Heightened clinical utility of smartphone versus body-worn inertial system for shoulder function BB

17 Pages·2017·1.25 MB·English

RESEARCHARTICLE
Heightened clinical utility of smartphone
versus body-worn inertial system for shoulder
function B-B score
ClaudePichonnaz1,2*,KamiarAminian3,Ce´lineAncey1,Herve´Jaccard1,2,
EstelleLe´cureux4,CyntiaDuc3,AlainFarron2,BrigitteM.Jolles2,NigelGleeson5
1 PhysiotherapyDepartment,HauteEcoledeSante´Vaud(HESAV)//HES-SO,UniversityofApplied
SciencesWesternSwitzerland,Lausanne,Switzerland,2 ServiceofOrthopaedicsandTraumatology,
DepartmentofMusculoskeletalMedicine,UniversityHospitalofLausanne,Lausanne,Switzerland.,CHUV-
a1111111111 UNIL,Lausanne,Switzerland,3 LaboratoryofMovementAnalysisandMeasurement,EcolePolytechnique
a1111111111 Fe´de´raledeLausanne(EPFL),Lausanne,Switzerland,4 Directionme´dicale,CHUV-UNIL,Lausanne,
a1111111111 Switzerland,5 SchoolofHealthSciences,QueenMargaretUniversity,Edinburgh,Scotland
a1111111111
*[email protected]
a1111111111
Abstract
OPENACCESS
Background
Citation:PichonnazC,AminianK,AnceyC,
JaccardH,Le´cureuxE,DucC,etal.(2017) TheB-BScoreisastraightforwardkinematicshoulderfunctionscoreincludingonlytwo
Heightenedclinicalutilityofsmartphoneversus movements(handtotheBack+lifthandastochangeaBulb)thatdemonstratedsound
body-worninertialsystemforshoulderfunctionB-
measurementpropertiesforpatientsforvariousshoulderpathologies.However,theB-B
Bscore.PLoSONE12(3):e0174365.https://doi.
Scoreresultsusingasmartphoneorareferencesystemhavenotyetbeencompared.Pro-
org/10.1371/journal.pone.0174365
videdthatthemeasurementpropertiesarecomparable,theuseofasmartphonewould
Editor:AntoineNordez,UniversitedeNantes,
offersubstantialpracticaladvantages.Thisstudyinvestigatedtheconcurrentvalidityofa
FRANCE
smartphoneandareferenceinertialsystemforthemeasurementofthekinematicshoulder
Received:March25,2016
functionB-BScore.
Accepted:March8,2017
Published:March20,2017 Methods
Copyright:©2017Pichonnazetal.Thisisanopen Sixty-fivepatientswithshoulderconditions(withrotatorcuffconditions,adhesivecapsulitis
accessarticledistributedunderthetermsofthe andproximalhumerusfracture)and20healthyparticipantswereevaluatedusingasmart-
CreativeCommonsAttributionLicense,which
phoneandareferenceinertialsystem.Measurementswereperformedtwice,alternating
permitsunrestricteduse,distribution,and
betweentwoevaluators.TheB-BScoredifferencesbetweengroups,differencesbetween
reproductioninanymedium,providedtheoriginal
authorandsourcearecredited. devices,relationshipbetweendevices,intra-andinter-evaluatorreproducibilitywere
analysed.
DataAvailabilityStatement:All.xlsxfilesare
availablefromtheFigsharedatabase(https://
figshare.com/s/295439a2dba9bf9635be). Results
Funding:FundedbySwissNationalScience Thesmartphonemeanscores(SD)were94.1(11.1)forcontrolsand54.1(18.3)forpatients
FoundationGrantnumber135061http://p3.snf.ch/
(P<0.01).Thedifferencebetweendeviceswasnon-significantforthecontrol(P=0.16)
Project-135061.Thefundershadnoroleinstudy
andthepatientgroup(P=0.81).Theanalysisoftherelationshipbetweendevicesshowed
design,datacollectionandanalysis,decisionto
publish,orpreparationofthemanuscript. 0.97ICC,−0.6biasand−13.2to12.0limitsofagreement(LOA).Thesmartphoneintra-
evaluatorICCwas0.92,thebias1.5andtheLOA−17.4to20.3.Thesmartphoneinter-
Competinginterests:KamiarAminianiscofounder
ofGaitUpcompanyproviderofPhysilogusedasa evaluatorICCwas0.92,thebias1.5andtheLOA−16.9to20.0.
