BioTensegrity

BioTensegrityFasciaandthefallacyofbiomechanics.Part1JohnSharkey,ClinicalAnatomist.MSc.,DepartmentofClinicalSciences,UniversityofChester/NTC,Dublin,Ireland*Correspondenceto:JohnSharkeyMSc.UniversityofChester/NationalTrainingCentre16aStJoseph’sParadeDorsetStDublin7,IrelandE-mailaddress:john.sharkey@ntc.iewww.johnsharkeyevents.comIntroductionBiotensegrityisemergingasthemostsignificantdevelopmentinhumananatomyinrecentyears.With important ramifications for awide range ofmedical practitioners including surgeons, bio-engineers and humanmovementspecialists.Bespokedissectiontechniquesareprovidinganewvisionandunderstandingofthecontinuityofthe human form. A fresh look at the human fasciae highlights its role in providing continuous tension throughout itsnetwork.Theterm“Tensegrity”wascoinedbyBuckminsterFullercombiningthewords‘tension’and‘integrity’.Fuller’sstudentKennethSnelsonbuiltthefirstfloatingcompressionstructureof“tensegrity”in1949whileDrStephenLevinanorthopedicsurgeonwastheprotagonistof“BioTensegrity”intheearly1970’s.AsaClinicalAnatomistIhaveinvestigatedthismodelandtheroleoffasciainmydissectionstobetterunderstandthemechanismsofhumanmovementandchronicpain while providing new anatomical knowledge and awareness leading to less invasive surgical and non-surgicaltherapeuticinterventions.UnderstandingBioTensegrityBorrowingfromFuller’sterm“tensegrity”,asyntacticof“tension”and“compression”,Levin(1975)addedtheterm“Bio”referring to living structures. BioTensegrity is the application of Fuller's tensegrity concepts to biologic structure andphysiology.IntheBioTensegritymodelthelimbsarenotacollectionofrigidbodysegments.Theupperandlowerlimbsare semi-rigid, non-linear, viscoelastic bony segments. These segments are interconnected by non-linear, viscoelasticconnectors including cartilage, joint capsules and ligaments, with an integrated non-linear, viscoelastic active motorsystem,themuscles,tendonsandfascia(connectivetissue).BioTensegritycountersthenotionthattheskeletonprovidesaframeforthesofttissuestohangupon.InsteadBioTensegritystructuresareintegratedpretensioned(self-tensioned)continuous myofascial networks with floating discontinuous compression struts (skeleton) contained within them. Acolumnwhosecenterofgravityisconstantlychangingwhileitsbaseisrapidlymovinghorizontallywouldrequireforcestoogreattoconsider.Theforcesbecomeincalculableifthecolumniscomposedofseveralrigidbodies,hingedtogetherbyflexible,virtuallyfrictionlessjoints.

Figure 1. When simple compressive loads are applied, compressive and shear stress must exist on planes that are oriented obliquely to the line of application of the load (Levin 1995. With permission).

A rigid columnneeds tobebaseheavy to support the incumbent loadabove. Internal shear forces are createdby theweightofthestructure(Fig.1),whichinturnwouldbedestabilizing.Energywouldberequiredinlargeamountstokeepthe structure intact. Humans are Omni directional, as are all biological organisms, in order that the tension elements

functionatalltimesintensionregardlessofthedirectionofappliedforce,whilethecompressionelementsinbiologicalstructures"float"inatensionnetwork(Levin1995).BuildingalivingstructureTo construct a biologic organism on the principles of tensegrity, the tensegrity trussmust be linked in a hierarchicalconstruction.Startingattheinfinitelysmallsubcellularcomponent.Importantlyitmusthavethepotentialtobuilditself.The structurewouldbeone integrated tensegrity truss thatevolved from infinitely smaller trusses that couldbebothstructurally independent and interdependent at the same time. Ingber (2000) described this truss as the icosahedron(Fig.2)

