Term
| What are malformations? What causes them? |
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Definition
- Intrinsic abnormalities
- Occur early in development
- Difficult to change
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Term
| What causes deformations? |
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Definition
- Caused by extrinsic factors
- Occur later in development than malformations
- More likely to have spontaneous recovery |
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Term
| What are the 3 causes of deformities? |
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Definition
1. Fetal constraint
2. Aberrant fetal position
3. Abnormal fetal movement |
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Term
| Conditions that cause fetal constraint |
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Definition
- Increased uterine tone
- Large fetus
- Multiple fetuses
- Oligohydramnios (decreased amniotic fluid)
- Prominent lumbar spine |
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Term
| Conditions that cause aberrant fetal position |
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Definition
- Breach (kicking limited)
- One body part impinging on another |
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Term
| Conditions that cause abnormal fetal movement |
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Definition
- Myelomeningocele (spina bifida)
- Cerebral palsy |
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Term
| Forces in developmental biomechanics |
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Definition
- Gravity
- Limited in utero
- Very much present after birth
- Profound effect on posture and movement of newborns
- Muscle contractions
- Begin influence in utero
- Skeletal development dependent upon muscle forces
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Term
| What happens to the lever arm for GM in coxa vara? How does this affect for production? |
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Definition
- Lever arm for GM longer
- GM force required to hold pelvis level is smaller |
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Term
| What happens to the lever arm for GM in coxa valgus? How does this affect force production? |
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Definition
- Lever arm for GM shorter
- GM force required to hold pelvis level is larger
- Often seen in cerebral palsy
- Ground reaction force pushes head of femur superiorly, may lead to subluxation/dislocation |
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Term
| What are stress and strain in the stress-strain relationship? |
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Definition
- Stress:
- Intermolecular resistance to deforming actions
- Measured as load/cross-sectional area
- Strain:
- Amount of deformation resulting from external area
- Measured as deformation/original length (percent of original length)
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Term
| What is endochondral bone growth responsible for? |
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Definition
- Length of bone
- Size and shape of articular cartilage
- Alignment of joints
- Alignment of muscle, tendon and ligament attachments
- Stimulation of muscle to grow |
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Term
| What is appositional bone growth? |
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Definition
- Growth transverse to long axis
- Begins in fetus and continues throughout adult life
- Continuous deposition of bone
- Responsible for new bone formation and resorption of bone
- Allows bone to remodel |
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