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
referencesysteminthestudy.Theotherauthors Conclusions
havedeclaredthatnocompetinginterestsexist.
TheB-BScoreresultsmeasuredwithasmartphonewerecomparabletothoseofanin-
ertialsystem.Whilesinglemeasurementsdivergedinsomecases,theintra-andinter-
evaluatorreproducibilitywasexcellentandwasequivalentbetweendevices.TheB-Bscore
measuredwithasmartphoneisstraightforwardandasefficientasareferenceinertialsys-
temmeasurement.
1.Introduction
1.1.Currentmethodsforshoulderfunctionevaluationinclinicalsettings
Theshoulderisthesecondmostfrequentlyaffectedbodysite[1].Thequalityoftoolsforthe
evaluationofshoulderfunctionisofprimaryinteresttoadequatelyaddresstheproblemsof
thislargepopulationandthereforelimittheimpactofshoulderpathologiesonpatientsand
society.Shoulderfunctionisusuallyevaluatedusingquestionnaires.Dozensofevaluation
toolsexistbutmosthavenotundergoneafullvalidationprocess[2,3].Thusthemeasurement
oftheshoulderfunctionaloutcomeremainsacontroversialissue.
Severalreviewsofliteraturehaveconcludedthatnosinglequestionnaireofshoulderfunc-
tionofferedsuperiorityregardingmeasurementproperties[3–5],whileoneconcludedthatthe
DASH(DisabilitiesoftheArm,ShoulderandHand)scorecomparedfavourablytootherques-
tionnaires[6].Asaconsequence,alargevarietyofoutcomemeasurementstoolshavebeen
used,hinderingthedevelopmentofscientificevidenceaboutthetreatmentofshouldercondi-
tions[2].
Clinicalquestionnaireshavetheadvantagesofhandinessandlowcost.Conversely,they
presentintrinsiclimitationsrelatedtolanguageandculturalissues,respondents’interpreta-
tionsandcontentvalidity[7,8].Thevalidationofquestionnaires’stranslationsintovarious
languagesisatime-consumingandcumbersomeprocess.Moreover,thedelineationbetween
objectiveandsubjectiveevaluationisnotalwaysclearlydefinedinquestionnaire-basedassesss-
ment,withbothapproachesproducingdifferentresults[9,10].
1.2.Computerizedshoulderfunctionevaluation
Laboratory-basedmovementanalysisovercomestheselimitationsanddisplayshighaccuracy
andprecision.Ithasthusbeenlargelyusedinresearchstudiesaimingatthecharacterization
andevaluationofshouldermotion.Mostmotionanalysisstudieshaveaddressedthedevelop-
mentofinnovativemeasurement’methodsmainlyandhaveinvestigateddifferencesbetween
healthyandpathologicalparticipants’groups.However,noneofthemhadproposedashoul-
derfunctionscorethatcouldbepossiblyusedtomonitorpatientclinicalevolution,tothebest
ofourknowledge.
Although3Dlaboratorymotionanalysissystemshaveassumedagrowingimportancein
research,it’stheirapplicationinclinicalsettingsthathasremainedlikelytobelimitedbycom-
plexityandcost.So,embeddedsystems,likeinertialmeasurementunits(IMU)havealsobeen
developedforshoulderevaluation,astheirportabilityandpracticalityfacilitatestheproce-
duresformeasurement.
Measurementsusingembeddedsystemsmayprovideawell-balancedcompromisebetween
practicalityandreliability.Theymaythusconstituteavaluablealternativetoquestionnairesor
laboratory-basedevaluation.Theembeddedsystems’resultsarehighlycorrelatedtolaboratory
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
measurementsanddisplayadequateaccuracyforclinicalevaluation.Also,theiruseisnot
restrictedtolaboratorysettingsandthemeasurementcompletioniseasier[11].Body-worn
sensorshavebeenappliedwithpromisingresults,tomeasurearmandshouldermovementin
variousconditions[12–20].
