BONES Flashcards
(45 cards)
what is epiphysis?
it is the part of the long bone that extends from subarticular bone plate to the base of growth plate
what is metaphysis and why is it important?
course cancellous bone
important in hematogenous infections, tumors, and skeletal malformation (arthritis)
*highly susepatable for infections
why does arthritis cause deformed joints?
because it occurs in the metaphysis ie the part of the bone that causes change
what is diaphysis?
body/shaft of the bone
zone between 2 metaphysis
what is the definition of woven bone?
haphazard organization of collagen fibers
seen in fetal developing skeleton and at growth plates
always abnormal in adults unless it is seen in fractures within the first few weeks of injury (before it becomes lamellar)
what is the definition of lamellar bone?
regular-parallels-alignment of collagen into sheets
what is a DEXA scan?
uses low xray waves to look at bone density
can also determine body fat
Normal DEXA scan values?
BMD no lower than 1 SD below the mean for young adult women
T>-1
What are the DEXA scan osteopenia (low bone mass) values?
BMD 1.0-2.5 SD below the mean for young adult women
T=-1 to -2.5
what is osteoporosis DEXA scan values?
BMD more than 2.5 SD below the young adult mean
T<-2.5
what are T scores based on?
standardized values of otherwise healthy 30 year old females
what is the Z score based on?
age and gender
does not always have a bell shaped curve for every age and gender so T scores are most generally used instead
where is the most sensitive place to scan for the DEXA?
the spine because of the abundance of cancellous bone, so osteoporotic changes are most conspicuous (seen the best)
can lead to kyphosis (dogwager’s hump)-because vertebral bodies get shorter
How sensitive is a DEXA scan?
it will miss 30% of individuals with osteoporosis
ie the DEXA with come back normal
who should get a DEXA?
woman 65 or older man age 70 or older if you break a bone after age 50 women of menopausal age with risk factors PM woman under 65 with risk factors man age 50-59 with risk factors
what are other reasons to get a DEXA?
an x ray showing bone loss
back pain with possible break in spine
height loss of 1/2 in or more within 1 year
total height loss of 1 1/2 inches from your original height
NOF recommendations for Ca
adults under 50
adults over 50
1000 mg
1200 mg
with Vit D
NOF recommendations for Vit D
adults under 50
adults over 50
400-600 IU
800-1000 IU
* daily dose of sunlight at peak time from a minimum of 20 minutes
what are normal vit D levels?
75 nmol/L or higher
30 ng/ml or higher but less than 50 ng/ml
what is deficient Vit D?
inadequate?
< 30 nmol/L (<12 ng/mL)
30-50 nmol/L (12-30 ng/mL)
what is adequate Vit D?
Bad?
> or = 50 nmol/L (> or = 30 ng/ml)
125 nmol/L (>50 ng/ml)
what is the bisphosphonates MOA and what are the four drugs?
inhibit osteoclasts
- alendronate- take weekly
- risedronate-take weekle
- ibanddronate-take monthy
- zoledronic acid-take every year
MOA of forteo?
rPTH
intermittent exposure stimulates osteoblasts
MOA for denosumab?
antibody to RANKL