Figure2.Icosahedron Ingber found conclusive evidence that tensegrityprovides thebest explanation for the cytoskeletonof the cell. In factIngberalsostatesthatitisnotpossibletoexplainwhyskinstretcheswhenmusclecontractsotherthanbytensegrity.NobonesaboutitBone brittleness is approximately the same inMarsupials as in aRhinoceros as the stiffness and strength of bones isroughlythesameinallanimals.Animalsbiggerthanalion,suchashorses,runningorjumpingontheirslimlimbs,wouldbreakandfracturetheirboneswithaleap.Basedonlinearmechanicallaws,whicharethefoundationofbiomechanicalmodels,animalmassmustcubeastheirsurfaceareaissquared.ThisshouldmeanthatanimalsasbigasaRhinoceroswillcollapseundertheirownweight.Workingelasticallyatstrainsaroundathousandtimeshigherthanstrainsthatordinarytechnologicalsolidscanwithstanddemonstratesthatbiologicaltissuesbehavedifferentlythannon-biologicmaterials.IfthiswasnotthecaseLevin(1982)informsusthattheskullshouldexplodewitheachheartbeatduetothebloodvesselsexpandingandcrowdingout thebrain.As theyreach fullness theurinarybladdershouldthinandburst.Thepregnantuterusshouldburstwiththecontractionsofdelivery.Notexclusively,mechanicalbutalsophysiologicprocesseswouldbeinconsistentwithlinearphysics.Pressurewithinaballoondecreasesasaballoonempties.Theheartoftheproblemisthat thereareseveralassumptionsregardingbiologic tissuesthatarenotvalid.Biologic tissues, includingmusclesandfascia,havenonlinear stress/straincurves.Unfortunately, inbiomechanics the initialpremise thatmuscles, fascia, andindeed,anybiologicmaterial,canbeboundbytherulesofhardmatterphysicsis,accordingtotheinformationcomingoutofthecondensedsoftmatterlaboratories,flawed.Ligamentsandfascia,bonesandcartilagewoulddolittletosupportouruprightformsifnotforthecollectiveactivityofanintegratedmyofascialsystem.

Figure3.Thedenserboneislaiddownwherethecompressionstressisgreatest.Conversely,thesoftestboneiswherethereistheleastcompressiveload.Therefore,byexaminingbonedensityitispossibletodeterminewhatbonetakesthemost stress, and which the least. For example, the calcaneus and the metaphyseal ends of long bones take littlecompressiveloads(Wolff'sLawinbone).

ThecellularlevelAt the cellular level, using fluoroscopic imaging, Guimberteau et al (2010) provided strong visual evidence that fasciacontainsawaterfilledvacuolarsystemthatiscapableofslidingindependentoftherateofcontractionofmuscle.Inturnitiscapableoffacilitatingandsupportingcapillariesthroughoutthefascia.Sharkey(2012)providedfreshfrozencadaverimages(Fig4)ofthefasciaprofundusatthemacrolevelreflectingthisfractalmicrovacuolarstructurewhilerevealinganicosahedron like (tensegrity) composition where fractal elements inter-relate, creating a body wide framework ornetwork.Thisstructureisabletochangeormaintainshapeandformwithinafluidbaseallowingdeformationfollowedbyareturntoitsoriginalstate,whilstmaintainingvolume.Thiscreatesastable,yetflexibleenvironmentnecessaryforfasciatoactasamediumforforcetransmission(Huijing,2009).

Figure 4. Providing a stretching force to the tissues of the anterior forearm, on a fresh frozen cadaveric specimen,Sharkey,J.,highlightsthefractal,chaoticarrangementofthedeepfascia.(PhotobySharkey,J.2010)Thisnewmodel forbiologicstructuresbasedontheconceptof tensegrity identifies fasciaas thetensional,continuousmember.Inatensegritycontinuoustensileforces(fromthemyofasciatissue)providean“ocean”withinwhichthestrutsfloat(inthehumanbodythesecouldbetheboneswhicharenotcontinuouswitheachotherandtheydonottransmitcompressiondirectlyontoeachother).ThetensionalmembersarecontinuousanddistributetheirtensionloaddirectlytoallothertensionalmembersasdescribedbyFullerin1961.Thefascialoceansbecomeseas,lakes,rivers,streamsandbrooks(Sharkey.2008).Newtonian,Hookianandlinearmechanicalpropertiesarethebasisforthebuildingofallthingsnon-biological (Levin 1995). This description supports the more recently accepted image of a continuous tissue,ubiquitous innature, connecting left to right, front toback, top tobottom,embracingandpermeating theentirebody.Mesenchymalderivedconnectivetissuesprovidingabodywidenetworkofcommunication(SchleipandMuller.2013).Thevisceralorgansintegratestructurallyandphysiologicallyintothissystem.TherearenolimbsegmentboundariesandthesmallerbonesandjointsofthehandsandfeetfullyintegrateintotheBioTensegritymodel.Thespineisatensegrityturretthatintegrateswiththelimbs,headandtailandalsotothevisceralsystem.Achangeoftensionanywherewithinthe system, such as the mid back, is instantly signaled to everywhere else in the body such as the sphenobasilarsynchondrosis chemically andmechanically.There is a total body responsebymechanical transduction.The structureworksequallywellrightsideup,upsidedown,inthesea,land,intheairorinspace.Itresolvesmanyoftheinadequaciesofpresentbiomechanicalmodels.Van derWal (2009) suggests this dynamic connection between the connective tissue and themuscle is a “structuralsupport” capable of adapting to increasing or decreasing joint range and alsodistancebetweenbones throughout thejointrangeofmotion.VanderWal(2009)referstothesedynamicconnectionsas“Dynaments”.Thesedynamentsarenotnecessarilysituateddirectlynext tothe jointcavityor inthedeeppartof the jointregion.VanderWaalcontendsthatsomemuscleshavethesespecialisedconnectivetissuestructuresattheproximalendonly,someatthedistalendonly,someatbothends,andsomeatneitherend.Fasciaplaysanimportantroleinsupportingmusclecontractionasitlinksmuscles together and non-muscular structures by means of these myofascial pathways and by direct attachment ofmusclesintotheconnectivetissuestructuresaroundthejoint(Sharkey,J.2012.Fig.5).VanderWal,(2009)hasinformedus that none of themuscle fibers of supinator insert directly onto the humeral epicondyle, but attach bymeans of aconnectivetissueapparatus.Nerveendingsinthesestructuresareingreaternumberwherethestressesarethehighest,particularlyintheproximalordistalendofthe‘dynament’.