Despitethesimplificationofthemeasurementproceduresprovidedbybody-wornsensors
theiruseforshoulderfunctionevaluationhasremainedlimitedinclinicalsettings.Severalbar-
riersstillhinderthewide-spreaduseofsuchdevicesamonghealthprofessionals.Therequire-
mentsfortheroutineapplicationinclinicalpracticeareverydemandingas,inadditionto
measurementproperties,time,practicability,user-friendlinessandcostareofconcern.
Usingasmartphoneforevaluationpurposesmightcontributetomeetingtheserequire-
mentsandfacilitatingtheregularuseofcomputerizedmovementanalysisincurrentpractice.
Likeembeddedmeasurementsystems,mostsmartphonesarenowfittedwithbuilt-inacceler-
ometersandgyroscopes.Usingadedicatedapplication,theycanthusbeusedformovement
analysis.
1.3.Presentsmartphoneapplicationsforshoulderevaluation
Numeroussmartphoneapplicationshavebeendevelopedforpatientevaluation,patienteduca-
tionortoassisthealthcareprofessionalsintheirpractice.Theapplicationsaddressingthe
assessmentofshoulderrangeofmotion(ROM)generallydemonstratedadequatemeasure-
mentproperties[21–23].However,ROMisonlyonecomponentofshoulderfunctionandno
smartphone-basedassessmentscoreforshoulderfunctionhasbeenvalidatedtoourknowl-
edge.Thevalidationofsmartphone-basedoutcomeswouldbeofinterestbecauseofthehigh
prevalenceofshoulderconditionsandoftheexistingcontroversyaboutshoulderfunction
questionnaires.
Smartphone-basedevaluationinclinicalconditionsisvaluableonlyprovidedthatthemea-
surementpropertieshavepreviouslybeenvalidated.Thisismandatoryasimportantdecisions
aretakenbasedonclinicaloutcome.Thesmartphoneresultsmightpossiblydifferfrominer-
tial-basedsystemsasthesensors’featureshavenotbeenspecificallydesignedforscientific
measurement.Anextensivevalidationprocessisthusneededbeforeclinicalimplementation.
1.4.Inceptionofasmartphoneapplicationforshoulderfunction
Coleydevelopedashoulderfunctionscoringsystemusinginertialsensors.Heproposedarela-
tivelysimpleshoulderfunctionscorebasedonthreedimensionalmeasurementsofapower-
relatedmetricusingaccelerometersandgyroscopes(Pscore)[11].Theprocedurereliedona
sequenceofsevenfunctionalmovementsbasedontheSimpleShoulderTestfunctionalscore
[24].Thisapproachdemonstratedclinicalrelevancefollowingrotatorcuffandarthroplasty
surgery.Itclearlydiscriminatedhealthyfrompathologicalsubjects,wascorrelatedtoclinical
scoresanddisplayedgoodresponsiveness[11].However,thefulltestprocedurerequired
around20minutes,whichprecludedroutineapplicationinclinicalsettings.
Ko¨rveretal.[25,26]proposedakinematicscorebasedonangularrate(ARScore).This
scorerequiredlessthan5minutestoperformasitincludedonly“armtotheback”and“arm
behindthehead”movements.Itdemonstratedhighintra-andinter-evaluatorreproducibility,
withintraclasscoefficientofcorrelation(ICC)of0.95and0.91,respectively.Thediagnostic
sensitivitywas98%andthespecificity81%.However,thecriterion-basedvalidityforshoulder
functionevaluationwaslimited,ascorrelationswiththeDASHandSST(simpleshouldertest)
clinicalscoreswereweak[24,27].
ThelatterweaknesswasnotfoundfortheB-BScore,asimplifiedversionofPScoreinclud-
ingtwomovementsonly(handtotheBack&handupwardsasiftochangeaBulb)[28].This
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
scorewasdevelopedbasedonprincipalcomponentanalysisandmultipleregressionoftheP
Scoreoriginaldata.TheB-BScoreresultsshowednosignificantdifferencewiththePscore
duringthefirstyearaftershouldersurgeryandbothscoreswerehighlyrelated(R2>.97).The
diagnosticsensitivitywas97%andthespecificity94%forpatientsfollowingrotatorcuffsur-
geryorshoulderarthroplasty.Thecorrelationswithcurrentclinicalquestionnairesranged
from0.51to0.77,indicatingthattheB-BScorehadgoodcriterion-basedvalidityforshoulder
functionevaluation.Thus,thesimplifiedmodeliscomparabletothePScorebutpresentsprac-
ticaladvantagesthatfacilitatetheevaluationofshoulderfunctioninclinicalpractice.
