Bone Infection

Question 1

spread of osteomyelitis in children vs adults? most common organism?

Answer 1

children: hematogenous; S. aureus
adults: contiguous/direct innoculation; polymicrobial

Question 2

Define sequestrum, involucrum, cloaca, sinus tract, Brodie abscess

Answer 2

• A sequestrum is a piece of necrotic bone that is separated (sequestered) from viable bone by granulation tissue. A sequestrum is a surgical lesion that can chronically harbor living organisms and function as a nidus for recurrent infection if not resected.
• An involucrum is living bone surrounding necrotic bone.
• A cloaca is an opening on the involucrum.
• A sinus tract is an opening from the infection to the skin surface.
• A Brodie abscess is a form of subacute osteomyelitis characterized by central lucency and peripheral sclerosis.

Question 3

Brodie abscess ddx

Answer 3

osteoid osteoma

Question 4

reason for hematogenous infection for kids

Answer 4

vascular metaphysis/bridging vessels across epiphysis, sluggish flow within metaphyseal venules; infection begins intramedullary through Haversian/Volkmann canals

Question 5

exuberant periostitis is most common in? ddx?

Answer 5

children; loose periosteum, more likely to get periostitis; may mimic Ewing sarcoma

Question 6

most common site of hematogenous osteomyelitis in adults?

Answer 6

spine

Question 7

chronic drainage of sinus tract for osteomyelitis predisposes pt to?

Answer 7

SCC

Question 8

Ddx for diabetic foot osteomyelitis

Answer 8

neuropathic joint (midfoot)

Question 9

definition of chronic osteomyelitis

Answer 9

6 weeks+

Question 10

osteomyelitis of Garre? Ddx?

Answer 10

sclerosing osteomyelitis; ddx includes lymphoma, sclerotic mets, osteoid osteoma

Question 11

organisms in osteomyelitis

• Staph
• Salmonella
• Pseudomonas
• TB

Answer 11

staph: hematogenous
salmonella: sickle cell
Pseudomonas: puncture wound through of foot through sneaker
TB: Pott disease, spine

Question 12

how does GU infection spread to spine?

Answer 12

epidural venous Batson plexus

Question 13

most sensitive test for early osteomyelitis

Answer 13

MRI and scintigraphy, 3 phase Tc99m MDP bonescan

Question 14

Tc MDP bone scan for acute osteomyelitis shows? cellulitis?

Answer 14

osteomyelitis: + on flow, blood pool, and delayed phase
cellulitis: + flow, blood pool, negative on delayed

Question 15

WBC and sulfur colloid scintigraphy, osteomyelitis

Answer 15

increased uptake on WBC and reduced activity on sulfur colloid

Question 16

types of WBC scans

Answer 16

indium 111-WBC and Tc99m HMPAO WBC; indium has a higher dose ; Tc99m dissociates and leads to GU excretion

Question 17

MRI imaging findings of osteomyelitis

Answer 17

high T2 marrow signal, low T1 signal (edema)

fluid collections, nonenhancing necrotic bone

Question 18

common spread of septic arthritis in kids?

Answer 18

hip from proximal femoral metaphyseal osteomyelitis (within the hip joint capsule)

Question 19

site of septic arthritis in drug users

Answer 19

SI and acromioclavicular joints

Question 20

Hallmark of necrotizing fasciitis ; causing bacteria

Answer 20

soft tissue gas ; Clostridium or gram positive rods