The Universal Prosthesis -- Appendixes 2005-11-18 - A4

= Table of Contents Contents A B C D E F G H I K L N Q R S T U V X Y Z

Design for All Summary__________________________________ 2 Internship Summary_______________________________________ 3 Project Timeline__________________________________________ 4 Socket Designs Timeline___________________________________ 5 History of Prosthetics_ __________________________________ 6 Calculations on Prevelance_ ______________________________7 Residual Limb Dimensions_________________________________ 8 Customer Organizations and Resources__________________ 10 Producers of Components________________________________ 12 Available Feet___________________________________________ 14 Connective Components & Pylons_______________________ 15 ICEX Manual___________________________________________ 16 Idea Sketches_____________________________________________17 Frame Overlays - 1 to 12_______________________________ 25 Mechanical Analysis - FBD&FEM_______________________ 37 Total Concept Presentation_ ____________________________ 39 Fitting Procedure________________________________________ 40 Price Estimation_________________________________________ 41 J. Foort - Innovation in Prosthetics_ ____________________ 44 Comparison Table________________________________________ 56 Technical Drawing of the Frame_________________________ 57

Boudewijn Wisse - The Universal Prosthesis - Appedixes

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A Design for All Summary Prosthesis for Tibial Amputees focused on the 3rd World



2002 - TU Delft



By : Boudewijn Wisse, Wouter van Dorsser, Farshad Soleymani

Summary:

For the subject ‘Design for All’ at The Faculty of Industrial Design Engineering of Delft University of Technology in The Netherlands we designed a prosthesis for mine victims in Sri Lanka.

After

thoroughly doing different analyses, like a medical analysis for which we made two visits to orthopedic specialists in the Dijkzigt hospital in Rotterdam, a social analysis and an analysis of existing prostheses, we could make a list of the most important requirements for our design of the prosthesis.

We have developed one concept for the prosthesis foot (Rocker foot) and 3

concepts for the socket of the prosthesis (Leather concept, Polymer concept and a Redesign of a concept which was made years ago by another Industrial Designer Inne ten Have). The three concepts will be discussed with our teacher Johan Molenbroek and two specialists Henk Kooistra and Inne ten Have whom are connected to this project, to eventually choose / combine the best solutions.

O

ur design philosophy is that our design will be made at a prosthetic workshop in Sri Lanka, by the local prosthetists using local means. The prosthesis is standardized and has a ‘Western look’ to it and the owner of the prosthesis can manage to use this design for the rest of his life. The design of our prosthesis is self explaining. The owner or his/ her supervisors can easily figure out how the prosthesis is made and if necessary they can repair or adjust the prosthesis themselves.

Boudewijn Wisse - The Universal Prosthesis - Appedixes

A

B Internship Summary The alternative prosthesis



2002 - Sri Lanka, Colombo



2003 - TU Delft, The Netherlands



By: Boudewijn Wisse, Wouter van Dorsser

Summary:

These are the results of a project in which a new concept for prostheses for the trans-tibial (below-knee) amputees of Sri Lanka was developed.

Although civilian landmine victims are a minor cause, Sri Lanka copes with

a shortage of care for amputees. The lack of prosthetists is the bottleneck, resulting in a low production capacity of prostheses and little aftercare.

Other problems include: Price, locating amputees, difficulties distributing prostheses and the long time needed to fit, produce and adjust prostheses.

Research

trails and prototypes strongly suggest that the situation could be improved with an alternative for trans-tibial prostheses, in this report presented as the “DFU” (Designed For You)..

Though

the design philosophy is very strong, the actual design is not optimised and could still be altered. Therefore this project needs to be continued, so the design will be implemented and much more trans-tibial amputees can be helped.

Not

only trans-tibial amputees will benefit in such a way. The freed production capacity can then be used to produce above knee prostheses or otheses.

Boudewijn Wisse - The Universal Prosthesis - Appedixes

B

F Calculations on Prevelance The following data is collected from the World Health Organisation (WHO).

1

2

3

4

5

Total Population

Amputated Arm

% of pop.

% of all

Africa

655.477.000

1.041.000

0,1588

19

America’s

837.966.000

662.000

0,0790

12

Europe

874.178.000

614.000

0,0702

11

Columns: 1. 2. 3. 4.

Area or criterion Total amount of persons in that area Total amount of amputees in that area Total amount of amputees divided by the total amount of persons = the percentage of that area which has an amputation 5. Total amount of amputees of the area divided by the total amount of amputees of the world = percentage of world figure of amputees living in that area. 1

F

Boudewijn Wisse - The Universal Prosthesis - Appedixes

2

3

4

5

Total Population

Amputated Foot/leg

% of pop.

% of all

Africa

655.477.000

3.235.000

0,4935

22

America’s

837.966.000

1.115.000

0,1331

7

Europe

874.178.000

1.416.000

0,1620

9

SE Asia’s

1.559.810.000

5.769.000

0,3699

39

Western Pacific

1.701.689.000

1.591.000

0,0935

11

Eastern Mediterranean

493.091.000

1.833.000

0,3717

12

Males

3.083.884.000

8.025.000

0,2602

54

Females

3.038.327.000

6.934.000

0,2282

46

TOTAL

6.122.211.000

14.959.000

0,2443

100

Table F-1: Figures about the estimated amount of foot or leg amputees by point prevalence according to the World Health Organisation

SE Asia’s

1.559.810.000

1.692.000

0,1085

30

Western Pacific

1.701.689.000

899

0,0001

16

Eastern Mediterranean

493.091.000

644

0,0001

12

Males

3.083.884.000

3.623.000

0,1175

65

Females

3.038.327.000

1.930.000

0,0635

35

TOTAL

6.122.211.000

5.552.000

0,0907

Table “F-2: Figures about the estimated amount of arm amputees by point prevalence according to the World Health Organisation.

Our own data [The Alternative Prosthesis, Appendix B.2] suggests 65% of the amputations being transtibial in developing countries. The following picture from internet (source unkown) indicates 55% transtibial amputations in Western countries.

G Residual Limb Dimensions

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Statistics

The following data is derived from population patient cards studied in Sri Lanka [source: Report – appendix B.2 and data files].



stump lengths (mm)

Foot sizes (Jaipur)

Leg length (mm)

P.T. circumference (mm)

Mean

166

7,56

433,9

304

Standard Error

4,4

0,08

11,5

2,77

Median

160

7

45

305

Mode

140

7

45

320

Standard Deviation

52

0,88

53

28,7

Minimum

0

6

325

155

Maximum

381

9

500

368

Sum

2312,145

885

91122

32623

Population (n)

139

117

21

107

P5

166 - 1,65 X 52=80

6,1 (6)

345

258

P95

166 + 1,65 X 52=250

9,0 (9)

520

352

G

Length

M

easurements of below knee stump lengths. Important data, derived from 139 patient cards in Sri Lanka:

In Western countries we may expect some less variation because of better

standardized procedures in the hospitals. Maybe the mean length is a little higher because of a longer mean total body length. Notice that the P5 is equal to the minimal length due to biomechanical considerations [see section 3.1.2]. A P5 to P95 tibial length seems acceptable.

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Foot sizes

Feet are applied to the prosthesis in several sizes, varying from 6 to 10 with half a steps in between (6, 6½, 7, etc). The need for several foot sizes needs to be considered while discussing the distribution of the universal prosthesis.

G

Circumferences

From

the same data circumferences where obtained at several distances from the patellar tendon. This data adds up to the following figure:

In this figure it becomes clear that circumferences vary much less around

the patter tendon than about 160 mm below it. Also note that almost half of the amputees have their stumps ending at this level.

H Customer Organizations and Resources Organizations 3rd W - Adopt-AMinefield

Raising awareness and funds to clear landmines and help survivors

3th W - POF

Prosthetics Outreach Foundation

International - CIR

The CIR is a worldwide humanitarian network of individuals and organizations that promote the full potential of people with disabilities through education, innovation, and advocacy.

