RadiographicOccultbonetrauma:CasePresentationandLiteratureReview

AnaCristinaManzanoDaz1

CarlosAlejandroGarcaGonzlez2

Summary

Thisarticlepresents13casesofpatientswithbonetraumaatthetimeoftheconsultation,

occult intheconventional radiographsandlater evidentinmagnetic resonanceimaging

(MRI),.Medicalrecordsofthesepatients,incaseswhereXraysorCThadbeenreported

asnormal,werereviewedPersistent pain, with functional impairment, unresponsive to

medical treatment was the most common feature leading to clinical indication of MRI.

KeyWords(MeSH)

OccultFracture

Xrays

Magneticresonanceimaging

Woundsandinjuries

Introduction

1MDRadiologist.DepartamentodeRadiologa,HospitalUniversitariodeSanIgnacioPontificiaUniversidadJaveriana,Bogot,Colombia.2RadiologistResidentIV,DepartamentodeRadiologa,HospitalUniversitariodeSanIgnacioPontificiaUniversidadJaveriana,Bogot,Colombia.

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Somebonelesionscausedbyacutetraumaorunusualmechanicalloadarenotdetectedon

conventionalradiographs,eitherbecausetheyareunapparentorduetodiagnosticerror.

Magneticresonanceimaging(MRI)hasbeenprovedtobeausefultooltodiagnosethese

occultXrayslesions,duetoitshighspatialresolutionandabilitytodiscriminatedifferent

typesof tissue(1).Thisdiagnostic methodis indicatedforstressfractures, avulsionor

hiddenfractures(2).Patients inwhichMRIhasbeenperformedforsuspectedmeniscal

injury, avascular necrosis or rotator cuff lesions, mayshow radiographic hiddenbone

lesionssuchasintraosseoustrabeculardisruption,edema,hemorrhageorstresslesionsof

thetibialplateau,femoralcondyles,acetabulum,proximalhumerus,amongothers(3).We

present 13 cases of patients with trauma whose bone lesions were unapparent on

conventionalradiographs,butevidentinmagneticresonanceimaging(MRI).

CASEPRESENTATION

Case1

Occult fracture of the scapular glenoid. 69 y.o patient with blunt trauma to his right

shoulder.Hecomesbackfivemonthslaterduetopersistenceofpain(Fig.1).

Case2

Occultfractureofthehumeralhead.45y.o.patientwithdirecttraumatohisrightshoulder.

Threemonthslaterhecomplainsofpersistentpainandrotatorcuffsyndrome(Fig.2).

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Case3

Avascularnecrosisofthelunate.60y.opatientpresentswithhyperextensiontraumatothe

wrist.Onemonthlatershecomesinduetopersistentpain(Fig3).

Case4

Occultfractureofthescaphoid.A45yearoldpatientwithhyperextensiontraumatothe

wrist.Severalmonthslatercomplainsofpersistenceofpain.(Fig.4)

Case5

Occult fracture of the inferior pubic ramus 73 y.o.woman hit by a car, whose initial

emergencyconsultationwasdiagnosedwithsofttissueinjuriesofthepelvis.8dayslater

duetopersistentpaininrighthipshecomesbacktotheemergencyroomwhereaCTscan

isordered..(Fig.5).

Case6

Occultfractureoftheacetabulum.79y.o.patientwithlefthipinjury.Hecamebackten

dayslaterasheremainssymptomatic,andanMRIwasperformed(Fig.6).

Case7

Occult fractureofthepatella.. 27y.opatient withblunttraumatohisrightknee.The

patientcontinuedwithpain,soMRIwereperformed,(Fig.7).

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Case8

Occultfractureofthetibialspine29y.o.axialtraumatohisknee.Duetothepersistentpain

andfunctionallimitation,MRIwasperformed(Fig.8).

Case9

Occultfractureofthetibialplateau.30y.o.patientwithrightkneeinjuryoccurredin a

trafficaccident.15dayslater,hereferspersistentpain,soanMRIwasperformed.(Fig.

9).

Case10

Occultfractureofthefibula.42y.o.patientpresentswithblunttraumatohiskneeafterin

amotorvehicleaccident.Theinitialradiographshowednofractures.Thepatientconsulted

againonemonthlaterduetopersistentpainandlimp(Fig.10).

Case11

Occultfractureofthetalus48y.o.patientpresents withtraumatohisheel afterfalling

froma1meterdistance.Painandfunctionalimpairmentpersist(Fig.11).