Pichonnazetal.[29]investigatedthemeasurementpropertiesofasmartphone-basedver-
sionoftheB-BScoreinvariousshoulderpathologies.Diagnosticpower,responsivenessand
concurrentvaliditywithshoulderfunctionquestionnaireswereinsufficientforshoulderinsta-
bility,butwereappropriateforpatientsconservativelytreatedforrotatorcuffconditionsor
capsulitis,andpatientssurgicallyorconservativelytreatedforproximalhumerusfracture,
whencomparedtoacceptedclinimetricstandards.
Despitethesepromisingresults,itremainspresentlyunknownifthemeasurementobtained
usingasmartphonearecomparablethoseobtainedusingareferencehumanmovementanaly-
sissystemanddisplayequivalentreproducibility.Ifso,theuseofasmartphonefortheB-B
Scoremeasurementmightofferacost-effectiveandstraightforwardclinicaloutcome
measurement.
1.5.Studyaimandhypotheses
Theaimsofthisstudyweretoinvestigatethevalidityandreproducibilityofasmartphone-
assessedkinematicshoulderfunctionB-BScore,andtocomparetheperformanceofthe
smartphonetoareferenceinertialsystem.
Thus,thestudyhypothesisisthattheB-BScoremeetstherequirementsofavalidshoulder
functionscore.Thisimpliesthatthedifferencesbetweenthecontrolandthepathological
groupbutnotthedifferencebetweendevicesshouldbesignificant,theICCs(cid:21)0.80forinter-
device,intra-evaluatorandinter-evaluatorreproducibility,thelimitsofagreement(LOA)
betweendevices(cid:20)10%andthebias(cid:20)5%[30,31].TheB-BScoreresultsshouldalsobecoher-
entwiththoseofshoulderfunctionquestionnaires.
2.Materialsandmethods
2.1.Studysample
AprospectivecohortstudywasconductedbetweenAugust2011andMay2014attheDepart-
mentofTraumatologyandOrthopaedicSurgeryoftheUniversityHospitalofLausanne.Ethical
approvalwasgrantedbytheHumanResearchEthicsCommitteeoftheCantonofVaud
(CER-VD),protocolnumber205/10.Patientsgavetheirsignedinformedconsentforparticipa-
tioninthestudy.ThestudywasregisteredunderClinicalTrials.govIdentifier:NCT01431417.
Threehealthyparticipantswhereinadvertentlymeasuredwithinthetwoweeksprecedingthe
registrationdate.Themeasurementprotocolwasstrictlyidenticalforallparticipantsandwasin
linewithstudydeclaration.
Theincludedpatientswereadults>18yearold.Theypresentedwithoneofthefollowing
shoulderconditions,asrecordedduringtheirfirstmedicalconsultationatthespecialized
shoulderconsultationunitofthehospital:rotatorcuffcondition,adhesivecapsulitis,proximal
humerusfracturei.e.thepathologiesforwhichtheB-Bscoremeasurementpropertieswere
knownasappropriate[29].Withtheexceptionofpatientswithfracture,patientswhogave
theirconsentunderwentthemeasurementsessionwithintwoweeksfollowingmedical
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
consultation.Measurementswereperformed6weekspoststabilisationforpatientswith
humerusfracture,providedthattheradiologicalcontrolshowednormalconsolidation.
Fortherotatorcuffconditionorcapsulitis,patientswereselectedwhorequiredonlycon-
servativetreatment.AstheB-BScorehadpreviouslybeenvalidatedafterrotatorcuffand
arthroplastysurgery[28],itwasofinteresttoexploreitsvalidityindifferentpopulations.Sur-
gicalandconservativefracturetreatmentwereincludedinthesamegroupastheevolution
andfunctionalprognosisissimilarinbothpopulations[32].
Agroupofparticipantsyoungerthan35years-oldwithouthistoryofshouldercondition/
pain,wasalsoincludedtoevaluatetheperformanceinahealthypopulationandthestabilityof
thescore.Theseparticipantswereselectedpurposefullytobeyoungerthanthepatientsto
avoidbiasrelatedtothehighprevalenceofasymptomaticrotatorcufftearabove40yearsold
[33].