Boudewijn Wisse - The Universal Prosthesis - Appedixes

H

NL - VRIN

Landelijke samenwerkingsverband van revalidatie-instellingen

NL - VRA

Nederlandse Vereniging van Revalidatie Artsen, website met veel resources.

UK - BAPO

British Association of Prosthetists and Orthotists

UK - Limbless Association

Information for Amputees in the UK

USA - ACA

Amputee Coalition of America

USA - amputee-online. com

Resource and forum for amputees

USA - AOPA

American Orthotic & Prosthetic Association

USA - ISPO

United States Member Society of the International Society for Prosthetics and Orthotics

International - IAOP

International Association of Orthotics & Prosthetics

International - Interbor

International dome association of national O&P trade associations

International – IPRLS

International Institute for Prosthetic Rehabilitation of Landmine Survivors is a Tuftsaffiliated non-profit organization, which strives to help landmine survivors to regain the quality of life. Also developers of the Rolling Joint Ankle aka Free-flow foot.

USA - NAAOP

US National Association for the Advancement of Orthotics and Prosthetics

USA – NARIC

US National Rehabilitation Information Center.

USA - NRAF

US National rehabilitation awareness foundation

USA - OPAF

Orthotic and Prosthetic Assistance Fund

International - ISPO

International Society for Prosthetics and Orthotics

USA – U.S. DVA

US Government - Department of Veterans Affairs

NL - CVZ

Het College voor zorgverzekeringen (CVZ) coördineert en financiert de uitvoering van de Ziekenfondswet en de Algemene Wet Bijzondere Ziektekosten (AWBZ).

USA - UASA

United Amputee Services Association

NL – I-S-P-O

ISPO Nederland is de Nederlandse vereniging van de International Society for Prosthetics and Orthotics

NL - LVvG

Landelijke Vereniging van Geamputeerden

NL - NPI

Het Nederlands Paramedisch Instituut is het paramedisch kenniscentrum in Nederland en voor alle paramedische beroepen actief op de volgende drie terreinen: Documentaire informatievoorziening, Onderzoek & ontwikkeling, Deskundigheidsbevordering.

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Web-resources and Journals International - oandp. com - the global resource for Orthotics & Prosthetics information.

The leading Internet information resource for professionals and consumers with an interest in the orthotics and prosthetics field. Also publishes the Journal of Prosthetics & Orthotics.

NL - Orthobode

Orthobode is een tijdschrift dat informatie en opinie biedt over ontwikkelingen in de orthopedische branche.

Important Prosthetic Workshops and revalidation centres in the netherlands

LIVIT

Region Den Haag

Jongenengel

International - CIRRIE database (2)

The database from the Center for International Rehabilitation Research Information and Exchange. Contains only research conducted OUTSIDE of the US

POI

Prosthetics and Orthotics International

Physical Medicine and Rehabilitation

Official Journal of the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation [Elsevier / WB Saunders], also see Science Direct database

TU Delft Library

Electronic Journals available on multiple subjects

AbleDATA

ABLEDATA provides objective information on assistive technology and rehabilitation equipment available from domestic and international sources to consumers, organizations, professionals, and caregivers within the United States.

REHAB-Data

From NARIC. Contains only research conducted INSIDE of the US

H

Roessingh

Twente

OIM Groep

North of Netherlands

Sophia Revalidatie

Den Haag

Design and Research in Prosthetics in the Netherlands Movi

Bewegingstechnologisch ontwerpbureau

I Producers of Components Most important for the project / big players: Bauerfeind.nl

www.bauerfeind.nl, www.bauerfeind.de, www.bauerfeind.co.uk, www.bauerfeindusa.com

Components and accessory

Blatchford (Endolite)

www.blatchford.co.uk, www.endolite.com

Endolite (ESK knee, DR2 foot, Mercury foot, Multiflex, SACH, ATF)

Fillauer

www.fillauer.com

Durashock pylon, EAS Alignment systems, 3S, Hosmer,

Hanger Orthopedics Group

www.hanger.com

ComfortFlex, springlite

Kingsley

www.kingsleymfg.com

SACH (strider) foot, Steplite, B.O.A. Alignable BK System - (BuiltIn-One Point Alignment), Also distributor, etc

Ortho Europe [Utrecht] / Ohio Willow Wood

www.ortho-europe.com, www.owwco.com

Össur Total Solutions

www.ossur.com

Flex-Foot, Icelock, Iceross, Mauch, The Pin, Total Concept, Total Knee, Total Shock, Ices

Otto-Bock Healthcare

www.ottobock.de, www. ottobockus.com

Components (C-Leg, Harmony, Springlite feet) and materials

Seattle Systems

www.seattlesystems. com

Seattle Foot, Voyager Foot/ankle

Streifeneder

www.streifeneder.de, www.eurointl.com

Components, materials

Ohio Willow Wood (import), Alpha Liners,

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Medium importance Airlimb

www.medwing.com

Air-limb, inflatable IPOP

Ambroise [Enschede]

www.ambroise.n

The Wilmer and UTX orthoses

Amputee treatment center

www.amputee-center. com

Pump-It-UP! Socket

Atlas International

www.atlasortho.com

Components and materials

Basko [Amsterdam, international]

www.basko.com

Silicone-kits and components.

Cascade

www.cascade-usa.com

Components and materials

Flo-Tech Orthotics and Prosthetics.

www.1800flo-tech.com

APOPPS (Adjustable Postoperative, Protective and Preparatory System)

Orthomedics

www.orthomedics.com [currently not working]

Prefabricated Adjustable AK Socket, Redi-Lite

Simbex

www.simbex.com

Active Contact System (fluid pump) IC-110

USMC

www.usmc.com [currently not working]

Components

I

Boudewijn Wisse - The Universal Prosthesis - Appedixes

No information about: Alblas, Tehlin, Nordic, O&P Enterprises Inc,

Less important: Acor

I

Prosthetic cones, materials

Freedom-Innovations

Sports feet and liners

AEGIS

Liners, sleeves, locks

Jim Smith Sales

Distributor

ALPS South Corp. Knit-Rite

Prosthetic Socks

American Plastics

materials

MICA

Genesis II foot series, Evolution foot

American Prosthetic Components Inc

APCI, components

Practitioner’s Support Laboratory

Fabrication techniques/support

Aulie Prosthetic Devices

water sports components

Prosthetic Research Specialists

Shrinkable U-Fleet Skin Sleeves

Bolt Systems Inc

liners

Rampro Activankle and Swimankle

Sports components

College Park Industries

CPI, TruStep foot, TruPer foot

Royal-knit

Socks

Coyote Design

locks, liners, materials, integrators

RX textiles

Materials

ESP (Engineered Silicone Products)

liners, valves

Silipos

Gel liners

Engineered Silicone Products (ESP) Victhom

Human bionics

Fabtech Systems

materials

Farablock

Fanthom pain relief

Ferrier Coupler Inc

couplers

ForeSee Orthopedic Products

4C: Custom, Carbon, Composite, Creation components

Remarks:

Orthotic/Prosthetic Laboratories acquired by Otto-bock. Euro

International represents FG Streifener, but offers also some other products.

Hosmer & Centri are Fillauer companies. Resources at: http://www.oandp.com/, http://www.oandpbiznews.com/, and obtained from LIVIT Den Haag, obtained from literature.

This results in a slightly America orientated list of companies.

N ICEX Manual - 1

Boudewijn Wisse - The Universal Prosthesis - Appedixes

N

N ICEX Manual - 2

Boudewijn Wisse - The Universal Prosthesis - Appedixes

N

N ICEX Manual - 3

Boudewijn Wisse - The Universal Prosthesis - Appedixes

N

N ICEX Manual - 4

Boudewijn Wisse - The Universal Prosthesis - Appedixes

N

N ICEX Manual - 5

Boudewijn Wisse - The Universal Prosthesis - Appedixes

N

N ICEX Manual - 5

Boudewijn Wisse - The Universal Prosthesis - Appedixes

N

Q Idea Sketches

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Q

(1) - How can you adjust the size (length and circumference) of a socket/cyclinder?

