prosthesis for tibial amputees focused on the 3rd world

Prosthesis for Tibial Amputees focused on the 3rd World Introduction Report “Design for All” – April 2002

Written by: Boudewijn Wisse IO9964426 Wouter van Dorsser IO9195386 Farshad Soleymani IO9784809

Mentors: Johan Molenbroek

Henk Kooijstra Inne ten Have

I'm going to Graceland Poor boys and Pilgrims with families And we are going to Graceland And my traveling companions Are ghosts and empty sockets I'm looking at ghosts and empties But I've reason to believe We will all be received In Graceland Paul Simon - Graceland

Prosthesis for Sri-Lanka TU-Delft 2002 Wisse, v Dorsser, Soleymani

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Preface This is a paper which is made in the context of Design for All. Design for all is an optional subject that is taught at the Faculty of Industrial Design Engineering of Delft University of Technology in The Netherlands. The assignment for this subject has been given to us by Mister J. Molenbroek (Associate Professor who teaches Design for All) and Mister H. Kooistra (Dutch surgeon, who independently works in Sri Lanka as a surgeon and helps victims of landmines). There are different groups working on this assignment and there is a price (3 roundtrip tickets to Sri Lanka to implement the solution) to be won for the group which comes up with the best solution or design for the assignment. According to us the succes of the solution is dependent of the people (their culture and good will) in Sri Lanka. We therefore see a decent analysis as the first and most important requirement to be able to implement designs in Sri Lanka. The purpose of this paper is to inform everybody who is interested in our solutions for a prosthesis which can be produced and used in the third world. This paper is written in March till May 2002. It will (hopefully) be the introduction for a project in Sri Lanka with local disabled, for which will be tried to implement the design and/or to make necessary improvements. In Appendix I we will give individual motivations why we follow this optional subject and why we choose this design project. Boudewijn, Wouter & Farshad


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Table of contents Summary.......................................................................................................................... 3 Introduction ..................................................................................................................... 4 Analysis ………………………………………………………………………………………… 5

Social Analysis of Sri Lanka.......................................................................................... 5 Medical analysis.......................................................................................................... 11

Lower leg................................................................................................................. 11 Amputation .............................................................................................................. 11

Gait Analysis ............................................................................................................... 14 Force Diagram ............................................................................................................ 15 Prostheses .................................................................................................................. 16

History ..................................................................................................................... 16 Sockets.................................................................................................................... 17 Shanks .................................................................................................................... 20 Foot-ankle systems ................................................................................................. 21 Conclusion Prostheses Analysis ............................................................................. 25

Production ................................................................................................................... 27 Available Materials .................................................................................................. 27 Available production methods ................................................................................. 28 Standardization ....................................................................................................... 29

Life Cycle Analysis ...................................................................................................... 31 Synthesis ....................................................................................................................... 33

Design Philosophy ...................................................................................................... 33 List of Design Requirements ....................................................................................... 34

Common.................................................................................................................. 34 Shank ...................................................................................................................... 34 Foot-ankle system................................................................................................... 34 Socket ..................................................................................................................... 35 Production and implementation............................................................................... 36

Experiments and evaluation........................................................................................ 37 Concepts ..................................................................................................................... 40

Concept 1: The rocker-foot...................................................................................... 40 Concept 2: The socket by Inne redesigned............................................................. 41 Concept 3: The textile / leather socket .................................................................... 44 Concept 4: The polymer socket............................................................................... 46 Concept 5: Knowledge transfer ............................................................................... 47 Concept 6: Implementation plan.............................................................................. 49

Conclusion .................................................................................................................. 52 References.....................................................................................................................53 Appendix........................................................................................................................ 54

Appendix I: Individual motivations............................................................................... 54 Appendix II: Exercises................................................................................................. 58 Appendix III: Manual – Producing prostheses............................................................. 60 Appendix IV: Manual - How to design prostheses ...................................................... 65 Appendix V: The measurement prosthesis ................................................................. 70 Appendix VI: Tempur .................................................................................................. 71 Appendix VII: Patents.................................................................................................. 72


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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. Our design philosophy is that our design will be made at a prostheses workshop in Sri Lanka, by the local prostheses builders 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.


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Introduction The problem Many third world countries are or were a “playground” for civil wars. Millions of mines, left-over weapons of these wars, but still potentially lethal, are scattered over 70 countries in Africa, Asia, Europe, the Middle East and the Americas. Landmines strike thousands of innocent victims every year, shattering lives and destroying futures. According to estimates made by the International Committee of the Red Cross, every month at least 2,000 people, usually innocent civilians, are killed or injured by land mines; the equivalent of a new victim every 20 minutes. Sri Lanka is one of the countries where landmines are still used resulting in many landmine victims, which usually lose a lower leg…. It is necessarily to come up with a good solution to provide everybody with a hard needed prosthesis. Question to answer According to Henk Kooistra the most urgent problems to be solved can be formulated as follows:

• How is it possible to produce cheap prostheses? • Which applicable materials are resistant to wear? • How can an acceptable walk pattern be created without the use of an ankle joint? • How can prostheses be produced in third world countries using only materials

and manufacture knowledge of that country? • Can a manufacture method be invented which doesn’t need technicians (with two

years of training) but can be executed by the local bicycle shop? • Is it possible to produce a socket for growing children, without having to replace

the prosthesis (too often)? In this report, first an analysis of the problem is presented. The questions above are addressed and evaluated, resulting in criteria and eventually a list of requirements. Next we will develop some solutions for these problems based on the criteria. These can be tested in Sri Lanka with the included implementation plan.


