Developmental biomechanics

Question 1

What is developmental biomechanics the study of?

Answer 1

Study of how forces affect the MSK system over the life span

Question 2

Main forces impacting developmental biomechanics

Answer 2

Body weight/gravity (external)
Alignment + pull/force of muscles (internal)

Question 3

Why is developmental biomechanics important

Answer 3

Development of MSK system is part of tx and dx

Question 4

When does formation of MSK system occur

Answer 4

2nd - 8th week of post conception (embryonic period)

Question 5

When do limb buds appear?

Answer 5

4th week (upper limb slightly before lower limb)

Question 6

Up to what week do major congenital abnormalities occur?

Answer 6

8 weeks (start of the fetal period)

Question 7

Categories of congenital abnormalities and what phase they occur in

Answer 7

Malformations (embryonic)
Deformations (fetal)
Disruptions (fetal)
Dysplasias (fetal)

Question 8

During what period do malformations arise?

Answer 8

Period of organogenesis (weeks 2-8)

Question 9

Of what origin are malformations?

Answer 9

Teratogenic
Genetic
Idiopathic

Question 10

Examples of malformations

Answer 10

Phocomelia
Limb hypoplasis

Question 11

Terotogenic origin

Answer 11

Something external (meds, radiation, illness/fever)

Question 12

Genetic origin

Answer 12

Mutation

Question 13

Is lower or upper limb more susceptible to congenital limb loss

Answer 13

Lower

Question 14

What is a key difference between infant + children bones and adult bones

Answer 14

Bones are softer in infants/children because they haven’t been ossified

Question 15

When do deformations occur in development?

Answer 15

Occur at the end of gestation (fetal stage)

Question 16

Cause of deformations

Answer 16

Intrauterine crowding
Position

Question 17

Examples of deformation

Answer 17

Torticollis
Club foot

Question 18

t/f deformations are more common in multiples

Answer 18

true

Question 19

When do disruptions occur

Answer 19

Later in gestation (fetal stage)

Question 20

Cause of disruptions

Answer 20

Teratogenic, traumatic, or other physical insults to the fetus interfere with growth

Question 21

Examples of disruptions

Answer 21

Congenital/amniotic constriction bands

Question 22

Why do dysplasias occur

Answer 22

Result from altered growth that occurs before and/or after birth

Question 23

Examples of dysplasias

Answer 23

Achondroplasia
Developmental hip dysplasia

Question 24

Are dysplasias isolated?

Answer 24

They can be, but can also be more widespread

Question 25

2 distinct processes of bone formation

Answer 25

Endochondral ossification Intramembranous ossification

Question 26

Role of ossification

Answer 26

Form bone by replacing cartilage, but differing in method

Question 27

What type of ossification is more common and what bones do not follow this method

Answer 27

Endochondral ossification is more common Clavicle, mandible and skull are formed by intramembranous

Question 28

Primary ossification center

Answer 28

Midportion of long bones Ossify outward until entire shaft are ossified at birth

Question 29

Secondary ossification centers

Answer 29

Develop during infancy and early childhood at the end of bones

Question 30

Growth plate

Answer 30

Cartilage between 1st and 2nd ossification centers

Question 31

Directions bones grow

Answer 31

Length: long bones grow in length at epiphyseal plate Girth: bones increase in size through addition and accumulation of new bone on the bone surface

Question 32

When is the most rapid period of growth in long bone girth

Answer 32

Prenatally

Question 33

What is necessary for bones to growth

Answer 33

WB + muscle forces

Question 34

2 ways that muscle fibers increase

Answer 34

Hyperplasia: Prenatally increase in # of muscle cells Hypertrophy: after birth increase in size of muscle cells

Question 35

How to stimulate growth of muscle fibers

Answer 35

Resistance training

Question 36

Directions of muscle growth

Answer 36

Diameter: related to intensity of activity during growth Length: addition of sarcomeres and lengthening of sarcomeres

Question 37

Clinical implications of the MSK system development

Answer 37

-immature MSK system is vulnerable to abnormal mechanical forces + pressures -Compliance of MSK system procides for successful response to tx intervention (plasticity)

Question 38

Wolff Law of bone transformation

Answer 38

Mechanical stresses modulate bone shape + internal architecture Proportional: High strength = high stress

Question 39

Skeletal molding mechanism

Answer 39

Strain

Question 40

Components of strain

Answer 40

Compression Tension Torsion

Question 41

Tension modeling effects

Answer 41

Tendon + ligament attachments are loaded in tension, resulting in trochanters, tubercles, prominences and ridges

Question 42

Compression modeling effects

Answer 42

WB results in increase in growth rate at the compression sites of epiphyseal plate and increase in cross sectional diameter

Question 43

Torsion modeling effects

Answer 43

Twisting thru the shaft or longitudinal axis of a bone (tibial torsion)

Question 44

Clinical significance of adaptations of muscles and bone

Answer 44

Mechanical forces affect the shape of the maturing skeleton which in turn affect the biomechanical function of the MSK system

Question 45

Norma developmental progression of the knees

Answer 45

Genu varum earlier on straight limbs due to WB Genu valgum; development of more mature gait pattern

Question 46

Clinical implications of tension

Answer 46

Spasticity provides asymmetric pull risk of subluxation/dislocation Ilizarov disease

Question 47

Clinical implications of compression

Answer 47

Ankle and genu varum/valgum Flattening of femoral head resulting in slipped capital femoral epiphysis + osteopenia

Question 48

Clinical implication of torsion

Answer 48

Femoral anteversion results in in toeing