Fold

Multilink

Make ellips with belts

Diaphragm

Telescope

WC-roll (rotate and pull)

Insert piece

Like a poster (roll)

Fill (foam or coating)

Inflate or fill

Flower principle

Bend inwards or outwards

Roll (circumference)

Roll (length)

Harmonica (straw principle)

Bamboo

Screw it

Bend/Stretch

Saw it

Add length

two plates _ (perpendicular)

two plates_ (parallel)

Distal end cup

Patellar tendon flap

(2) - Or a pylon?

Bolt

rotate and move up

Q Idea Sketches

Boudewijn Wisse - The Universal Prosthesis - Appedixes

(3) - How to make a frame (that can carry the body weight) deformable?

Pivots and locks

two shells (detach, deform,

Increase deformation

Deformation only one way

Ti-rap - Ski-Shoe lock

Self-locking force

(4) - How to attach a deformable part to a rigid skeletal frame?

Melt

Weld

Glue

Dip and coat

Plait / Weave

Add bag

Wrap

Inject

Q

Q Idea Sketches

Q

Boudewijn Wisse - The Universal Prosthesis - Appedixes

(5) How to align a loadable frame/pylon?

Bend

Clasp with screws

Movement in _ horizontal plane

Angle by lever

Pivots

Standard solution

Multi holes

Slide

Angle by _ deformation

Standard Pivot

Shorten one side

Multi Angle cube

(6) How can one prosthesis make total contact with a wide range of different shaped residual limbs? How can a tight fit be assured?

Suck / vacuum

Follow

(De)form soft _ tissues

Inflate/fill

Two cut cylinders

Q Idea Sketches

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Q

(7) - How to improve weightbearing properties and pressure destribution of the socket?

Partly loaded distal end pad

Turn to increase stiffness

Force redirect _ with pulleys

Distal End gel pad

Force analysis with pylon in

Extra dampening

Tensile strap _ (front to back)

4 bar mechanism

(8) - How can the fitting and alignment procedure become easier? Make the procedure Incorporate use-cues For length and for angle

Simplify Less steps Fit, production and alignment Standerdize the actions Always 5

degree flexion

Multi 4-bar mechanisms

Vertical dampening How to communicate the angle?

High feedback speed During the fit

the patient can Adjust the fitting

Use easy to identify

Talk

Knee-hight while sitting

3D compensated view

Q Idea Sketches

Boudewijn Wisse - The Universal Prosthesis - Appedixes

(9) - How can a tight fit of the socket be accented during load (stance) and a comfortable fit during rest (sitting, swing-phase)?

Change load_ area’s

Tranfer forces

Remove _ compensation

Strangle-fitting (worg-fitting)

Leave space

(10) - How to improve vertical dampening while keeping control and direct sensory feedback during use?

Dampening as low as possible

Restricted _ dampening

System only reacts to high

Q

Q Idea Sketches

Q

Boudewijn Wisse - The Universal Prosthesis - Appedixes

(11) - How to don and dof prosthesis?

Fix it with a _ elastic ring

Roll (condom/_ liner principle)

Klick

Shove

Tie

(12) - How to don and dof a prosthesis when the patient has a bulbous residual limb shape?

Two parts

Stay below_ tangents

Bend/Deform

Screw last part

Wrap

Deform/bend

Zip it

Use Belts

Q Idea Sketches

Boudewijn Wisse - The Universal Prosthesis - Appedixes

(13) - How to increase weight bearing properties of bendable pylon?

attach surface below (1)

Attach surface above

Rotate perpendicular to

(14) - Principles for the pylon:

Basic shapes

Below (standard) Front

Side

Back (incl. 4 bar mechanism)

Q

Q Idea Sketches

Boudewijn Wisse - The Universal Prosthesis - Appedixes

(15) - How does the soft part contribute to the stiffness of the whole?

Harden it

Fill

Add tensile

force Make it elastic

Add springs

see

(16) - How to make a deformable socket solid/force resistent within 10 minutes? Freeze it Warm it, then cool it UV (light)- _ trigger

Inflate

Remove something Remove compensation

Add pressure Add something Wrap it

Fill Electro- trigger

Chemical reaction Chemical- _ trigger

Concrete

Glue Epoxy / Resins

Thermal- _ trigger Burn it!

(17) - How to integrate a suspension system and connective components in the universal prosthesis?

Condyle part

Knee cuff

Suction bag

Multi pylon ends

Lock it Deform it

Deform forces much bigger

Screw tight Increase tension_

Q

R Frame Overlay - 1

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

The leg and the knee; impressions of the view from outside. Also the common peroneal nerve is shown. If the peroneal nerve is damaged, the patient will suffer from dropfoot. For the amputee, damage and pressure on the peroneal nerve can result in pain and dis-comfort.

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R

R Frame Overlay - 2

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

R

Impressions of the muscles and some bones. The big muscles such as the gastronemicus are pressure tolerant. Muscle-bone conbination is especially presure tolerant, such as the borders of the tibia (where the muscle overlaps the tibia. The tibial crest, without muscle protection is very sensitive. The patellar tendon is very pressure tolerant.

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R Frame Overlay - 3

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

R

The bones in the (residual) limb can transfer load best. however, in amputees, the distal end of the bone is very sensitive. Distal loading is therefore not recommanded. Because the gatrocnemicus (kuitspier) takes a lot of space, it will easily deform while loaded (no bones to transer the load to!)

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R Frame Overlay - 4

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

R

Sensitivity and pressure tolerance: Summarizing, the (residual) limb is extremely pressure tolerant in the blue area’s, tolerant in the green area’s, neutral in the yellow area’s, sensity in the orange area’s and pressure intolerant in the red area’s

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R Frame Overlay - 5

Boudewijn Wisse - The Universal Prosthesis - Appedixes

352 mm 304 mm

166 mm 250 mm

mean total leg lenght 434 mm

80 mm

258 mm

circumferences

scale approx. 1 : 3.8

Impressions of different residual limb sizes: black P05 circumference and P05 length. green P50 circumference and P50 length. orange P95 circumference and P95 length. underlay: Pressure sensitivity ± 15% Variation in length is much bigger (mean ± 50% for P5 & P95) than in circumference (mean ± 15%). Note: Residual limb shapes can differ from shown. anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R

R Frame Overlay - 6

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

1

1 1

1 2

R

3

4 2

4 surface max pressure area green 230 + 30 kPa 700 mm2 blue 1+2+3 60 + 30 kPa 6500 mm2 red 1 0 + 30 kPa 2700 mm2 +20 kPa is hydrostatic pressure after fabrication. From the pressure tolerance of the different residual limb area’s and the data about the variance in length and circumference for P5-P95, suitable area’s (blue) for the hard parts of the universal prosthesis are selected. Area’s to avoid pressure are shown in red. Note: the area’s are selected on tissue properties and anatomy only, not on biomechanics.

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R Frame Overlay - 7

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

R

y-axis

x-axis

Hydrostatic pressure over the total area of the residual limb (green border line) of 30 kPA will result in an additional upwards force of about 310 N. Warning: as shown above, the FBD is not in equilibrium in plane x and z! anterior (frontal plane)

lateral (saggital plane)

surface max F angle Fy Fxz green 160 N 60 140 81 blue 1 60 N 18 20 57 blue 2 180 N 19 60 170 blue 3 150 N 14 35 146 blue 4 570 N 20 195 536 Force vectors should be normal to the tissue/skin and can be devided in a Fx, Fy, Fz component. Free Body Diagrams per plane are shown. Forces for hard parts only, so with -30 kPa per area for hydrostatic pressures. Total Fx when all blue&green surfaces are used at maximum pressure is 450N, which is 50% of the body weight of an 90 kg (heavy) user. Optimal use for all blue and green surfaces is needed for hard socket parts. posterior (frontal plane)

R Frame Overlay - 8

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

Blue : Pressure area’s (medium stiffness) These area’s transfer the highest loads to the risidual limb.

