©ken l schreibman, phd/md 2010 schreibman.info osteomyelitis always a diagnostic puzzle...

©Ken L Schreibman, PhD/MD 2010 schreibman.info

Osteomyelitis

Always a Diagnostic Puzzle

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Osteomyelitis: Put the Pieces Together

MRIActive

RADIOGRAPHSRecent

HISTORY

ClinicalSurgical

CTChronic


Osteomyelitis: TopicsDefinitionsActiveChronic

MechanismsHematogenousDirect spread

ImagingRadiographsCTMRI

Bone Model

Cortex

Marrow


Osteomyelitis: Definitionscomes from Greek:

osteon = bone myelos = marrow itis = inflammation

“Inflammation of bone marrow”Infection of bone marrow

MRIMarrow

High SensitivityLow Specificity

Marrow inflammation from infection looks like inflammation from any other cause

“Osteomyelitis”


Osteomyelitis: DefinitionsActive Osteomyelitis

vsChronic Osteomyelitis


Osteomyelitis: DefinitionsActive Osteomyelitis“Aggressive”Resembles Tumor

Cortex DestructionPeriosteal Reaction


Active Osteomyelitis 16yoM distal fibula pain 3w after inversion injury

HISTORY

Clinical Followup

“Aggressive”Cortex DestructionPeriosteal Reaction


Osteomyelitis: DefinitionsChronic Osteomyelitis“Non-Aggressive”Resembles Callus3 Characteristics:

Involucrum: “wrap”Thick periosteum around infected bone

Sequestrum: “set apart”Piece of dead, infected, bone

Cloaca: “sewer”Opening in cortex throughwhich pus can escape

RADIOGRAPHSActive ≠ Chronic


Active vs Chronic Osteomyelitis

RADIOGRAPHSActive ≠ Chronic

ActiveOsteomyelitis

ChronicOsteomyelitis


Active Osteomyelitis“Aggressive”Cortex DestructionPeriosteal Reaction

16yoM distal fibula pain 3w after inversion injury

ActiveOsteomyelitis


Chronic Osteomyelitis 19yoM fibula pain2.5years later…

2.5 years

ChronicOsteomyelitisRADIOGRAPHS

Active ≠ Chronic


Chronic Osteomyelitis 19yoM fibula pain2.5years later…

ChronicOsteomyelitisInvolucrum

Sequestrum

Cloaca

CT

Fibula

Tibia


Chronic Osteomyelitis

6 weeks later

Involucrum Developing 42yoM Diabetic

10 more weeks


27yoM s/p removalRt Femoral RodChronic Osteomyelitis

Involucrum

27yoM s/p removalRt Femoral Rod

CT Scout



InvolucrumSequestrum


CT Scout

Axial Slice

Coronal ReformatCoronal Reformat



InvolucrumSequestrumCloaca


CT Scout

Axial Slice

Oblique CoronalOblique Coronal


Osteomyelitis: MechanismsDirect Spread adjacent tissuesMost common causeDecubitus ulcerSeptic arthritis

PUS


Decubitus Ulcer Ischium

Ischium Ischium

T1

52yoMquadriplegic

T1



Puncture into boneStepped on nailExternal fixatorRing sequestrum

Ring SequestrumChronic Osteomyelitis

InvolucrumSequestrumCloacaPoor Union

RADIOGRAPHS



Puncture into boneStepped on nailExternal fixatorRing sequestrum

HematogenousSite related to patient age


Hematogenous OsteomyelitisSite related to patient age

MatureBone

ImmatureBone

PhysisEpiphysis

Metaphysis

Diaphysis

Art

erio

leA

rter

iole Venule

BloodSupplyBloodSupply

SepticEmboliSepticEmboli

Infectionoccursat end

of

Infectionoccurs at

metaphysisof


Hematogenous Osteomyelitis 1yoM streppneumonia


Hematogenous Osteomyelitis 1yoM streppneumonia

3 months later


Osteomyelitis: ImagingMany Imaging Options:RadiographsCTMRUSNuc Med

What to order when?


Osteomyelitis: What to Order When………… ALWAYS!