Thesamplesizecalculationwasbasedonthedataofapilotstudythatincluded7controls
and16patients.Thecalculationwasmadesothat,withasignificancelevelatP<0.05,the
powerof0.80wasreachedwhentheminimalstandardsforacceptablepropertiesofthescore
weremet.Fourty-sixpatientswererequiredconsideringalowestacceptableICCof0.80,corre-
spondingtoasubstantialcorrelation,andanexpectedICCof0.90fortwomeasurements[31,
34].Ninepatientswererequiredtogettheexpectedpowerforthedifferencebetweenthe
patientsandthecontrolgroup[35,36].Aconsiderablylargersamplewasenrolledtogetpre-
ciseestimationsofresultsandtoallowsubsequentsubgroupanalysisinfurtherinvestigations.
Exclusioncriteriawerebilateralshoulderconditions,anyconcomitantpainorcondition
involvingtheupperlimborcervicalspine,medicalcontraindicationtoexecutemovements
requiredforscorecompletion,tumour,neurologicalconditioninterferingwiththetestandan
insufficientlocallanguageleveltogivetrulyinformedconsentortounderstand
questionnaires.
2.2.B-BScorecalculation
TheB-BScorewascalculatedaccordingtothemethoddescribedinPichonnazetal.andColey
atal.[11,28].Apower-relatedparameterwasextractedfromtherecordedsignals:therangeof
accelerationwasmultipliedbytherangeofangularvelocity,withameasurementunitof
[(deg/s)×(m/s2)],foreachmovement.Thisparameterwascalculatedforeachaxisandfor
eachmovementoftheB-BScore(“handtotheBack”movementand“lifthandastochangea
Bulb”movement)andadded,separatelyforeachsideandforeachmovement.Theratioofthe
performanceoftheaffectedsiderelativetothehealthyside(orthedominantsiderelativeto
thenon-dominantsideforhealthyparticipants),expressedinpercentage,wasthencalculated
foreachofthetwomovements.Thevaluesofthemovementswerethenweightedusingthe
equation:B-BScore=16.71+0.32xhandtotheBack.+0.45xlifthand.
Onehundredpercentrepresentsaperfectbalanceincapabilitybetweensidesandthescore
decreasesinaccordancewiththeseverityoffunctionalloss.Forexample,whileatypical
healthypersonperformsnearto100%,theaveragepatientmightreach46%beforesurgery,
67%at3monthsand71%at6monthsaftersurgery.
2.3Experimentalsystem:Smartphone
Asmartphone(iPod1,Apple,Cupertino,USA)waschosenasthesupportdeviceforthedevel-
opmentoftheapplication.Itwasfittedwith3Dbuilt-insensors(Accelerometers:±2gpreci-
sion:±0.02g;Gyroscopes:±500deg./sprecision:±0.2deg./s;Samplingfrequency:100Hz)
[37].Anapplication,callediShould(instrumentedshouldertest)wasprogrammedinObjec-
tive-C[38,39].Thisapplicationenabledtheacquisitionoftheaccelerationandangular
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
Fig1.SchemaoftheapplicationstepsfortherecordingofaB-Bscore.From:PichonnazC,DucC,GleesonN,AnceyC,
JaccardH,LecureuxE,etal.MeasurementPropertiesoftheSmartphone-BasedB-BScoreinCurrentShoulderPathologies.Sensors
(Basel).2015;15(10):26801-17.
https://doi.org/10.1371/journal.pone.0174365.g001
velocitysignalsduringthemovementsoftheB-BScoreandthecomputationoftheB-BScore
value,asdescribedintheFig1.Oncetheapplicationwaslaunched,thesmartphoneprovided
instructionstotheuser,throughthesmartphoneloudspeaker,whentoperformascoremove-
ment.Foreachscoremovement,theapplicationrecordedtheaccelerationandangularveloc-
itysignalsforapredefinedperiodof10sec.Themovementswerefirstperformedwiththe
healthysideandthenrepeatedwiththepainfulside.Attheendofthetest,theB-BScorewas
directlycalculated,displayedonthesmartphonescreenandthenstoredonthesmartphone.
