Biomaterials: A Tantalus Experience PDF
Preview Biomaterials: A Tantalus Experience
biological and medical physics, biomedical engineering Forfurthervolumes: http://www.springer.com/series/3740 biological and medical physics, biomedical engineering Thefieldsofbiologicalandmedicalphysicsandbiomedicalengineeringarebroad,multidisciplinaryand dynamic.Theylieatthecrossroadsoffrontierresearchinphysics,biology,chemistry,andmedicine.The BiologicalandMedicalPhysics,BiomedicalEngineeringSeriesisintendedtobecomprehensive,coveringa broadrangeoftopicsimportanttothestudyofthephysical,chemicalandbiologicalsciences.Itsgoalisto providescientistsandengineerswithtextbooks,monographs,andreferenceworkstoaddressthegrowing needforinformation. Booksintheseriesemphasizeestablishedandemergentareasofscienceincludingmolecular,membrane, andmathematicalbiophysics;photosyntheticenergyharvestingandconversion;informationprocessing; physicalprinciplesofgenetics;sensorycommunications;automatanetworks,neuralnetworks,andcellu- larautomata.Equallyimportantwillbecoverageofappliedaspectsofbiologicalandmedicalphysicsand biomedicalengineeringsuchasmolecularelectroniccomponentsanddevices,biosensors,medicine,imag- ing,physicalprinciplesofrenewableenergyproduction,advancedprostheses,andenvironmentalcontroland engineering. Editor-in-Chief: EliasGreenbaum,OakRidgeNationalLaboratory,OakRidge,Tennessee,USA EditorialBoard: MasuoAizawa,DepartmentofBioengineering, JudithHerzfeld,DepartmentofChemistry, TokyoInstituteofTechnology,Yokohama,Japan BrandeisUniversity,Waltham,Massachusetts,USA OlafS.Andersen,DepartmentofPhysiology, MarkS.Humayun,DohenyEyeInstitute, Biophysics&MolecularMedicine, LosAngeles,California,USA CornellUniversity,NewYork,USA PierreJoliot,InstitutedeBiologie RobertH.Austin,DepartmentofPhysics, Physico-Chimique,FondationEdmond PrincetonUniversity,Princeton,NewJersey,USA deRothschild,Paris,France JamesBarber,DepartmentofBiochemistry, LajosKeszthelyi,InstituteofBiophysics,Hungarian AcademyofSciences,Szeged,Hungary ImperialCollegeofScience,Technology andMedicine,London,England RobertS.Knox,DepartmentofPhysics andAstronomy,UniversityofRochester,Rochester, HowardC.Berg,DepartmentofMolecular NewYork,USA andCellularBiology,HarvardUniversity, Cambridge,Massachusetts,USA AaronLewis,DepartmentofAppliedPhysics, HebrewUniversity,Jerusalem,Israel VictorBloomfield,DepartmentofBiochemistry, UniversityofMinnesota,St.Paul,Minnesota,USA StuartM.Lindsay,DepartmentofPhysics RobertCallender,DepartmentofBiochemistry, andAstronomy,ArizonaStateUniversity, Tempe,Arizona,USA AlbertEinsteinCollegeofMedicine, Bronx,NewYork,USA DavidMauzerall,RockefellerUniversity, NewYork,NewYork,USA BrittonChance,DepartmentofBiochemistry/ Biophysics,UniversityofPennsylvania, EugenieV.Mielczarek,DepartmentofPhysics Philadelphia,Pennsylvania,USA andAstronomy,GeorgeMasonUniversity,Fairfax, Virginia,USA StevenChu,LawrenceBerkeleyNational Laboratory,Berkeley,California,USA MarkolfNiemz,MedicalFacultyMannheim, UniversityofHeidelberg,Mannheim,Germany LouisJ.DeFelice,DepartmentofPharmacology, VanderbiltUniversity,Nashville,Tennessee,USA V.AdrianParsegian,PhysicalScienceLaboratory, NationalInstitutesofHealth,Bethesda, JohannDeisenhofer,HowardHughesMedical Maryland,USA Institute,TheUniversityofTexas,Dallas, Texas,USA LindaS.Powers,UniversityofArizona, Tucson,Arizona,USA GeorgeFeher,DepartmentofPhysics, UniversityofCalifornia,SanDiego,LaJolla, EarlW.Prohofsky,DepartmentofPhysics, California,USA PurdueUniversity,WestLafayette,Indiana,USA HansFrauenfelder, AndrewRubin,DepartmentofBiophysics,Moscow LosAlamosNationalLaboratory, StateUniversity,Moscow,Russia LosAlamos,NewMexico,USA MichaelSeibert,NationalRenewableEnergy IvarGiaever,RensselaerPolytechnicInstitute, Laboratory,Golden,Colorado,USA Troy,NewYork,USA DavidThomas,DepartmentofBiochemistry, SolM.Gruner,CornellUniversity, UniversityofMinnesotaMedicalSchool, Ithaca,NewYork,USA Minneapolis,Minnesota,USA Jozef A. Helsen Yannis Missirlis Biomaterials A Tantalus Experience With 166 Figures 123 ProfessorDr.JozefA.Helsen KatholiekeUniversiteitLeuven,DepartmentofMetallurgyandMaterialsEngineering DeCroylaan2,3001Leuven,Belgium E-mail:[email protected] ProfessorDr.YannisMissirlis UniversityofPatras,DepartmentofMechanicalEngineeringandAeronautics 26500Patras,Greece E-mail:[email protected] BiologicalandMedicalPhysics,BiomedicalEngineering ISSN1618-7210 ISBN978-3-642-12531-7 e-ISBN978-3-642-12532-4 DOI10.1007/978-3-642-12532-4 Springer Heidelberg Dordrecht London New York LibraryofCongressControlNumber: 2010938119 ©Springer-VerlagBerlinHeidelberg2010 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting, reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublicationor partsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9,1965,in itscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violationsareliableto prosecutionundertheGermanCopyrightLaw. Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnotimply, evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotectivelawsand regulationsandthereforefreeforgeneraluse. Coverdesign: eStudio Calamar Steinen Printedonacid-freepaper Springer is part of Springer Science+Business Media (www.springer.com) Foreword ThebookwrittenbyProf.HelsenandProf.Missirlisisdifferentfrommanybooks Ihavereadonbiomaterials.Itshareswiththebestbooksonthetopicaccuracyand clarity. But it goes beyond that. This book has body and soul. The authors, who havebeenmyfriendsformanyyears,haveengravedtheirspiritinmanypartsofthe work.Inthesenseofhumorthatcropsupeverywhere,inthecriticalattitudetoward block-bustersandderniercriesthatfunctionaschemoattractantstoscientistslook- ingforfunds,whentheyunveilcompellingevidenceoffailedhopesandpromisesof “almost-perfect”implantconcepts,IrecognizeJefandYannis.Theyhavelefttheir fingerprintseverywhere.If,insteadofwritingabooktheyweretryingtoplotaper- fectcrime,theywouldberapidlydiscoveredbyanapprenticedetective.References made to history – not only of biomaterials, but also of mankind – are abundant, putting science in social and humane context. This is something you do not find whilesearchingdatabases.Culturehastobedeeplyembeddedinyourmindtofill fringesin the discourse so accuratelyand smoothly.As they say, with remarkable honesty, the book is not comprehensive. They go as far as mentioning important topicsthat are notcovered.Instead of danglingconversationon so-calledhottop- ics,theypreferredtodrawourattentiontobiomaterialswhosehistoryillustratesthe multifaceted and critical perspective that one should take at anything in science. The length with which they discuss dental materials and amalgams is a perfect example of this. Although I have never investigated dental materials, I found this chapter a beautiful example of an evolutionary view on biomaterials, going from amalgams for dental fillings to regenerating teeth. It is also an excellent demon- strationofthemultidisciplinaryapproachthatProf.HelsenandProf.Missileshave adoptedthroughoutthebook.Mechanicalproperties,degradationbehavior,design, thermodynamics, kinetics, and a wide range of materials are harmoniously dealt with in the chapter. The way the book opens is extremely creative and provoca- tive. In the first chapter, they refer to the “perfect human machine”. I would add wonderfuland mysterioushuman machine.Then, in the second chapter, the topic is “the failing human machine”. They could not have chosen a more distressing, buttrue,title.ThehomagetheymaketoProf.Charnleyisunquestionablydeserved. The quotation of Charnley’s sentence on the limitations of technology is remark- able. We shouldhave it at the entrance of everylab. The pairingof corrosionand toxicityof degradationproductsisveryopportune.In manybooksthey arenotso v vi Foreword intimately related, although corrosion has a double facet: it is detrimental to the materialand to the environment.In case of biomaterialsdegradation,the environ- mentis the body.In this respect, the authorsrelievethe anxietysome peoplemay feelaboutcarryingsomethingthatismadeofpotentiallytoxicelements.Complex formation and precipitation of metal compounds in the vicinity of implants may bethereasonforrestricteddamagecausedtotissues.Improvementinmanufactur- ingpractices,morestringentqualitycontrolsandgreaterawarenesstobiomaterials propertieshavebeenresponsibleforincreasedimplantsafetyandsurvival.Thebook hasmanyotheraspectsthatappealedme.Iwillmentiononlyacoupleofthem.One wasthe use ofmagnesiumfoams.Itgoesagainstmainstreamthinkingto consider usingametalthatishighlyreactiveinthebody.Wewerebroughtupinthebeliefin certaindogmas,andhighcorrosionresistanceisoneofthem.However,ifwetake the other side of the coin, which was spotted in the 1970s by polymer chemists, biodegradationcomesasa“whynot?”approach,evenformetals.Finally,Iwould like to refer to heart valves because they are an excellent example of the dilem- maswefacewhenconfrontedwithnaturalandartificialbiomaterials.Theissueof reproducibility of properties crops up in any discussion about the use of natural materials. However, mimicking the natural tissue is a goal of any tissue engineer. Valve-replacement surgery has taught us that