Rev. bras. ortop. vol.51 número3

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r e v b r a s o r t o p . 2016;51(3):374–377

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

w w w . r b o . o r g . b r

Case

report

Stress

fracture

in

acetabular

roof

due

to

motocross:

case

report

夽

Alexandre

de

Paiva

Luciano

∗

_,

_Nelson

_Franco

_Filho

DisciplineofOrthopedicsandTraumatology,SchoolofMedicine,UniversidadedeTaubaté,Taubaté,SP,Brazil

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r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received14May2015

Accepted11June2015

Availableonline2April2016

Keywords:

Stressfracture

Acetabulum

Athleticinjuries

a

b

s

t

r

a

c

t

Oneofthefirststepstobetakeninordertoreducesportsinjuriessuchasstressfracturesis

tohavein-depthknowledgeofthenatureandextentofthesepathologicalconditions.We

presentacasereportofastressfractureoftheacetabularroofcausedthroughmotocross.

Thistypeofcaseisconsideredrareintheliterature.Thedescriptionoftheclinicalcaseisas

follows.Thepatientwasa27-year-oldmalewhostartedtohavemedicalfollow-upbecause

ofuncharacteristicpaininhislefthip,whichwasconcentratedmainlyintheinguinalregion

ofthelefthipduringmotocrosspractice.Afterclinicalinvestigationandcomplementary

tests,hewasdiagnosedwithastressfractureoftheacetabularroof.

eTraumatologia.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://

creativecommons.org/licenses/by-nc-nd/4.0/).

Fratura

de

estresse

no

teto

acetabular

por

motocross:

relato

de

caso

Palavras-chave:

Fraturasdeestresse

Acetábulo

Traumatismosematletas

r

e

s

u

m

o

Umdosprimeirospassosparasereduziremlesões,comoafraturadeestressenoesporte,

éconhecermosenosaprofundarmosnoestudodanaturezaeextensãodessapatologia.

Aseguirapresentamosumrelatodecasodefraturadeestressenotetoacetabularpor

motocross.Casoconsideradoraronaliteraturaconsultada.Descric¸ãodoquadroclínico:

pacientede 27anos; masculino, iniciouseguimentomédicopor dores incaracterísticas

noquadrilesquerdo,concentradasprincipalmentenaregiãoinguinaldoquadrilesquerdo

duranteapráticademotocross.Apósinvestigac¸ãoclínicaeporexamescomplementares,

diagnosticou-sefraturadeestressenotetoacetabular.

OrtopediaeTraumatologia.Este ´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND

(http://creativecommons.org/licenses/by-nc-nd/4.0/).

夽

StudycarriedoutattheDisciplineofOrthopedicsandTraumatology,FaculdadedeMedicina,UniversidadedeTaubaté,Taubaté,SP,

Brazil.

∗ _{Corresponding}_author_.

E-mail:paivaortopedia@gmail.com(A.dePaivaLuciano).

http://dx.doi.org/10.1016/j.rboe.2016.03.004

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rev bras ortop.2016;51(3):374–377

375 Introduction

Stressfracture isaboneinjurycausedbytheinability ofa

bonetowithstandchronicoverload,amongotherreasons.1,2

Itdiffersfromtraumaticfracturesinosteoporoticbones.We

canalsodefinestressfractureasaninadequateadaptationof

theboneinresponsetothemechanicalloads.3_Microscopic

fis-suresinbonemorphology,withoutrestfrommechanicalloads

andwithoutadequatetimefortheirrepair,mayresultinstress

fracture.3

The first clinical description of stress fractures was

reportedbyBreithaupt,aGermanmilitarysurgeonin1855,

apudArmstrongetal.4_Stechow_reported,_in_1897,_apud

Arm-strong et al.,4 _the _first _radiographic _confirmation _of_stress

fracturesinmilitaryrecruits,thefractureofametatarsalbone.

ThediagnosisremainedonlyamongthemilitaryuntilPirker

apudArmstrongetal.,4_Iwamoto_and_Takeda5_reported_the_first

stressfracturediagnosisinathletes,atransversefractureof

thefemoraldiaphysisin1934.

There has been an exponential growth of motocross

practice throughout the world, with an increase also in

the number of amateur practitioners. Due to the extreme

physical and physiological demands associated to worse

physicalfitness,amateurridersoftensufferfromfatigue.A

localizedmusclefatiguemay resultininadequate function

on demands that are specific to the sports modality, thus

affectingthe performanceand resultinginmusculoskeletal

injuries.6

Motocrosscompetitionsare usuallycarriedoutinclosed

tracks with distances that can reach 1500m. These tracks

incorporatenaturalterrainfeatureswithvaryingnumbersof

jumpsandcurves.Peopleunfamiliartothesportoftenassume

thatthepilotdoesnothingmorethandriveamotorized

vehi-clearoundafield.However,motocrossplacesahighdegree

ofphysicalstresson the upperlimbsand gluteusmuscles

(Fig.1).