Theapplicationenabledexportingofallsaveddatatoacomputerforitsdirectcomparison
withthedatafromtheinertialsensorsofthereferencesystem.
2.4Referencesystem
Thereferencesystemforbody-wornmovementanalysiswascomposedof2inertialsensors
andadataloggersystem(Physilog1,GaitUp,LausanneSwitzerland).
Eachinertialsensorincludedthreedimensionalaccelerometersandgyroscopes(Acceler-
ometers:Analogdevice,ADXL210,±5g,precision:±0.2%ofFullScale;Gyroscopes:Analog
device,ADXRS250,±400deg/s,precision:±0.1%ofFullScale).Thedeviceresolutionwas16
bitsandthesamplingfrequencywas200Hz.
AninertialmeasurementsystemwasusedasareferenceinthisstudybecausetheB-BScore
hasbeenpreviouslydevelopedbasedonthisapproach,andbecauseinertialsensorsprovide
directmeasurementsofangularvelocitiesandaccelerationsusedinthescorecalculation.Ini-
tialstudytry-outsshowedthattheinfluenceofmeasurementerrors(offset,sensitivityordrift)
wasnegligibleinthestudycontext.
2.5.Measurementprocedure
Theinertialsensorsofthereferencesystemwereplacedoneachhumerus,3cmabovethe
midpointofthelineconnectingthelateralepicondyle(EL)andmedialepicondyle(EM).The
sensor’saxeswerealignedtotheanatomicalframeofthehumerusfollowingtheISBrecom-
mendations[40,41]:Yhonthelineconnectingthegleno-humeral(GH)jointandthemid-
pointofELandEM,pointingtoGH;XhonthelineperpendiculartotheplaneformedbyEL,
EMandGH,pointingforward;ZhonthelineperpendiculartoXhandYh,pointingtothe
right(Fig2).Thesmartphonewasalsoattachedtothebackofthearmwithanarmband.The
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
Fig2.Inertialsensorsandsmartphoneplacementandaxes.(a)Theinertialsensormodule(Physilog®
referencesystem)attachedtothearmwithmedicaltapeandconnectedbycabletothedataloggercarriedon
wait.Thesmartphoneisattachedtothearmwiththearmband.(b)Testcompletionof“handtotheceiling”.
https://doi.org/10.1371/journal.pone.0174365.g002
loweredgeofthesmartphonewasset3cmabovetheupperedgeoftheinertialsensors’mod-
ule[29].Similartopreviousworkangularvelocitiesandaccelerationsinthesensorframehave
beenusedtocalculatetheB-BScore[11,28].
Aftersetting-upofthesystems,theparticipantswatchedavideo-recordeddemonstration
oftheexecutionoftheB-BScore.Theywereinstructedtodothemovementsinthepainfree
ROM,attheirself-selectedspeedandintheirnaturalway.Thestartingpositionwasthearm
alongsidethebody,inarelaxedposition.Movementswereexecutedinastandingpositionfol-
lowingthesmartphone-recordedinstructions.Thepatientsundertookfirst3repetitionsofthe
twoB-BScoremovementsonthehealthyside(puthandtotheback+handtotheceilingasto
changeabulb)andthenrepeatedthetaskonthepathologicalside.Thecontrolsexecutedthe
sameprocedurebeginningonthedominantside.
Themeasurementprocedurewasrepeatedtwicealternatingbetweentwoevaluators.All
evaluatorswereexperiencedphysiotherapistsengagedintheproject,whohadpreviouslybeen
trainedtothescorecompletion.Thefirstevaluatorwasrandomlyassigned.Allmeasurement
systemsweredetachedforinter-evaluatoradministrationofassessmentstoaccountforthe
variabilityinducedbypossibleinconsistentsensors’placementinclinics.Thescorewascalcu-
latedbasedonthemeanofthe3replicationsbecausethepilotstudyshowedthatthevariability
wasnotsignificantlydifferentwithahighernumberofrepetitions.
