Prosthesis

Upper and Lower Limb Prosthesis

1. Dr.SanjibKumar Das, Fellow Doctoral
MPT (Musculoskeletal Disorders)
PhD (Ergonomics & Human Factors)

2. Prosthetics
•Prosthesesareusedtoreplaceamissinglimbandto
restoreorprovidefunction.
•Theyaremanufacturedbyaprosthetistandfitona
custommadebasisontothepatient.
•Ideally,prosthesismustperformitsfunction,beeasy
tomaintain,donanddoff,becomfortabletowear,
anditshouldpreferablybelightweight,durable,and
cosmetictolookat.

3. ClassificationofProsthesis
ProstheticConstructionDesign
Exoskeletal Endoskeletal

4. ExoskeletalProsthesis
•Anexoskeletalprosthesisgainsitsstructural
strengthfromtheouterlaminatedshell,through
whichtheweightofthebodyistransmitted.
•Thisshellusuallymadeofaresinsocket,whichisquitedurable,
overafillermaterialofwoodorfoam,andthewholeprosthesis
isshapedtoprovideacosmeticappearanceoftheamputated
limb.
•Theoppositesurvivinglegistakenforreferenceforshape
lengthandskincolor.

5. EndoskeletalProsthesis
•Itgainsitsstructuralintegrityfromtheinner
endoskeleton—apylonmadeofmetalorcarbon
fibre,whichisalightinternalmodularcomponent
toprovideweightbearing.
•Thecosmeticappearanceisprovidedbyshaped
foamcoversslippedoverthemodularcomponents.
•Advantagesofthisdesignincludetheeaseof
alignmentofthecomponentsandtheiradjustments,
andtheabilitytointerchangecomponentsby
removingthefoamcover.
•Thedisadvantageofthisdesignisthatthefoam
coverisnotverydurableandneedstobereplaced
often.

6. ComponentsofaProsthesis
Thebasiccomponentsofprosthesisare:
•Socketmadeofplasticorresin
•Bodyoftheprosthesis
•Harness/suspensionsystem
•Controlsystem(notrelevanttolowerlimbprostheses)
•Terminaldevice:Fortheupperlimbtheterminaldeviceisthehand
andforthelegitisthefoot.

8. Terminaldevicesareclassifiedas:
•Cosmetichands
•Body-poweredhooksandhands
–Voluntaryopening(VO)
–Voluntaryclosing(VC)
•Externallypoweredhooksand
hands.
•Myoelectric
–Digital
–Bionicarm

10. MyoelectricProsthesis
•Amyoelectricprosthesisusessignalsor
potentialsfrommusclesthrough
electromyography,withinapersons
stump.
•Thesignalsarepickedupbyelectrodes
onthesurfaceoftheskinwhichactivates
abattery-drivenmotorthatoperatesa
prostheticcomponent,likethefinger.
•Controlofthemotorregulatestheextent
orspeedoftheprosthesis,suchaselbow
flexionorextension,oropeningand
closingofthefingersoftheterminal
device

11. Advantages
•Useofnaturalmusclestimuli.
•Moreaccuratecontrolwithlessenergyexpenditure.
•Eliminatestheshoulderharness&decreasedbodymovementto
controlprosthesis.
•Themyoelectricprosthesisprovidesmoremobility,pinchforce,
andcosmeticappearancethanbodypoweredprostheses.
Disadvantages
•Theyareveryexpensive
•Intheeventofabreakdown,itneedsveryskilledtechnicalbackup
torepair.
•Alsotheyneedservicingonaregularbasis
•Theenergysourceisfromabattery,whichwouldhavetobe
rechargedregularly.
•Myoelectriccomponentsmaygetdysfunctionalinwateroraround
magneticorelectronicfields.

14. BKprosthesisfortranstibialamputations:PTBprosthesis
•Thepatellartendonbearing(PTB)
socketisthestandardtranstibial
socket.Itisalaminatedplastic
socket.
•Thebodyweighthastobetakenon
thepatellartendon.
•Apartoftheweightisborneoverthe
condylarflares.
•Areasofrelieffrompressureinclude
theheadofthefibula,thedistalends
ofboththetibiaandthefibula,and
theshin.

15. PTBprosthesis
•Theproximalposteriorwallofthesocket
bulgesposteriorlytoallowforthemuscle
bulk.
•Thelevelofthiswallmustbelowenoughto
allowtheclienttositwiththekneeflexedat
least90°degrees,yethighenoughtoprevent
unduebulgingoffleshoverthebrim.
•Theproximaledgeisroundedtopreventsharp
pressureonthebackoftheknee;groovesare
providedatthemedialandlateralcornersfor
thehamstringtendons.
•Theanteriorwallreachestopatellarleveland
hasashelfthatcorrespondstoandshiftsthe
weightonthepatellartendon.Themedialand
lateralwallsreachapproximatelytothelevel
oftheadductortubercle.

