““Approach to Lower Extremity Approach to Lower Extremity OsteomyelitisOsteomyelitis””

A A radiologicradiologic tour of a patient encountertour of a patient encounter

David David GuoGuo, HMS III, HMS IIIGillian Lieberman, MDGillian Lieberman, MDBIDMC, October 2009BIDMC, October 2009

Our learning goalsOur learning goalsReview lower extremity anatomyReview lower extremity anatomy

Discuss menu of available of testsDiscuss menu of available of tests

Demonstrate classic findings of Demonstrate classic findings of osteomyelitisosteomyelitis on on plain film and MRIplain film and MRI

Develop and refine the differential diagnosis for Develop and refine the differential diagnosis for osteomyelitisosteomyelitis

Meet our patient, Mr. JMeet our patient, Mr. J

39 year39 year--old homeless male with old homeless male with history of HIV, ETOH abuse, and history of HIV, ETOH abuse, and traumatic R ankle fracture traumatic R ankle fracture s/ps/p ORIF ORIF 3 years ago 3 years ago

Arrives in ED with a painful, swollen Arrives in ED with a painful, swollen right ankleright ankle

Our patient: HPIOur patient: HPI

First noticed pain 3 weeks ago in his First noticed pain 3 weeks ago in his right ankle while walkingright ankle while walking

5 days ago, medial right ankle 5 days ago, medial right ankle became red and swollen with burning became red and swollen with burning sensationsensation

Our patient: differential diagnosis #1Our patient: differential diagnosis #1CellulitisCellulitisOsteomyelitisOsteomyelitisFractureFractureSeptic arthritisSeptic arthritisOsteoarthritisOsteoarthritisRheumatoid arthritisRheumatoid arthritisGoutGoutTumorTumor

What radiologic test should we What radiologic test should we order first?order first?

Menu of testsMenu of tests

Plain FilmPlain FilmMRIMRICTCTUltrasoundUltrasoundNuclear medicineNuclear medicine–– ThreeThree--phase bone scanphase bone scan–– WBC scanWBC scan–– FDG PETFDG PET–– GalliumGallium

Anatomy: review

Before we continue to the plain film findings, we will review the anatomy of the ankle region

Anatomy: bones of the footAnatomy: bones of the foot

www.sportspodiatry.co.uk/foot_footanatomy.htm

Anatomy: the mortise jointAnatomy: the mortise joint

www.usuhs.mil/fap/resources/imag/AnkleX-Rays

Mortise jointMortise jointTibialTibial plafondplafond

TalarTalar domedome

FibulaFibula

LateralLateralMalleolusMalleolus

TalusTalus

MedialMedialMalleolusMalleolus

TibiaTibia

Normal Ankle Normal Ankle XrayXray, , Mortise ViewMortise View

Our patient: plain film

Now back to our patient

We will start with earlier images for baseline comparison

Our patient: ankle plain film,Our patient: ankle plain film, 3 months prior3 months prior

AP Mortise Lateral

BIDMC PACS

Our patient: plain film highlights, Our patient: plain film highlights, 3 months prior3 months prior

Disruption of Disruption of trabeculartrabecular lineslines

Metallic Metallic washerwasher

Increased Increased sclerosissclerosis

NarrowingNarrowing joint spacejoint space

Osteoarthritis, secondary to Osteoarthritis, secondary to infection or fractureinfection or fracture

BIDMC PACSAnkle XAnkle X--ray, Mortise Viewray, Mortise View

Our patient: ankle plain film, Our patient: ankle plain film, currentcurrent

AP Mortise Lateral

BIDMC PACS

Our patient: plain film highlights, Our patient: plain film highlights, currentcurrent

Area of Area of increased increased lucencylucency in in medial aspect of distal medial aspect of distal tibialtibialmetaphysismetaphysis

Area of Area of increased sclerosisincreased sclerosis in in distal tibiadistal tibia

Increased soft tissue Increased soft tissue swellingswelling

Cortical erosionCortical erosion

PeriostealPeriosteal new bone formationnew bone formation

BIDMC PACSAnkle X-ray, Mortise View

Our patient: summary from Our patient: summary from plain filmsplain films

There is a process occurring in theThere is a process occurring in the……Soft tissue: Soft tissue: –– SwollenSwollen

Bone:Bone:–– Chronic process: causing Chronic process: causing sclerosissclerosis–– Acute process: causing Acute process: causing lucencylucency

Joint: Joint: –– NarrowingNarrowing lossloss of of cartilagecartilage arthritisarthritis

Our patient: differential diagnosis #2Our patient: differential diagnosis #2

What test should we order next?What test should we order next?