Clinicalquestionnaireswerealsocompleted.Threecurrentlyusedshoulderfunctionques-
tionnaires[QuickDisabilitiesoftheArmandShoulderscore(QuickDASH),Simpleshoulder
test(SST),ConstantscoreandConstantrelativescore(basedonanage-andsex-matchednor-
malpopulations)],theEuroQolgenericqualityoflifequestionnaire[EQ-5D]andthepain
visualanalogscale(VAS)[24,42–44].TheConstantScorewasundertakenaccordingtothe
modifiedguidelinesofConstant[45].Theshoulderfunctionquestionnaireswereselected
becausetheyrepresentcurrentstandards[3,4,46,47].Theyallowedtheevaluationofthecon-
currentvalidityfortheB-BScorebutnotofitsvalidityagainsta‘goldstandard’,duetothe
controversysurroundingshoulderfunctionevaluation.
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
2.6.Analysis
Descriptivestatisticsincludingmean,standarddeviation(SD)andboxplotswereperformed
forpatients’characteristicsandoutcomesofbothgroups.ThedifferencebetweentheB-B
ScoresmeasuredbyeachdevicewasevaluatedusingtheWilcoxonrank-sumtest.Therelation-
shipbetweentheB-BScoresofeachdevice,andtheintra-andinter-evaluatorreproducibility
wereevaluatedusingtheICC,measurementerror(ME:standarderrorofthemeandiffer-
pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ence),standarderrorofmeasurement[SEM:ðpooledSD(cid:2) 1(cid:0) ICCagreementÞ]andBland
andAltmanLOAanalysis.Intra-evaluatorreproducibilitywascalculatedcomparingthe1st
withthe2ndscoreobtainedbythesameevaluator,forthetwoevaluators.Inter-evaluator
reproducibilitywascalculatedcomparingthescoreobtainedbyoneevaluatorwiththescore
bytheotherevaluator,forthe1stand2ndevaluator’smeasurement.TheShapiro–Wilktestand
Komolgorov-Smirnovtestswereusedforthenormaldistributionanalysis.Thediscriminative
powerwasevaluatedbythesignificancelevelforthedifferencesbetweengroups(Mann-Whit-
ney)andbetweenstages(Wilcoxon).
3.Results
3.1.Studysample
Twentyhealthyparticipantsand65patients(20withrotatorcuffcondition,23withfractures,
22withcapsulitis)wereincluded.
Thepopulationcharacteristicsandthesignificanceofthedifferencesbetweengroupsare
describedinTable1.
3.2.Scoreoutcome
Theoutcomesofthecontrolgroupandthepatientgroup,forthesmartphoneandtherefer-
encesystem(Physilog1),respectively,arepresentedinTable2andinFig3.
Thedifferencebetweenthecontrolandthepatientgroupwassignificantforthereference
systemandthesmartphone(P<0.01).
Thedifferencebetweenthereferencesystemandthesmartphonewasnon-significantfor
thecontrol(P=0.16)andforthepatientgroup(P=0.81).
3.3.Measurementreproducibility
TheShapiro-WilkandKomolgorov-Smirnovtestsconfirmedthenormaldistributionofdata
(P>0.05)inthepatientandinthecontrolgroup,regardlessofdevice.Thenumericaland
graphicalpresentationsofreproducibilityofmeasurementforinter-devicesandintra-and
inter-evaluatorcomparisonarepresentedinTable3andFig4.
Table1. Participants’characteristics.
Patient(n=65) Control(n=20)
Agemean(SD),years 58.5(14.2)** 28.2(6.2)
Sex(%women) 63 50
Weightmean(SD),kg 75.2(15.8) 74.7(17.4)
Bodymassindexmean(SD),kg/m2 26.6(5.8) 24.2(3.9)
Sizemean(SD),m. 1.68(0.10) 1.75(0.10)
Handdominance(%right-handed) 92 90
Affectedside(%dominantside) 43 -
**Significantdifferencebetweengroupswithp-value<0.01.
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
Table2. MeanandstandarddeviationofB-BScoreusingthesmartphoneandthereferencesystem.
Unitofscoresare%representingtheperformanceofthepathologicalsidecomparedtothehealthyside.
Mean(SD),% Referencesystem Smartphone
Min;max
Control 97.0(13.8) 94.1(11.1)
79.5;125.2 71.9;115.7
Patient 54.0(19.0) 54.1(18.3)
21.5;114.5 21.7;108.2
Legend:SD:standarddeviation;Min:minimummeasuredvalue;Max:maximum
measuredvalue.
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3.4.Clinicalquestionnaires
Theresultsofshoulderfunction,painandqualityoflifequestionnairesarepresentedinTable4.
