Low Yield Flashcards
What are the generic blood supplies to long bones?
1) Nutrient artery (2/3 inner blood supply)
2) metaphyseal-epiphyseal system
3) periosteal system (outer 1/3 blood supply)
What is the difference in direction of blood flow in mature and immature long bones?
Peds: outside-in (periosteal predominates)
Adult: inside-out (nutrient system predominates)
Disruption of which vascular system interrupts the major source of nutrients to the growth plate?
perichondral artery
Congenital unilateral transverse absence of the forearm results from vascular insult to which of the following?
Apical Epidermal Ridge (AER)
Responsible for formation of limb bud
What areas of the embryo are responsible for the various planes of growth?
1) Apical Epidermal Ridge (AER)- proximal to distal
2) Zone of Polarizing Activity (ZPA)- ant to post; Shh and HOX
3) Ventral Ectoderm- Ventral to dorsal; WNT-7
What does each somite layer form of the spine in the embryo?
1) Scleroderme- vertebral bodies and annulus
2) Myotome- myoblasts
3) Dermatome- skin
Regulated by homebox gene
What age does a person reach peak bone mass?
16-25yo
What are the daily requirements for calcium?
2000 mg/day for lactating women
1500 mg/day for pregnant women, postmenopausal woman, and patients with a healing bone fracture
1300 mg/day for adolescents and young adults
750 mg/day for adults
600 mg/day for children
What is the role of PTH in bone metabolism?
1) bone: causes osteoblasts to secrete IL-6 and IL-1 which leads to bone resorption, causes osteoblasts to secrete RANKL which activate osteoclasts and lead to bone resorption
2) kidney: stimulates 25-hydroxy Vit D to 1,25-hydroxy Vit D (active form) which leads to increased Ca++ absorption and PO4- secretion
What is the role of calcitonin in bone metabolism?
Leads to decrease in calcium; osteoclasts have a receptor for calcitonin, calcitonin inactivates osteoclasts
Inc. serum Ca > secretion of calcitonin > inhibition of osteoclasts > dec. Ca (transiently)
What is the role of vitamin D in bone metabolism?
1) Leads to increased Ca resorption in the intestine and kidney
2) Promotes osteoid mineralization
Deficiency leads to osteomalcia and rickets; phenytoin can disrupt Vit D metabolism
Gigantism which is caused by oversecretion of growth hormone affects what area of the growth plate?
Proliferative zone
What are the effects of estrogen supplementation?
1) Increased bone mineral density via decreased breakdown
2) Increased risk of: heart dz, breast cancer
3) Decreased risk of: hip fx, endometrial cancer (if given w/ progestin)
Peak bone mass attainment in both men and women is most dependent on which sex-steroid?
Estrogen
What are BMP-2 and BMP-7 used for?
BMP-2: open tibia shaft fractures with IM nail, single level ALIF fusions
BMP-7: nonunions
Altered BMP-4 signal transduction is known to be associated with which of the following diseases?
Fibrodysplasia ossificans progressiva
What do motor evoked potentials and sensory evoked potentials monitor?
SEP: monitor integrity of dorsal column sensory pathways of the spinal cord
MEP: monitor integrity of lateral and ventral corticospinal tract of the spinal cord
What are some factors that increase radiation exposure during fluoro cases?
1) imaging large body parts
2) closer proximity to X-ray source
3) use of large c-arm vs mini c-arm
What is the seroconversion of HIV and HBV from a needle stick?
HIV- 0.3%
HBV- 35-60%
A decrease in alkaline phosphatase would most likely be manifest in which metabolic disorder?
Hypophosphatasia;
caused by a mutation in the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP)
What metabolic abnormalities are found in hypoparathyroidism?
decreased plasma calcium levels
increased plasma phosphate levels
decreased 1,25(OH)2 Vitamin D levels
Caused by decrease secretion of PTH from chief cells
Patient with chronic renal disease would have increased production of what hormone in relation to bone metabolism?
Increased PTH
What diseases are related to Charcot changes of the shoulder?
Syringomyelia- Most common cause Hansen's (leprosy) Syphilis DM Alcoholism
What radiologic exam can be performed to distinguish Charcot joint from an infected joint?
Indium WBC scan
Charcot (cold), Osteomyelitis (hot)