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Analysis

Social Analysis of Sri Lanka Geography Sr_ Lank_ Praj_t_ntrika Camajaváti Janarajya (as the Democratic Socialistic Republic of Sri Lanka is officially named) is with its area of 65610 km² about 1.6 times bigger than the Netherlands. It’s easily found on the world map by looking just below the tip of India. Because of the mountains in the middle of the country the landscape differs quite a bit from place to place (0 m (sea level) to 2524 m (Pidurutalagala)). This combined with the climate (tropical monsoon- (north) & tropical forest (south)) makes Sri Lanka an ideal place for many different plants and animals to live. Among the rubber trees other important trees can be found like ebony, mangrove, orchids, palm trees, panda wood, rhododendron and satinwood. The capital Colombo, with its 1 300 000 (1995) inhabitants is the biggest city. Criteria:

• The prosthesis must be resistant to tropical weather. o The prosthesis should be resistant to heat. o The prosthesis should be resistant to water and moisture.

• If wood is used in the prosthesis, then ebony, mangrove, palm trees, panda wood, rhododendron and satinwood are possibilities.

Inhabitants Sri Lanka has 19.500.000 inhabitants (in 2000 (www.lanka.net)). Sri Lankan inhabitants have different ethnic backgrounds and different religions (see the pie charts). While religion is not a major issue in Sri Lanka, ethnic background is, resulting in a war between the Tamils and the Singhalese (see the paragraph “war”). Another important difference between people in Sri Lanka to be mentioned is the difference between man and women. Although most women work, they are socially unequal to men, but they have great influences in there own families. In most cases they manage the cash flow of the family.

Buddhist

Christians

Muslims

Hindus

Pie Chart “Religion”: Religion in Sri Lanka (% of population)

Singhalese (74)

Tamils (18)

Moors (7)

other (1)

Pie Chart “Ethics”: Ethnic groups in Sri Lanka (% of population)

Picture “map”: Sometimes Sri Lanka is referred to as “Paradise Island”


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Ranil Wickremesinghe (center) was the first Sri Lankan prime minister in 20 years to visit the epicenter of the island's rambling ethnic war

Peace breakthrough in Sri Lanka COLOMBO, Sri Lanka -- Peace efforts in war-torn Sri Lanka have been given a further boost, with the national government and Tamil Tiger rebels agreeing to conduct talks in May.

The government announced on Wednesday it would conduct face-to-face discussions with the rebels in an effort to end the 18-year civil war, which has ravaged the country.

Figure “News”“: Recent news gives hope for oncoming peace. - CNN - March 27, 2002 Posted: 1255 GMT

The official languages of Sri Lanka are Singhalese and Tamil. English is recently added to these and is understood by many in the big cities (and the tourist areas). Combined with the knowledge that 90% of the country is educated (between 5 and 10 years of age), almost every body can read and understand Singhalese. Tamil is understood only by the Tamils (thus about 20% of the population) and English by about 10%. Although Sri Lanka was under Dutch colonial rule many years ago, no-one speaks Dutch. Criteria:

• A manual can contain text. o First language for local use should be Singhalese. o International papers can be written in English.

• The prosthesis or the manual should not offend any ethnic or religious group. War There is a civil war raging for over 18 years now in Sri Lanka between the Liberation Tigers of Tamil Eelam (LTTE) and their adversaries, the authorities. The war zone in the north is cluttered with landmines, planted by both parties to injure the enemy and to slowdown traffic and support. Unfortunately, both civilians and military are victims of these landmines. The amount of victims of these (amputees) is 10.000 to 20.000 (confidential numbers are difficult to find). Fortunately, peace negotiations give hope for a stop of the war (see the article on the right). While the use of landmines could be banned in the near future, old landmines will still be active for years. Add a possible “boom” of victims due to the migration of refugees back to their home grounds. 500.000 people will “go home” when the ongoing peace discussions are successful.


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Economy 6 million inhabitants are registered as employed (this amount seems to be low, but that’s because the government does not count the northern and the East provinces and there are many people not reporting work) While the majority of the income of Sri Lanka is due to tourism, there is also some industry. Important occupations are farming, selling goods in the city market, rubber tapping (see picture), weaving, fishing and tea leaves picking. Major (export) products are jewels, phosphate, graphite, wood, plaster, rubber and tea Although proud on their free-market economic system, the economic situation of Sri Lanka has not been improved by it. While the poor inhabitants were getting poorer by the day, the more rich people started to buy luxurious goods (like car, bikes and Hifi) from western countries. This influenced the import/export balance negatively. According to the government of Sri Lanka, this situation is slowly improving since 1993. The growth of the national income is now between 5 and 7 percent per year. But Sri Lanka is still in great international debts and full with poor people. The currency is the Rupee. 1 Euro is about 83 Rupees (March 2002). As can be seen in the table, almost every body who can work is working, as well men (94%) as women (89%). This is a good sign. It tells us the people maybe are poor, but not unwilling to work or to help. Prostheses could enable many to work normally. Also, we can expect effort from the ones who work in the production factory. It’s not unthinkable some amputees are willing to help (work) if they are helped with a good prosthesis. If we can encourage amputees to build their own prosthesis, we find cheap labour and he of she learns to build and fix prosthesis (for himself and the neighbourhood). Criteria:

• A prosthesis should assist people in their work. • Both “normal people” and amputees should be able to

work in a factory. • Amputees are willing to work for their prosthesis. If its possible, let amputees

build their own prosthesis.