May show evidence of active infectionBone destruction, periosteal reaction

May show evidence of chronic infection Involucrum

Screen for metalOrthopedic hardware, foreign bodies

Unexpected findingsFractures,

Delineate current anatomySurgical resections,

RADIOGRAPHS NEED TO BE RECENT

vs

RadiographsRadiographs

gas in soft tissuesgas in soft tissues

neuropathic deformityneuropathic deformity


66yoM h/o DiabetesPresents in Sept swollen footMR is requested to “r/o Osteo”

Are there radiographs?Yes

…3 months ago

Repeat radiographs obtained now, prior to MR, reveal…

Need for Recent Radiographs Example

June September

Neuropathic destruction of the Lisfranc joint

Normal Lisfranc joint


Osteomyelitis: What to Order WhenRadiographs …………ALWAYS!CT……………………. Chronic

CasesCT best for calcified structures

InvolucrumSequestrumCloaca

CT of the extremities is insensitive for:Bone marrow pathologySoft tissue pathology



CasesMRI..…………………. Active Cases

Shows extent of soft tissue edemaExcellent for demonstrating abscesses

and other drainable fluid collectionsSensitive for bone marrow pathology

Can be overly sensitiveat expense of specificity

Infected bone marrow resembles marrow edema due to other causes


Osteomyelitis: MR Imaging

T1 T2

Bone Model

X-rays

CortexMarrowMarrow



T1 T2Surro

undi

ngSu

rroun

ding

Tissues (fat)Tissues (fat)

CortexMarrowMarrow

CortexMarrow

Surro

undi

ngSu

rroun

ding


Bone Model

X-rays

CortexMarrowMarrow



T1 T2fsSurro

undi

ngSu

rroun

ding


CortexMarrowMarrow

CortexMarrow

Surro

undi

ngSu

rroun

ding


Bone Model

X-rays

CortexMarrowMarrow


Osteomyelitis: MR ImagingPath=FluidT1=DarkT2=BrightT1fs+GdEnhancement Inflamed Uniform

Abscess Wall

Cyst NotT1

(STIR)T2fs



T1T1fs(STIR)

T2fs

+Gd

EnhancementInflamed UniformAbscess WallCyst Not


Osteomyelitis: MR ImagingDetection of the non-enhancing pus pocket (abscess) is crucialPresence of soft tissue abscess

proves the edema in underlying bone marrow is osteomyelitis.

Site for aspiration for culture.If IV Gd doesn’t get into abscess,

IV antibiotics won’t get in either,abscess may require drainage.


Osteomyelitis: MR Imaging 63yoM Diabeticwith heel ulcer

Arterial Ca++

T1

IR

Minimal Marrow Edema

T1fsIVGd

Enhancing cellulitisNo non-enhancing

abscess pocket

Intact cortex


Osteomyelitis: MR Imaging 63yoM Diabetic2 weeks later…

Intact cortex

2 weeks earlier

Cortical destruction

IRT1fs

IVGd

More marrow edemaMore tissue edema

Non-enhancingabscess pocket


Intact cortex

2 weeks earlier

Cortical destruction

Osteomyelitis: MR Imaging 63yoM Diabetic

2 weeks later…

T1T1fs

IVGdIR

Marrow edemaAbscess Pocket


Decubitus Ulcer Ischium

T1

52yoMquadriplegic

T2fs

Abscess?

Abscess!T1fs+Gd


Osteomyelitis: MR Imaging 1yoF Swollenleft lower leg

R L Periosteal ReactionPeriosteal Reaction

MetaphyseallucencyMetaphyseallucency


Osteomyelitis: MR Imaging 1yoF Swollenleft lower leg

T1T1fs

IVGdT2fs

Periosteal ReactionPeriosteal Reaction

MetaphysealMetaphyseal Non-enhancing abscessIntra-osseous

Brodie AbscessBrodie Abscess



CasesMRI..…………………. Active CasesUS……….…………… Fluid/

AbscessUS guided aspiration for cultureCannot assess bone involvement

Nuc Med.……………. Problem CasesWhere MR specificity is decreased

Neuropathic feet Infected hardware


Infection around metal: MRI

T,K 21yoM

T2fs T1fsIVGd

We can see soft tissues

around bone

We can see soft tissues

around bone

Enhancing granulation tissue

(phlegmon?)

Enhancing granulation tissue

(phlegmon?)

We can’t see the marrow within boneCannot evaluate for “osteomyelitis”


Infection around metal: Nuc MedRequires 2 Radiopharmaceuticals

1)Tc-Bone Scan (Active bone metabolism)2)In-WBC Scan(Areas of WBC accumulation)

1)BS: Sen/Spec2)WBC:Spec/Sen


Infection around metal: Nuc Med

FemurFemur

Tibia

Femur

Tibia

S,B 31yoM

Tc-Bone Scan In-WBC Scan RemovedTibia Plate

PlacedAntibiotic

PMM-Beads

PlacedAntibiotic

PMM-BeadsTibiaPlate

FemurPlate


Charcot (Neuropathic) Foot

P,K 65yoF

T1 T2fsT1fs+IV Gd

Tc99m MDP In111 WBC

Abscess

Infection


Osteomyelitis: Put the Pieces Together

MRIActive

RADIOGRAPHSRecent

HISTORY

ClinicalSurgical

CTChronic

©ken l schreibman, phd/md 2010 schreibman.info osteomyelitis always a diagnostic puzzle...

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