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Biomechanics Exam 2 > Forefoot Deformities > Flashcards

Forefoot Deformities Flashcards

1
Q

define forefoot deformities

A

the forefoot appears inverted or everted relative to the rearfoot when the STJ is neutral position and the MTJ is maximally pronated

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2
Q

forefoot deformity is measured in relation to

A

rearfoot

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3
Q

when measuring forefoot deformity place the patient —(prone or supine)

A

prone

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4
Q

the plane of the — is compared to the perpendicular of the calcaneal bisection

A

MT heads

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5
Q

we use the plane of the MT heads as a representation of the

A

MTJ

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6
Q

define forefoot varus

A

the forefoot is inverted to the rearfoot when the STJ is in neutral position and MTJ is maximally pronated

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7
Q

forefoot varus may be a result of

A

abnormal frontal plane ontogeny

lack of adequate valgus torsion of the talar head and neck

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8
Q

what are other deformities that will function similar to forefoot varus?

A
  1. forefoot supinatus
  2. dorsiflexed 1st ray
  3. plantarflexed lateral column
    - plantarflexed 5th MT
    - plantaflexed cuboid
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9
Q

what adaptation occurs with forefoot supinatus

A

soft tissue adaptation as a result of the forefoot functioning in a chronically inverted position

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10
Q

forefoot supinatus results in

A
  1. forefoot varus w/ subtalar pronation at end range or motion
  2. flexible forefoot valgus
  3. STJ pronation at end range of motion as a result of other deformities
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11
Q

causes of forefoot varus

A

congenital
bony
primary

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12
Q

causes of forefoot supinatus

A

acquired
soft tissue
secondary

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13
Q

clinical appearance of forefoot varus

A
  • The lesser tarsus appears flattened from lateral to medial (when viewed dorsally)
  • The lesser tarsus has a longer radius of curvature which makes the foot look wider (when viewed dorsally)
  • The malleoli appear lower because of the relative dorsiflexion of the forefoot on the rearfoot
  • When standing in NCSP, the first metatarsal head will not bear weight
  • There is a rigid resistance to additional MTJ pronation when the STJ is in neutral position and the MTJ is maximally pronated
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14
Q

clinical appearance of forefoot supinatus

A
  • Normal frontal plane curvature of the lesser tarsus
  • Normal dorsal plantar thickness when viewed from the medial side of the foot
  • A plantarflexory force at the navicular will reduce/eliminate the inverted forefoot position
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15
Q

another name for dorsiflexed 1st ray

A

MPE = metatarsus primus elevatus

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16
Q

how are sagittal plane 1st ray deformities defined

A

by their ROM

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17
Q

what is a dorsiflexed 1st ray deformity

A

1st ray has more dorsiflexion than plantarflexion available so that the neutral position of the 1st ray is dorsiflexed

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18
Q

how can sagittal plane deformities be described

A
  1. rigid/flexible

2. congenital/acquired

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19
Q

what is a rigid dorsiflexed 1st ray

A

unable to plantarflex below the plane of the lesser MT heads

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20
Q

what is a flexible dorsiflexed 1st ray

A

able to plantarflex below the level of the lesser MT heads

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21
Q

what is a congenital dorsiflexed 1st ray

A

has normal or greater than normal ROM, but is dorsally displaced

22
Q

what is an acquired dorsiflexed 1st ray

A

has less than normal ROM and is dorsally displaced

23
Q

how does a dorsiflexed 1st ray tend to compensate

A

in a manner similar to the other inverted forefoot deformities

24
Q

what happens when you have an abnormally plantarflexed cuboid relative to the calcaneus

A

the lateral column will then follow w/ this plantarflexed position
results in lowering of the lateral column relative to the medial column

25
Q

plantarflexed cuboid results in what type of deformity

A

inverted forefoot deformity

26
Q

what happens to the lateral column when the 5th ray is in a plantarflexed position

A

the lateral side of the foot becomes relatively lower than the medial side putting the forefoot in an inverted position (another cause of forefoot deformity)

27
Q

how do you compensate for a plantarflexed 5th ray

A

similar to that of other inverted forefoot deformities

28
Q

how do you compensate for forefoot varus when no other deformity is present

A
  • the patient is standing in NCSP
  • the medial side of the forefoot will be off the ground (generally by the amount of the forefoot deformity)
  • GRF will push up on the lateral side of the foot, lateral to the STJ and MTJ axis
29
Q

does the MTJ help compensate for forefoot varus?