Agriculture, Hunting &ForestryManufacturing

Mining & Quarrrying

Construction

Services

Pie Chart “Economy”: Different occupations in Sri Lanka (% of population)

As % of Labour force by sex

Year Source (Excluding North & East Provinces)

Total No. ('000)

Male Female

2000 Quarterly Labour Force Survey

6343 94.1 89.0

Table “Economy”: Occupation and Labour in Sri Lanka (% of population)

Picture “rubber tapping”


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Social welfare and developmental help As everybody can understand, social welfare is not as advanced in a developing country such as Sri Lanka, as it is in European countries such as the Netherlands. First of all not enough money can be collected for good hospitals and different kinds of developments. Also, not enough qualified personnel is present. The army hospitals (instead of the civil hospitals) are the main place where landmine victims are amputated. The army also buys and distributes prostheses (but mainly for the military). These circumstances are the reason that little prostheses are made in Sri Lanka. Current designs are very costly and time consuming to produce. They require qualified personnel (medical to fit the prosthesis and technical due to the difficult production process) and sometimes expensive machines. Therefore humanitarian help is given by some parties in Sri Lanka (Friends in need, white pigeon and poor attempts from bigger organizations) to reduce the amount of amputees without a proper prosthesis. Unfortunately some devices distributed by these organizations are cultural or even physical inappropriate for them. Recently, some organizations have withdrawn their financial support for prostheses. Currently, 1800 prostheses are being built each year in Sri Lanka, while a production of 5000 is needed. This results in long waiting lists (up to 15 years) and no possibility to repair or change a prosthesis (if you get one, you get one for your entire life). A big amount of the amputees are children (60% of all who are amputated each year), who search wood for cooking in landmine infected areas. Their number is expected to increase rapidly. The Red Cross says a child injured at the age of 10 will need about 25 artificial limbs during their lifetime, but in many countries crutches are all people can afford. But, because of the long waiting list (and of course the aging of the children), almost all prosthesis have to be fitted on adult amputees. Because the long duration of the war, only a small percentage of all the current amputees is a child. If the waiting list can be reduced (eliminated) than children can be helped. Criteria:

• First focus on reducing the waiting list (prostheses for adults) then start producing prostheses for children.

• The prosthesis should be cheap. o The factories should become independent from (financial) charity in the

future. • The prosthesis can be made in large quantities.

o 3000 prostheses can eventually be produced each year) (also see the chapter “production and implementation”, page 38)


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Customs, Aesthetics A prosthesis is culturally appropriate if it allows users to engage in everyday physical activities in rural Sri Lanka, such as squatting (an important body posture in Sri Lanka and India for resting, sitting, eating and using toilets), walking barefoot or with thongs (flip-flops) over rough terrain, and submersing the prosthesis in water (for washing feet or walking in farm fields during rainy season). People wear thongs, shirts and sarongs. Another custom is wearing no shoes or sandals in house. Although Sri Lankan people won’t confront they are poor, an inferiority complex is not uncommon. This results in the wish for luxurious goods and also high tech production methods (“Import products are cool”). Therefore an interesting aspect of the production of third world prostheses (like the Jaipur limb) is that it is locally manufactured, which has great social impact on the local society. It supports a feeling of equality. The aesthetics of the design is also important. Some of the currently used prostheses can be described as "like something from the Dark Ages," with a look and manufacturing and fitting processes at least 20 years out of date. Important is to realise that people of Sri Lanka don’t do things our way, but the results are as good. If a good prosthesis will be the result of the cooperation between western and local people, trust on both sides is needed. Criteria:

• The factory should encourage social integration. • The aesthetics are important. The prostheses must be

a wanted item. • The prosthesis can be submersed in water or mud. • The prosthesis allows squatting. • The prosthesis can easily be taken off and put on. • The prosthesis can be fitted with a flip-flip. This flip-flop

can be replaced / taken off.

Picture “shoes”: The local custom is to remove shoes when entering buildings

Picture “cowboy boot”: This cowboy boot could be a prosthesis…… Who wouldn’t want one?

Picture “Squatting”: This labourer, which makes a camera cover from camel leather, clearly illustrates the way people squat while working.


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Travel Especially people with one leg have difficulties to make a long trip. If the factory where they receive their prosthesis is far away, the trip to and back from this factory is an expensive event, which maybe occurs once in their lives. It is important that these people are being welcomed at the service centre with great care and hospitality. The residence should be decent. After the long trip back to their homes, people are deprived from medical attention. They cannot be expected to make the trip again when the prosthesis is broken. Ways to get around the country are train, bus, taxi, bike and rental car, although the roads are not that good. The main speed of travel is about 30 km/hour. Bikes, Mopeds and Bicycles (and things like them as Rickshaw’s are together with carts (driven by animals) the main way of travel in many third world countries. Even transportation of goods is done in ways not imaginable to us (see the picture to the right). A bicycle repair shop can be found literally on every corner in a city. If you have a flat tire, rescue is always near. Criteria:

• The factories should be spread around the country. • The service centres should be hospitable. • The design should be easily repaired in the local village (home, carpenter, local

bike shop, etc)

Picture “bikes”: This collection of bikes shows how people think about aesthetics and how they “upgrade” normal bikesto a kind of carts.

Picture “bicycle”: This transporter in Delhi shows the creative use of bikes in Third World countries.


