Overview of Knee Dis Articulation
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Transcript of Overview of Knee Dis Articulation
Overview of Knee Disarticulation
Gerald Stark,BSME,CP,FAAOP
Knee DisarticulationAdvantages/ChallengesBiomechanicsImpression TechniquesInterface DesignsKnee Types
Knee Disarticulation Prevalence0.7-2%1
20% in Some Centers2
CopenhagenToronto
Superior FunctionPoor CosmesisMost aren’t Optimized
Socket DesignAlignment
Slowly Declining KD NumbersMedicare KD Services
0
50
100
150
200
250
300
350
400
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Year
Num
. of S
ervi
ces
L5310-11L5150
Knee Disartic AdvantagesDr. Pinzur, Loyola Univ. 2
Full EndbearingMore Physiologic than AK,BK
Longer Lever ArmBetter Sitting BalanceSelf-Suspension
Lower TrimlinesPhysiologic
Decreased Blood LossResistance to Infection
Growing Use in ChildrenPreserves Femoral EpiphysisAvoids Bony OvergrowthDirect Load TransferGrows at a Slower Rate
Growth RestrictionFit as Transfemoral
Knee Disartic ChallengesDifferent than Transfemoral
Fewer NumbersLess CosmeticLength for Componentry
Limited componentryAccommodate Bulbous EndKC Proximal to Distal End
Surgical TechniquesPat. Tendon Sutured to Cruciate
Retain PatellaGastroc Wrapped Anterior for PadReduction Osteoplasty
Not for Vascular PatientsSagittal or A-P ClosureGritti-Stokes AmputationIPOP Rarely Provided
Knee Disartic BiomechanicsFull Weight BearingFulcrum Under Knee
Center of Rotation DistalNo Prox. Weight Bearing
Non-ischial Wt. BearingProximal Medial PressuresKD inverse of TFLower Trimlines
Impression TakingSelf-Suspension & Load Bearing 50%-50%Load Bearing
Adjustable StandVolumetric Control
Not Applying TensionMedial Wall ShapingNo Ischial or Gluteal Wt Bearing
Can’t Tolerate the Weight
Interface DesignsMolded LeatherMedial DoorStovepipe-Pelite BuildupPneumatic Pads or SleeveLiner w/SuctionLiner w/LockPartial Suction w/TES BeltSegmental Socket w/Strap
Molded Leather LinerUncosmetic & CumbersomeAdjustable ContoursDifficult to Make
Leather LinerAdaptable ShapeCreates Suspension
Different Tensions
Medial DoorExternal Strap & DoorVolume Adjustable
Don’t Need PadsCondylar Shape CrucialSlightly More ComplicatedFull End BearingCan use a Sock
Stovepipe-Pelite BuildupMore Bulky
Increased Wall ThicknessEasy to Use & MakeMore EnclosedMore PaddingGood for Bony LimbsSplit Distal Cup over Condyles
Pneumatic Pads or BuildupPneumatic PadsSilicone BuildupExcellent Suspension
Superior ComfortDifficult to Fix Volume ChangeComplicated ConstructionThicker Wall
Liner w/SuctionGel Liner w/ Leak ValveDistal Valve
Constant LeakMini Valve in Attachment
Most PopularMay Inhibit Weight BearingVolume Dependent
Add PadsIncreases Distal Bulk
Partial Suction w/TES BeltHypobaric Sock w/ ValveProximal Suspension
TES BeltBulky; Could use Self-Suspension
Not as Volume DependentCan use a SockMore End Bearing
Liner w/LockLiner w/ External Lock
Summit Lock~Coyote DesignsSki Binding LockMust Glue OnExternal HoleAccommodate Volume Change
Segmental Socket w/StrapZettl Type-Growth Comp. 3
Distal End CupProximal Cuff
Expanding BarsSupracondylar StrapsGrowth Compensation
JuvenilesLess Contact w/Skin
Knee DesignsExternal Knee HingesSingle Axis KneeWeight Act. Friction ControlPolycentric HingesManual LockingControl Options
FrictionHydraulicPneumatic
External HingesLess Cosmetic
Cumbersome, Damages ClothsNo Inherent Stability
Set More AnteriorDictated by KC
Back Check & Ext. AssistLeather Upper
Great Custom FitEasy to SuspendAccommodates Bulbous End
Exoskeletal Variations
PolycentricKD Specific Kinematics
Smoother MovementShin Shortening
Less Stability RequiredVertical Anterior Link
Longer Posterior LinkGreater Translation
Proteval Acphapend
More ProximalMore AnteriorDescends DistallyMore Voluntary Control Some Involuntary Stability
Century 22 Total Knee
Very Proximal CenterDescends RapidlyLock Mechanism
Toe Moment NeededEasy Moving 15 mm Clearance
Enhanced Voluntary Control
Proximal CentrodeMoves AnteriorEasy to FlexDoes not Lock Patient“Triggered” 4-Bar24mm Clearance
Control OptionsFriction Control
Mechanical SpringHydraulic
Hosmer YokePneumaticManual Locking KneeStance Flexion Control
References1) Bennet, A, Limb Prosthetics, 6th edition, Demos Publications, New York, NY, 1989.2) Pinzur, M., Chapter 19A: Knee Disarticulation/Surgical Procedures, Atlas of Limb Prosthetics, 2nd Edition, Mosby Year book, St. Louis, MO, 1992.3) Michael, J., Chapter 19A: Knee Disarticulation/Prosthetic Management, Atlas of Limb Prosthetics, 2nd Edition,, Mosby Year book, St. Louis, MO, 1992.4) Jennings, J., Wontorcik, L., “Fitting a Knee Disarticulation as a BK Utilizing the ALPS Locking Pin as a Pseudo-Tibial Lever: A Single Case Review”, Journal of Prosthetics & Orthotics, 1998, Vol. 10, Num. 1, pp. 7-10.5) Kempfer, J. “Technical Note: Thermoplastic Use in the Geriatric Knee
Disarticulation Prosthesis”, Journal of Prosthetics & Orthotics, 1991, Vol. 3, Num. 1, pp. 38-40.