Osteoporosis and Bone Health

Question 1

Is bone a greater proportion of cortical or trabecular bone?

Answer 1

Cortical (80%)

Trabecular (20%)

Question 2

Approximately what percentage of bone is remodelled each year?

Answer 2

10%

Question 3

Where does bone remodelling occur?

Answer 3

Bone remodelling units
At the beginning the cycle, osteoclasts appear on a previously inactive surface and begin to resorb the bone
Osteoclasts are then replaced by osteoblasts that fill the cavity by putting down osteoid that is mineralised to form new bone
After a normal bone remodelling cycle the resorption cavity is completely refilled with new bone
However, in osteoporosis, there is a relative or absolute increase in resorption over formation that leads to increased bone loss

Question 4

At which age is bone mass at its peak?

Answer 4

Bone mass peaks at age 30

Bone loss starts around age 40

Question 5

Deficiency of what is the major determinant of bone loss in women after menopause?

Answer 5

In women, oestrogen deficiency is the major determinant of bone loss after the menopause

Question 6

Armatase inhibitors and bone mass

Answer 6

Armatase inhibitors stop production of oestrogen in post menopausal women, they are used in breast cancer. They can lead to bone loss.
So can glucocorticoids

Question 7

Risk factors for fracture

Answer 7

Previous fragility fractures
Current use or frequent past use of oral glucocorticoids
History of falls
Family history of hip fracture
Other secondary causes of osteoporosis
Low BM (10 cigarettes per day)
Alcohol intake >4 units per day

Question 8

Family history of which type of fracture is a risk factor for fractures?

Answer 8

Hip fracture

Question 9

Previous fractures as prediction of future fracture (colles, hip and spine)

Answer 9

Colles fractures DOUBLES risk of hip fracture
Fracturing one side of hip increases risk of fracturing other side
Any previous fractures increase risk of spine fracture independent of bone density

Question 10

Corticosteroids and bone

Answer 10

Direct: Reduction of osteoblast activity and lifespan
Suppression of replication of osteoblast precursors
Reduction in calcium absorption

Indirect: Inhibition of gonadal and adrenal steroid production