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Medical analysis Lower leg There are different kinds of prostheses required for different amputations. At the right the different kinds of prostheses are featured in a drawing. The most common leg amputation in Sri Lanka is below the knee. In Sri Lanka 78% of the amputees has a “tibial” (lower leg) amputation. A leg that has been amputated halfway between the knee and ankle works best for walking with an artificial limb. The cause of this ratio is the “design philosophy” of the Pakistan Ordnance Factories (which make the cheap landmines that are used in the Sri Lankan war), which is that: “It is better to disable man than to kill him. A wounded man requires attention, conveyance and evacuation to the rear, thus causing disturbances in the traffic lines of the combat area. Also a wounded person has a detrimental psychological effect on his fellow soldiers.” It’s because of this that the landmine is designed to destroy only a part of the victim’s body. Because tibial prostheses are the most needed type of prostheses, we will focus our design on these. Criteria: • The prosthesis must be a tibial prosthesis

Amputation The amputation of the patients’ lower leg takes place in a hospital. The leg is amputated halfway the lower leg. The fibula is cut 2 cm shorter than the Tibia, so the calf muscle (sural muscle) has enough space to form a good stump. According to specialists in the Dijkzigt Hospital in The Netherlands, it’s not recommended to put pressure on the limb during the first two weeks after the operation. After this period the patient here in The Netherlands gets a temporary prosthesis for a period of 5 months. Such a temporary prosthesis is necessary because the stump shrinks if it is not subjected to forces. The patient needs to keep moving the limb, because otherwise it will become deformed and finally because the patient needs to get used to a prosthesis. The picture on the next page shows a temporary prosthesis that we saw at the Dijkzigt Hospital in The Netherlands.

Picture “amputed leg”

Picture “anatomy”: Different kinds of prostheses are used for different amputations


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In Sri Lanka the reasons for having a temporary prosthesis will be the same as in The Netherlands, but it’s too costly to buy a temporary prosthesis. From the time a leg has been amputated until a limb is fitted, daily exercises are needed to keep the hip and knee muscles strong and to avoid contractures. If weakness and contractures already exist, these should be corrected as much as possible before a limb is fitted (see picture “fitting a limb”). It can also help to (for example while sleeping) strap on a wooden splint on the leg, in such a way that the amputated leg is forced to be straight. (See also Appendix II–exercises for preventing contractures). Criteria:

• It’s better to wait with getting a prosthesis in the first 6 months after the amputation.

• Do exercises during the untill you get a prosthesis after the operation to avoid contractures.

• The stump has to be vertical in the prosthesis. The knee has to be stretched.

Picture “temporarily leg”: A temporarily leg as currently used in the Netherlands

Picture “Fitting a limb”: The knee joint should almost be stretched while standing on a prosthesis. 2-5 degrees angles are normal.


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During our second visit to the Dijkzigt Hospital we were told which areas on the stump we could put under pressure and which areas on the stump we should avoid putting pressure on. We were given a foam model by the Hospital, which had all these critical points drawn on it. We put an epoxy layer around this model and marked all the critical points with colours. In the picture below you see this model (of the right leg). The red parts are the areas where pressure should be avoided, because these are bony bumps and bony areas (shin bone). The blue hatched areas are suitable to be put under pressure and the fully coloured area (patellar tendon) is capable of carrying a lot of pressure. The areas which are not coloured are not capable of carrying a lot of pressure. The blue hatched area above the knee prevents the prosthesis from sliding down the leg through the prosthesis. The better the prosthesis fits around the stump, the less friction there is between the prosthesis and the stump (while under stress or without). The tip of the stump is slightly put under pressure to avoid sliding downwards in the prosthesis and to have a good positioning of the pressure on the kneecap tendon. Furthermore it’s important to divide the pressure on an as big as possible contact surface. Criteria:

• The stump needs to be put under pressure according to the picture “foam model”. • Sliding and friction should be avoided. • The force on the patellar tendon has to be positioned properly. • The prosthesis needs a big contact area to help the distribution of the force. The

maximum pressure should be low (except for on the patellar tendon, which can handle the pressure).

Picture “foam model”: The blue areas can be loaded. Red areas should be avoided


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Gait Analysis Normal walking creates the need for dorsiflexion (toes up) and plantarflexion (toes down) of the ankle joint. The whole angle changes during motion of the ankle joint in the sagittal plane (see picture “planes in a human body”) about 45°. 10 to 20 degrees angle change is dorsiflexion. The remaining 25° to 35° is plantarflexion. (see picture ”ankle angles in gait”) When the heel touches the surface, the ankle undergoes some degree of plantar flexion. This plantarflexion holds on until the total foot is flat on the ground. The motion changes into dorsilflexion when the body moves over the supporting foot. Plantarflexion appears again while the heel lifts from the ground at the end of the stance phase. When the toes push off, at the beginning of the swing phase, the ankle bends further into plantarflexion, then changes shortly into dorsilflexion and back again into a low degree of plantarflexion when the heel touches the surface. If we use an ankle joint we can also have some dorsiflexion and plantarflexion. Without an ankle joint this is not possible. We than have to improve gait another way (see paragraph “foot-ankle systems, B, III”) Criteria: • The prosthesis should

simulate a normal gait. • The angle between the

normal foot and the prosthetic foot should be two times 15 degrees.

Figure 1

Picture “planes in the human body”: The gray area is the sagittal plane

Picture “ankle angles in gait”: The angle of the ankle changes about 45 degrees while in normal gait.

Picture “degrees”: The angle between the two feet should be two times 15 degrees.