16. AKprosthesisfortransfemoralamputations
TheQuadrilateralSocket
•Itisnamedforitsfourwallsthathaveaspecific
function.
•Distally,thesocketiscontouredtoprovidetotal
contactfortheresiduallimb.
ThePosteriorWall
•Mostoftheweightisbornealongtheposterior
wall.Theischialtuberosityandsomegluteal
musclesrestontopofthewall,whichisthicker
mediallythanlaterally.
•Internally,thewalliscontouredforthehamstring
muscles,whileexternally,itisflattoprevent
rollingofthethighinsitting.
•Theheightoftheposteriorwallisdeterminedby
thepositionoftheischialtuberosity.

17. AKprosthesisfortransfemoralamputations
TheAnteriorWall
•Itrises about 5cmsabove the height of theposterior wall.
•Itis convex laterally to allow space for the bulk of the rectus
femorismuscle.
TheLateralWall:
•Thelateralwallisashighastheanteriorwall.
•Inside,thewallinclinesmediallytosettheresiduallimbinabout
10°ofadduction.Thelateralwalliscontouredtodistributepressure
evenlyoverthatside,andbearsomeoftheweight.
TheMedialWall:
•Isverticalandpreventsmedialmovementoftheresiduallimb
withinthesocket,especiallyduringstance.
•Areliefchannelisbuiltintothecornerofthemedialandanterior
wallsfortheadductorlongustendon.
•Themedialwallandtheposteriorwallareofthesameheight.
•Hitchingonthepubicramus,whichcausesalotofirritation,is
avoidedbyloweringthemedialwall.

18. BilateralTransfemoralAmputationsStubbies
•Stubbyprosthesesor“stubbies”aregenerally
prescribedonlyforindividualswithbilateral
transfemoralAKamputationswhoare
motivatedtoambulatebutwhoarenot
candidatesforfittingwithfulllengthprostheses.
•Theyaremosteffectiveforindividualswith
shortresiduallimbs.
•Stubbyprosthesesdonothaveanykneejoints.
Theyhaveabovekneesockets,aswithAK
prosthesisandtopreventthewearerfrom
fallingbackwardareprovidedwithmodified
rockerbottomfeet.

19. BilateralTransfemoralAmputationsStubbies
•Theyareshorterthantheoriginallimbs,tobringdownthe
centerofgravity,andtherebyincreasestability.
•Stubbiesalloweasybalanceandthepatientwalkswith
lesserexpenditureofenergy.
•Ambulationcausesexaggeratedtruncalrotation.Short
canesorcrutchesareusuallyneededforsupport.
•Sittinginachairandclimbingstairsarelittledifficult
becauseofshortnessofprosthesis.
•Manypeoplefindstubbiescosmeticallyunacceptable
becauseoftheextremereductioninheight.

21. MultiaxisFeet
•Singleaxisfeetallowmovementofthefootinone
axis,upanddown.
•Multiaxisfeetmoveupanddownaswellassideto
sidetoconformtounevensurfacesbetterthansingle-
axisfeet.
•Multiaxisfeethaveanklemotion,whichabsorbsthe
stressofwalking,reducingwearandtearonthe
prosthesis.

22. NondynamicResponseFeet
SolidAnkleCushionHeel
•Thesolidanklecushionheel(SACH)footisanon-
articulateddevicewithasolidwood,aspongerubberheel
wedge,andamouldedcosmeticforefootwithorwithout
individualtoes.Mildhyperextensionoftherubbertoe
andforefootispossibleinlatestanceandpushoff.

23. JaipurFoot
•TheSACHfoothasdisadvantagesthatithastobe
usedonlywithshoessincetheshapesofthetoesare
notdiscernible.
•InIndia,wherebarefootwalkingisprevalentin
villages,togetherwiththepracticeofnotwearing
shoesinsidethehomesandtemples,itwasbutnatural
thattherewasaneedforacheapalternativetothe
SACHfootwhichwouldalsobecosmetic.
•ItwasdevelopedatSMSMedicalCollege,Jaipurby
ProfPKSethiandteam.
•Itprovidesbarefootwalking.Thefootandankle
assemblyismadeofrubbermaterial.
Advantages
•Cosmeticallywell-acceptedintheruralpopulationwhopreferbarefootambulation.
•Theelasticityoftherubberprovidesenoughdorsiflexiontopermitanamputeeto
squat,transverserotationofthefootonthelegtofacilitatewalkingandcross-legged
sitting,andsufficientrangeofinversion-eversiontoallowthefoottoadaptitself
whilewalkingonunevensurfaces.
•Exteriorismadeofawaterproofdurablematerial,forworkinfields
•Lessexpensive
•Therawmaterialislocallyavailable.

28. DynamicResponseFeet

29. ThankYou
Dr.SanjibKumar Das, Fellow Doctoral
MPT (Musculoskeletal Disorders)
PhD (Ergonomics & Human Factors)
Mail: [email protected]
Contact No: [phone]/ 8169951520 (India)