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Bone disorders p419-p420

Terms in this set (42)

achondroplasia
failure of:
not affected:
longitudinal bone growth (endochondral ossification)
membranous ossification
short limbs; large head relative to limbs
achondroplasia
constitutive activation of _____ inhibits _____
fibroblast growth factor receptor (FGFR3)
inhibits chondrocyte proliferation
achondroplasia
>85% of mutations occur sporadically and are associated with _____
the condition also demonstrates _____ inheritance
advanced paternal age
autosomal dominant
achondroplasia
life span and fertility
normal
osteoporosis
_____ bone loses mass and interconnections despite normal bone mineralization and lab values (serum Ca and PO4)
trabecular (spongy) bone
osteoporosis diagnosis
bone mineral density test (DEXA) with a T-score of <-2.5
osteoporosis can be caused by
long-term exogenous steroid use
osteoporosis can lead to _____ fractures
vertebral crush fractures
acute back pain, loss of height, kyphosis
osteoporosis type I
postmenopausal
increased bone resorption due to decreased estrogen levels
osteoporosis type I - types of fractures
femoral neck fracture, distal radius (Colles) fracture
osteoporosis type II
senile osteoporosis; affects men and women >70 years old
osteoporosis prophylaxis
regular weight bearing exercise and adequate Ca and vitamin D intake throughout adulthood
osteoporosis treatment
biphosphonates, PTH, selective estrogen receptor modulator, rarely calcitonin; denosumab (monoclonal antibody against RANKL)
failure of normal bone resorption due to defective osteoclasts
osteopetrosis
thickened, dense bones that are prone to fracture
osteopetrosis
osteopetrosis
bone fills marrow space:
pancytopenia, extramedullary hematopoiesis
osteopetrosis mutation
carbonic anhydrase II
impair ability of osteoclasts to generate acidic environment necessary for bone resorption
x-ray shows bone in bone appearance
osteopetrosis
can result in cranial nerve impingement and palsies as a result of narrowed foramina
osteopetrosis
osteopetrosis - potential cure
bone marrow transplant - osteoclasts are derived from monocytes
vitamin D deficiency in adults and children
adults: osteomalacia
children: rickets
osteomalacia/rickets due to
defective mineralization/calcification of osteoid
osteomalacia has an increased alkaline phosphatase (ALP) due to
hyperactivity of osteoblasts (osteoblasts require alkaline environment)
common, localized disorder of bone remodeling caused by increase in both osteoblastic and osteoclastic activity
paget disease of bone
mosaic pattern of woven and lamellar bone
paget disease of bone
long bone chalk-stick fractures
paget disease of bone
increased blood flow for increased arteriovenous shunts may cause high output heart failure
paget disease of bone
increased risk of osteogenic sarcoma (osteosarcoma)
paget disease of bone
hat size can be increased
paget disease of bone
hearing loss is common due to auditory foramen narrowing
paget disease of bone
stages of paget disease
lytic: osteoclasts
mixed: osteoclasts + osteoblasts
sclerotic: osteoblasts
quiescent: minimal osteoclast/osteoblast activity
paget disease of bone treatment
bisphosphonates
infarction of bone and marrow, usually very painful
osteonecrosis (avascular necrosis)
osteonecrosis (avascular necrosis) caused by
trauma, high-dose corticosteriods, alcoholism, sickle cell
osteonecrosis (avascular necrosis) most common site
femoral head (due to insufficiency of medial circumflex femoral artery)
bone enlargement, bone pain, arthritis
paget disease of bone
a bony manifestation of an endocrine disorder
osteitis fibrosa cystica
hyperparathyroidism
osteitis fibrosa cystica
high PTH - excess osteoclastic activity
Type IA pseudohypoparathyroidism (albright hereditary osteodystrophy)
osteitis fibrosa cystica
PTH resistance at the renal tubules - low serum calcium and high phosphate
low calcium - high PTH
"brown tumors"
osteitis fibrosa cystica
cystic spaces lined by osteoclasts filled with fibrous stroma and blood
bone is replaced by fibroblasts, collagen, and irregular bone trabeculae
polyostotic fibrous dysplasia
part of McCune Alright syndrome
polyostotic fibrous dysplasia
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