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Force Diagram The diagram to the right shows one of the major principles in prosthesis design. It shows how biomechanics can explain the places that are most loaded (mostly put under pressure) by the prosthesis. How a prosthesis can be evaluated this way is illustrated in chapter “The socket by Inne redesigned”. The red arrow indicates the force created by the mass of the body. We can estimate its magnitude by taking the mass of the total body. For a person with two legs we would have to multiply this by 94 % (because we have to subtract one lower leg and foot) and then again by the gravitational acceleration (9.81). Of course, with amputees, the weight of the leg is already “subtracted”. 600 Newton is an average. 800 can be used for “heavy” persons. Fg = Mbody * 9.81 = …. N The black arrow (Ft) is the force loaded on the knee (patellar) tendon by the prosthesis. This force is mainly used to support the bodyweight of the person. Because the body can only resists perpendicular (normal) forces and no shear forces on the skin and this is the only part which is not totally vertical, we can assume that this force is the only one which supports bodyweight. The blue force upward (Fry) is this reaction force on the gravitational force (Fg). The horizontal blue arrow (Frx) is the force needed to achieve the angle (α) that the black arrow makes. The angle (α) between this force and the Ft (the black arrow), has to as big as possible, but you can not influence it, because it is dictated by the angle the patellar tendon makes. Here it is drawn about 60o, but later experiments proved that 30o to 45o is more likely (see concept 2 and the experiments). We can now calculate the Ft and Frx: Fry = Fg Frx = Fg / tan (α) Ft = Fg / sin (30o) Because of the Frx, now translation (the leg moves to the right) will occur if we don’t add a force to the right. Force Fx1 (the purple arrow pointed to the left) is born. This force could be exactly the same as Frx if no turning would exist. Unfortunately Force Fx1 will make the leg turn clock wards. To counteract this movement we need Force Fx2 (the lowest force). With the right formulas we can find their magnitudes: No turning: Fx1 * b = Fx2 * a Solve for Fx2: Frx + Fx2 = Fx2 * a / b No translation: Fx1 = Frx + Fx2 Fx2 = Frx / (a/b - 1) The example with concept 2 shows that force Fx1 is almost 3 times the weight of the person! Criteria:

• Distance “a” should be as big as possible, while distance “b” is as small as possible.

Diagram “forces in the stump”: This picture shows the major forces which a socket applies to the stump.


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Prostheses History Biomechanics, Biology, Medical Science, all have had interests in the design of prostheses for a long time (especially since world war two, because lots of people lost a body part during that war). In the beginning these prostheses where cheap and easily fabricated (just like the prostheses we want to design). The big difference is the social context and the fact that people in the western world are able to “upgrade” or replace their prosthesis at least once every year. Years later, prostheses became more advanced, using high-tech solutions and parts. This development was possible due to the integration of mechanics and medical science (which became biomechanics and ergonomics) and the increasing welfare. The basic components The basic components of lower leg prosthesis are the socket, the shank and the foot-ankle system. It’s important to realize that the design has to be a synthesis. All the problems have to be addressed equally and at the same time. The weight of a prosthesis is an important factor. Because the prosthesis is “dead material” it has to be as light as possible. If the prosthesis is very light, it can be blown away and new difficulties arise. A good weight seems to be around 1.5 kg. The socket is the part of an artificial limb that fits onto the patient's residual limb. A good fit of the socket on the stump is one of the most important -and difficult- parts of limb making. A shank is a structural component of a prosthesis which connects the socket to the foot-ankle system and transfers the load of body weight to the foot and the floor. It can be designed to be adjustable to allow growth of the amputee. Next is the foot-ankle system. This lower part of the prosthesis has to provide a decent winding of the foot and enough support. Also, this is the visible part of the prosthesis, making its aesthetics important. Sometimes the patient wears a prosthetic sock which is generally worn with an artificial limb to provide additional padding for bony surfaces. Sometimes people even wear a “Soft Socket”, which is a soft liner within a socket to provide cushioning. Hereafter we describe different kinds of solutions and designs of sockets and feet. Criteria:

• The weight of the prosthesis should be above 0.5 and below 2 kg.

Socket

Shank

Foot-ankle system

Picture “basic components”: The basic components of a below-knee prosthesis are the socket, the shank and the foot-ankle system.


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Sockets Suction Sockets For active amputees with good blood circulation, a close fit between the stump and the socket can create a suction that holds the prosthesis in place. In this kind of socket, called a suction socket, nothing is worn on the stump. When blood circulation is poor, a sock is worn over the stump and the socket is held in place by a belt around the pelvic area. The shape of the socket is crucial for comfort and functionality. The socket should allow blood circulation without being loose. Quadrilateral sockets Quadrilateral sockets are nearly rectangular in shape when viewed from the top. They are among the most commonly used sockets in third world countries, as they provide almost total contact with the limb. Inflatable sockets Sometimes Inflatable sockets can be used. These sockets are quite big, but can expand by adding air, thus leading to a tight fit. In richer countries, these prostheses are sometimes used as a temporarily solution. Strong inflatable parts are needed to withstand the high pressures. Also, there is a risk for a “flat” prosthesis. Bamboo socket This socket is made by putting two layers of cotton stocking (with in between the two stockings a plastic bag) over the stump and knee and to wrap the stump and knee with plaster bandage. Then a bamboo is split at one end into a few strips and the plaster socket is then put between the bamboo strips. This same socket can be used for a PVC plastic pipe prosthesis. Advantages:

• Simple to make. • Low cost. • Easily available.

Disadvantages:

• It doesn’t last long. • It looks primitive.

Picture “bamboo socket”: This picture shows a very cheap and easy made prosthesis.


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Leather socket Advantages:

• The socket is open at the bottom of the stump, which makes it cooler, and also allows for growth.

• Leather is available almost everywhere. • It’s comfortable in hot weather. • It can easily be adjusted to the stump as it

becomes smaller or bigger. • It’s soft and easily takes the shape of the stump,

and therefore self-corrects moulding mistakes. Disadvantages:

• You have to “use” animals for their pelts. • Leather has to be treated to be resistant to water.

