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S1 Biomechanics > Biomechanics Development > Flashcards

Biomechanics Development Flashcards

1
Q

how is the newborn skeleton different from the adult skeleton

A

made of cartilage
-more compliant
-weaker and capable of creep
bone greadually copies configuration of cartilage over the first 25 years of life

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2
Q

shear forces

  • orientation to epiphyseal plate
  • caused by…
  • results in…
A

parallel to epiphyseal plate
normal pull of muscle around a joint
results in normal torsional changes in long bones
ex. lateral tibial torsion

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3
Q

compression forces

-orientation to epiphyseal pate

A

perpendicular to plate

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4
Q

what determines the size, shape and mass of your bones

A

genetics
environment
mechanical forces applied to bone through movement
pathology

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5
Q

skeletal development timeframe

A

5th week of gestation to end of skeletal ossification (25 years)

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6
Q

neonatal biomechanical problem list

A 
rigid kyphotic spine
hip soft tissue contractures
shallow acetabulum
femoral structure
genicular differences
tib-fib torsion
ankle and foot structure
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7
Q

resolution of rigid kyphotic spine

  • when and how does it begin?
  • when can a child perform a cobra
  • what is required to successfully perform a cobra?
A

begins in 1st month of life as baby learns how to lift head against gravity in prone
capable of cobra by 4th or 5th month
requirements
-controlled extension throughout cervical, thoracic, and lumbar spine
-stabilize pelvis via simultaneous contraction of gluteal muscles

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8
Q

development of full mature spinal curves take ____

A

years of movement against gravity in a quadruped, sitting and standing position

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9
Q

hip soft tissue contractures

-which structures contribute to tightness

A

hip flexion
-iliofemoral and ischiofemoral (anterior) ligaments
-hip flexors (iliopsoas, sartorius, rectus femoris)
lateral rotation contracture

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10
Q

hip flexion contracture impeded what arthrokinematic movement?

A

distal and anterior glide of femoral head

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11
Q

shallow acetabulum

-how does acetabular shelf form?

A

muscle tension and body weight
-act to pull the femoral head into the acetabuluim
activities that apply hip extension, medial rotation, and abduction force (newborn kicking, 4 point, crawling, standing)

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12
Q

differences in the femur between a newborn and adult

A

coxa valga
antetorsion
femoral varus bowing

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13
Q

angle of inclination in newborn

A

150 degrees (adult 125)

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14
Q

how is the issue of coxa valga resolved

A

enlarge of greater trochanter
-due to action of piriformis, gluteus medius, and gluteus minimus
-i.e., external rotators, abductors, and extensors
this compression leads to a laying down of bone tissue along the uppermost border of the femoral neck

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15
Q

femoral varus bowing

-how does it resolve?

A

resolves by cantilever flexure drift

-compression forces cause resorption of bone on convex side and new bone growth on concave side

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16
Q

femoral antetorsion

  • what is it?
  • angle in newborns
  • angle in adults
A

medial twist of the femoral shaft, distal on proximal
newborn - 40 degrees
adult - 10 degrees

17
Q

how does antetorsion resolve in children

A

resolution of hip flexion contracture
-allows glut. max. and add. magnus to fire
consistent tensile loading by the muscles that extend and laterally rotate the hip

18
Q

what muscle stabilizes the pelvis/femur during actions that extend and laterally rotate the hip
-this muscle with contribute to resolution of…

A

gluteus medius

-will contribute to resolution of antetorsion and coxa valga

19
Q

why does the newborn appear laterally rotated if they have femoral antetorsion

A

soft tissue contracture (lateral rotators)

retroverted acetabulum

20
Q

appropriate femoral torsion values at

  • birth
  • 1 year
  • 9 years
  • adult
A

birth: 40
1 year: 35
9 years: 21
adult: 15-20

21
Q

differences in knee between newborn and adult

A

flexion contracture
medial genicular position
genu varum

22
Q

how great is the knee flexion contracture in newborns?

-when does it resolve?

A

30 degrees

resolves in first few months of life

23
Q

medial genicular position

  • newborn appears to have…
  • when does it resolve
  • resolves with what type of activities
A 
apparent tibial varum
resolves with knee flexion contracture
activities
-belly crawling
-walking
-these activites apply lateral rotation force to proximal tib-fib
24
Q

changes in genu valgum/varum from birth to adulthood

-what causes the changes

A

genu varum early in development
-stimulates bone growth on medial condyles
genu valgus at 2-3 years
-stimulates bone growth on lateral condyles
genu valgum resolves through weight bearing

25
Q

how much genu valgum/varus is present at…

  • birth
  • 3 years
A

birth
-17 degrees varum
3 years
-12 degrees valgum

26
Q

genu valgum to ideal alignment

  • how much valgum is present at 8 years
  • how does it resolve
A 
8 years: 5 degrees
resolution: compression forces on condyles
due to
-decrease in coxa valga
-genicular position
-femoral varus bowing
27
Q

lower leg torsion at the transmalleolar axis (TMA)

  • torsion in newborn
  • torsion in adult
A

newborn: 0 degrees
adult: 20 to 30 degrees posterior to frontal plane (fibula behind tibia)

28
Q

how does TMA torsion occur to resolve to adult values?

-what type of movements cause this?

A

requires lateral rotatory torque across growth plates of tibia and fibula
movements
-toe standing
-ambulation

29
Q

“W” position may lead to increased…

A

femoral anteversion

30
Q

sitting on the feet is commonly associated with…

A

internal tibial torsion

31
Q

differences in ankle between newborns and adults

A

excessive talocrural dorsiflexion

shortened fibula

32
Q

differences in ankle between newbors and adults

A

hindfoot varus - open chain

hindfoot valgus during infancy and the onset of weight bearing

33
Q

relaxed calcaneal stance angle

-equation

A

RCS = 7 minus (age of child)
-Valmassey
this is the amount of calcaneal valgus they should have

34
Q

foot progression angle

  • how is it measured?
  • negative versus positive value
  • what should values be at birth, 3 years, and adult
A 
angle between
-longitudinal axis of foot
-line of progression of gait
in-toeing = negative value
out-toeing = positive value
birth: 10 degrees
3 years: 2-6 degrees
adult = 0- degrees
35
Q

thigh-foot angle

-how is it measured

A

prone
knee at 90 degrees
foot in congruity
measure posterior thigh bisection and plantar heel bisection
-so you draw a line through the middle of the thigh and a line through middle of the heel to the 2nd toe, and you compare the angle they make

36
Q

typical thigh-foot angle at

  • 1 year
  • 3 years
  • 5 years
  • 15-19 years
  • adult
A 
1 year: -3 degrees (toes point medially)
3 years: +5 degrees
5 years: +11 degrees
15-19 years: +12 degrees
adult: +18 degrees
37
Q

antetorsion vs anteversion

A

antetorsion
-relation of femoral head to femoral condyles
anteversion
-relation of femoral head to frontal plane

S1 Biomechanics (12 decks)

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