Figure5.FascialcollagenuslinksbetweenPalmarisLongusandassociatedneigbouringmuscles.(PhotoSharkey,J.,2012)Several research studies have revealed fascial connections resulting in myofascial force transmission between bothadjacent and antagonistic muscles (Bojsen-Moller et al. 2010). A vital mechanism for interaction betweenmuscles isextramuscular myofascial force transmission, which is essentially the generator for intermuscular myofascial forcetransmission.Myofascialinteractionwasshownforsynergisticmusclesinvolvingbothintermuscularandextramusculartransmission(HuijingandBaan2001;Huijing.2003).

Figure6.Strongseptafromthedeepfasciaareexposedastheskinandsubcutisisdistracted.(Sharkey,J.2013)

Dictatedbychangesinmovementandposturemechanicalforces,comprisingoftensionandcompression(themembersof BioTensegrity)may provide ameans of communication resulting in connective tissue signaling (Fig. 6). Similar toLangevin (2005), Purslow and Delage (2012) propose that the fascia translates these signals into a whole bodycommunicationsystem.Suchconnective tissuesignalingwouldbeaffectedbychanges inpostureandmotionandmaylose mobility in pathological conditions or when experiencing pain. Due to the intrinsic relationship that connectivetissuehaswith,amongothers,thelungs,intestines,heart,spinalcordandbrain,connectivetissuesignalingmayhaveareciprocalinfluenceonthefunctions,normalorpathological,ofawidespectrumoforgansystems.Reedsdiscovery(inFindley2012)thathyaluronans,whichareosmoticallyactivecompounds,areanessentialingredientintheinterstitialmatrix,andwhengivenfreeaccesstofluidwillswell,ispotentiallyanimportantfindingandonewhichrequiresmoreattentionandinvestigation.Thisswellingisrestrainedbyextracellularmatrixfibersthroughβ1integrinmediatedcontractionwhentheyareactively tensedbyconnective tissuecells.Thisdemonstrates therole that tensionplays inrestraining theextracellulargroundsubstance,whichnormallywouldbeunder-hydrated, fromretaining fluidtherebyreducingitscapacitytoswell.