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R

R Frame Overlay - 9

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

Hard socket: Blue : Pressure area’s (medium stiffness) Red: Connective part of hard socket (high stiffness) Green: Connective but movable part (high tensile strength)

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R

R Frame Overlay - 10 scale approx. 1 : 3.8

Velcro with big area

R

Boudewijn Wisse - The Universal Prosthesis - Appedixes

The connective textile to the other part is integrated in one frame and attached with Velcro on the other.

Dubble layer glass fiber in between the frame parts

A tighening mechanism to increase tensile forces when needed during the fitting procedure.

Long, thin extentions of the interface frame (blue) help to shape the final prosthesis and to support the residual limb.

The strip is completely fastened to the frame parts on this side

In height adjustable. If needed the extruding frame parts can be sawn and discarded. The connective component is empty inside. It is not round, but elliptical to transfer torque The connection with the foot is compatible with standard foot components.

anterior (frontal plane)

Complete design of the hard socket and connective components. lateral (saggital plane)

posterior (frontal plane)

R Frame Overlay - 11

Boudewijn Wisse - The Universal Prosthesis - Appedixes

R

R Frame Overlay - 12

Boudewijn Wisse - The Universal Prosthesis - Appedixes

scale approx. 1 : 3.8

anterior (frontal plane)

lateral (saggital plane)

posterior (frontal plane)

R

S Mechanical Analysis - FBD

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Niet op schaal

S

BODY 40

40 400 N

400 N 1030 N

1030 N

400 N

400 N

70

PT

1030 N

70

MP

400 N

1030 N

630 N

630 N

260

END

Fixed (72 Nm)

CONNECTOR

Fixed (88 Nm)

Static Analysis that will be used for the FEM-analyssis. First the FBD of the residual limb is drawn (middle). The situation is simplified to 100% Patellar Tendon

Bearing of (half of the) body weight (80 KG). The needed bulge inclination (see figure 3-9) varies between 45 and 60 degrees, of which the first statically results in higher forces and is used in the calculations. The 400 N (BODY) which needs to be beared results in two 400 N components at the PT. The resulting moment and translational forces are compensated at Mid-Posterior (MP) and the distal END. All these forces (expect the body weight) are applied on the risidual limb by the frame parts (left: posterior, right: anterior). The frame parts are fixed in the connector which for the FEM-analysis can be taken as fixed in space.

S Mechanical Analysis - FEM

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Deformation map

Side view of load

Back view of load

3D-view of load

Displacement overlays

The loads from the FBM are transfered to:

Strain map

Place of act

load name

height

colour

the most proximal edge of the model

the PT-load

at PT=0

in yellow

the two end vertexes of the proximal edge

the band-pull

at PT=0

in dark green

A intersection curve

the distal end load

at PT=140

in purple

Start of straight frame shape

constraint

at PT=260

in light green

In general, we can see that: - Under the load presented here the shape stays roughly the same, - The pattellar tendon dent (edge) wants to press harder in the residual limb (the depicted displacement cannot occur during use, because then the knee/ PT is “in the way”). - Before production, the frame shape has to be optimized to reduce stresses in the material, especially more distally.

Stress map

S

U Fitting Procedure 1

Boudewijn Wisse - The Universal Prosthesis - Appedixes

2

3

6 5

4

6

7

17 18

10

12

9

14 13 15 8

11

16

U

V Price Estimation

Boudewijn Wisse - The Universal Prosthesis - Appedixes

V

Rough price estimation. All prices in Euro’s. The machining, assembly, etc is calculated from man/machine hour prices. This keeps the chose of producting in own facilities or out-sourced open. Amount of kits: Produced parts:

1000,00 Pieces

Material costs

10000,00

Production tools

Price per piece

Material costs

Comment

Production tools

Price per piece

Interface frame L Ant+Post

1000

1,25

4000,00

5,25

10000

1,25

8000,00

2,05

20 out of 1 m2, ABS

Interface frame R Ant+Post

1000

1,25

4000,00

5,25

10000

1,25

8000,00

2,05

20 out of 1 m2, ABS

Weight-bearing frame L Ant+Post

1000

1,75

4000,00

5,75

10000

1,75

6000,00

2,35

20 out of 1 m2, Hylite

Weight-bearing frame R Ant+ Post

1000

1,75

4000,00

5,75

10000

1,75

6000,00

2,35

20 out of 1 m2, Hylite

Liner inside

1000

0,15

6000,00

6,15

10000

0,15

6000,00

0,75

3E/kg raw material, The inside and the outside are extruded together

Liner outside

1000

0,15

1,00

0,15

10000

0,15

1,00

0,15

3E/kg raw material

Pad

6E/kg raw material

1000

0,30

2000,00

2,30

10000

0,30

2000,00

0,50

Connector L

500

2,78

90,00

2,96

5000

1,99

90,00

2,01

Connector R

500

2,78

91,00

2,96

5000

1,99

91,00

2,01

Inner Seal L

1000

0,15

3000,00

3,15

10000

0,15

3000,00

0,45

Inners Seal R

1000

0,15

3000,00

3,15

10000

0,15

3000,00

0,45

V Price Estimation Machinecosts:

Cost per hour

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Amount per hour

Cost per hour

Amount per hour

cut+draw

4000

150,00

240,00

0,63

150,00

480,00

0,31

Double extruder

1000

1500,00

2000,00

0,75

500,00

2000,00

0,25

Cutting

1000

100,00

600,00

0,17

100,00

600,00

0,17

Welding

1000

100,00

240,00

0,42

100,00

240,00

0,42

Moulding (pad)

1000

100,00

240,00

0,42

100,00

240,00

0,42

cut+draw

1000

150,00

20,00

7,50

150,00

30,00

5,00

moulding

1000

100,00

360,00

0,28

100,00

360,00

0,28

Bought in :

Pieces

Price per piece

Price per piece

Screws

6000

0,01

60000

0,01

Straws

3000

0,01

30000

0,01

Minivalve

1000

1,50

10000

1,00

Outer Seal (elastic band)

1000

0,10

10000

0,08

Pyramid connection core

1000

0,50

10000

0,50

Spray with foam

1000

12,00

10000

10,00

Special nozzle

1000

2,00

10000

0,50

Velcro

1000

0,03

10000

0,03

Paper box

1000

4,00

10000

2,00

Manual 1

1000

4,00

10000

2,00

Manual 2

1000

4,00

10000

2,00

Protective foam

1000

3,00

10000

2,00

Gel pads

4000

1,00

40000

0,80

Sock

1000

1,00

10000

1,00

Kit extra’s

Cutting and deepdrawing or injection moulding

CNC machining.

V

V Price Estimation Assembly:

Pieces 1000

Cost per hour 150,00

Boudewijn Wisse - The Universal Prosthesis - Appedixes

Amount per hour 6,00

Price per piece 25,00

Pieces 10000

Cost per hour 150,00

Amount per hour 15,00

Price per piece 10,00

Price overview: material

54,05

24,73

machining

12,03

6,53

assembly

25,00

10,00

kit

20,00

12,20

Total price:

111,08

53,46

V

X J. Foort - Innovation in Prosthetics THE KNUD JANSEN LECTURE

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X

colleagues Steve Cousins, Richard Hannah, David Cooper, Carl Saunders and Margaret Bannon over the past 15 years.

COPENHAGEN 1986

Innovation in prosthetics and orthotics J. FOORT Medical Engineering Resource Unit, University of British Columbia All correspondence to be addressed to Mr. J. Foort, Medical Engineering Resource Unit, University of British Columbia, Shaughnessy Hospital, 4500 Oak Street, Vancouver, B.C. V6H 3N1, Canada.

Introduction

As I look back over my 35 years in the field of prosthetics and orthotics

I have appreciated experiences

in projects outside my work environment too. The most recent was the cooperation that developed around Computer Aided Socket Design and Computer Aided Manufacturing between the group at UBC and the groups at University College London and West Park Research, Toronto. I am pleased that cooperation is being extended by new initiatives developing between the original groups and others. I speak of these things to convey to you the team basis for developments and the positive effect cooperation between people has on advances in our field.