Case12

Bonecontusionofthecalcaneus.Apatientwith53yearsoldwhohasablunttrauma(axial

load)ofthefoot.Hehadaconsultationamonthlaterduetopersistentpain(Fig.12).

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Case13

Stressfractureofthetalus.Apatientwith56yearsoldwithpersistentpainintheankleand

nohistoryofobvioustrauma.T1sagittalMRIoftheankleshowedastressfractureofthe

talus(Fig.13).

Discussion

TraumaticboneinjuriesthatareocculttoconventionalXraysare:bonecontusion,stress

fracturesandfractures.

Bonecontusion

Bonecontusionorbruisingofthebone"isatrabecularboneinjurythatcanresultinpain

andfunctionalimpairment(1).Itisinvisibleonconventionalradiographs,asitrepresents

bonemarrowedemaandmicrofractures,withoutinterruptionofthecortexInMRIbone

contusions are readily evident as bone marrow edema and hemorrhage and appear

hyperintenseonT2weightedfatsuppressedimages,(1)(Case5).Itcanbeseenasearlyas

1to30hoursaftertheinjury(4),Theaveragetimeofclearanceofabonecontusionis42

weeks(5).

88%ofbonecontusionsinthekneedisappearin16months,butcanbepresentuptotwo

yearslater(6).Diffusionimages aremoresensitivethanspinechotechniquestoquantify

edema.Therearemanycausesofbonemorrowedema,includingbonecontusion,whichis

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oneofitsfewreversiblecauses.(7).Differentialdiagnosisincludeinfiltrative,neoplastic,

rheumatologicdiseases,,transientosteopenia,etc.

Ahistoryoftraumaisthemaindiagnostickey.Closefollowupofpatientsisadvisableto

ruleoutcomplications,sincebonecontusionscanprecedefracturesorarticularcollapse.

Nobonecontusionshouldbeconsideredinnocuous(8).Bonecontusionsareproducedby

directblow,axialcompressionofadjacentbonesortensileforcesinanavulsioninjury.

Locationofthebonecontusioncanpredictthemechanismoftraumaandassociatedlesions.

Traumainsportsinvolving kneeflexionandvalgusforces presentbonecontusionsof

lateralfemoralcondyleandlateraltibialplateauassociatedwithanteriorcruciateligament

tears(9).

Inwristtrauma,bonecontusions arecommon,occurring inupto63%ofpatientswith

normalradiographsandpersistentpain.Themostfrequentlyfracturedbonesarescaphoid,

thelunateandthetriquetrum,respectively(10).

StressFractures

Stressfracturesareinjuriesresultingfromrepetitivemechanicalforcesonnormalbone.

Earlyfindingsincludebonemarrowhyperemia,hemorrhageandedema.Ifabiopsyshould

beperformedinstressfracture inearly stages, it couldsuggestaneoplasm,duetothe

presenceofimmaturecellsintherepairingprocess(1).MRIalsocandetectbonemarrow

edemaandthefracturelineillbeidentifiedwhileabonescanshowsnonspecificuptake(1).

Xraysarenormal,inparticularatthisstage,whileT2weightedimagesarehighlysensitive

toidentifyboneedemaandT1andT2weightedimagesidentifythefracturelineextending

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through bone marrow and cortex.(Fig. 13). As time passes by, up to six weeks for

diaphyseal lesions and four weeks for metaphyseal fractures, The fracture can be

identifiedonlyinvolvingonecortex andmayormaynotbeassociatedwithperiosteal

reactionandsomeendostealboneformation(2).

Fractures

Aradiographically occult fracture is one that was initially unapparent on the Xray or

unnoticedbytheobserver (2). Thesemaybeincomplete ornondisplacedfractures (1)

usuallyinvolve epiphysisandmetaphysis,unlikestressfractureswhichoccurmostlyat

themetaphysis.On MRIitpresentsasalowsignallinearlesion(bestvisualizedinspin

echoT1andT2weightedimages),surroundedbyalargearea, ofpoorlydefined,bone

marrowedema(2)(cases18).Thefractureiscontinuouswiththecortexandextendsinto

thebonewithaperpendicularorientationtothecortexandthetrabeculaethatunderwent

theabnormal weightorforceofthetrauma.IlldefinedlowsignalareasonT1weighted

images or cortical irregularity may represent an osteochondral injury (2). All occult

fractures have a good clinical outcome and, on average, patients reintegrate to daily

physicalactivityinthreemonthstime(6).