A

no b/c MTJ is already maximally pronated

30
Q

when compensating for a forefoot varus, how much will the STJ pronate

A
  • until GRF is equal across the planatar aspect of the foot

- fore deformities of 5’ or less, the STJ will pronate to the same degree as the forefoot deformity

31
Q

what happens when the forefoot varus deformity is greater than 5’

A

the talus will be so far adducted and plantarflexed relative to the calcaneus, that the STJ will go to end range of pronation

REMEMBER: end range of eversion is 10’
end range of inversion is 20’

32
Q

define forefoot valgus

A

forefoot is everted to the rearfoot when the subtalar joint is in neutral position and MTJ is maximally pronated

33
Q

name 3 everted forefoot deformities

A
  1. forefoot valgus
  2. plantarflexed 1st ray
  3. dorsiflexed cuboid
34
Q

in forefoot valgus the plane of MT heads 2-4 (or 5) is — to the rearfoot when the STJ is in —position and the MTJ is —

A

everted
neutral position
locked

35
Q

in forefoot valgus the 1st MT head may be —of metatarsal heads 2-4

A

in the same plane

note: compare to MT head 2-4 and not 2-5 b/c 5th ray has an independent axis

36
Q

is it common or uncommon for the 1st MT head to be plantarflexed relative to the plane of 2-4

A

common

uncommon for 1st MT head to be dorsiflexed relative to the plane of MT heads 2-4

37
Q

how is a flexible (mobile) forefoot valgus deformity compensated

A

compensated completely by supination at the LMJA if 5’ or less

38
Q

how is a rigid forefoot valgus deformity compensated for

A

compensatory supination at:

LMJA, STJ, OMJA is >5’ deformity

39
Q

what are some additional compensations for a flexible forefoot valgus that may occur before the subtalar joint is required to supinate

A
  • dorsiflexion of the 1st ray to raise the 1st MT head up to the level of the 2nd MT head
  • dorsiflexion at the 3rd cuneiform-navicular articulations to raise the medial column (MT heads 1-3) up to the level of the 4th MT head
  • plantarflexion of the 5th ray
40
Q

when compensating for a flexible forefoot valgus deformity how far will the LMJA supinate?

A

to end range of supination of 5’ (a form of overcompensation?)

41
Q

define plantarflexed 1st ray deformity

A

range of motion is greater in the direction of plantarflexion compared to dorsiflexion
first ray neutral position = PF

42
Q

how can you describe plantarflexed 1st ray

A

felxible vs. rigid

congenital vs. acquired

43
Q

why may plantarflexed 1st ray occur

A
  1. may occur as an isolated deformity
  2. may occur w/ a concomitant forefoot valgus ( will act like a forefoot valgus)
  3. may occur w/ a concomitant forefoot varus (act like a forefoot varus)
44
Q

how can compensation occur in an isolated plantarflexed 1st ray

A

dorsiflex 1st ray

if 1st ray can dorsfilex up to the level of the lesser MT heads, the PFFR = flexible (no other compensation will occur)

45
Q

if an isolated PFFR can not dorsiflex up to the level of the lesser MT heads what compensation occurs

A

LMJA will supinate

called a rigid PFFR

46
Q

in an isolated rigid PFFR how far will LMJA supinate

A

to end range or motion which may result in STJ pronation

47
Q

if the PFFR is significant enough what other compensation must occur

A

STJ supination

OMJA supination

48
Q

Elftman’s theory review: when the STJ pronates for compensation more —is available at the MTJ

A

eversion

49
Q

for every 1’ of STJ pornation the MTJ everts

A

1.2’

therefore we do not always have to pronate the exact amount to compensate for a deformity

50
Q

the 1st ray may be able to plantarflex to compensate for some varus deformities (ie rearfoot varus), why?

A

if the rearfoot is in an inverted position, the PL will have a more effective lever arm to apply a greater internal plantarflexory moment at the 1st ray

the patient may pronate until the medial side of the foot hits the ground before the rearfoot gets to rectus (0) which results in an RCSP of NOT 0

51
Q

in combined forefoot and rearfoot deformities what must you do first

A

figure out where the forefoot will be relative to the floor when the pt is standing in NCSP with the MTJ maximally pronated!

Biomechanics Exam 2 (11 decks)

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