Wereportacaseofstressfractureoftheacetabularroof

duetomotocrosspractice.

Fig.1–Motocrossbiomechanics,jumpsandcurves.

Clinical

case

description

A27-year-oldmaleamateurmotocrossrider,searched

med-ical attention due to uncharacteristic pain in his left hip,

concentratedintheinguinalregionduringmotocrosspractice

duringamonth.Hedeniedchronicmedicationuse,previous

surgeriesorpreviouslydiagnosedchronicdiseases.

Thepatientcompetedinamateurclosed-circuitraces,with

distances ranging from 1200 to2500m, including frequent

jumps,alwayswhilewearingpersonalprotectiveequipment.

Hehadtrainingsessionsthreetimesaweekandcompetitions

ontheweekends,whichlastedbetween15and30min.

Physicalexaminationatadmissionshowedweight70kg,

height1.75m,BMI=22.87,withnoabnormalfacies.

Physicalexaminationofthelefthip:

• Inspection:mildlimpingduringgait;withoutatrophies. • Palpation:nopainonpalpationofboneandsofttissue

struc-turesoftheanterior,lateral,posteriorandmedialregionsof

thelefthip;

• Specific tests: Trendelenburg: negative; Ludloff: negative;

Thomas:negative;Ober:negative.

• Degreeofmobility:extension0◦–30◦,flexion0◦–120◦,lateral

rotation0◦_–45◦_, _medial_rotation ₀◦_–35◦_, _abduction₀◦_–50◦_,

adduction0◦_–30◦_.

• Neurologicalstrengthtest:GradeV:fullmotionagainstgravity

andagainstgreatresistance.

Concomitantly, imagingtestswererequested:hip

radio-graphy on 03/03/2011 disclosed no signs of fracture, no

abnormalitiesintheacetabularversionangle,andno

defor-mities.Duetothelackofrelevantinformationsobtainedby

radiographies,hipMRIwasrequestedandperformedonthe

sameday(Fig.2).

Discussion

Publicationsonthephysicalandphysiologicalstressobserved

inmotocrosspilotsafteranofficialcompetitionand/or

tech-nicalandtacticaltrainingarestillscarce.Thus,tounderstand

theneuromuscularandbiomechanicalvariablesofthissports

modalitycanbeoneofthefirststepstoreduceinjuriessuch

asstressfractures.

Stressfractureshavebeendescribedinmanysports

modal-ities,suchasathletics,tennis,basketball,volleyball,football

andbaseball.7,8_However,_we_found_no_articles_in_the_literature

onstressfracturesintheacetabularroofcausedbymotocross

practice,whichdemonstratestherarityofthereportedcase.

Thereare severalfactorsforriskofstressfracture. They

aredividedintointrinsic(gender,age,ethnicity,andmuscle

strength),extrinsic(trainingregimen,footwear,training

sur-faceandtypeofsport),biochemical(bonemineraldensityand

bonegeometry),anatomical(footmorphology,leglength

dis-crepancyandkneealignment),hormonal(delayedmenarche,

menstrualdisorders and contraceptiveuse)and nutritional

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376

rev bras ortop.2016;51(3):374–377

Fig.2–LinearhyperintenseimageonT2andSTIR sequences,surroundedbyareaofedemawithpoorly definedlimits;acetabularroofstressfractureissuggested.

