear forces between tibia and femur

58
Q

t/f
the ACL and PCL help to guide arthrokinematics and provides proprioceptive feedback via mechanoreceptors

A

true

59
Q

when is the ACL most taut

A

some fibers taut in flx but increasingly taut as reach ext

60
Q

how does the ACL run

A

runs posterior
superior and lateral to medial side of lateral epicondyle

61
Q

what muscle is responsible for pulling tibia anterior during ext

what is the effect on the ACL

A

quads pull tibia ant last 50-60 degrees ext

tension on ACL limits slide

62
Q

what is the anterior drawer test

why is this test used to test the ACL

A

leg is at 90 degrees
PT pulls proximal tibai anterior

ACL is 85% of passive resistance to anterior glide

63
Q

what muscle, if contracted incorrectly, affects the results of the anterior drawer test

why/how

A

hamstring spasm will prevent tibia from anterior glide if the ACL is damaged

d/t the attachment of the hamstrings on the tibial and fibula head

64
Q

__% of sports-related to ACL are noncontact

A

70%

65
Q

what are some mechanisms of injury to the ACL

A

strong quad activation
valgus collapse
excessive ER
hyperextension

66
Q

when is the PCL most taught

A

knee flexion

67
Q

explain the posterior drawer test

A

proximal end of tibia posterior
knees in 90 degrees
knees sag at 90 degrees hip/knee flexion

68
Q

what are the common mechanisms on injury to the PCL

A

high energy trauma
falling onto a fully flexed knee - “dashboard injury”

69
Q

what muscle is the stabilizer of the patellofemoral joint

A

quad

70
Q

tibial on femoral patella slides relative to

A

fixed trochlear groove

71
Q

femoral on tibial (squat) the trochlear groove slides relative to

A

fixed patellla

Biomechanics II (7 decks)

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