there is no such a thing like a sin- glesolutiontoaproblem.Lifeis,fortunately,morecomplexthanchoosingbetween blackandwhite.Daringtothinkdifferentlyisalsotheonlyroutetowardsinnovative scienceandtechnology.Thisbookisanexcellentexampleofthisattitude. Prof. Ma´rio A. Barbosa INEB, Porto (Instituto de Enghenharia Biomedica, Portugal) Porto M.A.Barbosa June2010 Preface Newtechnologiesdon’tsimplyreplaceoldones...theyjustaddanotherlayerofcomplexity toourlives. DavidRooney WisewordsextractedfromRooney’sbookRuthBelville:TheGreenwichTimeLady. Thisphrasemaystandforthemixoffactsandfigures,historicalbackgrounds,old andnewgroundbreakingdesigns,andstate-of-the-artandfutureperspectivesinthe biomedicalworld.Thatisallwhatthisbookisintendedtobeabout.Bridgingpast andpresent–thehighwaytothetop,thez-axis–isparticularlycherishedthroughout thetext.Distinctexitsofthehighwayaretakenforroamingthroughthelandscape foranxy-viewonthebiomedicalfield. In the early 1980s, new materials were the magical keys, which opened doors whenapplyingforgrantswiththehopetohaveashareintheEuropeanfleshpots. Ceramicsareoneofthosemiracleproducts:afullceramicmotorblockandceramic ballbearingswithoutlubricationwouldallowtostarttheenginewithjustoneclick of the contact key even in the middle of a night in Siberia. Just one or two cars with ceramic engines were ordered to be manufactured but thirty years later, few cars with ceramic motorscan be foundon the road,neither here nor in the arctic. Corrosionandwearwereanightmareformetalimplantsbutinertaluminumoxide solvedthese problems.Infact, nothingwas less trueandonlyin thecourseofthe lastdecade,themanufacturingofcomplexcompositesofaluminumandzirconium oxide emerged as a mature technology for manufacturing heads and cups for hip prostheses. The new magical key is ‘nano’. Not mentioning these four letters is begging for problemsin grant applications. But, fortunately,capturingpart of the flesh pot is not the aim of this book and therefore, the reader will not be flooded withexaggeratedpromisesbyinnovativeproposals. Research follows odd ways. Another hot research topic three decades ago was the manufacturingof complexmetal parts in near net shape using metal powders, an adaptation of a technology practiced by ceramists since ages. In the chapter Layer by layer, the reader will find how a variety of custom-mademetal implants are manufacturedtoday by techniques that are fundamentallydifferentfrom what was proposed three decades ago. Nickel-free alloys such as iron–manganese– aluminum, glass–fiber composites, porous coatings, and many other proposals to vii viii Preface solve recognized risks or shortcomingsof existing materials and implants did not resultinthebreakthroughstheypromised:whileconventionalstainlesssteelisstill an alloy in use for some (successful) implants, today’s porous coatings or porous devicesaredistinctlydifferentfromdesignsproposedinthe1980s.Fortune-telling isariskyprofession! Myths are vivid reflections on the invincible will of man to lengthen life in a comfortable way, so the eagerness to insert some mythological stories in the text wasirresistible.Archaeologicalbiomedicalartefactslooklessromanticthanmyths buttheyarethetangiblewitnessesofancientcreativity.Theyinstructusaboutthe biomedicalprogress,oranyotherkindofprogress.Theyareneverstand-aloneacts butareauniversalconversationbetweenaspiration,technologyandscience–xyz- space. The generic class of materials in this book are not bound to separate chapters. A story or case study at the beginning of a chapter introduces a problem and invites the readers explore solutions: for example, adequate implant design and manufacturingby adequate selection of (bio-)materialsor combination of materi- als.Occasionally,anexcursionfromthemainframeismadetosituateartificialand natural materials in a wider context, trace elements in the body or biomineralsin relationtothemineralworld... Science is a sustained effort to arrive at a unifying theory. Efforts are made to point to those characteristic propertiesof matter and materials that go beyondthe typicalcharacteristicsofonegenericclass.Tonameafew,theaustenite–martensite transformationasaphysicalprocesscommontosteel,shapememoryalloysaswell asto ceramics;grainsize anditsrelationtostrengthin ceramicsandmetalsalike; the role of grain boundariesand sensitivity to corrosion or chemical degradation; and scaling, similarity of properties at different scale lengths. The driving force for all physical or chemical processes is dictated by the Second Law of Thermo- dynamics, paraphrased in the text as Water does