Low Yield

Question 1

What are the generic blood supplies to long bones?

Answer 1

1) Nutrient artery (2/3 inner blood supply)
2) metaphyseal-epiphyseal system
3) periosteal system (outer 1/3 blood supply)

Question 2

What is the difference in direction of blood flow in mature and immature long bones?

Answer 2

Peds: outside-in (periosteal predominates)
Adult: inside-out (nutrient system predominates)

Question 3

Disruption of which vascular system interrupts the major source of nutrients to the growth plate?

Answer 3

perichondral artery

Question 4

Congenital unilateral transverse absence of the forearm results from vascular insult to which of the following?

Answer 4

Apical Epidermal Ridge (AER)

Responsible for formation of limb bud

Question 5

What areas of the embryo are responsible for the various planes of growth?

Answer 5

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

Question 6

What does each somite layer form of the spine in the embryo?

Answer 6

1) Scleroderme- vertebral bodies and annulus
2) Myotome- myoblasts
3) Dermatome- skin
Regulated by homebox gene

Question 7

What age does a person reach peak bone mass?

Answer 7

16-25yo

Question 8

What are the daily requirements for calcium?

Answer 8

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

Question 9

What is the role of PTH in bone metabolism?

Answer 9

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

Question 10

What is the role of calcitonin in bone metabolism?

Answer 10

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)

Question 11

What is the role of vitamin D in bone metabolism?

Answer 11

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

Question 12

Gigantism which is caused by oversecretion of growth hormone affects what area of the growth plate?

Answer 12

Proliferative zone

Question 13

What are the effects of estrogen supplementation?

Answer 13

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)

Question 14

Peak bone mass attainment in both men and women is most dependent on which sex-steroid?

Answer 14

Estrogen

Question 15

What are BMP-2 and BMP-7 used for?

Answer 15

BMP-2: open tibia shaft fractures with IM nail, single level ALIF fusions
BMP-7: nonunions

Question 16

Altered BMP-4 signal transduction is known to be associated with which of the following diseases?

Answer 16

Fibrodysplasia ossificans progressiva

Question 17

What do motor evoked potentials and sensory evoked potentials monitor?

Answer 17

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

Question 18

What are some factors that increase radiation exposure during fluoro cases?

Answer 18

1) imaging large body parts
2) closer proximity to X-ray source
3) use of large c-arm vs mini c-arm

Question 19

What is the seroconversion of HIV and HBV from a needle stick?

Answer 19

HIV- 0.3%

HBV- 35-60%

Question 20

A decrease in alkaline phosphatase would most likely be manifest in which metabolic disorder?

Answer 20

Hypophosphatasia;

caused by a mutation in the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP)

Question 21

What metabolic abnormalities are found in hypoparathyroidism?

Answer 21

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

Question 22

Patient with chronic renal disease would have increased production of what hormone in relation to bone metabolism?

Answer 22

Increased PTH

Question 23

What diseases are related to Charcot changes of the shoulder?

Answer 23

Syringomyelia- Most common cause
Hansen's (leprosy)
Syphilis
DM
Alcoholism

Question 24

What radiologic exam can be performed to distinguish Charcot joint from an infected joint?

Answer 24

Indium WBC scan

Charcot (cold), Osteomyelitis (hot)

Question 25

What treatment is indicated in a Charcot shoulder?

Answer 25

Arthrodesis, arthroplasty is contraindicated;
do not attempt during acute inflammatory stage (Eichenholtz 0-2) because of continued bone erosion
only perform during quiescent stage (Eichenholtz 3)

Question 26

What are 5 arthritic signs of Psoriatic arthritis?

Answer 26

1) asymmetric oligo/monoarticular arthritis affecting DIPJ, PIPJ, MCPJ
2) DIP-predominant arthritis
3) arthritis mutilans
4) symmetric, RF-negative polyarthritis
5) psoriatic spondyloarthropathy
Will also see nail pitting, pencil-in-cup and sausage digits

Question 27

What is a common cause of hypocalcemia characterized by bone mineralization deficiency due to electrolyte and endocrine abnormalities

Answer 27

Renal osteodystrophy

Question 28

What is the cause of hypocalcemia in renal osteodystrophy?

Answer 28

Due to the inability of the damaged kidney to convert vitamin D3 to calcitrol (the active form)
because of phosphate retention (hyperphosphatemia)

Question 29

What lab values are a/w renal osteodystrophy?

Answer 29

decreased calcium, increased serum phosphate, increased alkaline phosphate, increased parathyroid hormone