Acquired Bone Disorders

Question 1

What is osteoporosis?

Answer 1

a reduction in trabecular bone mass resulting in porous bone with an increased risk of fracture and increased marrow space (that fills with fat mostly)

Question 2

What are the most common forms of osteoporosis?

Answer 2

senile and postmenopausal

Question 3

How does menopause decrease bone mass?

Answer 3

• decreased serum estrogen
• increased IL-1, IL-6, and TNF levels
• increased expression of RANK, RANKL and increased osteoclast activity

Question 4

How does aging decrease bone mass?

Answer 4

there is decreased replicative activity of osteoprogenitor cells, osteoblast activity, activity of matrix-bound growth factors, as well as reduced physical activity

Question 5

What causes type 1 (postmenopausal) osteoporosis?

Answer 5

decreased osteoblastic activity

Question 6

What causes type 2 (senile) osteoporosis?

Answer 6

increased osteoclastic activity

Question 7

What is a very common fracture with osteoporosis?

Answer 7

proximal femoral fractures (high mortality in older adults). Note, a fall to the side increases the risk of hip fracture by about 6 times compared to falls in other directions

Question 8

What is a common treatment for osteoporosis?

Answer 8

Bisphosphates (also good for Paget’s disease)

Question 9

How do bisphosphates work?

Answer 9

they bind to hydroxyoptite and inhibits osteoclast activity

Question 10

AEs of bisphosphates?

Answer 10

1) corrosive esophagitis- take with water and remain upright for at least 30 minutes
2) osteonecrosis of the jaw

Question 11

What is osteomyelitis?

Answer 11

infection (most often bacterial) of the bone, typically in children caused from direct inoculation (trauma), contiguous spread (cellulitis), or blood spread

Question 12

How does osteomyelitis present?

Answer 12

bone pain with systemic signs of infection

Question 13

How does chronic osteomyelitis appear on x-ray (this is the best imaging for chronic)?

Answer 13

lytic abscess (aka sequestrum) surrounded by sclerosis of bone (aka involurum)

Question 14

How does acute osteomyelitis appear on MRI (this is the best imaging for acute)?

Answer 14

inflammation

Question 15

T or F. Get blood cultures before treating osteomyelitis

Answer 15

will commonly see elevated CRP and ESR (but not specific)

Question 16

What is the most common cause of osteomyelitis?

Answer 16

Staph aureus (90%)

Question 17

What is the most common cause of osteomyelitis in sexually active young adults?

Answer 17

N. gonorrhoeae

Question 18

What is the most common cause of osteomyelitis in sickle cell patients?

Answer 18

Salmonella (encapsulated)

Question 19

What is the most common cause of osteomyelitis in diabetics or IVDUs?

Answer 19

Pseudomonas (or candida or staph aureus)

Question 20

What is the most common cause of osteomyelitis of the spine (Pott’s Disease)?

Answer 20

Mycobacterium TB (giant cells without necrosis)

Question 21

What is the most common cause of osteomyelitis with prosthetic limbs/joints?

Answer 21

Staph epidermidis

Question 22

What is the most common cause of osteomyelitis from dog and cat bites?

Answer 22

Pasteurella

Question 23

What are a few common pathologies that raise ESR over 100mm/hr?

Answer 23

• Osteomyelitis (staph aureus mostly)
• temporal arteritis
• polymyalgia rheumatica

Question 24

What is the common end pathway for any pathology that disrupts vascular supply to the femoral head?

Answer 24

avascular necrosis/osteonecrosis

Question 25

What are some common causes of avascular necrosis/osteonecrosis?

Answer 25

- fracture/trauma - decompression sickness (the bends) - exo/endogenous corticosteroids - SCD - alcohol abuse - pancreatitis - storage diseases PASS FDS`

Question 26

What are some common causes of avascular necrosis/osteonecrosis in 4-10 yo boys?

Answer 26

legg calve-perthes disease (idiopathic)

Question 27

What is Paget's disease? Presentation

Answer 27

typically localized imbalance (increased) of osteoclast and osteoblast function-thick bone (idiopathic, possibly viral). Can be widespread Patients might present with hearing loss (due to narrowing of the auditory foramen), bow legs, kyphosis or increased hat size

Question 28

What is a suspected genetic cause of Paget's disease?

Answer 28

chromosome 18 mutations

Question 29

Paget's disease is the most common cause of what?

Answer 29

isolated elevated alkaline phosphatase in patients over 40 yo

Question 30

Paget's disease carries an increased risk of what?

Answer 30

osteosarcoma, increased AV shunts (heart failure), long bone fracture

Question 31

T or F. Serum Ca2+ and PTH are normal in Paget's disease

Answer 31

T.

Question 32

What are the phases of Paget Disease?

Answer 32

1) lytic- osteoclasts predominate 2) mixed- neither predominate 3) sclerotic- osteoblasts predominate leads to thick bones that fracture easily

Question 33

Skulls can take on a ____ appearance in Paget's disease

Answer 33

cotton wool

Question 34

What is Osteomalacia (adults)/rickets (kids)?

Answer 34

inadequate mineralization of osteoid leads to weak bones and fractures due to vitamin D deficiency leading to soft, bowing bones

Question 35

How do osteomalacia/rickets present in labs?

Answer 35

- decreased vitD, serum Ca2+ and phosphate (PO4) | - increased PTH and alkaline phosphate (due to increased osteoblast activity which need an alkaline environment)

Question 36

What stain can be sued to ID osteomalacia/rickets?

Answer 36

von Kossa stain: calcified tissue is black and they are covered by a layer of unmineralized osteoid (dark pink)

Question 37

T or F. There is abundant osteoid in Osteomalacia/rickets but it is not mineralized

Answer 37

T. Causing the bone to be weak and increase risk of fracture

Question 38

What causes primary hyperparathyroidism?

Answer 38

hyperplasia or tumor (adenoma) of the parathyroid gland

Question 39

What causes secondary hyperparathyroidism?

Answer 39

prolonged states of hypocalcemia due to chronic renal failure with resulting hyper secretion of PTH

Question 40

What does increased PTH cause?

Answer 40

it is detected by osteoBLasts which stimulate osteoclasts leading to unabated bone resorption causing cyst-like brown tumors within the bone

Question 41

What do the cyst-like brown tumors consist of?

Answer 41

fibrous tissue and woven bone without matrix

Question 42

Why do the tumors of hyperparathyroidism take on a brown appearance?

Answer 42

there is cyst formation within the bone making it prone to hemorrhage which then turns brown from residual hemosiderin

Question 43

Labs with hyperparathryoidism?

Answer 43

hypercalcemia, increased PTH and x-ray changed consistent with osteopenia secondayr will show decreased GFR

Question 44

What is osteitis fibrosa cystica (von Recklinghausen disease of bone)?

Answer 44

rare progressive disease of hyperparathyroidism with triad of: - increase bone cell activity - peritrabecular fibrosis - cystic brown tumors not seen often

Question 45

What is renal osteodystrophy?

Answer 45

collectively describes skeletal changes associated with chronic renal disease when the kidney cannot convert vitamin D to active form

Question 46

What does renal osteodystrophy encompass?

Answer 46

- increased osteoclastic bone respiration mimicking osteitis fibrosis cystica - delayed matrix mineralization (osteomalacia) - osterosclerosis - growth retardation - osteoporosis

Question 47

Pathology of renal osteodystrophy?

Answer 47

decreased vitD leads to reduced Ca2+ absorption by the intestine leading to hypocalcemia and increased PTH secretion leading to increased bone resorption