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FA - Musculoskeletal > MS - Path (Bone disorders) > Flashcards

MS - Path (Bone disorders) Flashcards

Pg. 419-421 in First Aid 2014 Sections include: -Achondroplasia -Osteoporosis -Osteoporosis (marble bone disease) -Osteomalacia/rickets -Paget disease of bone (osteitis deformans) -Osteonecrosis (avascular necrosis) -Lab values in bone disorders

1
Q

What is achondroplasia? What physical traits are versus are not affected, and why/why not?

A

Failure of longitudinal bone growth (endochondral ossification) => short limbs. Membranous ossification is not affected => large head relative to limbs

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2
Q

What is the molecular defect in achondroplasia, and what impact does that have?

A

Constitutive action of fibroblast growth factor receptor (FGFR3) actually inhibits chondrocyte proliferation.

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3
Q

What percentage of mutations leading to achondroplasia occur spontaneously, and with what condition are such mutations associated? Otherwise, what mode of inheritance does Achondroplasia exhibit?

A

> 85% of mutations occur sporadically and are associated with advanced paternal age, but the condition also demonstrates autosomal dominant inheritance.

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4
Q

Of what condition is Achondroplasia a common cause?

A

Common cause of dwarfism

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5
Q

How does Achondroplasia affect life span and fertility?

A

Normal life span and fertility.

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6
Q

In general, what bone and lab findings define osteoporosis?

A

Trabecular (spongy) bone loss mass and interconnections despite normal bone mineralization and lab values (serum Ca2+ and [PO4]3-)

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7
Q

How is osteoporosis diagnosed?

A

Diagnosed by a bone mineral density test (DEXA) with a T-score of < or = -2.5

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8
Q

What habit can cause osteoporosis?

A

Can be caused by long-term exogenous steroid use

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9
Q

What musculoskeletal complication can result from osteoporosis? What are 3 signs/symptoms of this condition?

A

Can lead to Vertebral crush fractures - acute back pain, loss of height, kyphosis

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10
Q

What are the types of osteoporosis?

A

Type I (Postmenopausal) & Type II (Senile osteoporosis)

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11
Q

What is the mechanism behind Type I osteoporosis?

A

Postmenopausal: Increased bone resorption due to decreased estrogen levels

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12
Q

What patient populations does Type II osteoporosis affect?

A

Senile osteoporosis: Affects men and women > 70 years old

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13
Q

What 2 fractures are associated with Type I (Postmenopausal) osteoporosis?

A

(1) Femoral neck fracture, (2) Distal radius (Colles) fracture

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14
Q

What is the prophylaxis for Type II (Senile) osteoporosis?

A

Prophylaxis: Regular weight-bearing exercise and adequate calcium and vitamin D intake throughout adulthood

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15
Q

What are 5 treatments for Type II (Senile) osteoporosis?

A

Treatment: (1) Bisphosphonates (2) PTH (3) SERMs (4) Rarely calcitonin; (5) Denosumab (monoclonal antibody against RANKL)

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16
Q

What is Denosumab? For what specific condition is it used as treatment?

A

Denosumab (monoclonal antibody against RANKL); Type II (senile) Osteoporosis

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17
Q

What is another name for Osteopetrosis?

A

Osteopetrosis (Marble bone disease)

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18
Q

What is the defect in Osteopetrosis, and what effect(s) does it have on the bone?

A

Failure of normal bone resorption due to defective osteoclasts => thickened, dense bones that are prone to fracture

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19
Q

What hematologic effect does osteopetrosis have, and why?

A

Bone fills marrow space => pancytopenia, extramedullary hematopoiesis.

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20
Q

What phenotypic effect do mutations related to osteopetrosis have? Give an example of such a mutation.

A

Mutations (e.g., carbonic anhydrase II) impair ability of osteoclast to generate acidic environment necessary for bone resorption

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21
Q

How does osteopetrosis appear on x-ray?

A

X-rays show show bone-in-bone appearance

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22
Q

What complications can result from osteopetrosis, and why?

A

Can result in cranial nerve impingement and palsies as a result of narrowed foramina

23
Q

What is a potential cure for Osteopetrosis, and why?

A

Bone marrow transplant is potentially curative as osteoclasts are derived from monocytes

24
Q

What deficiency causes Osteomalacia/Rickets? In which patient population is each of these conditions seen?

A

Vitamin D deficiency; Osteomalacia in adults, Rickets in children

25
Q

Explain the pathophysiology of Osteomalacia/rickets as it relates to the gross appearance of bone in these patients.

A

Due to defective mineralization/calcification of osteoid => soft bones that bow out.

26
Q

Explain the pathophysiology of Osteomalacia/rickets as it relates to the lab findings in these patients.

A

Low vitamin D => low serum calcium => high PTH secretion => low serum phosphate. Hyperactivity of osteoblasts => high ALP (osteoblasts require alkaline environment)

27
Q

What is another name for Paget disease of the bone?

A

Paget disease of bone (osteitis deformans)

28
Q

Is Paget disease of bone common? What kind of disorder is it, and what causes it?

A

Common, localized disorder of bone remodeling caused by increase in both osteoblastic and osteoclastic activity

29
Q

What are the lab findings associated with Paget disease of bone?

A

Serum Ca2+, phosphorus, and PTH levels are normal. High ALP.

30
Q

What histology characterizes Paget disease of bone?

A

Mosaic pattern of woven and lamellar bone

31
Q

What kind of fractures characterize Paget disease of bone?

A

Long bone chalk-stick fractures

32
Q

What cardiologic complication may result from Paget disease of bone, and why?

A

Increased blood from increased arteriovenous shunts may cause high-output heart failure

33
Q

What risk is increased with Paget disease of bone?

A

Increased risk of osteogenic sarcoma

34
Q

What 2 physical exam findings characterize Paget disease?

A

(1) Hat size can be increased (note marked thickening of calvarium) (2) Hearing loss is common due to auditory foramen narrowing

35
Q

What are the stages of Paget disease, and what cell(s) act(s) during each?

A

Stages of Paget disease: (1) Lytic - osteoclasts (2) Mixed - osteoclasts + osteoblasts (3) Sclerotic - osteoblasts (4) Quiescent - minimal osteoclast/osteoblast activity

36
Q

What imaging finding may indicate Paget disease of bone?

A

marked thickening of calvarium

37
Q

Why is hearing loss common in Paget disease?

A

Hearing loss is common due to auditory foramen narrowing

38
Q

What is another name for Osteonecrosis?

A

Osteonecrosis (avascular necrosis)

39
Q

What is Osteonecrosis? In general, how does it present?

A

Infarction of bone and marrow, usually very painful

40
Q

What are 4 causes of Osteonecrosis (avascular necrosis)?

A

Caused by trauma, high-dose corticosteroids, alcoholism, sickle cell.

41
Q

What is the most common site of Osteonecrosis (avascular necrosis), and why?

A

Most common site is femoral head (due to insufficiency of medial circumflex femoral artery).

42
Q

What change does Osteoporosis cause in the following lab values: (1) Serum Ca2+ (2) [PO4]3- (3) ALP (4) PTH?

A

(1) No change (2) No change (3) No change (4) No change

43
Q

What change does Osteopetrosis cause in the following lab values: (1) Serum Ca2+ (2) [PO4]3- (3) ALP (4) PTH?

A

(1) No change/Decrease (2) No change (3) No change (4) No change

44
Q

What change does Paget disease cause in the following lab values: (1) Serum Ca2+ (2) [PO4]3- (3) ALP (4) PTH?

A

(1) No change (2) No change (3) Increase (4) No change

45
Q

What change does Osteomalacia/Rickets cause in the following lab values: (1) Serum Ca2+ (2) [PO4]3- (3) ALP (4) PTH?

A

(1) Decrease (2) Decrease (3) Increase (4) Increase

46
Q

What bone description characterizes each of the following: (1) Osteoporosis (2) Osteopetrosi s (3) Paget disease (4) Osteomalacia/Rickets?

A

(1) Low bone mass (2) Dense, brittle bones (3) Abnormal “mosaic” bone architecture (4) Soft bones

47
Q

In what ways can Osteopetrosis affect Ca2+ levels, and in what context(s)?

A

Normal or low serum Ca2+; Ca2+ decreased in severe, malignant disease

48
Q

What change does Hypervitaminosis D cause in the following lab values: (1) Serum Ca2+ (2) [PO4]3- (3) ALP (4) PTH?

A

(1) Increase (2) Increase (3) No change (4) Decrease

49
Q

What are 2 causes of Hypervitaminosis D?

A

Caused by over-supplementation or granulomatous disease (e.g., sarcoidosis)

50
Q

What are the 2 types of osteitis fibrosa cystica? What change does each cause in the following lab values: (1) Serum Ca2+ (2) [PO4]3- (3) ALP (4) PTH?

A

PRIMARY HYPERPARATHYROIDISM: (1) High (2) Low (3) High (4) High; SECONDARY HYPERPARATHYROIDISM: (1) Low (2) High (3) High (4) High

51
Q

What physical finding characterizes osteitis fibrosa cystica, and what causes this?

A

“Brown tumors” due to fibrous replacement of bone, subperiosteal thinning

52
Q

What are 4 potential causes of primary hyperparathyroidism?

A

Idiopathic or parathyroid hyperplasia, adenoma, carcinoma

53
Q

In what context does secondary hyperparathyroidism often occur, and why?

A

Often as compensation for ESRD (low [PO4]3- excretion and production of activated vitamin D)

FA - Musculoskeletal (19 decks)

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