When wearing a wet, leather prosthesis, blisters can arise. Wet leather dries very slowly

Jaipur (aluminium) socket The foot, itself, is probably the better known component of the Jaipur limb, but the socket is just as important. Originally made of aluminium and PVC irrigation pipes and (now also aluminium in tandem with polypropylene in various versions). Most versions are open ended plug sockets which bear the amputee's weight on a popliteal shelf and patellar tendon bar (the upper calf muscle and just below the kneecap). The most common suspension system, or method of affixing the prosthesis, is a leather cuff above the knee. Here the socket is part of the shank and is made/ shaped directly on the stump. Advantages:

• Low cost. • Quickly fitted. • Low/light weight. • Easy to fit stumps of non-optimal size in the socket,

because the socket is open on both ends. • The socket is easy to produce.

Disadvantages:

• It requires a lot of skill as well as special equipment to make the limb.

• It can brake easily. • Less suitable for wet climates where water and

moisture can enter through the open end of the socket.

• Physically less attractive than most other prostheses.

• The aluminium absorbs heat in a hot climate and can become uncomfortable.

• The fact that it is produced manually makes alignment difficult.

Picture “leather socket”: This is one basic and useful design.

Picture “Jaipur limb”: Jaipur sockets as well as Jaipur foots exist.


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Mukti limb First a negative cast mould of the stump is made. Then a positive cast mould is made for the whole artificial leg, with the help of the negative mould. After that, plastic pipe is stretched over the leg mould, the leg mould inside the plastic is broken and removed and a rubber foot is fitted to the leg. Advantages:

• Quickly made. • Low-cost. • Easier to mould than PVC pipe. • Light weight.

Polypropylene prostheses The sockets of these prosthesis’s are also made with the help of negative and positive cast moulds. Advantages:

• It’s lightweight yet strong PP. • It’s flexible and easy to shape. • It’s more user friendly compared to for example metal. • It’s easy and comfortable to fit. • It’s water resistant and easy to clean.

Disadvantages:

• The plaster bandage is expensive. • In warm weather it can become uncomfortable and skin

irritation can be a result of that. There are of course other materials that are used for the production of sockets, like wood, fibreglass, carbon fibre, etc… More information can be found on the videotape “Phnom Penh’s Component factory and Battambang’s Prosthetic Workshop” (1998).

Picture “a mukti limb”

Picture “Polypropylene prostheses”: One “naked” and one “aesthetical” prosthesis are shown here. .


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Shanks There are two types of prostheses: exoskeletal (or crustacean) and endoskeletal. The shanks of exoskeletal prostheses are on the outside, typically made of wood, thermoplastic or polyester resin. The inside is usually filled with wood. These shanks are heavier, but more durable than endoskeletal prostheses. The Jaipur prosthesis, a type of exoskeletal prosthesis, can also be made using high-density polyethylene (HDPE) to make both the socket and the shank (see the picture below). The HDPE is available in the form of pipes designed for irrigating rice fields. It is thus easily available in many developing countries like for example Sri Lanka. Endoskeletal prostheses have the most lifelike appearance, but require careful maintenance. Their shank is on the inside. It is a central tube, called the pylon, which is usually made of aluminum. It is covered in foam or polypropylene and encased in a latex or fabric stocking for cosmetic purposes. These shanks are generally more attractive than those of the exoskeletal prostheses. Criteria: • It has to be easy to adjust the length of the shank or to replace it.

Picture “exoskeletal wooden prosthesis”: an easy and robust solution for the shank.

Picture “exoskeletal below-knee resin prosthesis”: Also notice the bilateral below-knee amputation.

Picture “the Jaipur limb”: A famous exoskeletal prosthesis.

Picture “endoskeletal prosthesis”: here you can see the lifelike appearance of the endoskeletal prosthesis andthe aluminum pylon which fits inside.


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Foot-ankle systems According to us there are two main principles to simulate normal walking with a tibial prosthesis. The first principle is one with an ankle joint and the second is one without an ankle joint. In case of the latter we must simulate the motion of the ankle in another way, which we will discuss at a later stage. A: Prosthesis with an ankle joint I A rubber joint In Sri Lanka there is a lot of rubber available. So it seems to be a good idea to make a rubber ankle joint. However we didn’t find an example of a rubber ankle joint in the literature. Nevertheless in other applications rubber joints are frequently used (see the pictures at the right, here a rubber joint is used for connecting a windsurf board and its sail.) II A metal joint Another way to simulate an ankle joint in a prosthesis is the use of a metal joint. In the literature we found different kinds of metal ankle joints. Most of them are using a high standard of technology which usually makes them very (see the pictures at the right). In other applications we also found metal joints usable for ankle joints.

Picture “windsurf joints”: Windsurf joints can resist sun and water.

Picture “metal joints”: This design by Otto-Bock contains metal a joint..


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B: Prosthesis without an ankle joint If we do not use an ankle joint, another way to simulate the motion of the ankle must be found. There are several broadly used solutions. I Springs There are two different materials (spring steel and laminated wood) to use for this solution. Most examples below are from existing patents that we found on the internet. Spring steel is difficult to manufacture. Laminated wood has a bigger chance of breaking when subjected to loading for a large amount of time, because of its fibre structure. Otto Bock, the biggest producer of prostheses in Europe uses these solutions only in very specific situations, because there are easier solutions like for example the foam rubber foot (see next page).