Stressfracturesusuallyoccuringroupsofyoung

individ-ualssubmittedtointensephysicalactivities.Thetibiaisthe

mostcommonsiteofinvolvementinathletesandaccounts

for50%ofthetotalcases.However,thefracturelocationvaries

dependingonthesportsmodalitypracticed.8

Theplainradiography isthe first imagingmethod used

inmostcasesand allowsassessingprobableabnormalities

on the acetabular version angle, an important differential

diagnosis forthe stress fracture. However, Magnetic

Reso-nanceImaging(MRI) isthe superior diagnosticmethod for

assessmentofstressfractures, withcomparablesensitivity

andhigherspecificitythanscintigraphy.Itcandemonstrate

the presence of fracture in cases where the conventional

radiographyisconsiderednormal.9_MRI_is_more_specific_than

scintigraphyindetectinghipstressfractures,differentiating

themfromothercausesofboneandsofttissuepain,suchas

avascularnecrosis,bursitisandiliopsoastendonitis.9–11

Williamsetal.12_demonstrated_the_importance_of_magnetic

resonanceimagingandscintigraphyinthediagnosisofstress

fracturesoftheacetabularroof.Theyevaluated178active

mil-itary personnel witha history of hip pain associatedwith

physical activity through plainhip and pelvis radiographs,

whichwereinterpretedasnormal.MRIandbonescintigraphy

showed that12of178patients (6.7%)hadimagingfindings

compatiblewithacetabularstressfracture.Twopatternswere

identified.Sevenofthe12(58%)patientshadstressfractures

ofthe acetabularroof. Inthis group,two casesofbilateral

stressfractureoftheacetabularroofwereidentified.Andfive

of12(42%)patientshadanteriorcolumnacetabularfractures,

whichrarelyoccurinisolationandalmostalwayswithastress

fractureofthelowerpubicramus.12_This_demonstrates_the

rar-ityandhowdifficultisthediagnosisofstressfractureofthe

acetabularroof.

Thediagnosisofhipstressfracturesmustbeconsideredin

anyathletewithhipand/ortheproximalportionofthethigh

pain,especiallyinsportsinvolvingjointimpact.Stress

frac-turescanalsobeobservedinthesacrumandtheischialramus,

neartheinsertionofthesemimembranosus,semitendinosus

andbicepsfemoristendons.10,11

Wedidnotfindaconsensusregardingthetreatmentof

stress fractures of the acetabular roof in the assessed

lit-erature. Therefore, forthiscase,weadoptedthe treatment

protocol formost of stress fractures in athletes. The

frac-turedescribedinthiscasewasconsideredtobeoflowrisk,

similar tomoststressfractures.13,14 _These _fractures_can_be

treatedwithatwo-stageprotocol.13,14_Stage₁_is_{characterized}

bypaincontrolthroughtheprescriptionofanalgesics,

reduc-tion oreliminationofsportsgesturesthatcausesymptoms

andintroductionofphysicaltherapymodalities.Ifthe

indi-vidualisunabletowalkwithoutpain,he/sheshouldremain

immobilized,forinstance,witharemovablestabilizing

ortho-sisand/orapairofcrutches.

Amodifiedactivitythatcanmaintainthephysicalstrength

andfitness,butwithreducedimpact,isprescribed.Activities

suchasrunningintheswimmingpool,ellipticalexercises,free

andstationarybicyclecanmaintainthephysicalstrengthand

fitness, beforethereintroductionofimpactexercises.

Exer-cisesinwaterandanti-gravityonescanbeusedasaresource

tograduallyreintroducesportsgestures.13,14

Phase 2ischaracterizedbyphase1interventionsplusa

gradualreturntosportspractice,tobestartedwhenthe

ath-lete has no pain and normal mobility, around 10–14 days

aftersymptomonset.Thetimetoresumethesports

move-mentsdependsonmanyfactors,includingtheseverityand

chronicity of the injury and functional morbidity level of

theathlete.13,14_For_this_patient,_treatment_started_with_pain

control through analgesic prescription, discontinuation of

motocrosspracticeandanyimpactactivity,followedby

phys-icaltherapy.Reintroductionofthesportsgesturebeganafter

symptomssubsidedandMRIcontrolwasperformed90days

aftersymptomonset,withgoodprogression.Heresumedfull

trainingafter120daysandreturntoraces180daysafter

begin-ningtreatment.

Conflicts

of

interest

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microstructureontheinitiationandgrowthofmicrocracks.J OrthopRes.2005;23(2):475–80.

3. BurrD,MigromC.Musculoskeletalfatigueandstress fractures.BocaRaton,FL:CRCPress;2001.

4. ArmstrongDW3rd,RueJP,WilckensJH,FrassicaFJ.Stress fractureinjuryinyoungmilitarymenandwomen.Bone. 2004;35(3):806–16.

5. IwamotoJ,TakedaT.Stressfracturesinathletes:reviewof196 cases.JOrthopSci.2003;8(3):273–8.

6. AvelaJ,KyröläinenH,KomiPV.Neuromuscularchangesafter long-lastingmechanicallyandelectricallyelicitedfatigue.Eur JApplPhysiol.2001;85(3–4):317–25.

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9.StollerDW,MaloneyWT,GlickJM.Thehip.In:StollerDW, editor.Magneticresonanceimaginginorthopaedics&sports medicine.SanFrancisco:Lippincott;1997.p.93–202.

10.KneelandJB.MRimagingofsportsinjuriesofthehip.Magn ResonImagingClinNAm.1999;7(1):105–15.

11.ResnickD,KangHS.Pelvisandhip.In:ResnickD,KangHS, editors.Internalderangementofjoints.SanDiego:Saunders; 1997.p.473–554.

12.WilliamsTR,PuckettML,DenisonG,ShinAY,GormanJD. Acetabularstressfracturesinmilitaryenduranceathletes andrecruits:incidenceandMRIandscintigraphicfindings. SkeletRadiol.2002;31(5):277–81.

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