exam 2 lecture 7/8 Flashcards

1
Q

GTPS:
- primary cause of:
- weak ___ _____
- plays a role:

A
  • lateral hip pain
  • hip abductors
  • tension stress; also compression (midstance & TFL)
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2
Q

what is Trendelenburg sign?

A

weak hip falls into pelvic on femoral adduction
contralateral hip drop

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3
Q

what is an uncompensated response of trendelenburg sign?

A

weak hip abductors
opposite side hip drop

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4
Q

what is a compensated response of Trendelenburg sign?

A

weak hip abductors
line of gravity shifts towards weak hip

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5
Q

when does the piriformis act as an external rotator?

A

hip extended, anatomical position
line of pull is posterior to the vertical axis of rotation

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6
Q

when does the piriformis act as an internal rotator?

A

hip flexed

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7
Q

using a cane reduces: (2)

A

compressive forces if in opposite hand
JRF by reducing activation of hip abductors (36%)

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8
Q

counterclockwise forces (hip ____) = clockwise forces (_____ and ______ weight held)

A

abd
BW; contralateral

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9
Q

connective tissue reinforcement of posterior capsule:

A

oblique popliteal ligament
arcuate popliteal ligament

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10
Q

muscular reinforcement of posterior capsule:

A

popliteus
gastroc
hamstrings

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11
Q

connective tissue reinforcement of posterior lateral capsule:

A

arcuate popliteal ligament
LCL
popliteofibular ligament

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12
Q

muscle reinforcement of posterior lateral capsule:

A

tendon of popliteus

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13
Q

where does the medial capsule run?

A

patellar tendon to posterior capsule medial side

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14
Q

connective tissue reinforcement of medial capsule:
- anterior 1/3:
- middle 1/3:
- posterior 1/3:

A
  • thin layer of fascia - medial patellar retinacular fibers
  • medial pat retinacular fibers, superficial and deep MCL
  • thick! starts near adductor tubercle, blends w SM tendinous expansion and posterior capsule & posterior oblique ligament. Pes anserine reinforces
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15
Q

muscular reinforcement of medial capsule:

A

SM
SGT - pes anserine

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16
Q

TF joint:
- _____, ______ femoral condyles. _____, ______ tibial plateaus
- ______ motion but ______ _____ provides stability
- ______ acts as gaskets to form seats for the femoral condyles

A
  • large, convex. flat, smaller
  • excessive; soft tissue
  • menisci
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17
Q

menisci:
- anchored to intercondylar region of tibia @ ____
- external edge of each meniscus is attached to tibia and the capsule by _____ _______
- the two are connected anteriorly by _______ ______

A

anterior/posterior horns
coronary ligaments
transverse ligament

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18
Q

what muscles are attached to the menisci which helps to stabilize

A

quads
SM
popliteus to lateral

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19
Q

which ligament in the knee attaches to the meniscus? which does NOT?

A

MCL
LCL (only attaches to lateral capsule)

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20
Q

what is the blood supply of the meniscus?

A

outer 1/3 - direct from genicular arteries (“red zone”)
inner 2/3 - avascular (“white zone”)
nutrition from synovial fluid (needs movement!)

21
Q

what is the primary function of the menisci?

A

decrease compressive forces (triples joint contact area, decreases pressure on articular cartilage)
becomes tensile stress and spreads out like a hoop

22
Q

what are secondary functions of meniscus?

A

stabilizing joint during motion
lubricating articular cartilage
providing proprioception
help guide arthokinematics

23
Q

how do meniscal tears most often happen?

A

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

risk increases with ligamentous laxity and malalignment

24
Q

what side of the meniscus is injured twice as frequently?

A

medial
valgus force (large stress on MCL/post-med capsule)

25
Q

ROM for knee flex & ext:

A

130-150 flex
5-10 hyperext

26
Q

what does the IAR or evolute in the knee do?

A

lengthens the moment arm of flexors and extensors musculature

27
Q

ROM of knee for IR/ER at 90 deg

A

40-45 deg
ER > IR

28
Q

how is rotation of the knee named?

A

position of tibial tuberosity relative to the anterior distal femur
*** slide 26

29
Q

tibial-on-femoral extension:
Meniscus pulled:

A

tibia rolls and slides anteriorly on femur
meniscus pulled anteriorly by quads

30
Q

femoral-on-tibial extension:
___ directs the roll

A

femoral condyles roll anteriorly and slide posteriorly on tibia
quads direct the roll and stabilizes the meniscus vs posterior shear of femur

31
Q

what is the screw home mechanism?

A

full ext requires 10 deg ER during last 30 deg of ext. this increases joint stability.
in open chain ext, tibia ER
in closed chain ext, femur IR

32
Q

what is the screw home mechanism driven by?

A

shape of femoral condyle (tibial follows medial condyle and creates ER) medial is longer
passive tension in ACL
slight lateral pull of quads

33
Q

explain the screw home mechanism for flexion?

A

opposite!
unlocking IR happens first - driven by the popliteus (can rotate femur or tibia)

34
Q

MCL:
- ____ and _____
- resists what force?
—superficial:
—deep:

A
  • flat and broad
  • valgus force (abd)
    — esp w knee flexed 20-30 deg
    — esp w knee in full ext (resist knee ext)
35
Q

LCL:
- ____, cord like
- resists what force?

A
  • short
  • varus force (add), knee ext, rotation extremes
36
Q

primary function of MCL and LCL

A

limit motion in frontal plane

37
Q

what are common mechanisms of injury of MCL?

A

valgus producing force with foot planted (‘clip’ in football)
severe hyperext of knee

38
Q

what are common mechanisms of injury of LCL?

A

varus producing force with foot planted
severe hyperext of knee

39
Q

function of ACL and PCL

A

resist extremes of all motions - primarily A-P shear forces between tibia and femur in sagittal plane motions (cutting)
helps guide arthrokinematics and provides proprioceptive feedback

40
Q

ACL:
- runs?
- 2 bundles:
— AntMed bundle taut in:
— PostLat bundle taut in:
- mostly resists?

A
  • posterior, superior, and lateral to medial side of lateral condyle
    — knee flexion
    — knee ext
  • extension
41
Q

general mechanics of ACL
last 50-60 deg ext:

A

force of quads pulls tibia ant and thus tension in ACL limits the slide

42
Q

common mechanisms of injury of ACL

A

large valgus producing force with foot planted
large axial rotation applied to knee with foot planted
sever hyperext of knee
landing, decelerating, cutting, pivoting over single limb
strong quad activation: excessive ER

43
Q

PCL:
- ____ than ACL
- increasingly taut with greater _____
- ____ glide partially limited by PCL
- injuries common or rare?

A
  • thicker
  • flexion (90-120 >est)
  • posterior
  • rare
44
Q

PCL MOI:

A

high energy trauma
falling onto a fully flexed knee (dashboard injury)

45
Q

PF at 135 deg flex:

A

superior pole below groove at lateral and odd facets

46
Q

PF at 90-60 deg:

A

in trochlear groove
contact area the greatest (only 1/3 area)

47
Q

PF at 20-30 deg:

A

contact at inferior pole
lost much of its mechanical engagement with groove

48
Q

PF at full ext:

A

rests completely proximal to groove on suprapatellar fat pad