Design and mechanical behavior of the MD series of bone dowels

154 Pages·1999·5 MB·English

by  Bianchi, John R.

DESIGNANDMECHANICALBEHAVIOROFTHEMDSERIESOFBONE
DOWELS
By
JOHNR.BIANCHI
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1999
ThisdissertationisdedicatedtoDominickandJeanBianchi,whoraisedmetofillthe
spacebetweenmyears;tomybrother,Michael,whohassomehowmanagedagreat
excuseinNOTgoingtoanothergraduation;andtomywife,Laurie,whohasmanagedto
findherselfinanother. Oneofthemostunselfishactsonehumanmaydofortheotheris
tosharethegiftoforganandtissuedonation. Thisresearchisdedicatedtothememory
ofthedonorsandtheirfamilies. Forifithadnotbeenforthem,thisresearchwould
neverhavebeenpossible.
ACKNOWLEDGMENTS
IwishtothankDr.ChesterE.SutterlinIII,MD,forteachingmeaboutspinal
surgeryandhowtoapplymyknowledgeofengineeringtoitspractice. IthankJamie
GroomsandRegenerationTechnologiesIncforfinancialsupportofthisprojectand
havingthestaminatoensurethatitwascarriedout. IamgratefultoJohnJ.Mecholsky,
Jr.forhispatienceandjudgement,andChristopherBatichforencouragingmetobegin
mystudiesatUF. IwouldliketothankmyDoctoralcommittee,AnthonyBrennan,
EdwardWalsh,DavidGreenspan,andAndrewRapoffforensuringthatthisresearchwas
carriedouttothehighestofstandards.IamthankfultoC.RandalMillsforhisintellectual
conversations,andJamesE.KeeslingJr,anEngineerwhocrossedthelineandbecamea
Statistician,assistingwithmanyofthestatisticalanalysis. IwouldtothankChris
Glymphforsettingthisresearchtopractice,KevinCarterforhismostvaluabletechnical
assistance,KevinRossforhelpingoutwiththemechanicaltesting,andSannaMartinez-
Saareforherartisticsketches. ButmostofallIwouldliketothankandacknowledgemy
wifeforherpatience,peptalks,comicrelief,andlove.
IwouldliketothankmanyofmyfamilyandfriendswhoinsuredthatIhada
goodtimeincludingthefoundingmembersoftheThunderingAmoebeaInvestment
Club: MattCorrigan,MikeRickey,DougMullin,DanGarlington,WillLyons,andMike
Lyons.
in
TABLEOFCONTENTS
page
ACKNOWLEDGMENTS
iii
LISTOFTABLES vii
LISTOFFIGURES ix
INTRODUCTION 1
REVIEWOFTHELITERATURE 5
TheFunctionandAnatomyofBone 5
MechanicsofBone 7
HistoricalDevelopmentofBoneasaTransplantableMaterial 14
IndicationsforSpineSurgery 19
SurgeryoftheSpine 20
SpinalMechanics 20
MechanicsofSpineFusion 21
BiologyofSpineFusion 21
SyntheticImplantsUsedforSpinalFusion 22
BoneGraftsUtilizedinSpineSurgery 23
InterbodyAutograftsorAllograftsforSpineSurgery 23
StructuralPropertiesofAllograftInterbodiesforSpinalFusion 38
AlternativeMaterialstoBone 39
AlternativestoSpinalFusion 40
Summary 40
LOCALSTRESSFIELD 42
Introduction 42
MaterialsandMethods 42
Results 46
HertzianContactBetweenConcentricCylinders 46
In-VivoLoadingConditions 46
Discussion 49
Conclusions 51
NORMALIZEDSTRENGTH 52
StructuralCharacteristicsofBone 52
IV
StructuralCharacteristicsofBoneDowels 54
TheoreticalStressAnalysis 55
ModesofLoading 55
MaterialsandMethods 56
SpecimenPreparation 56
MechanicalTesting 56
PhysicalMeasurements 58
DataAnalysis 58
NormalizedStrength 59
Results 60
FailureLoadofMD-IIBoneDowels 60
FailureLoadsofMD-IIDowelsasaFunctionofDiameter 61
FailureLoadasaFunctionofDimensions 61
FailureLoadsasaFunctionofDensity,Hardness,orUltrasonicVelocity 67
AnalyzingtheDatabyMultivariateRegressionAnalysis 70
ApplicabilitytotheBoneDowels 75
Conclusions 75
BIOMECHANICALQUALITYCONTROLPROCEDURE 77
Introduction 77
MaterialsandMethods 77
NormalizedStrengthofBoneDowels 77
AcceptableQualityCriteria 78
DesignLoadsontheDowels 78
ProbabilityofSurvival 78
WeibullApproachAppliedtotheBoneDowels 79
Validation 80
SpecimenPreparation 81
SampleSize 81
NondestructiveandDestructiveAnalysis 81
Results 82
WeibullModulus,InterceptandThresholdLoad 82
ValidationResults 85