Those of us who have worked together on various projects functioned best

when we recognized and used each others qualities. Among the qualities I am thinking of are drive, curiosity, imagination, persistence, patience, trust, confidence and the ability to share.

research, and consider those years from the point of view of the innovations I have witnessed and participated in, certain insights and influences stand out. They cluster around specific people and projects. Two years in Toronto with Fred Hampton and Colin McLaurin led to the establishment of the Canadian Plastic Syme’s Prosthesis, the Canadian Hip Disarticulation Prosthesis, plastic reinforcement of wooden prostheses and conception of the SACH Foot.

To keep sweet reasonableness alive between people, participants have had

The products of ten years at Berkeley with Chuck Radcliffe, Leigh Wilson,

Some were definite and decisive. Some pondered things over and came to

Bill Hoskinson, Frank Todd, Jim McKinnon and others, included design of the SACH Foot, the Quadrilateral above-knee (A.K.) socket, the Patellar Tendon Bearing below-knee (B.K.) prosthesis; conception of socket standardization, studies of prosthesis alignment and experiences with modular prosthetics.

Introduction

of modular prosthetics to the clinic, development of the electrical alignment unit, use of semiflexible sockets and work on standard sockets and standard cosmetic restorations were experiences of my 8 years in Winnipeg with lan Cochrane, Doug Hobson and Reinhard Daher.

Invention

of Shapeable Matrices, development of Tubular orthotics, development of Computer Aided Socket Design and design of the valgus varus resist knee orthosis are milestones of my Vancouver experiences with

to review their motives and consider the needs of their associates. How these associates functioned varied.

considered views. Some were very competent at the things they were trained to do. Some inspired new ideas on how to solve the problems we worked on. Some were able to take risks easily.

Assertiveness arrogance.

born of clarity of view could sometimes be mistaken for

While human relations are never without their problems, all of these people enlarged my capabilities and enriched my work life.

X There have been things I loved doing. Other things I have compelled myself

to do. My attachment has been to what I believe were keystone projects, projects that had the potential to generate multiple solutions. Inaddition, they were projects that suited my natural rhythms, abilities and needs, and were championed by colleagues who could fill the gaps in my own abilities. For the most part, the means used to solve problems were traditional engineering coupled to vigorous artisanship. A great deal of self education was involved.

Now we are at a new intersection of events. Many of the problems have

been defined but new means for problem solving are at hand. Although engineering and artisan skills are still required, there is a need to reassess our methods in light of the new means so that smooth and effective advances can be made. Re-education and new education are involved. Factors affecting innovation, on the other hand, will not change. Some already alluded to are:

1. A suitable field for inventing. 2. Colleagues who cooperate, lead and support. 3. A mix of skills and temperaments in the team. 4. People willing to take risks. 5. An environment conducive to study and experimentation. 6. A speculative attitude. 7. Tools and techniques for problem solving. 8. A willingness to reassess methods and means periodically. 9. Appreciation of accumulated skills and knowledge.

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X

Clinical studies of the quadrilateral socket for trans femoral amputees taught

us that the residuum cannot be treated as a homogeneous mass. I believe that an examination of derivation of this proposition in relation to design of the quadrilateral socket will help us to identify some factors associated with innovation and indicate the need for further innovation.

The quadrilateral socket

The quadrilateral socket for AK amputees was brought to the Biomechanics

Laboratory, University of California, USA from Germany by Eberhart and his team in 1949. It was assumed to be a suitable solution to prosthetic socket design for the above-knee amputee. The plan was to examine its characteristics and to test it clinically at the Laboratory. It was studied throughout the 1950s for rational factors that could” help to define it. Simultaneously, suction suspension was used, a factor that imposed greater demands on socket design, thereby highlighting problems with the quadrilateral socket.

Difficulties: _

Common difficulties encountered included (a) cysts on the residual limbs in areas contacting the medial and anterior brims; (b) formation of horny nodules, or keratin plugs in the ischialgluteal weight-bearing regions and (c) distal residuum oedema.

Shear

In order to develop the theme of innovation in prosthetics and orthotics, I will use a review of the problem of shaping structures that fit against the body for control of forces and movements. Although the emphasis will be prosthetic, the problem is common to both prosthetics and orthotics.

forces on tissues where they extended over socket edges were identified as contributing to cyst formation. Oedema was due to proximal wedging effects and to insufficient support of distal tissues. Nodules, or keratin plugs, were traced to high compressive forces which drove small corns inward, building them into pain-producing nail-like structures.

I

It was assumed by Radcliffe that if the ischium was stabilized on the seat

have organized the presentation around eight propositions which have a bearing on shape management. Factors I have observed as conducive to innovation are interspersed among them.

First proposition: Tissue density is non-homogeneous (1955)

of the quadrilateral socket by means of more positive anterior forces, these difficulties would be overcome. To achieve this, he proposed that soft tissues over Scarpa’s Triangle be compressed more positively as compared to harder muscular regions laterally. This led to the inward bulge over Scarpa’s Triangle characteristic of present day quadrilateral sockets.

X The differential displacement of tissues to effect even loading on the front of the residuum was a new idea that could be applied to any part of the body for force transfer and movement control.

In order to convey the requirements, he depicted the concept in biomechanical terms that practitioners might understand. Thereafterit became common practice to illustrate biomechanical events in this way, encouraging a more systematic analysis of fit and alignment. Innovative factors illustrated in this include:

10. A person able to derive and champion a new concept. 11. Use of engineering principles for socket design. 12. Confident application of the hypothesized solution. 13. Using a clinical environment for testing it.

The

solution helped to reduce the incidence of cysts, keratin plugs and oedema when applied to clinical study amputees.

Practitioners trying to follow the clinical study procedures however, found

Boudewijn Wisse - The Universal Prosthesis - Appedixes

X

Second proposition: Socket shapes can be standardized (1957)

Calculations

based on hazy ideas and gross assumptions to test the hypothesis that quadrilateral sockets could be standardized indicated that it might require approximately 11,000 one piece AK sockets (5,500 for each side of the body) to provide the range of sizes needed for a system that could be used with no more than small shape adjustments.

At that time, with no computers, storage, selection and distribution would be major problems in practical application.

To arrive at a more favourable format, the hypothetical socket was divided

into sections. Attention finally focussed on the brim area alone. If the brims were one-piece, only 150 would be required for each side of the body. If all four sides of each brim were adjustable, the number of brims required could be reduced to 3 for each side of the body.

The innovative impulse in this can be seen to follow out of: 14. A problem in strong focus. 15. The search for objective data. 16. A willingness to make assumptions in the absence of facts. 17. A practical objective.

the information difficult to interpret because it was essentially descriptive. Their difficulties were thought to be due to their failure to abide by the principles. Measurements were made of successful and unsuccessful sockets in order to identify differences that might be responsible. From these might come a more definitive set of instructions for socket design. It was soon apparent however that the dimensions being measured could be the same for sockets that were obviously different. At the same time, successful sockets were observed to appear very similar to one another. This led Bill Hoskinson and I to speculate that it might be possible to standardize quadrilateral sockets.

The results of this hypothesis included:

This is the next proposition:

The

a) establishment of jigs for fitting quadrilateral sockets, notably the Berkeley Adjustable Brims, b) prefabricated temporary sockets, c) adjustable sockets for the study of socket design parameters.

jig fitting method facilitated acceptance of quadrilateral sockets by making the design principles more obvious and the design methods more simple.

X Factors that influenced acceptance of jig fitting methods included: a) the desire for total contact sockets, which could be made easily by this method b) difficulties experienced in defining the quadrilateral socket shape, c) the desire to substitute plastic laminates for wood in socket construction, a feature of the brim fitting method.

In this we see how: 18. Converging ideas and overlapping experiences bring innovation to focus. 19. Simplification of methods enhances acceptance.

