Disorders of bone health

Question 1

osteoclasts

Answer 1

bone breakdown/ resorption cells

Question 2

osteoblasts

Answer 2

bone forming cells

Question 3

osteocytes

Answer 3

mature bone cells within bone matrix
help to maintain bone and act as mechanosensors

Question 4

what happens to bone with increasing age

Answer 4

increased osteoclast activity whihc is not matched by increased osteoblast activity
imbalance of bone breakdown and formation leading to osteoporosis

Question 5

osteoporosis

Answer 5

progressive systemic skeletal disease characterised by low bone mass and micro architectural deterioration of bone tissue with consequent increase in bone fragility and susceptibilty to fracture

Question 6

what happens to bone as you age

Answer 6

decreases in trabecular thickness
decrease in number of connections between vertical trabeculae
decrease in trabecular strength

Question 7

percentages of clinical outcomes

Answer 7

50% hip fracture patients cannot live independantly
20% of hip fracture patients die within a year of their fracture

Question 8

most widely used method of measurig bmd

Answer 8

DXA scans- predicts fracture risk independantly of other risk factors

Question 9

t score BMD reference ranges

Answer 9

Normal: -1.0 and above
Osteopenia (low bone mass): Between -1.0 and -2.5
Osteoporosis: -2.5 or lower
Severe Osteoporosis: -2.5 or lower with a history of fragility fractures

Question 10

lifestyle advice for management of osteoporosis

Answer 10

high intensity strength training
low impact weight bearing excersize
avoidance of excess alcohol
avoidance of smoking
fall prevention

Question 11

drug treatments for osteoporosis

Answer 11

calcium and vit d supplementation
bisphosphonates
denosumab
teriparatide
testosterone
HRT

Question 12

MOA of bisphosphonates

Answer 12

inhibit bone resorption by osteoclasts

Question 13

structure of bisphosphonates

Answer 13

analogs of phosphate, a natural compound involved in bone metabolism

Question 14

what do bisphosphonates have a strong affinity for

Answer 14

hydroxyapatite in bone, allowing them to localize to areas of active bone resorption.

Question 15

what happens when osteoclasts attempt to absorb bone containing bisphosphonates

Answer 15

the drugs are internalized by the osteoclasts.
* Inside osteoclasts, bisphosphonates interfere with essential cellular processes, impairing their ability to resorb bone

Question 16

examples of bisphosphonates

Answer 16

alendronate and risedronate

Question 17

denosumab

Answer 17

monoclonal antibody used primarily in the treatment of conditions involving bone loss

Question 18

normal bone remodelling

Answer 18

in a programmed sequence at discrete foci called bone remodelling units

at the beginnning osteo clasts appear on a previously inactive surface and begin to resorb the bone

osteoclasts are replaced by osteoblasts that fill the cavity by putting down osteoid that is mineralised to form new bone

after normal bone remodelling the resorption is completely refilled wiht new bone unlike in osteoporosis

Question 19

teriparatide

Answer 19

stimulates bone growth rather than reducing bone loss

anabolic agent

consider if severe osteoporosis

Question 20

sclerostin

Answer 20

protein produced. by osteocytes that inhibits bone formation to prevent over stimulation in skeletal

Question 21

romosozumab

Answer 21

humanised monocloncal antibody that inhibits sclerostin

improves BMD at hip and spine

Question 22

when to treat osteoporosis

Answer 22

consider treatment with anti resorptive therapy when T score </=2.5

Question 23

direct effects of corticosteroids on bone

Answer 23

reduction of osteoblast activity and lifespan
suppression of replication of osteoblast precursors
reduction in calcium absorption

Question 24

indirect effects of corticosteroids on bone

Answer 24

inhibition of gonadal and adrenal steroid production

Question 25

osteogenesis imperfecta

Answer 25

mostly autosomal dominant
secondary mutations of type 1 collagen genes

genetic disorder characterized by fragile bones that break easily, often with little or no apparent cause

Question 26

types of osteogenesis imperfecta

Answer 26

type 1- mild
type 2- neonatal
type 3 and 4- vert severe

Question 27

what do the more severe forms of osteogenesis imperfecta present in

Answer 27

fractures in childhood

Question 28

management of osteogenesis imperfecta

Answer 28

no cure only fracture fixation and bisphosphonates

Question 29

what is osteogenesis imperfecta caused by

Answer 29

mutations affecting the production or quality of collagen, an essential protein for bone strength and structure