ResultsinManufacturingSinceImplementationofNDEatRTI 85
Conclusions 88
PROCESSINGANDDONORDEMOGRAPHICSOFCORTICALBONE 89
Introduction 89
MaterialsandMethods 90
SpecimenPreparation 90
ExperimentalDesign 91
TreatmentGroups 92
PhysicalandMechanicalTesting 94
Results 97
Discussion 100
1
Conclusions 106
DONORDEMOGRAPHICS,PROCESSING,ANDDESIGNOFTHEMDSERIESOF
BONEDOWELS 108
Introduction 108
MaterialsandMethods 108
SpecimenPreparation 108
DonorAttributes 109
ProcessingParameters 109
DowelDesign 110
ExperimentalDesign 110
MechanicalTesting Ill
NormalizedStrength 11
StatisticalAnalysis Ill
ResultsandDiscussion 112
DonorDemographics 112
ProcessingParameters 114
Design 115
Conclusions 116
SUMMARY 117
REFERENCES 120
APPENDIXRAWDATA,REGRESSION,ANDWEIBULLANALYSIS 132
BIOGRAPHICALSKETCH 139
VI
1
LISTOFTABLES
Table page
2-1Ultimatestrengthofhumancorticalandcancellousbone 9
2-2Elasticconstantsforhumancorticalbone 9
2-3Axialloadbearingcapacityofdifferentvertebrallevels 20
2-4Invivoloadingonthehumanspine 21
2-5Loadbearingcapacityofvariousinterbodies 38
4-1 Bestregressionsubsets 72
4-2Regressioncoefficientsforvarioussizedowels 72
5-1Minimumsamplesizeforvalidation 81
5-2PossibleOutcomesforvalidation 82
5-3Weibullanalysisresultsforvariousdowels 83
5-4Validationactualoutcomes 85
6-1Axialcompressiontreatmentgroups 93
6-2Sheartreatmentgroups 93
6-3Diametralcompressiontreatmentgroups 93
6-4Densityofeachcompressiongrouppriortotreatment 97
6-5Ultimatecompressivestrengthofeachtreatmentgroup 97
6-6Densityofeachsheargrouppriortotreatment 98
6-7Ultimateshearstrengthofeachtreatmentgroup 98
6-8Densityofeachtransversetensiongrouppriortotreatment 98
VI
6-9Ultimatetransversetensilestrengthofeachtreatmentgroup 99
7-1Bonedoweltreatmentgroups 110
7-2Variationofstrengthof16mmMD-2duetoanatomicorigin 112
7-3Variationofstrengthof18mmMD-2duetoanatomicorigin 112
7-4Variationofstrengthof16mmMD-IIIasafunctionofdonorage 113
7-5Variationofstrengthof16mmMD-IIasafunctionofdonorage 113
7-6Variationofstrengthof18mmMD-IIasafunctionofdonorage 114
7-7 Variationofstrengthof20mmMD-IIasafunctionofdonorage 114
7-8Variationofstrengthof16mmMD-IIduetoprocessing 115
7-9Variationinstrengthbetween16mmMD-IIandMD-IIIdowels 116
7-10Variationinstrengthbetween18mmMD-IIandMD-IVdowels 116
vni
LISTOFFIGURES
Figure page
1-1SketchoftypicalMD-IIbonedowel 4
2-1Clowarddowel 27
2-2CrockDowel 27
2-3Vichthreadedcancellousdowel 28
2-4MD-IIandMD-IIIcorticalbonedowels 28
2-5Smith-Robinsoniliaccrestgraft 32
2-6Bailey-Bagleyiliaccrestgraft 32
2-7Tangent™corticalwedge 33
2-8Corticalringfromlongbone 35
2-9SR™graft 35
2-10Vertigraft™ 36
2-llFRA-Spacer™ 36
2-12ALIF™ 37
3-1TestJigforMoireLoading 45
3-2HertziancontactstressV-field 47
3-3HertziancontactstressU-field 47
3-4In-vivoloadingV-field 48
3-5In-vivoloadingU-field 48
3-6Typicalfracturepatternsobservedinbonedowelsunderaxialcompression 50
ix
4-1Cross-sectionofhumanfemur 53
4-2Typicalproductiondowels 54
4-3Dowelunderaxialcompression 57
4-4Histogramoffailureloads 63
4-5AveragefailureloadsofdifferentsizeMD-IIdowels 64
4-6Histogramoffailureloadsof16and20mmMD-2dowels 65
4-7Failureloadasafunctionofendwallthickness 66
4-8Failureloadof16mmMD-IIasafunctionofdensity 68
4-9Failureloadof18mmMD-IIasafunctionofdensity 68
4-10Failureloadof16mmMD-IIasafunctionofultrasonicvelocityincorticalring 69
4-11Failureloadof16mmMD-IIasafunctionofhardnessofcorticalbone 69
4-12Multipleregressionanalysisof16mmMD-IIbonedowels 73
4-13Multipleregressionanalysisof18mmMD-IIbonedowels 73
4-14Multipleregressionanalysisof20mmMD-IIbonedowels 74
5-1Probabilityplotsof16and18mmMD-2dowels 84
6-1ShearTestFixture 95
6-2Testconfigurationforaxialanddiametralcompression 96
A-lDeterminationofWeibullmodulusfor16mmMD-2 138