In spite of these meaningful consequences, the hypothesis on standardization

received a hostile response in general. I doubt if many of you will appreciate how heretical it was during the 1960s (and perhaps still is) to suggest that sockets can be standardized. I remember sending a paper based on standardization to an American journal approximately 20 years ago. The provocative title was “Instant Prostheses for Thigh Level Amputees.” The editors reply was that there was no space for the article in the journal at the time, and it could not be foreseen that there ever would be! My comment is this:

20. Negative attitudes toward innovations can either hamper their development or prolong their demise!

While I consider the proposition on socket standardization valid, it may be

that every successful shape will be computer banked and standardization will be bypassed. Banking all shapes overcomes obstacles to acceptance of standardization which include: a) the shape preferences and prejudices that people hold, b) concern for the population that might be excluded from coverage (i.e. congenital amputees), c) the lack of objective data.

Boudewijn Wisse - The Universal Prosthesis - Appedixes

X

Adjustable sockets constructed to study design parameters gave information

on sensitivity of residual limbs to changes in socket dimensions (1962). There is a need to continue this work 5 in the light of what we now know and need to know.

The adjustable sockets were suggestive of socket modularization, but did not lead to it. New fabrication techniques, an appreciation of the value of socket flexibility as exemplified in the Icelandic Socket and modular shapes in computer aided socket design systems may foster socket modularization.

Data for design could be derived from computer banked shapes and this in turn could lead to the impedance matching of sockets to residual limbs proposed by Ben Wilson and Eugene Murphy once the required data on tissue qualities is available.

Without

objective data on tissue qualities to use in design work, modularization will require that intelligent, workable assumptions be made. Following out of that, however, adjustable modular sockets could help refine these assumptions and ultimately be the basis for defining tissue qualities. Finally, with sufficient data available, standardization could be reconsidered. The computer would be used for shape storage and numerically controlled machines for production of the shapes.

I can add other innovation factors: 21. Advances may reduce the need for information, reduce its importance, or facilitate its acquisition. 22. New options precipitate new speculations. 23. Oscillation between various options indicates that we have insufficient data.

X

Boudewijn Wisse - The Universal Prosthesis - Appedixes

So far, I have indicated how the North American version of the quadrilateral socket evolved out of the original German design through clinical studies and how these developments established propositions which I now summarize:

(1) Residual limb tissue density is variable. (2) Socket shapes can be standardized An appreciation of the role of the skeletal frame in determining the shape of the quadrilateral socket led to the third proposition.

Third proposition: The (1965)

bony frame is the basis for socket design

For

example, the triangle defined by the tendon of adductor longus, the ischial tuberosity and the trochanter is the bony frame round which the proximal shape of the AK socket is designed. Deviations from the triangular shape come about because of the need to accommodate the tissue-muscle masses adjacent to the sides of the triangle in a biomechanically compatible way.

The facts of this are most clearly exemplified in sockets derived from hand cast impressions. Lean residual limbs tend to give a shape that resembles the plug fit type of socket. Heavily tissued residual limbs yield a more quadrilateral shape.

This proposition explains deviations from stereotyped socket shapes for any level of amputation. It can be taken into account in standardizing shapes and in adapting standard shapes for shape customization in the computer. It is relevant also in making biomechanical shapes from sensed topographical data. It indicates: a) why there are limitations in the Berkeley jig fitting method, which utilizes jigs of a single standard form, b) limitations of standard sockets currently used, c) what might be done to improve the biomechanical result, d) why computer aided socket design programs include means for customizing the standard reference shape e) why reference shape processing of bone geometry is significant for socket design

X

f) and why we need information on tissue qualities.

The patellar-tendon-bearing BK prosthesis

In

my opinion, development of the PTB prosthesis is a good model for this discussion of innovation in prosthetics and orthotics. I will stress the process rather than design in order toemphasize the mechanism of study and motivating factors involved.

Up until the late 1950’s at Berkeley, so much time and effort had gone into

development of AK prosthetics that there was an uneasy feeling that BK prosthetics had been neglected.

To

deal with this, Radcliffe called together a group of knowledgeable practitioners and educators to lay out a plan of attack on BK prosthetics with the researchers. It was agreed that in the studies the researchers would systematize prosthesis design and the educators would disseminate the information. They would also help format the information to be disseminated. The Veterans Administration would require prosthetists to take the courses as a condition for servicing VA clients.

This

was a very potent format — one I would recommend for solving other problems, one 1 wish was being followed in the development and dissemination of CAD/CAM for prosthetics and orthotics.

No

formal evaluation component was included. Each group made its contribution. That which would normally be done by evaluators was done directly by the prosthetists who applied the system. In retrospect, I would say that it was a satisfactory way to do it. In fact, considering the rate at which knowledge and means now develop, existing scenarios for evaluation seem more like seaweed around the propeller than a jib full of wind.

I will make another comment. The fascination with statistics on the part of our major funding agency, Health and Welfare Canada, is restricting Canadian prosthetics and orthotics research. In Berkeley, and elsewhere where innovations have advanced our field to a remarkable degree, the sample sizes

X used in the studies were sub-statistical. Results leading to commitment to adopt the PTB prosthesis rested on multiple fittings on no more than a dozen amputees, each different in various ways.

The

results were not expressed objectively so much as procedurally. We knew that our methods were better than existing ones, a fact confirmed by the rate of dissemination and application of the new information.

Competent judgement was substituted for evaluation — and I would add, at no loss.

The PTB prosthesis was essentially assembled from information modules. A modified form of the German practice of using the patellar tendon as a

weight-bearing surface introduced at the original workshop, was adopted. Total contact was already acceptable at the research level in socket design tor oedema control and was adopted for use in the BK system. At the same time, Shindler’s technique for making Kemblo inserts to line sockets made of hard blocked leather set in wood was adopted. Blocked leather and wood for the socket were replaced by plastic laminates. The SACH foot, now entering clinical application, was incorporated.

Simultaneously,

Blevins was making prostheses which he suspended by means of multiple socks with rubber buns stuffed between them and a knee strap. Galdick in San Francisco was making BK prostheses suspended by suction. Woodall was trying condylar suspension by 1962.

This gives you an idea of the many influences at work to give rise to the PTB

prosthesis and to stimulate innovation. Much of this information was present in the field but unintegrated.

Summarizing, 24. Innovation is enhanced by coordinated efforts based on shared motives. 25. Informed judgement can be equivalent to evaluation. 26. Information density affects innovation. 27. Accomplishments in one area affect events in another.

Boudewijn Wisse - The Universal Prosthesis - Appedixes

X

28. Practical hypotheses are quickly accepted. 29. Accident also plays a part.

Alignment

of trial prostheses at the biomechanics laboratory during checkout of procedures outlined by the review group was done in two steps. The socket-foot complex was aligned without the side joint and corset system in place, and then, upon completion of dynamic alignment of the foot-socket complex, the joint and corset system was added and aligned.

At

that time, it was considered hazardous for an amputee to walk for prolonged periods on a prosthesis without the corset and side joints in place to protect the knee. No explanation was given as to why some people were able to wear jointless Muley prostheses. When one of our test amputees rebelled at having the corset-joint system added to his prosthesis following successful trials without, the switch was made to what is now the PTB below-knee prosthesis. Controversy surrounded the PTB initially. Concerns remained that the knee would be damaged. Some critics said that only a few people could be successful PTB users, the majority would require side joints and corset.

Examination of the role of alignment on forces at the knee and application

of normal locomotion data led researchers to abandon the myth against jointless prostheses and led to emphasizing the flexed knee gait as an insurance against knee damage.

Factors pertinent to success of the PTB prosthesis seem to have been: a) a better understanding of how to shape and construct a socket; b) a better appreciation of the biomechanics of the prosthesis as exemplified by the improved definition of alignment; c) relating fundamental gait data to the practical situation; d) the experiences of successful wearers of Muley prostheses, e) development of the SACH foot; f) a switch to new prosthesis construction methods; g) significant simplification of the BK system.

X Factors favouring innovation were; 30. The existence of the “Muley” type of prosthesis. 31. Available fundamental information on locomotion. 32. An engineering-artisan approach to solving the problem. 33. Cooperative effort directed toward its implementation. 34. Including the amputees on the team. 35. Using accumulated information.