CellulitisCellulitisOsteomyelitisOsteomyelitisFractureFractureSeptic arthritisSeptic arthritisOsteoarthritisOsteoarthritisRheumatoid arthritisRheumatoid arthritisGoutGoutTumorTumor

Menu of TestsMenu of Tests

Plain FilmPlain FilmMRIMRICTCTUltrasoundUltrasoundNuclear medicineNuclear medicine–– ThreeThree--phase bone scanphase bone scan–– WBC scanWBC scan–– FDG PETFDG PET–– GalliumGallium

Our patient: normal anatomy Our patient: normal anatomy on T1 MRIon T1 MRI

FatFat

TendonsTendonsLigamentsLigaments

MuscleMuscle

CortexCortexBone Bone marrowmarrow

BIDMC PACS

Axial T1 MRI, distal R lower extremity

Our patient: T1 MRI findingsOur patient: T1 MRI findingsOn T1On T1……

Fluid is dark, fat is brightFluid is dark, fat is brightGives the broad Gives the broad ““anatomyanatomy””viewview

AbnormalitiesAbnormalitiesBone: lesion that is Bone: lesion that is hypointensehypointense to marrowto marrow

Soft tissue: lesion that is Soft tissue: lesion that is isointenseisointense to muscleto muscle

BIDMC PACS

Axial T1 MRI, distal R lower extremity

Our patient: T2 MRI findingsOur patient: T2 MRI findingsOn T2On T2……

Fluid is bright, fat is Fluid is bright, fat is dark.dark.Gives Gives ““pathologypathology”” viewview

AbnormalitiesAbnormalities

Soft tissue: improved Soft tissue: improved view of view of loculatedloculated fluid fluid collectioncollection

BIDMC PACS

Axial T2 MRI, distal R lower extremity

Our patient: STIR MRI findingsOur patient: STIR MRI findings

On STIR (Short Tau Inversion Recovery)On STIR (Short Tau Inversion Recovery)Fat is subtracted out, leaving fluid Fat is subtracted out, leaving fluid brightbrightWe show normal STIR for comparisonWe show normal STIR for comparison

AbnormalitiesAbnormalitiesDiffusely increased signal in tibiaDiffusely increased signal in tibiabone marrow edemabone marrow edemaCortical erosionCortical erosionPeriostealPeriosteal edemaedema

Axial STIR (normal) Axial STIR (at lesion)

BIDMC PACS

Our patient: T1 postOur patient: T1 post--gad MRI findingsgad MRI findings

On T1 postOn T1 post--gadgad……IV contrast (gadolinium) shows IV contrast (gadolinium) shows disruption of tissue boundarydisruption of tissue boundaryWe show T1 preWe show T1 pre--gad shown for gad shown for comparisoncomparison

AbnormalitiesAbnormalitiesDecreased signal in marrowDecreased signal in marrownecrotic bonenecrotic boneSinus tractSinus tract and abscessand abscess

Axial T1 pre-gad Axial T1 post-gad

BIDMC PACS

Our patient: summary from Our patient: summary from MRIMRISoft tissue: Soft tissue: –– LoculatedLoculated abscessabscess–– Sinus tractSinus tract to boneto bone

Bone:Bone:–– Diffuse Diffuse tibialtibial bone marrow edemabone marrow edema–– Cortical Cortical erosion and erosion and periostealperiosteal edemaedema

inflammatory processinflammatory process–– Necrotic boneNecrotic bone sequestrumsequestrum

Diagnosis?Diagnosis?

