(3) Osteomyelitis, Spondylodiscitis, Brodie Abscess Flashcards
What is osteomyelitis?
suppurative form of bone/marrow infection
What is the most common infectious organism of osteomyelitis?
staphylococcus aureus
What infectious organisms may cause osteomyelitis?
- staph aureus
- E. coli
- H. influenzae
- klebsiella
- streptococcus B
What infectious organisms may cause non-suppurative forms of osteomyelitis?
- TB
- syphilis
- coccidiodomycosis
What populations are predisposed to osteomyelitis?
- immunocompromised (corticosteroids, DMARDs, etc.)
- alcoholics
- newborns
- IV drug abusers
- diabetics (poor healing, ulcers)
- hemodialysis pts
- post-surgical
What are the 4 pathways of spread of osteomyelitis?
- hematogenous (MC)
- contiguous (adjacent) source
- direct implantation
- postoperative
What are the early imaging findings of osteomyelitis?
- soft tissue swelling
- aggressive bone destruction (permeative/motheaten, wide ZoT)
- aggressive periosteal Rxn (laminated, spiculated, codman)
- dark on T1 (replacement of marrow fat w/ bacteria, pus, hemorrhage)
What are the later imaging findings of osteomyelitis?
- sequestrum formation (may calcify)
- involucrum formation (periosteal Rxn)
- cloaca formation
- sinus tract
What is a cloaca?
an opening in the cortex of bone that allows bacteria to spread to other tissues
What is a sequestrum?
necrotic infected bone tissue
(area of permeative osteolysis, wide ZoT, may have calcification)
What is an involucrum?
an area of reactive bone formation that forms a sheath/wall around a sequestrum
What are some of the cardinal signs and symptoms of osteomyelitis?
- painful erythema & swelling/edema
- Rapid onset, high fever
- malaise
- ^ESR
- ^WBC
- pre-existing infection
When using the term “osteomyelitis” on its own, the implication is…
acute pyogenic osteomyelitis
What type of edema is produced by the tissue necrosis in osteomyelitis?
Purulent exudate
How long does it take for osteomyelitis to appear on x-ray in the extremities versus the spine?
- extremities: 7-10 days
- spine: 21 days
What is a sinus?
where pus drains from bone into the outside environment
If you see permeative destruction in the metaphysis of a kid, what is on your list of differentials?
- Osteomyelitis
- Osteosarc.
- Ewing sarc.
- lymphoma
If you see permeative destruction in the diaphysis of a kid, what is on your list of differentials?
- Osteomyelitis
- Ewing sarc.
- Osteosarc.
- lymphoma
What is spondylodiscitis?
acute suppurative infection of the spine (vertebrae and/or discs)
What follow-up is required to differentiate osteomyelitis from neoplasia?
MRI with contrast
What is the most common infectious organism of spondylodiscitis?
staph aureus
What is the radiographic latent period of spondylodiscitis?
3 weeks
What part of the spine is typically involved first in children with spondylodiscitis?
disc
What part of the spine is typically involved first in adults with spondylodiscitis?
ant. body endplate –> vertebral destruction & secondary disc involvement
(arterial pattern)
What are the imaging features of spondylodiscitis?
- ant. vertebral body destruction
- vertebral body destruction (endplate white line loss)
- disc destruction (disc height loss)
- paraspinal abscess
- phlegmon
What is the term for when the ALL is lifted by pus outside of the spine?
phlegmon
What is the term for the collection of pus around the spinal cord?
paraspinal abscess
What is the clinical significance of spondylodiscitis?
pus against dura = ^risk for meningitis & encephalitis
What clinical exam findings may indicate spondylodiscitis?
positive:
- Soto-hall test
- L’Hermitte sign
(d/t pus against dura -> dural inflammation)
Describe the treatment and prognosis for osteomyelitis and spondylodiscitis.
- prognosis better if Dx early
- IV antibiotics
- orthoses
- surgical debridement if Dx late
- possible jt replacement/fusion
What is a Brodie abscess?
subacute suppurative infection of bone
(localized, aborted form of suppurative osteomyelitis)
What is the most common infectious organism of a Brodie abscess?
staph aureus
How may a Brodie abscess present on a biopsy?
sterile
What is the typical clinical presentation of a Brodie abscess?
- night pain relieved by ASA
- M>F
- children
(clinically similar to osteoma, osteoblastoma, fatigue Fx)
What are the imaging findings of a Brodie abscess?
- geo. lytic
- sharp margins
- variable surrounding sclerosis (focal cortical thickening)
What is the most common location of a Brodie abscess?
metaphysis of tubular bones (MC = tibia)
Give 3 differential diagnoses in order of likeliness.
(Aggressive lytic in diaphysis of kid)
1. Osteomyelitis
2. Ewing sarcoma
3. Osteosarcoma
Give 3 differentials in order of likelihood.
(Aggressive lytic in meta-diaphysis of kid)
1. Osteomyelitis
2. Ewing sarcoma
3. Osteosarcoma
What structure is involved and what is the likely diagnosis?
1st distal phalanx
Dx: gas gangrene
What is the diagnosis?
Chronic osteomyelitis (acute?)
Patient has a history of infection. What is the most likely diagnosis?
Brodie Abscess
What is the term for this MRI finding?
Rim enhancement
(Dx: Brodie abscess)
What is the likely diagnosis? Give 2 radiographic findings that support your diagnosis.
Dx: Spondylodiscitis
- loss of subchondral white line
- loss of disc space
Give 3 differentials in order of likelihood.
- Osteomyelitis
- Ewing sarcoma
- Osteosarcoma
Patient presents with pain. Give 3 differentials.
- Brodie abscess
- chondroblastoma
- ABC
Patient presents with pain. Give 3 differentials.
- Brodie abscess
- osteoid osteoma
- osteoblastoma
Patient has a history of infection. What is the most likely diagnosis?
Brodie abscess
