MSK-infection

Question 1

How long are Rgx normal in OM?

Answer 1

7-10 d

Question 2

I say this, you say that: OM Spine

Answer 2

IV drug user

Question 3

I say this, you say that: OM Spine + kyphosis

Answer 3

Tb (gibbus deformity)

Question 4

I say this, you say that: OM UL SI joint

Answer 4

IV drug user

Question 5

I say this, you say that: psoas m abscess

Answer 5

Tb

Question 6

Is OM more common in adults or peds?

Answer 6

Peds

Question 7

Is septic arthritis MC in adults or peds?

Answer 7

Adults

Question 8

sequestrum

Answer 8

necrotic bone surr by granulation tissue

Question 9

involucrum

Answer 9

thick sheath of periosteal bone around sequestrum

Question 10

cloaca

Answer 10

defect in periosteum covering

Question 11

sinus tract

Answer 11

channel from bone to skin (lined w/ granulation tissue)

Question 12

chronic OM-definition, most spec sign

Answer 12

• OM > 6wks

- sequestrum = most specific sgx active chronic OM

Question 13

In setting of OM, who’s at risk for SCC?

Answer 13

draining sinus tract

Question 14

How do you know if OM is healed?

Answer 14

Return of normal fatty marrow

Question 15

acute bacterial osteomyelitis-3 categories

Answer 15

1) hematogenous (MC in child)
2) continuous
3) direct inoculation

Question 16

Hematogenous OM has a predilection for…

Answer 16

metaphysis long bones

Question 17

changes of bone <18 mo old ISO infection, cancer

Answer 17

vessels metaph –> epiph atrophy –> GP stops spread (can still occ)

• “septic tank” in metaph
• GP fuse –> septic tank resolves

Question 18

bone vessels infant vs child

Answer 18

• < 1 mo-transphyseal

- <18 mo- metaphyseal

Question 19

OM <1 mo old, < 18 mo old, 2-16 yo

Answer 19

• multi-centric, joint inv+, bone scan (-) 75%
• epiphyseal
• metaphyseal

Question 20

most sens & spec signs/sequences in OM

Answer 20

next to ulcer, cellulitis

• sens-STIR
• spec-T1 (-)

Question 21

ghost sign

Answer 21

indicative of neuro-osteoarthropathy with superimposed osteomyelitis.

refers to poor definition of the margins of a bone on T1-weighted images, which become clear after contrast administration.

Question 22

MC orgm of spinal OM/discitis

Answer 22

Staph aureus (IV drug user)

Question 23

phases spinal OM/discitis

Answer 23

VB –> disc –> adj VB

Question 24

spinal OM/discitis-imaging early vs late

Answer 24

• early
  
  • rgx: (-)
  • MRI: paraspinal/epidural inflamm. T2+ disc & enh
• late
  
  • rgx: irregular EP destruction, narrowing
  • MRI: T1-, T2+, enh

Question 25

MCC adult spinal OM/discitis

Answer 25

-surgery, procedure, systemic inf

Question 26

MCC pediatric spinal OM/discitis

Answer 26

hematogenous

Question 27

Labs spinal OM/discitis

Answer 27

ESR, CRP 80%

Question 28

best NM scan for spinal OM/discitis?

Answer 28

gallium (not wbc bone scan)

Question 29

who gets isolated discitis? classic hx?

Answer 29

- pediatric: direct blood supply to disc | - classic hx: <4 yo w/ URI

Question 30

how many people with Tb have MSK involvement?

Answer 30

5% (spine=MC)

Question 31

Pott disease-what, app, BWs

Answer 31

Tb of spine - disc spared (until late) - multi-level skip involvement - BWs: "large paraspinal abscess, Ca psoas pabscess, gibus deformity"

Question 32

Gibbus deformity

Answer 32

focal kyphosis in Pott dx

Question 33

Pott disease mimics

Answer 33

brucellosis (can have disc preservation)

Question 34

Tb dactylics (spina ventosa)-what, where, who, img

Answer 34

- short tubular bones of hands/feet in kids - smoldering infection w/o periosteal rxn - diaphyseal expansile lesion + ST swelling, no periosteal rxn

Question 35

rice bodies

Answer 35

sloughed, infarcted synovium w/ end stage RA, Tb of joints

Question 36

septic arthritis-where, who, img

Answer 36

- large joints (abundant metaphysical bs) - IV drug users: SI joint, sternoclavicular joint - RFs: immsupp (old, AIDS), fucked up joints (RA), hardware (prosthetic joints) - img: JE (must be present) , synovial enh

Question 37

how fast do you need to act w/ septic arthritis?

Answer 37

destroys joint in 48 hrs

Question 38

pseudoarthrogram sign

Answer 38

air in joint excludes joint effusion

Question 39

necrotizing fasciitis-who, MCC, app

Answer 39

- HIV, tx, DM, EtOH - polymicrobial --> GAS - fascial enh +/- gas (minority)

Question 40

Nec fasc of scrotum

Answer 40

Fournier Gangrene

Question 41

mc loc OM of foot

Answer 41

- metatarsals - phalanges - calcaneus