Picture “springs”: Here a few solutions for spring feet are shown. These are from the patents found in Appendix VII


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II (Foam) rubber The solution for the feet which is used the most is the foam rubber foot. These feet have heels that are pressed inwards (like a rubber sponge) at heel contact and the fingers of the feet bend a little at the ’roll over’ at the end of a step. In third world countries this method is used somewhat more primitive, but with the same principles. For example the Jaipur Foot. The Jaipur foot has an opening between the “thumb” and the rest of the toes (see the picture at the right), which causes a better unwinding of the foot, with the toes bending outward a little.

Picture “foam solutions”: Most famous as a third world solution for the foot is the Jaipur foot. The picture is a foot as used in Netherlands (and in our experiments).


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III A curved sole (Rocker-foot) Another way to simulate the way of walking without an ankle joint is with a curved sole. With a sole which is curve shaped, it still is possible to obtain a decent gait. The working principle of the Rocker-foot is that the back slopes in at an angle of 30 degrees with the floor for a softer heel strike and roll-up of the heel delays plantar-flexion of the ankle joint enabling the accelerating tibia to maintain a constant angle to the foot. The middle section is flat for firm standing on the flour. The front of the rocker-foot is rounded in at an angle of 25 degrees with the floor for easy ’roll over’ at the end of a step. With the help of the curved sole it’s possible to have a correct unwinding of the foot. A rocker sole delays forefoot contact until the leg can catch up. Then it advances heel lift to catch up with the leg as it moves over the foot. In Europe the rocker-foot is used for people who broke an ankle and have them in plaster to heal. In this example the rocker-foot is used as an orthesis, but we can also use it for prostheses. The rocker-foot can easily be made from wood (see the picture at the right).

Picture “curved sole”: this is not a badsolution. Good gait is possible with this design. Of course, nobody would call it beautiful.

Picture “rocker-foot principle”: due to the curved shape of the rocker-foot the angle of the ankle can be 90 degrees all the time in spite of plantar and dorsiflexion.

Picture “rocker-foot”: we tried this solution….it worked even better than expected!

Picture “rocker-foot”: the solution. Look at the flat parts for relaxed standing.


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Conclusion Prostheses Analysis Sockets In table “comparing the sockets” the sockets as just described are compared on a few points. The score we have given is meant for the sockets which will be made in Sri Lanka. The table shows two strong solutions. The first high-scoring socket is the leather socket. This socket seems to have little disadvantages, except that animal pelts are required for its production. The two strongest advantages of this socket are the facts that leather is a cheap, easy available material in Sri Lanka and that leather is comfortable in hot/ wet surroundings, if treated right. Later we shall try to design a solution which combines leather and denim. The second socket with a good prospectus is the one designed by Inne ten Have. The strongest advantages of this socket are the facts that it’s simple to produce, low cost and that it uses easily available materials. Another reason to experiment with this prosthesis is that it is never take in production. It would be a pity if a good design would not be implemented. While experimenting, we try to examine if adjustments to the design are needed. Socket Sri Lanka

Simple to make

Easy to repair

Low cost Easily available

Durable Aesthetical Low weight Comfortable in hot/ wet surroundings

Adjustable

Bamboo ++ ++ ++ + - - - - +/- - ++ Jaipur (Al.) + - + + - - + - - - Leather + + + ++ + + + +/- ++ Mukti + - + + + ++ ++ ++ - - Polypropylene +/- - - - - - ++ ++ ++ + - - Inne ++ + ++ ++ + + + +/- +/-

Table “comparing the socket”: The scores of the different sockets. Especially the leather and Inne’s solution score well Shanks The shank can be chosen depending on the solutions selected for the socket. Both exoskeletal and endoskeletal shanks have their advantages. In most cases, we can choose the shank that’s most easily produced (in combination with the socket and the foot). A shank which is adjustable in length is recommended.


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Feet The same comparison procedure as with the socket has been applied to the different solutions for the foot (see table “comparing the feet”). Again, two designs are very good. The first very good solution is the foam-rubber foot. This one has (especially the version from Otto-Bock and the one from Jaipur) the big advantage that it is aesthetically very appealing. The disadvantage is that is doesn’t improve the unwinding of the foot. The second solution is the use of a simple and cheap version of the rocker-foot (for example by using wood). This solution can provide a decent unwinding of the foot. A disadvantage is the (probably) high weight of the foot. Solutions using springs are much lighter, but other disadvantages do not justify their use (in third world countries). In the experimental phase we shall examine if we are able to combine the two solutions. The result has to be a foot which is easy to repair and produce, simulates the unwinding of the foot and has nice aesthetics. Foot Simple Easy to low cost Easily Durable Aesthetical Low weight good gait Sri Lanka to make repair available simulation

Metal - - - - - - - ++ ++ +/- ++ Springs +/- - - +/- - - - - + + Foam-Rubber + + + + + ++ +/- - Rocker-foot (wooden solution) ++ ++ ++ ++ ++ + - +

Table “comparing the feet”: Especially the foam-rubber and the rocker-foot solutions score well.


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Production

Available Materials • Aluminium, titanium, steel and alloys

Three different materials are most commonly used (in European countries) in the making of below-knee (lower leg) prostheses: aluminium alloys, titanium and polypropylene (see below). Titanium is extensively used in China for making expensive high-quality pylons, which are attached to the prosthetic foot and socket through an attachment plate. This considerably increases the strength and reduces the weight of prostheses. Fabrication of titanium parts is difficult, however, as special equipment is required to process the metal in an oxygen-free atmosphere. Aluminium is light weighting (weight), but brittle. Steel is strong and easy to deform and produce, but heavy. Metals are easy to produce and last for a long time. Attaching other parts of the prosthesis to the metal part causes more work and costs.