Fascia-AQuestionofProprioceptionSensory neural fibers have been identified within fascia utilizing unique staining techniques coupled with electronmicroscopy.Steccoetal (2007b), suggest that thisprovides theevidence that fasciacontributes toproprioceptionandnociception.Schleip(2003)arguesthatfasciaisthemainorganofperception,providingpropriception,nociceptionandvisceralinteroception.VanderWal(2009)statesthatfasciahasalmost1000%moresensorynerveswhencomparedtomuscleincludingGolgi,PacciniandRuffiniendings.Alsoincludedarealargenumberofmicroscopicunmyelinated‘free’nerveendings.Thesenerveendingsarefoundinanear ubiquitous manner in fascial tissues including periosteum, endomysial and perimysial layers, and in visceralconnective tissues.Other researchers confirm that fascia and fascial structures play a significant role in the facility ofproprioception (Langevin2006;Benjamin2009). Fascial components suchasmembranes, septa,deepandsuperficialfascia are suppliedwith ample proprioceptors to suggest it is functionally important in proprioception (Wood Jones1946;Standring2008).VanderWal (2009)argues thatrather thanbeingdue to its topography theabilityof the fascialstructures toprovidecentripetal mechanoreceptive information is due to its structural and architectural relationship withmusculoskeletaltissue.Steccoetal(2008)considerthetensionalforcestransferredtothefascialexpansionsandtendonsandthepossibleaffectsonproprioceptors.Inthiswayforcesarespreadacrossawideareainseveraldirectionsprovidingthenecessaryfeedbackviaproprioceptionforeconomicalandefficientmovementatlocalandmoredistantsites.VanderWal’s(2009)researchhighlightstheactivityandroleofthemechanoreceptor.Definednotonlybyitsfunctionalproperties,butalsobyits architectural environment. He argues that it is the architecture of the fascial connective tissue in relation to themusculartissuecomponentsandskeletalelementsthatplayamajorroleinthecodingoftheproprioceptiveinformationbeingprovided.Asalreadystatedfasciaarchitecturehastheabilitytomediateforcesthatcausedeformationofreceptorsthat are not directly attached to the fascia itself representing the main stimulus for mechanoceptors, effectingproprioceptiveoutput(VanderWal,2009).Mechanoreceptive information needed for the process of proprioception originates not only from fascia and otherconnective tissue structures but also from mechanoreceptive or even tactile information from skin, muscles, jointsurfaces,and jointstructures.VanderWal’sresearchdemonstrates thatmechanorecptorsare triggeredbymechanicaldeformation. Proprioceptors monitor timing, intensity, duration and release of tissue deformation in a very precisemanner.Myofascialconnectionsprovideanatomicalcontinuity linkingsynergisticmuscles toallowreciprocal feedbackviamultiplepathways,ofamechanicalandneuralnature,aspartsofaspecificfasciawouldbetensionedinaselectivemannerresultinginaspecificpatternofproprioceptiveactivation(Sharkey2008).Stecco(2009)observedthatmusclespindlesattachtotheperimysiumsuggestingthatthespindlesaremonitoringtheconnective tissue tension as a primary function. Free nerve endings are, for the most part, nociceptive. PaciniancorpusclesandGolgiorgans,whichareencapsulated,monitorandrespondtolocaltissuecompressionasaresultofrapidmovements and vibration. EncapsulatedRuffini endings,which are only partially encapsulated, respond to changes inaxialtension.Guimberteau et al (2010) has provided the foundation for a new vision of anatomy. This new vision embraces globaldynamicsandcontinuousmatter(atissuecontinuum)andshedsnewlightontherelationshipsbetweentheconnectivetissuesof thehumanbodysuchasdense sheetsofmuscle coverings, aponeuroses, specific local adaptations includingligaments, tendons, blood vessels, lymphatic’s and nerves encased. This and other recent research supports andencouragesamoreglobalperspectiveencouragingsurgeonstoappreciatethattheyareworkingonanorgansystemandnot simply an individualmuscle, thus encouraging a sparring approachwhen incising tissue in an effort to curtail thedisruption of the surrounding fascial tissues and architecture of the anatomical location. This new vision calls intoquestion the very foundations of the classical anatomical views held to date and should have a profound impact oncurrent procedures and methodologies for a wide range of surgical procedures and post surgical medical exerciseinterventions. Guimberteau et al (2010) demonstrated that the continuity of the connective tissue is not interrupteddespitedistensionduringslidingorglidingmotions.Sharkey(2012)providedastrongvisualrecordofthecontinuityofthefasciasuperficialisinFigure6.GuimberteaufurthersuggestedthisnetworkresembledaTensegrity icosahedron. Inthe icosahedrontheoutershell isunder tension. The vertices are held apart by internal compression "struts" that float in the tension network (Levin.1975).Theicosahedrontensegrityisanaturallyoccurring,completelytriangulated,trussthatis3dimensional(Sharkey,J. 2010 hypothesized that BioTensegrity works on the 4th Dimension). BioTensegrity is gravity independent, flexiblehingedOmni-directionalstructurewhosemechanicalbehaviorisnonlinear.

Figure6.Aviewofthesuperficialfasciaremovedasoneautonomousstructure.(Sharkey.J.2013)Inpart2ofthis3partseries:JohnSharkeywilldiscussBioTensegrity,FourBarLinkagewithClinicalImplicationsformanualandmovementtherapies.

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