Our patient: diagnosis of Our patient: diagnosis of osteomyelitisosteomyelitis

DefinitionDefinition: : infection of the bone marrowinfection of the bone marrow–– AcuteAcute: evolves over : evolves over days to weeksdays to weeks–– ChronicChronic: evolves over : evolves over months to yearsmonths to years, with relapses, with relapses

Bacteria remain in Bacteria remain in sequestrasequestra, where antibiotics cannot , where antibiotics cannot reachreach

Route of spreadRoute of spread–– Contiguous spreadContiguous spread

Trauma, bone surgery, foreign body implantTrauma, bone surgery, foreign body implant–– Vascular insufficiencyVascular insufficiency

Diabetic foot ulcer Diabetic foot ulcer –– HematogenousHematogenous spreadspread

NidusNidus of infection, more often in childrenof infection, more often in children

Risk factorsRisk factors–– Drug abuseDrug abuse, trauma, HIV, transplant, diabetes, foreign bodies, trauma, HIV, transplant, diabetes, foreign bodies

Source: Lew, Daniel and Francis Waldvogel. Lancet 2004. “Approach to imaging 

modalities in setting of suspected osteomyelitis. Up‐To‐Date, accessed 10‐14‐09. Applies to Mr. R

Our patient: treatment summaryOur patient: treatment summaryOrthopedics performed Orthopedics performed drainage and debridementdrainage and debridementtwice and got bone biopsytwice and got bone biopsy

Bone biopsy returned positive for Bone biopsy returned positive for PseudomonasPseudomonas

Received 6 weeks of Received 6 weeks of IV IV CefepimeCefepime

Prognosis: Mr. R will likely return with Prognosis: Mr. R will likely return with acuteacuteexacerbations of exacerbations of chronic chronic osteomyelitisosteomyelitis

Review of imaging approachReview of imaging approachPlain FilmPlain Film: : good good first stepfirst step, but limited sensitivity (14%)*, but limited sensitivity (14%)*

MRIMRI: : the the preferred modalitypreferred modality,, showing extent of soft tissue and showing extent of soft tissue and bone marrow inflammationbone marrow inflammation–– 91% sensitivity, 82% specificity**91% sensitivity, 82% specificity**

CTCT: : modality of choice modality of choice when MRI is unavailablewhen MRI is unavailable

UltrasoundUltrasound: : limited use, sometimes for pediatrics and limited use, sometimes for pediatrics and sickle cellsickle cell

Nuclear medicineNuclear medicine: : similar sensitivity to MRI, but bone similar sensitivity to MRI, but bone turnover can be turnover can be nonnon--specificspecific–– ThreeThree--phase bone scanphase bone scan–– WBC scanWBC scan–– FDG PETFDG PET–– GalliumGallium

*Tumeh et al. Disease activity in osteomyelitis: role of radiography. Radiology 1987 Dec;165(3):781-4

**Matowe, L. and F. Gilbert. How to synthesize evidence for imaging guidelines. Clinical Radiology. 2004 (59): 63-68

FakeFake--outs on MRIouts on MRIFindings on MRI can be Findings on MRI can be nonnon--specificspecific–– FractureFracture–– Postsurgical changesPostsurgical changes–– OsteonecrosisOsteonecrosis–– Adjacent arthritisAdjacent arthritis–– NeoplasmNeoplasm

The following examples demonstrate the The following examples demonstrate the importance of considering importance of considering clinical history clinical history with with imaging findingsimaging findings

Companion Pt 2: Lesion on MRICompanion Pt 2: Lesion on MRI

64 64 yoyo M with CML and M with CML and lung cancer presenting lung cancer presenting with ankle painwith ankle painMRI shows MRI shows distal fibular distal fibular lesionlesion, but biopsy needed , but biopsy needed to distinguish amongto distinguish among–– OsteomyelitisOsteomyelitis–– Inflammatory arthritisInflammatory arthritis–– TumorTumor

Lung cancer metastasis!Lung cancer metastasis!

