2. Bone structure and Function Flashcards
What drugs are available for osteoperosis?
Bisphosphonates- increase osteoclast death (alendronic acid)
Selective oestrogen receptor modulator- increases oestrogen functions (tamoxifen)
Parathyroid hormone- stimulates bone formation
What are osteocasts sensitive to?
Strain magnitude
Strain rate
Number of cycles
Load distribution
How do the osteocytes interact with other cells?
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Osteocyte network- key. network connectivity decreases with age.
What happens when bone is strained?
Higher strain= more bone formation
What is the refractory period in bone growth?
Bones need a recovery or refractory period to stimulate growth
How is trabecular force modeeled?
Grows in reponse to stress. Will model itself on the forces that it experiences and will adapt over time
When bone is lost where is it lost from first?
The least used trabeculae (spongy bone)
How can you image/ test bone
X-ray
DEXA scanning
CT
How do you estimate bone strength?
Combination between compact and trabecular bone
distance to inner vs distance to outer
How do bones grow axially?
Periosteal apposition- growth on outside of cortex
Endocortical resorption- erosion on the inside of the cortex
Describe the changes in bone in postmenopausal women?
After 6 years the diameters or the periosteum and the medulla are significantly increased.
However the cross sectional modes of inertia also increases to compensate
Strenght index (bending index) is only significantly smaller after 14 years.
How does hip geometry affect fracture risk?
Longer the ilium width (hip axis) greater the fracture risk
Wider the femeral neck length
Wider the femoral head diameter
What is meant by strong steady and straight for bone health?
Steady- do balance exercises to maintain muscle and strength exercises
Strong- train muscle stregnth as well as high impact bone exercises
Straight- practice correct posture for lifting as well as exercises that promote good posture