With

regard to the last spur to innovation, I would comment that technologists who are about to do fundamental design work for the production of orthopaedic shoes using computer aided design methods would be wise to take into account what the practitioners can teach them! Much of the information that designers will need resides in the shoe lasts and methods of measurement and last modification used by the practitioners.

Innovations spawned by development of the PTB prosthesis included the

air cushion socket, adjustable sockets, transparent sockets, adjustable spring loaded end-bearing sockets, sockets fabricated directly on residual limbs, foam-in-place end pads, suspension from the patellar and femoral condyles and inflatable bladders in sockets.

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X

The need and the obvious solution led to the next proposition: Fourth

proposition: Modular structures optimize prosthetic

management

The

(1955 — )

modular-like designs in the research laboratories that foreshadowed modern modular systems did not seem attractive to prosthetists; the Northwestern University BK pylon with alignment and length adjustability built-in and the University of California Polycentric Knee for above-knee amputees are examples.

It

was apparent that a comprehensive modular system that overcame whatever obstacles were inhibiting development was needed if the potential advantages were to be exploited. This realisation influenced me to adopt modular prosthetics for clinical use when I went to Winnipeg, Manitoba in 1963. My conviction was that modularizing prosthetics would speed up access of amputees to prosthetic care. It would also help people learn prosthetic practices and would lead to economies.

The

36. New innovations spawn innovation of variants.

emphasis in Winnipeg was on physical rehabilitation in a newly established hospital designed for that purpose. However, the prosthetics clinic was bogged down in wooden leg making practices of the times. Geographic isolation and absence of modern technical resources in prosthetics inhibited change.

Modular prosthetics

I came as an expert. What I proposed for clinical application in fact was

During the 1960s, a major problem, and still a problem to quite an extent in

North American prosthetics, was the degree of immutability in prostheses. When there were difficulties, the socket was usually the problem. To replace the socket required major modifications to the prosthesis, even replacement of the entire prosthesis.

experimental. I had worked in an environment linked to innovating and wished to bring the attitudes associated with innovating into the clinic. The aim was to have a comprehensive and adaptable modular system that included as many prefabricated elements as possible. The system would be used to manage patients with any level of amputation through their full spectrum of care from immediately post surgery to return to community life.

In

The design process would be evolutionary with the designed system used for

experimental modular-like prostheses however, the option for quick exchange of components existed.

what it was good for at every stage of development. A system with the least number of parts would be designed and common parts and tools would be

X

Boudewijn Wisse - The Universal Prosthesis - Appedixes

used as far as possible.

X

A

key feature would be rapid assembly-disassembly and reassembly for quick adjustment and socket exchange.

possibility of incorporating unsatisfactory features into the final design. In my view reaching objectives in this manner must be one option to consider in the interest of economizing on time, costs and effort (I must admit that I would always choose this approach).

Only a few basic elements had to be designed to manage BK, AK and HD

Shaped

prostheses. All other parts were available or could be adapted.

We tried to make the system suit a basically rural environment so that a

person who was distant from services might be able to manage repairs using community resources, including the local hardware store.

This experience illustrates: 37. Integrating what exists in new ways is innovating. 38. Experimentation can be a part of a service system. 39. Problems can be tackled from the users point of view.

The risks that might be involved in adopting a modular system for clinical

use seemed small compared to the advantages to be gained in overcoming the bottlenecks affecting amputee rehabilitation.

Results were positive. No amputee had to postpone rehabilitation because of the prosthesis.

In fact, it became common for a training prosthesis to be delivered on the

components were a source of problems, especially with the BK amputees. Although standard cosmetic covers had been designed, and also standard socket receptacles to link the sockets to distal components, the sockets themselves were all custom made. This was reasonable for definitive prostheses, but training prostheses require frequent socket changes. Successes with the AK prefabricated sockets motivated us to develop prefabricated BK sockets in response to the bottleneck experienced.

Nineteen sockets were made for each side of the body. Use of these sockets taught us that five sizes for each side of the body were

sufficient to fit all of the new amputees managed in this way and that one size alone met 50% of the needs. This illustrates other factors in innovating:

40. Previously successful patterns are followed. 41. Every experience is treated as an information source.

We

were acutely aware of limitations imposed by standardization. Standardizing can mean that someone is left out unless the standardized item is adaptable. Such implications for the client need to be kept clearly in mind during innovating. That is:

42. A sense of responsibility must influence what is done.

day prescribed.

The evolutionary design approach allowed defects in design to be overcome

as a means of extending usefulness of the system while it was used for what it would permit. At first, the objective was to keep people walking until the definitive prostheses were delivered. Stage by stage, the system was improved until finally it could be used definitively.

Evaluation

proceeded in tandem with design. This circumvented the

Shape sensing

At that time, obtaining limb shapes by means of a shape sensing method, subject of the next proposition, seemed like a possible solution to the limitations imposed by standardizing.

X Fifth proposition: Shape (1961)

Boudewijn Wisse - The Universal Prosthesis - Appedixes

X

sensing gives data for interface design

quantify shoe last shapes for the USA Veterans Administration, a forward looking project which we completed in December 1980.

When the idea of automating shape management for the fitting of sockets

We set up design criteria and had fabricated on principles demonstrated by

and cosmetic restorations was first raised in 1960, there was no sympathy for it at Berkeley. In fact there was strong scepticism toward it in the research community when I raised it as a proposal at a meeting of the Subcommittee on Socket Design of CPRD in 1965. Although I was chairman of the subcommittee, the proposition did not even win a place in the minutes.

Dr. Vickers and Doug Dean at UBC Mechanical Engineering Department, a machine that gave a single continuous moire shoe last map.

Saunders forced the system to work by putting the data into the computer

43. An innovative idea in its first stages is fragile.

point by point. He soon appreciated that quick input of data was necessary if sensing was to be a part of automating prosthetic procedures.

I had discussed shape management by automated means in a letter to Colin

In later studies of what was being done in Japan where considerable expertise

McLaurin in June 1961. In practical terms, Frank Todd and I constructed a left side shank model from a right side shank model by means of photographic silhouetting in 1962 and that was all that was attempted until I returned to the idea in 1969.

When the gap between conception and initiation of work is considered, one can appreciate 10 that:

44. Innovators must be patient and persistent. 45. A concept has to be suited to its times for acceptance. Our first formal attempt to sense shape for prosthetic applications involved use of the shadow moire phenomenon. These studies spanned the period 1972 to 1980. A prosthesis replicated in Vancouver, using the moire technique for sensing the shape and a numerical controlled carver for producing the models, was worn by the recipient for three years.

We were introduced to the shadow moire technique by Dr. Duncan, then

Head of Mechanical Engineering at UBC. He was actively engaged in shape processing for ocean bottom survey, boat hull design and machine design purposes.

Using

a system that he had built to obtain multiple view photographic contour maps around objects, Steve Cousins and I produced a number of maps and models of residual and intact limbs.

On the basis of this work, Tony Staros established a contract with us to

in shape processing had developed, he identified the flying spot technique as significant. It offered direct, rapid deposit of data into the computer at an affordable cost.

These experiences taught us to: 46. Look outside our field for information. 47. Go for information where the information density is greatest.

The light streak technique has been adopted at West Park Research Centre, Toronto, Canada, where, by agreement between us, sensing shape has become a central project while we concentrate on manipulating shape.

Because sensed shape is topographical, it must be used in conjunction with

tissue quality data or be subjected to manipulation to derive the required biomechanical shape. This weakness in topographic mapping methods for derivation of biomechanical shapes has yet to be overcome.

On the other hand, biomechanical data are inherent in standard shapes and

this fact can be the basis for deriving custom shapes. I proposed this concept first during the 1SPO course in AK prosthetics held here in Denmark in 1978. (You may recall, that in Winnipeg 50% of new BK amputees were found to fit into a single standard socket size).