BIDMC PACSAxial T2 MRI, distal L fibula

Companion Pt 3: Lesion on MRICompanion Pt 3: Lesion on MRI

22 22 yoyo M with left anterior M with left anterior leg painleg pain

MRI shows MRI shows midmid--tibialtibiallesionlesion with cortical with cortical erosion and erosion and soft tissuesoft tissueinvolvement: tumor or involvement: tumor or infection?infection?

EwingEwing’’s sarcoma!s sarcoma!

BIDMC PACS

Axial T2 MRI, L mid-tibia

Selected examples of alternative Selected examples of alternative modalitiesmodalities

Plain FilmPlain FilmMRIMRICTCTUltrasoundUltrasoundNuclear medicineNuclear medicine–– ThreeThree--phase bone scanphase bone scan–– WBC scanWBC scan–– FDG PETFDG PET–– GalliumGallium

Most commonly used first-line

Other available approaches

Companion Pt 4: Companion Pt 4: OsteomyelitisOsteomyelitis Gallium/Bone ScanGallium/Bone Scan

37 37 yoyo M with history of M with history of IV drug use presents IV drug use presents with fevers, chills, rigors with fevers, chills, rigors and back painand back pain

Gallium/bone scan shows Gallium/bone scan shows increased uptake at increased uptake at right right sacroiliac jointsacroiliac joint

Acute Acute osteomyelitisosteomyelitis

Anterior Posterior

Posterior Posterior-Oblique

Courtesy of Dr. DonohoeGallium/Bone Scan

Companion Pt 5: Companion Pt 5: OsteomyelitisOsteomyelitis on on FDG PET/Bone scanFDG PET/Bone scan

69 69 yoyo M with HTN, IV drug M with HTN, IV drug use presented with use presented with ““10/10 10/10 back painback pain””

Received PET scan following Received PET scan following incidental lung mass found incidental lung mass found on CTon CT

Increased uptakeIncreased uptake in in vertebra!vertebra!

L1L1--T12 vertebral T12 vertebral osteomyelitisosteomyelitis (confirmed with MRI)(confirmed with MRI)

FDG PET CT (C-) Fusion

Courtesy of Dr. Donohoe

Sagittal View

ConclusionConclusionPlain filmPlain film and and MRIMRI are the modalities of choice for are the modalities of choice for suspected suspected osteomyelitisosteomyelitis

Classic findings for Classic findings for chronic chronic osteomyelitisosteomyelitis include:include:–– Plain film: lucent or sclerotic change, cortical erosion, Plain film: lucent or sclerotic change, cortical erosion,

periostealperiosteal reactionreaction–– MRI: bone marrow edema, abscess or sinus tract, MRI: bone marrow edema, abscess or sinus tract, sequestrasequestra

Differential diagnosis of Differential diagnosis of osteomyelitisosteomyelitis should include should include tumortumorand and inflammatory arthritisinflammatory arthritis

Imaging findingsImaging findings can be noncan be non--specific, so specific, so clinical historyclinical history is is paramount to diagnosisparamount to diagnosis

AcknowledgmentsAcknowledgments

Erica GuptaErica GuptaMary Mary HochmanHochmanKevin Kevin DonohoeDonohoeJim WuJim WuCorrieCorrie YablonYablonGillian LiebermanGillian LiebermanMaria Maria LevantakisLevantakis

ReferencesReferencesTumeh et al. Disease activity in osteomyelitis: role of radiography. Radiology 1987 Dec;165(3):781-4Matowe, L. and F. Gilbert. How to synthesize evidence for imaging guidelines. Clinical Radiology. 2004 (59): 63-68Pineda et al. Imaging of osteomyelitis: current concepts. Infect Dis Clin North Am. 2006 Dec;20(4):789-825 Lew, Daniel and Francis Waldvogel. Lancet 2004. Approach to imaging modalities in setting of suspected osteomyelitis. Up-To-Date, accessed 10/14/09Websites– http://emedicine.medscape.com/article/393345-overview– www.sportspodiatry.co.uk/foot_footanatomy.htm– www.usuhs.mil/fap/resources/imag/AnkleX-Rays