Osteoporosis Flashcards
Trabecular bone
Space for marrow storage, strength and lightness
At the ends of long bones and the inner part of short/flat/irregular bones
Cortical bone
Most of mature skeleton, compact bone laid down concentrically around Haversian canals
osteogenic cells
unspecialised cells from mesenchyme that undergo cell division to form osteoblasts
osteoblasts
bone-forming cells derived from stroll cells that synthesise and secrete much of bone matrix - also have high ALP
osteoclasts
from monocytes, carry out bone resorption sue to acidic pH and proteolytic enzymes
osteocytes
mature bone cells formed from osteoblasts which maintain cellular activities within bone
diagnosing osteoporosis
- Dual energy X-ray absorptiometry (DEXA) which assesses bone mineral density
- Osteoporosis is BMD T score of -2.5 or less at either lumbar spine or femoral neck
What is a z score?
- Z-score: (patients BMD - age-matched mean) / age-matched SD
- Assesses bone loss compared to expected bone loss for age-matched peers
What is a T score?
- T score: (patient’s BMD - young adult mean) / young adult SD
- T score is most important
osteopenia T score boundaries
-1 to -2.5
MOA biphosphonates
inhibit bone resorption and decrease osteoclast activity
E.g. biphosphonates
alendrotnic acid, risedronate sodium
raloxifene MOA
Selective estrogen receptor modulator = decreased bone resorption and increase bone mineral density
HRT = increase osteoblast activity
denosumab MOA
monoclonal antibody
inhibits osteoclast formation and decreases bone resorption
periosteum
outer fibrous layer where tendons attach, inner cellular layer of stem cells