Inthehandandwrist,themostcommonfractureoccursinyoungadultscaphoid,witha

highcomplicationrateofnonunion,delayedunionoravascularnecrosisofthisbone(11).

Iftheinitialradiographisnormalandclinicalsuspicionishigh,aCTscanorMRImustbe

performed(2).Inmanyclinicalsettingsthediagnosismaytakeuptotwoweeksormore

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beforethefracturebecomesapparentinthexray,duetoboneresorption(2).Treatment

consistsofsixmonthsofimmobilization(1114)(cases3and4).

Intheshoulder,occultfracturesofthegreatertuberosityarethemostfrequentandsimulate

rotatorcufflesionswhich,additionally,mayevencoexist.

Theyareusuallyunapparentwhenthereisnodisplacementoffragments(15)(cases1and

2).Thekneeisthejointmostofteninjured(2). Radiographicoccultbonelesionsofthe

kneehavean incidence of16%inMRI(8). Theyareusually located on thefemoral

condylesandthetibialplateau.Theymayextendverticallyandrarelycrossgrowthplates

(15). Avulsionfractures of the lowerpoleof thepatella occur mainly in the immature

skeleton of patients that practice vigorous knee extension. (2). MRI identifies a non

displacedfracture.Lesionsoftheposteriorlateralcomplex,thebicepstendonandlateral

collateralligament,areassociatedwithavulsionfractureofthefibularhead(2)(cases7

10).

Inthehip,theincidenceofoccultfracturesis2%10%inpatientswithpersistentpost

traumaticpain(11).InelderlypatientsitiseasilydetectedonMRI,whereasaCTscanmay

benormalinthefirstdaysaftertrauma(1).SomecentersperformasingleT1weighted

coronalimage,whenanoccultfractureissuspectedinthehip.Costislowercomparedto

othermorecomplexprotocolsandmaybediagnosticonitsown.(13)(Cases5and6).In

conventionalradiographs,theobturatorfatplanesigncanindicateanoccultfractureofthe

acetabulum(14).Italsoshouldbesuspectedinelderlypatientswithmildtraumatothehip

andposttraumaticpain(15).AMRIofthehipismuchmoresensitivethanconventional

radiographandCTscanstodiagnoseoccultfracturesofthehip(16).

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Italsoavoidsunnecessaryhospitalizationsanddelaysindefinitivetreatment(17).There

areevidencebasedalgorithmsfordiagnosesofoccultfracturesthattakeintoaccountthe

riskfactorsandtypeoftrauma.Identifiedriskfactorsinclude:femalegender,womenwith

osteoporosis, alcoholism, malnutrition, endocrine diseases, advanced age, steroid use,

inactivityandpoorcalciumintake(18).

Inthefootandankle,talarfractureoftenoccursatitsneckordome,indorsiflexionor

inversion trauma. Scaphoid fractures occur in athletes and are usually due to stress.

Diagnosiscantakeup4months(7)(cases11and12).

Inarecentcostanalysissegmentstudy204pediatricpatientswithtraumaandnormalinitial

radiograph were followed up. 13% had fractures and, of these, 29% had not been

adequatelytreated.Halfofthepatientsdidnthavefracturesandweretreatedasiftheyhad.

Thecostofperformingmagneticresonanceinalimitedtraumaprotocol(onlyoneT1and

T2weightedimages carriedoutinfiveminutes)iscomparablewiththedirectcostsof

inadequateinthesepatientsandcanbemuchlessthanthecostofadefinitivetreatment.If

alimitedtraumaprotocolMRIisperformed,tothesepatientstherewouldbeappropriate

immediatetreatment,especiallyimportantinchildrenwithhiddenSalterHarrisfractures,

withoutwastingresources(19).

Conclusion

The persistence of musculoskeletal pain that does not improve with the conservative

treatment,itisthemostcommonsituationthatleadstopatientconsultingagaintoexplore

itscauses.DisablingorpersistentpaininpatientsshouldbestudiedwithMRItoruleout

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occultbonelesions.Ourseriesofcasespointstotakespecialcareindetectinghiddenhip

fracturesinelderlypatients,andkneefracturesinyoungpatients.Wesuggestevaluating

thecosteffectivenessofMRI,performaunabbreviatedtraumaprotocol,forevaluationof

occultfracturesinaspecialgroupof highriskpatientsinsteadofwaitingforpersistent

chronicpain.

