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Evidence-based and biomechanical considerations for selection of mechanical prosthetic knees

Evidence-based and biomechanical considerations for selection of mechanical prosthetic knees. Andreas Kannenberg, MD PhD , Director Medical Affairs. Background. Importance of prosthetic knee selection.

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Evidence-based and biomechanical considerations for selection of mechanical prosthetic knees

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  1. Evidence-basedandbiomechanicalconsiderationsforselectionofmechanicalprosthetickneesEvidence-basedandbiomechanicalconsiderationsforselectionofmechanicalprostheticknees Andreas Kannenberg, MD PhD, Director Medical Affairs

  2. Background Importanceofprosthetickneeselection Fortransfemoralamputeesselectionofthemostappropriateprosthetickneeiskeytosuccessfulrehabilitationandreintegrationintosocialand professional life. The prostheticknee must meettwo essential needs: providethegreatestsafetypossibleduringambulation supportasmanyaspossibleactivitiesofdailyliving

  3. Body ofevidence on prosthetickneeselection Mechanicalprostheticknees – 2 systematicreviews • van der Linde et al. 2004 • only 5 studies on mechanicalprosthetickneeshadgoodenoughqualitytobeincluded in thereview • onestudyconcludedthat a Mauch SNS with a lock mayenablevascularamputeestoadopt a higherwalkingspeedascomparedto an unlockedkneeunit • advancedswing phasecontrolmechanisms (pneumaticorhydraulic) mayimprovegaitsymmetryandvelocityofactiveprosthesisusers van der Linde H, Hofstad CJ, Geurts ACH, Postema K, Geertzen JHB, van Limbeek J: A systematicreviewoftheeffectof different prostheticcomponents on human functioningwith a alowerlimbprosthesis. J Rehabil Res Dev 2004, 41 (4): 55-70

  4. Body ofevidence on prosthetickneeselection Mechanicalprostheticknees – 2 systematicreviews • Samuelsson et al. 2012 • Systematicreviewof all studies in lowerlimbprosthetics • 818 studiesfound • 737 excludedas not pertinentorduplicates • 73 studiesexcludedforpoorquality • 8 studieshadsufficientmethodologicalqualitytobereviewed • Not a singlestudywithmechanicalprosthetickneeshadenoughmethodologicalqualitytobeincluded in thereview. Samuelsson KAM, Töytäri O, Salminen AL, Brandt Å: Effectsoflowerlimbprosthesis on activity, participation, andqualityoflife: a systematicreview. ProsthetOrthotInt 2012, 36(2): 145-158

  5. Prosthetickneeselection Do prosthetickneeclassificationshelp? • Variouskneeclassificationsexist • all arebased on technologiesusedforstanceand swing control • extensive backgroundknowledgeoffeaturesandfunctionsofkneetechnologiesisneeded • featuresandfunctionsofprosthetickneesusingthe same technologymaydifferremarkably • prosthetickneeclassifications do not facilitateclinicaldecisionmaking

  6. Prosthetickneeselection Biomechanicalconsiderations – Stancecontrol Kneeflexion underweightbearing no kneeflexion limited kneeflexion unlimited kneeflexion • lockedknee • frictionbrakeknee • 4-bar polycentricknee • multiaxial knee (≥5 axes) • bouncingadapter • hydraulicknee • modified after: Blumentritt S: Biomechanical aspects of the indications of prosthetic knee joints.Orthopädie-Technik 2004,55(6):508-524 (Article in German)

  7. Mechanicalkneestabilityandfunction A reciprocalrelationship Function Stability* freesingleaxisknee lockedknee frictionbrakeknee 4-bar polycentricknee multiaxial knee(≥5 axes) hydraulicknee *Stability =preventionofkneecollapseduringlevelwalking ( ≠ Safety !!! ) Safety = stabilityduringlevelwalking + stabilityduringwalking on uneventerrains, slopes, stairs + toeclearance + stumblerecovery • modified after: Blumentritt S: Biomechanical aspects of the indications of prosthetic knee joints.Orthopädie-Technik 2004,55(6):508-524 (Article in German)

  8. 3R40 Lockedknee • Benefit • total stability (preventionofkneecollapse) at all timesandcircumstances • Disadvantages • walkingwith a stiffprosthetic leg at all times • compensatorymovementstoproducefootclearance • nostanceflexionforshockabsorption • does not supportreciprocalgait (step-over-step) on unevengroundorslopeandstairdescent 3R41 Suitableformobility grade 1 (household) ambulatorsoramputeeswhoare not abletosafelycontrola morefunctionalkneeonly.