• Polypropylene, Thermoplastic or Polyester resin Polypropylene has three advantages over aluminium: it is much lighter; it is cheaper and setting up production facilities may be easier for PP than for aluminum

• Foams, Tempur (see Appendix VI) and Polyfoam Foams are easy to shape.

• FiberGlass Fiberglass if used wisely can be a lot cheaper in a third world country than in a first world country

• Leather Leather is available almost everywhere, also in Sri Lanka. Leather is comfortable in warm weather; it adjusts its shape easily to the person who’s wearing it.

• Wood, Bamboo Wood is available almost everywhere

• Clay, Plaster Plaster of Paris or another high accuracy plaster is needed if you want to produce negative limb moulds.

• Useful products Using recycled products could greatly decrease the costs of the prosthesis

o Car Tires o Bicycles / Mopeds o Ropes, Strings, o Fabric and textile,

Picture “materials”: A picture of a market in India shows all kinds of materials daily used in third world (households). Some of these materials are ideal for use in prostheses.


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Available production methods Industry Not intended as a factory for prostheses, in industry area’s large factories can be found which can produce almost everything we can produce in European countries (at a lower price and often with a lower quality). If needed, large quantities of parts can be obtained from these factories. The use of large quantities of parts requires difficult logistics (if you want to distribute them over the whole country and is therefore not recommended). Funded prostheses workshops The prostheses are now often made specifically for one person. The production method is standard and the prostheses builders of the workshop are craftsmen who are very good in reproducing prostheses. The craftsmen know how to make moulds of the stump of the residual limb with plaster and are experienced fitting prostheses on patients. These craftsmen usually don’t develop any new solutions or designs and if they do, they would hardly draw it on paper. Instead they will start producing the new design immediately, learning from trial and error. Often there is one person in charge of the workshop and maybe he is also the one taking care of all the financial matters. These workshops in third world countries like Sri Lanka have the following equipments, which are mostly in bad condition: Grinding machine, bending bench, hand power drill, column power drill, electrode welding machine, halogen welding machine, a small belt sanding machine, a sewing machine, moulds for making a Jaipur foot, a heating oven and all kinds of hand tools. Such a workshop also often functions as a village repair shop, because it could be the only place which has such equipment. Sri Lanka’s electricity net uses 220 Volts, so the same tools can be used there as are used in European countries. Bicycle repair shops If we want to estimate what can be done at these often mentioned bicycle repair shops we can use the following slogan: “the shopkeeper there can do the same, as we can do here at home”. Of course, not only bicycle shops can repair or manufacture prostheses, also carpenters or maybe even local sewing shops or other local industry. Homes People can always make little adjustments themselves, like adding buttons or adjusting a screw. We can not ask too much from “home improvements”, because these people do not have the same tools as we do at home. Combined A large amount of prostheses needs to be produced every year. This way a production of 3000 pieces a year could be realised. For example: “1000 at 3 small factories, 1000 at local blacksmiths, bicycle shops etc, 1000 by repairing the prostheses at home”. Criteria: • The prosthesis can be manufactured in a prostheses workshop • The prosthesis can be repaired in a bicycle repair shop. • It would be better if the prosthesis can be manufactured in a bicycle repair shop.


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Standardization When you would be asked to build one prosthesis, for only one patient, how would you undertake this? Probably, you want to know a lot about the patient’s needs and measurements, and then design a good solution for this particular patient. When you, after this, would be asked to build ten prostheses for ten different people, how would you undertake that? Probably, for building the first few prostheses, you would follow the same process each time, as you did for making the one single prosthesis. After a while, however, you would notice that all prostheses you designed and built show similarities in some way. Noticing this, you would realize that you are making duplicated efforts when designing the whole prosthesis again for each child. Also, on that moment you would start thinking about the use of similar parts in every prosthesis. Thus, before you continue the building of the ten prostheses, you design some parts, which you can make easily and which you can use for every prosthesis. Cheaper The process of ´standardization´ has started. Standardization means, that all parts, assemblies or even whole products, that don’t need to be different, are made equal. On a low, but very important level, some parts are already standardized. Think of the bolts or the screws that have been made in a particular standard. On a higher level, the foot can be completely standardized. Without these standard parts (and even assemblies), the costs of a prosthesis might become too enormous. So, the answer to the question 'why standardization?' is: because it makes things cheaper. And cheaper things have two advantages: They are for more people available and in the same time they can provide more income for the people who make them. The following example shows how that is possible. The quality of the prostheses Many people have the idea that 'standardization' and meeting peoples particular needs' are in conflict with one another. However, this is anything but true. In fact, the modern sense of the industrial term ‘standardization’ is based on the principle 'meeting the particular needs of many people’. The particular needs are met by 'building' a product as a sort of modular system, out of standardized and changeable parts. Because of this modularity, a great variety of 'particular needs' can be realized. Besides, because of the low costs of standard parts, such a product will be available for many people. So, the quality of the prosthesis for the particular patient is not in danger, and can even be improved by using the principles of standardization. Different levels of standardization Different parts of the design and different users either need specific adaptations to the design or can use standard parts. In this context, we can distinguish between different levels of standardization (see table: “levels” on the next page). Of course there are no clear borders drawn between the levels. Different parts (for example foot and socket) can use different levels.


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Level 1 Every prosthesis designed for a particular user. Except from the standard

buying parts you use to build these prostheses, there is no standardization at this level.

Level 2 A wide range of particular standard designs. Each design meets the needs of only a small range of users. Although, at this level, the prostheses can be highly standardized, the standardization level of your workshop as a whole is not very high. The wide range of different models will take a lot of time changing the production, and causes low routine to build the prostheses.

Level 3 A small range of partly standardized designs. