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Review / Wrong Answers > DIT review - MSK 1 > Flashcards

DIT review - MSK 1 Flashcards

1
Q

Differentiate between the two types of bone formation: endochondral and membranous ossification

A
  • Endochondral ossification
    • Chondrocytes lay down cartilage matrix first
    • Osteoclasts and osteoblasts replace cartilage with woven bone, then remodel to lamellar bone
    • Occurs in axial skeleton, appendicular skeleton, and base of skull
  • Membranous ossification
    • Woven bone formed directly without cartilage, then later remodeled to lamellar bone
    • Occurs in skull and facial bones
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2
Q

What is the mutated gene in achondroplasia, and what is its normal function

A
  • Achondroplasia is a defect in endochondral ossification
    • Defect of FGFR3 (gain-of-function)
      • Normally responsible for inhibition of cartilage proliferation
      • Constitutive activation of FGFR3 = inhibited chondrocyte proliferation
    • Autosomal dominant with full penetrance
      • Homozygosity is lethal
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3
Q

What are the 2 main benign and 2 main malignant primary bone tumors?

A

Benign: Osteochondroma, Giant cell tumor

Malignant: Osteosarcoma, Ewing sarcoma

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4
Q

What part of the bone (diaphysis, metaphysis, or epiphysis), do the following tumors occur:

  • Osteochondroma
  • Giant cell tumr
  • Osteosarcoma
  • Ewing sarcoma
A
  • Diaphysis:
    • Osteoid osteoma
    • Ewing sarcoma
  • Metaphysis:
    • Osteosarcoma
    • Osteochondroma
  • Epiphysis:
    • Giant cell tumor
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5
Q

What bone tumor is a lateral projection with overyling cartilage cap?

A

Osteochondroma

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6
Q

What is Codman triangle, and what tumor is it associated with

A

Elevation of the periosteum due to tumor

Seen in osteosarcoma

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7
Q

What bone tumor is associated with “onion-skin” appearance

A
  • Ewing sarcoma
  • X-ray reveals “onion-skin” appearance – tumor grows within medullary center of bone, pushing outwards and causing periosteum (outer layer) to lay down new layers of bone
  • THINK: eWING = Chicken WINGS and onion rings
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8
Q

What tumor is associated with “soap bubble” appearance

A

Giant cell tumor (“osteoclastoma”)

Soap bubbles are in the epiphysis and Giant cell tumor is the only one in the epiphysis

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9
Q

What tumor is associated with sunburst appearance on x-ray

A

Osteosarcoma

  • THINK: osteoSarComa (S = sunburst and C = Codman)
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10
Q

Which bones are usually affected in giant cell tumor

A
  • distal femur or proximal tibia (knee region)
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11
Q

What are the proliferating cells involved in Ewing Sarcoma

A

Poorly differentiated cells derived from neuroectodem

Biopsy reveals small round blue cells resembling lymphocytes

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12
Q

What translocation is associated with Ewing sarcoma

A

t(11;22)

THINK: 11 + 22 = 33 (Ewing’s jersey number)

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13
Q

What is the defect in osteogenesis imperfecta

A
  • Defect in Collagen type I
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14
Q

Presentation of osteogenesis imperfecta

A

Clinical features:

Multiple fractures

Blue sclera (exposure of choroidal veins)

Hearing loss (fracture of bones of middle ear

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15
Q

What is the basic premise behind osteoporosis

A
  • Reduction in trabecular (spongy) and cortical bone mass loss
  • Usually due to increased bone resorption (osteoclast > osteoblast)
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16
Q

Causes of osteoporosis

A
  • Old age
  • Decreased estrogen levels
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17
Q

Describe the labs in osteoporosis (calcium, phosphate, PTH, and alkaline phosphatase)

A

All labs are normal

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18
Q

What disease is due to disordered bone remodelling due to increased osteoclastic and osteoblatic activity

A
  • Paget disease of the bone
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19
Q

What disease is due to disorder of bone resorption (decreased osteoclast function)

A

Osteopetrosis

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20
Q

What disease is associated with increasing hat size

A

Paget disease of the bone

21
Q

Describe the clinical features of osteopetrosis

A
  • Fractures
  • Bone fills marrow space
    • Extramedullary hematopoiesis
    • Pancytopenia
    • “Bone-in-bone” x-ray
  • Vision and hearing loss
    • Impingement of cranial nerves
  • Hydrocephalus
    • Narrowing of foramen magnum
22
Q

What are the lab values in osteopetrosis (calcium, phosphate, PTH, ALP)

A
  • Usually normal
  • May have decreased Ca2+ in severe disease
23
Q

Treatment of osteopetrosis

A
  • Bone marrow transplant (osteoclasts derived from monocytes)
24
Q

Describe the presentation of rickets

A
  • Bow legs, rachitic rosary, frontal bossing (enlarged forehead), pigeon-breast deformity
25
Q

What are the lab values in rickets/osteomalacia (calcium, phosphate, PTH, ALP)

A
  • Decreased vitamin D
  • Decreased Ca2+
  • Increased PTH
  • Decreased phosphate
  • Increased alkaline phosphatase (hyperactivity of osteoblasts)
26
Q

What are the stages of Paget disease?

A
  • Lytic – osteoclasts
  • Mixed – osteoclasts + osteoblasts
  • Sclerotic – osteoblasts
  • Quiescent – minimal osteoclast/osteoblast
27
Q

Describe the clinical features of Paget’s

A
  • Mosaic pattern of woven and lamellar bone
  • Increased hat size due to skull thickening
  • Hearing loss due to impingement of cranial nerve
28
Q

What are the labs in Paget’s (calcium, phosphate, PTH, ALP)

A
  • Isolated elevation of alkaline phosphatase (due to end osteoblastic phase)
    • All other labs are normal
29
Q

What are complications of Paget

A
  • High output cardiac failure – due to increased blood flow from formation of arteriovenous shunts in bone
  • Osteosarcoma – end-stage osteoblasts at risk for mutation
30
Q

What is osteitis fibrosa cystica

A
  • Bony manifestation of an endocrine disorder (e.g. elevated PTH causing bone resorption)
    • High PTH = excess osteoclastic activity = “brown tumors” in bone (cystic spaces lined by osteoclasts filled with fibrous stroma and blood)
31
Q

Causes of Osteitis fibrosa cystica

A
  • Hyperparathyroidism
    • High PTH causing high Ca2+, low PO43-, and high ALP
  • Pseudohypoparathyroidism (akak Albright hereditary osteodystrophy)
    • Renal tubules resistant to PTH
    • Low Ca2+ and high PO34-
    • High PTH in response to low Ca2+
32
Q

What is polyostotic fibrous dysplasia?

A
  • Bone is replaced by collagen and fibroblasts
33
Q

What is the triad in polyostotic fibrous dysplasia

A
  • Endocrine disorder (Precocious puberty)
  • Café-au-lait spots
  • Polyostotic fibrous dysplasia
34
Q

What are the 4 muscles of the rotator cuff?

A

SItS:

Supraspinatous

Infraspinatous

teres minor

Subscapularis

35
Q

What function does each muscle of the rotator cuff have in movement of the arm?

Supraspinatous, Infraspinatous, teres minor, Subscapularis

A
  • (1) Supraspinatus
    • Abducts arm initially (before deltoid kicks in)
    • Most common rotator cuff injury
    • Assessed with “empty can” test
  • (2) Infraspinatus
    • Laterally rotates arm
  • (3) Teres minor
    • Adducts and laterally rotates arm
  • (4) Subscapularis
    • Medially rotates and adducts arm
36
Q

What structures are commonly damaged in anterior shoulder dislocation

A

Axiallary nerve

Posterior circumflex artery

37
Q

What are the bones of the wrist

A
  • Wrist bones = So Long To Pinky, Here Comes The Thumb
    • Scaphoid, Lunate, Triquetrum, Pisiform, Hamate, Capitate, Trapezoid, Trapezium
38
Q

Which nerve is affected in carpal tunnel syndrome

A

Median nerve

39
Q

What are risk factors of osteoarthritis

A

Age, obesity, trauma

40
Q

Which arthritis improves with use and which worsens with use

A

Osteoarthtis - pain worsens with use

RA - pain worst in the morning and improves with use

41
Q

Which arthritis is associated with eburnation of bone

A

Osteoarthritis

42
Q

Differentiate between Heberden and Bouchard nodes

A

Heberden - DIP

Bouchard - PIP

43
Q

Which arthritis spares the DIP?

A

RA

44
Q

Most common affected joints in osteoarthritis

A
  • Mostly affects weight-bearing joints (hips, lumbar spine, knees), PIP and DIP
45
Q

Which arthritis has symmetric and which has asymmetric joint involvement

A

OA = asymmetric

RA = symmetric

46
Q

What is pannus, and which arthritis is it associated with?

A

Pannus = inflamed granulation tissue in RA

  • RA is a systemic autoimmune disease that causes synovitis which leads to the creation of pannus (inflamed granulation tissue)
    • Recall that myofibroblasts within granulation tissue contract, which is what causes a lot of symptoms of RA
47
Q

What HLA is associated with RA?

A

HLA-DR4

48
Q

Which arthritis is associated with subluxation and wrist and finger deviation?

A

RA

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