  9. 3R49/15, 3R42 Frictionbrakeknee • Benefit • abletoflexduring swing phase – morenatural swing patternandfootclearance • Disadvantages • requiresfullextensionatheelstrike • nostanceflexionforshockabsorption • does not allowforkneeflexionatlatestance (pre-swing) • does not supportreciprocalgait on unevengroundorslopeandstairdescent 3R90 / 3R92 Suitablefor high mobility grade 1 (household) andlowtomedium mobility grade 2 (limited community) ambulators.

  10. 3R78 3R36/20 4-bar polycentricknee • Benefit(s) • usuallyverysafeatheelstrike • shorteningofcalfduring swing – improvedfootclearance • allowsforkneeflexionatlatestance – morenaturalanddynamicgaitpattern • shorteningofthighduringsitting – morenaturalappearance • Disadvantages • requiresfullextensionatheelstrike • nostanceflexionforshockabsorption • does not supportwalking on unevenground, slopes, andstairs • information on centroderequiredtomatchkneeandpatient 4-bar kneeswith a safecentrodearesuitablefor medium to high mobility grade 2 (limited community) andmobility grade 3 (unlimitedcommunity) ambulators.

  11. Multiaxial kneewith ≥5 axes • Additional benefitsto 4-bar knee • maysupport limited stanceflexionforshockabsorption • maysupportwalking on shallowslopesandsligthlyunevenground • Disadvantages • requiresfullextensionatheelstrike • stanceflexionof ≥5° requiresstanceextensiondampeningtopreventbuckling • does not supportreciprocalgait on heavilyunevengroundorsteeperslopeandstairdescent 3R60 EBS / 3R60 EBSpro Multiaxial kneesaresuitablefor medium to high mobility grade 2 (limited community) andmobility grade 3 (unlimitedcommunity) ambulatorswhotoleratestanceflexion.

  12. Hydraulicknee • Benefits • maysupportstanceflexionforshockabsorption • maysupportloadingforsitting down • maysupportreciprocalgait on unevengroundaswellasslopeandstairdescent • Disadvantages • requiresfullextensionatheelstrike • stanceflexionof ≥5° requiresstanceextensiondampeningtopreventbuckling • switchmechanismbetweenstanceand swing issusceptibletounintentionalswitching – amputee must alwaysbe “alert“, prepared, andabletotakeovercontrolwith residual limbor fall in a controlledmanner 3R80

  13. Hydraulicknee Hydraulickneesaresuitableformobility grade 3 (unlimitedcommunity) and 4 (veryactive [“athlete“]) ambulatorsonly.

  14. 3R55 Free singleaxiskneeandverydynamic 4-bar knee • Benefits • fullvoluntarycontroloftheprosthesis • mayallowfor (free swing) reciprocalgait on unevengroundaswellasslopeandstairdescentifproperlymotorcontrolledbythe residual limb • Disadvantages • absolutelynosafetyfeaturesotherthanposterioroffsetofthekneeor instant centerofrotation, respectively • requiresfullextensionatheelstrike • requiresexcellent residual limbstrengthandcoordinationtocontrolandsecuretheprosthesisatanytimesandcircumstancesaswellastheabilityto fall in a controlledand “safe“ manner 3R95

  15. Free singleaxiskneeandverydynamic 4-bar knee Free singleaxisandverydynamic 4-bar polycentrickneesaresuitableformobility grade 4 (veryactive [“athlete“]) ambulatorsonly.

  16. Prosthetickneeselection Biomechanic al considerations – Swing control Swing phasecontrol lowto medium rangeofgaitspeeds one (fixed) gaitspeed fullspectrumofgaitspeeds Friction Pneumatic Hydraulic Swing extensionassistiffullextensionpriortoheelstrike.cannotbereachedreliably

  17. C-Leg researchsummary • 14 clinicaltrialswith 236 patients • 12 biomechanicalstudieswith 129 patients • 5 patientsurveyswith 368 patients • 3 health-economicstudieswith 146 patients in 3 countries • 1 systematicreview The C-Legcombinesexcellentsafety (not onlystability) andsupportoffunction such assafereciprocalgait on uneventerrainandslopeandstairdescent.

  18. Summary Currentclinicalevidenceandtechnicalclassificationsdon´tfacilitate individual prosthetickneeselection. Kneeselectionmaybebased on biomechanicalconsiderations on certainstanceand swing controlfeaturestobematchedwiththephysical (and mental) capabilitiesaswellasmobilityneedsoftheamputee. Manufacturershavetoprovidemoredetailedinformation on theirprosthetickneesthantheycurrently do on theirwebsites, marketingmaterials, andinstructionsforuse. Manufacturersaresummonedtoinitiateandsupportresearchwiththeirprosthetickneestoproduceclinicalevidencetobetterguide individual clinicaldecisionmaking. Prosthetickneeselection

  19. Thank you foryourattention. andreas.kannenberg@ottobock.de

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