4.Discussion
ThisstudyfocusedonthedevelopmentandvalidationoftheshoulderfunctionB-BScore
measuredbymeansofasmartphone.Usingshoulderfunctionscoresderivedfromadedicated
Fig3.B-BScoreoutcomeinbothgroupsusingthereferencesystem(Physilog®)andthe
smartphone.
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Validityofthesmartphone-basedmeasurementoftheshoulderfunctionB-Bscore
Table3. Inter-devicesandintra-andinter-evaluatorreproducibilityofthemeasurements.
ICC(95%CI) LOA(%) Bias(95%CI) ME(%) SEM(%)
Inter-devices 0.97(0.94–0.98) -13.2to12.0 -0.6(-0.9to1.1) 0.7 4.0
Intra-evaluator
Smartphone 0.92(0.89–0.94) -17.4to20.3 1.5(0.0to2.9) 0.7 6.6
ReferenceSystem 0.92(0.89–0.94) -19.3to19.6 0.1(-1.4to1.6) 0.8 6.6
Inter-evaluator
Smartphone 0.92(0.90–0.94) -16.9to20.0 1.5(0.1to3.0) 0.7 6.6
ReferenceSystem 0.93(0.91–0.95) -18.1to20.0 1.0(-0.5to2.4) 0.7 6.4
ICC:intraclasscoefficientofcorrelation;95%CI:95%confidenceinterval;LOA:limitsofagreement;ME:measurementerror;SEM:standarderrorof
measurement
https://doi.org/10.1371/journal.pone.0174365.t003
smartphoneapplication,thestudyaimedatthetechnicalandclinicalvalidationofthemwithin
variousshoulderpathologies.Providedthatthescoreisvalid,itcanofferavaluablealternative
toconcurrentassessmentmethodsasitisaccessibleandquicklyperformed.
4.1.Devicescomparison
Thereferencesystem(Physilog1)andthesmartphoneproducedcomparableB-BScoreout-
comesregardinggroupmeasurements.Althoughthespecificitiesofthemeasurementsystems
weredifferent,e.g.sensorsnoise,sensorrangesandsamplingfrequency,thesmartphoneper-
formanceappearedtobesufficientforthescores’propermeasurement.Themeandifferences
betweenthedeviceswerenon-significantandoflimitedmagnitude(0.0%forthepatient
groupand2.9%forthecontrolgroup).Thesedifferencesareminorinproportiontothe42.9%
and40%differencebetweenthepatientandthecontrolgroup,forthereferencesystemand
thesmartphone,respectively.
Anexcellentrelationshipwasfoundbetweenmeasurementsfromthedevices(ICC0.97).
Moreover,theBlandandAltmananalysisdemonstratedthatthesystematicerrorofthesmart-
phonewasminor.TheMEandSEMwereacceptablewhenconsideredinrelationtothemini-
mum-maximumrangeofthescoresinthestudysample.Conversely,theLOAexceededthe10%
criterionthathaddefinedthethreshold.Thus,thePhysilogandtheiPodareinterchangeablefor
groupmeasurement,butthemagnitudeoftheLOAmightprecludethedevices’routineexchange.
4.2.Groups’comparison
Therewerenodeviationsawayfromtheplannedsamplingforthisstudy.Nosignificantdiffer-
encewasobservedbetweenthegroups,exceptforage.Thecontrolgroupwaspurposefully
youngerthanthepatientgroupasitwasofprimaryimportancethatthereferencepopulation
hadhealthyshoulders.Thepatientcharacteristicswererepresentativeofthepopulationcom-
monlytreatedforshoulderpain[1,48].
TheB-BScoredifferencebetweenthecontrolandthepatientgroupswashighlysignificant
regardlessofthedevice.Hence,theB-BScoreclearlydiscriminatedthepatientgroupfromthe
healthygroup.
4.3.Scorereproducibility
Theintra-andinter-evaluatorreproducibilitywasexcellent(0.92to0.93)andcomparable
betweendevices.Asshownbythenon-significantdifferencebetweenB-BScorescomputed
fromreferenceandsmartphonedevicesandbythesmallbias(<1.5%)derivedfromtheBland
PLOSONE|https://doi.org/10.1371/journal.pone.0174365 March20,2017 10/17