MSK-infection Flashcards
How long are Rgx normal in OM?
7-10 d
I say this, you say that: OM Spine
IV drug user
I say this, you say that: OM Spine + kyphosis
Tb (gibbus deformity)
I say this, you say that: OM UL SI joint
IV drug user
I say this, you say that: psoas m abscess
Tb
Is OM more common in adults or peds?
Peds
Is septic arthritis MC in adults or peds?
Adults
sequestrum
necrotic bone surr by granulation tissue
involucrum
thick sheath of periosteal bone around sequestrum
cloaca
defect in periosteum covering
sinus tract
channel from bone to skin (lined w/ granulation tissue)
chronic OM-definition, most spec sign
- OM > 6wks
- sequestrum = most specific sgx active chronic OM
In setting of OM, who’s at risk for SCC?
draining sinus tract
How do you know if OM is healed?
Return of normal fatty marrow
acute bacterial osteomyelitis-3 categories
1) hematogenous (MC in child)
2) continuous
3) direct inoculation
Hematogenous OM has a predilection for…
metaphysis long bones
changes of bone <18 mo old ISO infection, cancer
vessels metaph –> epiph atrophy –> GP stops spread (can still occ)
- “septic tank” in metaph
- GP fuse –> septic tank resolves
bone vessels infant vs child
- < 1 mo-transphyseal
- <18 mo- metaphyseal
OM <1 mo old, < 18 mo old, 2-16 yo
- multi-centric, joint inv+, bone scan (-) 75%
- epiphyseal
- metaphyseal
most sens & spec signs/sequences in OM
next to ulcer, cellulitis
- sens-STIR
- spec-T1 (-)
ghost sign
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.
MC orgm of spinal OM/discitis
Staph aureus (IV drug user)
phases spinal OM/discitis
VB –> disc –> adj VB
spinal OM/discitis-imaging early vs late
- early
- rgx: (-)
- MRI: paraspinal/epidural inflamm. T2+ disc & enh
- late
- rgx: irregular EP destruction, narrowing
- MRI: T1-, T2+, enh
MCC adult spinal OM/discitis
-surgery, procedure, systemic inf
MCC pediatric spinal OM/discitis
hematogenous
Labs spinal OM/discitis
ESR, CRP 80%
best NM scan for spinal OM/discitis?
gallium (not wbc bone scan)
who gets isolated discitis? classic hx?
- pediatric: direct blood supply to disc
- classic hx: <4 yo w/ URI
how many people with Tb have MSK involvement?
5% (spine=MC)
Pott disease-what, app, BWs
Tb of spine
- disc spared (until late)
- multi-level skip involvement
- BWs: “large paraspinal abscess, Ca psoas pabscess, gibus deformity”
Gibbus deformity
focal kyphosis in Pott dx
Pott disease mimics
brucellosis (can have disc preservation)
Tb dactylics (spina ventosa)-what, where, who, img
- short tubular bones of hands/feet in kids
- smoldering infection w/o periosteal rxn
- diaphyseal expansile lesion + ST swelling, no periosteal rxn
rice bodies
sloughed, infarcted synovium w/ end stage RA, Tb of joints
septic arthritis-where, who, img
- 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
how fast do you need to act w/ septic arthritis?
destroys joint in 48 hrs
pseudoarthrogram sign
air in joint excludes joint effusion
necrotizing fasciitis-who, MCC, app
- HIV, tx, DM, EtOH
- polymicrobial –> GAS
- fascial enh +/- gas (minority)
Nec fasc of scrotum
Fournier Gangrene
mc loc OM of foot
- metatarsals
- phalanges
- calcaneus