X

Boudewijn Wisse - The Universal Prosthesis - Appedixes

This leads us to the general hypothesis of the next proposition. Sixth

proposition:

given

anatomical

The

shapes

feature

or

of its

all

examples

biomechanically

X

This leads to the next proposition: of

any

matched

representation are sufficiently similar to permit shape matching on a mathematical basis using a standard shape as the reference

(1978) and Strathclyde Paper #1, 1984.

That is, you can make a standard shape bigger, make it smaller, make it

Seventh proposition: Shapeable matrices can be used to construct biomechanical structures directly (1977)

A shapeable matrix is a structure made up of nodes and links in a format that permits it to be contoured to match a required shape. You may liken it to a flexible lattice that can be made rigid once shaped and be returned to flexibility for re-shaping.

longer or shorter, make it differentially flatter or deeper in any direction and add or subtract from a particular point any required amount starting with a preconceived shape that serves as a biomechanically relevant core or reference shape.

The

My UBC colleagues have designed the current CASD (Computer Aided Socket

Design of shapeable matrices grew out of brainstorming sessions led by

Design) system on the basis of this proposition. Colleague Dave Cooper has extended its application to derive the shape of bones in vivo using external bony landmark measurements.

The

hypothesis stems from attempts to standardize sockets and from attempts to adapt sensed shapes to socket design.

The hypothesis does not discount the significance of shape sensing. Shape sensing can be used:

a) to deposit shapes in the computer for further processing; and b) for defining how a shape should be processed.

Reference shape modelling has elegance. It can be used for internal as well as

external anatomical structures and has no adverse effects on the person for whom the shape is being developed. It can be used for other than anatomical features. It can be used in conjunction with other techniques, such as shape sensing. It is, in fact, a concept of general significance.

The next gap to leap is that of constructing the interface with a degree of elegance comparable to that offered for designing it.

new emphasis could be on structures that can be assembled in the shape format required and remain amendable for post fitting adjustment. The seating systems developed at the Bioengineering Centre University College London and at MERU are the only examples of shapeable matrices so far.

Steve Cousins when he worked with the team at the Medical Engineering Resource Unit, Vancouver in 1977.

With advent of the Shapeable Matrix, shape management is targeted from two directions:

a) On the one hand, computer graphic techniques for shape management can be used to define the shape. b) On the other, mechanical matrices can be used to build up the shaped structures directly.

Yet to be achieved is the mating of computer and matrix to allow configuration of the matrix by computer.

The aim should be to develop universal matrix building blocks from which

any shape can be constructed. This may lead to modularization of interfaces, or modularization may circumvent development of matrices. If the matrix approach is circumvented, there may be some gains but there will also be losses. The matrix approach is much more fundamental even though design is difficult. Hybrid modular-matrix systems, as proposed by Cousins, may develop as stepping stones to either matrix or modular structures.

X This illustrates other factors in innovating: 47. The path to choose is the more fundamental one if an innovation is to be far reaching. 48. Concepts can be combined.

Difficulties experienced with hand assembly and adjustment of miniature

shapeable matrices which we have attempted to design for direct use against the body have led us to the eighth proposition:

Eighth proposition: Shape dependent components will be produced

Boudewijn Wisse - The Universal Prosthesis - Appedixes

X

Intermediate steps might include (a) the design of programmable moulds, or

(b) design of matrix elements that can be assembled by computer controlled robots.

When all of this is put together, we can say: a) Biomechanical shape is determined by bone geometry and tissue quality. b) Biomechanical shapes can be standardized. c) Standard shapes can be customized. d) Shape sensing can capture and classify shapes. e) Interfaces can be constructed from matrices. f) Matrices can be constructed by robots.

by robot constructors

To produce sockets directly by computer controlled robots, while difficult, You may well consider the long and arduous course of actions bringing us to would set the stage for a manufacturing method that precludes the need for moulds. Such an approach is infinitely compatible with computer aided design.

these possibilities. We can mesh them easily on the basis of hindsight. What step could have been omitted, what influences of colleagues on one another done without?

It is also compatible with the needs in prosthetics and orthotics which are

The adoption of matrices, computers, shape sensing, internal and external

now so heavily dependent on custom made moulds for production of shape determined components.

This view is shared by our colleagues in Toronto at the West Park Research Center where it is proposed to use a robot constructor to make seats.

The dream is that CAD and CAM will become so intimately meshed that the

design and fabrication of shaped objects will proceed simultaneously. Also, it will be possible to have raw material managed in a way that will deliver an interface that varies in stiffness according to the way in which materials are delivered from the nozzles held by the robot constructor.

Establishment

of computer controlled robot constructors would be as revolutionary in production technology as was the introduction of mass production.

reference shapes and robot constructors is equivalent to a new date zero for design of shaped components for use in prosthetics, orthotics, and orthopaedics. We come to this as a consequence of the technology that surrounds us or can be envisioned on the basis of what surrounds us. We have merely to take note of it, reassess our problems in the light of it and act innovatively.

An important principle to guide us is to derive solutions that have widespread uses. This will help make what we design available to the disabled population. Matrices are like this. They could dim the boundary between prosthetics and orthotics and the boundary between disabled and able bodied persons. Computer aided design already does this. Robotic constructors are likely to have the same affect. I urge you to this — aim for universal solutions.

X Epilogue

I have tried to show how, starting with limited information, some propositions

Boudewijn Wisse - The Universal Prosthesis - Appedixes

X

I personally feel that copyrighting and patenting are impediments to the

The time and effort and innovative skills of many people, some unknown,

free flow of information. Researchers would not be corrupted by the impulse to protect what they innovate in order to derive gain if the social means were available for the work they wish to do. The political problem is to foster mechanisms by which such programmes can be funded and the benefits be directly applied where the needs exist.

Persons within or between groups need to be linked to permit complementary

As I see it, we must be free of attitudes that keep us bound to our particular

that foster solution of difficult problems have come into focus.

have been involved. That there are such people with the time and resources to solve problems is a prime requirement. They need to be in environments that are conducive to original thinking.

problem solving paths to develop. Innovating is not the province of a person or a group but is a flower that grows out of the human garden.

Innovative impulses need to influence not only what and how we design, but

how we organize to do so. The need for cooperation and joint involvement in large projects is growing. Fortunately, the technical means are available to foster this. Seemingly separate entities such as standardizing shapes, designing modular systems, sensing shape, manipulating shape, transmitting shapes over the telephone, designing matrices and constructing custom shapes by robots coalesce as lively possibilities for automation of design and production of shaped components for prostheses, orthoses and orthopaedic footwear.

I cannot help but wonder how all of these things might have fared had they been part of an overall strategy fostered by cooperation of all of us engaged in prosthetics/orthotics research over the past few decades.

The

necessity is for designers to overcome indifference to colleagues, mistrust, greed and jealousy so that field-adoption of comprehensive systems that can develop from joint efforts will be realized.

institutions. We must discount nationalism and ideologies to become truly conscious of our roles in relation to the world’s people. Every person in our field plays some part in this. Manufacturers do when they make quality the factor of significance intheir competition. Designers do when they encourage the best things to be used by the various participants in the rehabilitation field regardless of origins. Practitioners do when they stay informed and use what is best in the developing armamentarium. Educators do by trying new things, selecting the best and disseminating information about them. Funding agencies do when they are sensitive to grass roots inputs that identify appropriate objectives for research in support of services. Politicians do when they transcend political boundaries in response to world-wide needs.

These are the sorts of ideals that thoughtful men have brought to us down through the years.

An innovative approach to their implementation is to be encouraged. ISPO is the means by which we keep in touch with each other for furtherance

of our common interests. They are the sorts of interests Knud Jensen held for ISPO which he saw as an important element in the evolution of a brotherhood dedicated to the well-being of physically disabled people throughout the world.

I appreciate the chance I have had to outline a course of events that illustrates the innovative process, to give you these thoughts through the Knud Jensen lecture and to wish you an inspiring 5th World Congress of the ISPO.

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Precise

measurements

can

Z

be

found in the solidworks models

accompanying this report.

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