not flow uphill or, viewed from the top of the hill, All nature’s streets are one way and downhill. The ultimate definition of the law is that in a closed system (like the universe), all irreversible processes lead to an increase of entropy.An apocalypticconsequenceof the Sec- ondLawistheinevitabilityofdeath.Thisstatementwas,unintentionallyweguess, nicelyillustratedinanotherwiseverycharmingGermanvillage:nexttoasignpost, which mentioned Zum Friedhof, we saw another sign post saying Einbahnstrasse (to churchyard,one-waystreet)!Butdespite thesediscouragingstatements, we do stayalivequiteanumberofyears.Inaway,ourbodysucceedscheatingthesecond law bybuilt-innegativefeedbacksystemsorhomeostaticmechanismsto keepthe increaseofentropyundercontrol.Thesemechanismshavedirectconsequencesfor implantsaswellasforthebody.Homeostasis(Homeodynamicsinreality)willoften bereferredtointhetext. An inspection of the Table of Contents shows that conventional items such as metals,toxicity,corrosion,ceramicsor,ingeneral,materialsforhardtissuereplace- mentsare,discussedinanumberofpages,apparentlyoverrepresentedwithrespect to cellular or physiological response. The counterbalance are the two chapters on heart valve substitutes and tissue engineering. Should it not be the other way round? On the one hand, it is beyond doubt that substantial progress has been Preface ix made in understanding tissue response to foreign materials. On the other hand, the long-term success of, say, (even conventional) total hip prostheses is undeni- ably remarkable, while decades long studies of surface modification to enhance biochemical and physiological compatibility resulted in rather modest successes. Exception might be made for orthopedic hydroxyapatite coatings, but the initial success of hydroxyapatite-coateddental implants is vanishing. Experience taught us that close fit seems to be more beneficial than surface modification, selecting of course materials with an otherwise good record of service. The Gallo–Roman dentalimplant(Chap.10)isaquiteunexpectedsupportforthatview.Newforming technologypermits manufacturingcustom-madeprostheses fast and at reasonable cost.Onechapterisdevotedtoformingtechniquesformetalsaswellasforceram- icsandpolymers(Chap.7).Theelastomer-coatedprosthesisdiscussedinChap.11 isanotherproposalformeeting,amongotherrequirements,aclosefit.Buthistory teachesusthatonceatechnologyisnearlyperfect–thinkaboutsteamengines–one nolongerneedsit.Tissueengineeringislurkingatthecornertounderminetheworld ofthematerialsscientists,fromcartilagetoheartvalves.Maynotbetomorrow,but somewheredownthelineitisboundtohappen. Permanentimplantsneedmaterialswithlong-termstabilityandresistancetocor- rosionandwear,forexample,definitelywhenconsideringthatevenyoungpatients are getting implants. For controlled drug delivery devices, which do not endure high loads, materials that dissolve gradually in the course of time are required. Nonpermanent implants subject to moderate loads, which are currently removed whenfunctionalsupportisnolongerneeded,arepotentialcandidatesforbeingman- ufactured out of very corrosivealloys, whose dissolution rates (and productionof hydrogen)can be tightly monitored.Chapter 8 is devoted to a discussion of these alloys. Theexcellentsurvivalrateofpermanentimplantsdemandsanupdatedattention totoxicity.Thetoxicbehaviorofthemajorelementsiselaboratelystudied.Noalloy, however,is inert. Many of the minorelements have documentedtoxic, mutagenic orcancerogenicpropertiesbuttheeffectofsustainedexposureoverlongperiodsof timeisnotknown. Understandingmacroscopicprocessesbystudying(inter-)reactionsatmolecular, atomic,orcellularlevelisanoblegoalandtheultimatedreamofscientist.Thetrend is already seen as toxicity testing is carried out on human cells instead of animal cells,tostudyfrictionatnanoscalelevelorsimilarresearchinalmosteverydomain ofscienceandtechnology.Thequestionremainswhetheritcanreflectthebehavior of materials at the macroscopic level. For the time being, it is not (yet) true, for example, in friction research. It has long been a concernof physicists and Robert March formulatedit already fortyyears ago in his elegantbookPhysics for Poets ([1],p.96),whenhewrote: Thoughlawsdescribingthebehaviorofatomsare,atleastinprinciple,thebasisforthe behavioroflargerobjects,itisinconvenientandperhapsevenimpossibletosousethemin practice.Onthebasisofthis,aphysicistmightwellsuspectthat,forexample,evenifpsy- chologyweretobecomeaperfectlyexactscience,itwouldbeoflittlevalueinunderstanding society.
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