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Figures

Fig. 1. Occult fracture of the scapular glenoid. (A) The initial radiograph shows no

fracture. Coronal spinechoT1weightedMRI(b)showsthefractureof thesuperior

aspectoftheglenoid(arrow).

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http://www.ncbi.nlm.nih.gov/pubmed/19382319?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSumhttp://www.ncbi.nlm.nih.gov/pubmed/19382319?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSumhttp://www.ncbi.nlm.nih.gov/pubmed/19382319?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

Fig.2Undisplacedfractureofthegreatertuberosityofhumerus(N1).(A)Theinitial

radiographisnormal.CoronalspinechoT2weightedalowsignal fractureline(black

arrow)visiblealsointhePDimage.(c).

Fig.3.Avascularnecrosisofthelunate.(A)Theinitialradiographshowsnoabnormality.

CoronalspinechoT2MRI(B)shows hyperintensity(whitearrow)ofthelunatemedial

aspectdueavascularnecrosiswithcysticdegeneration.Notetheirregularityoftheulnar

insertionofthetriangularfibrocartilage,suggestiveoftear.

Fig.4.Occultfractureofthescaphoid.(A)Theinitialradiographshowsnoabnormality.

InCoronalspinechoT1weightedimage(B)showsthefractureofthescaphoidasalow

signalline(arrow)andcoronalSTIRT2weightedimage(c)showsaedemaofthebodyof

thescaphoid(arrow).

Fig.5.Occultinferiorpubicramusfracture.(A)Pelvisradiographshowsnofracture.)A

smallfracturewentunnoticedontheCTscan(b)(arrow).CoronalT2weightedimage(c)

showsedemaatthefracturesite(arrow).

Figure6.Occultfractureoftheacetabulum.(A)Hipradiographshowsnofracture.CT

coronal image of the pelvis is normal (b)l.Coronal T2 weighted MRI demonstrates(c)

edemaandthelowsignalsfractureline(arrow)intheanterioraspectoftheacetabulum,

Fig.7.Occultfractureofthepatella.(A)Conventionalradiographshowsintraarticular

fluid.MultisliceCTscanwas(b)readasnormal.CoronalspinechoT2image(c)shows 13

edema of the lower pole of the patella (white arrow In retrospect the fractures was

apparentontheCTscan,(whitearrow)asanavulsionfracture.

Fig.8.Occultfractureofthetibialspine.(A)Conventionalradiographshowsnofracture.

)CoronalmultisliceCtreformation(B)wasreadasnormal,althoughtherewasasubtle

fractureof themedial tibial plateaucortex(blackarrow). CoronalT2weighted image

showed(c)edemaandanondisplacedobliquefracture(whitearrow) ofthetibialspine

whichextendstothecortexoftheproximalmetaphysisofthetibia.

Fig.9.Occultfractureofthetibialplateau.(A)Initialradiographdoesntshowfractures.

T2weighted coronal image(B) shows edemaanda lowsignal line (arrow) in the

externaltibialplateau.

Fig.10.Fibularoccult fracture.(B)Theinitial radiographshowsnofracture.MRT2

weightedSTIRcoronalimagehidentifiesanextensiveedemaoftheheadofthefibula(c)a

lowsignalfracture(arrows),onthecoronalspinechoT1weightedimage.

Fig.11.Occultfractureofthetalus.(A)Theinitialradiographshowsnofracture.Sagital

spinechoT1images(b)demonstratesthetalarneckfractureasalowsignalline(arrow)

andsagittalT2weightedSTIRimages(c)showsassociatededema(arrows).

Fig.12.Calcaneusbonecontusion(a).Theinitialradiographshowednofractures.There

is anareaof sclerosis in theposterior tubercle of thecalcaneus which represents the14

fracture.Thecoronal(b)andsagital(c)STIRT2weightedimagesshowhighsignalofthe

posteriorlateralaspectofthecalcaneus,representingboneedema.

Fig.13.Stressfractureofthetalus.T1weightedcoronalMRIshowsalinearfractureof

thetalus.(arrows).

Contact

AnaCristinaManzanoDaz

HospitalUniversitariodeSanIgnacio

RadiologyDepartment

Carrera7No.4062,piso2

Bogot,Colombia

acmanzano@javeriana.edu.co

Receivedforevaluation:October4th,2009

Acceptedforpublication:November17th,2009

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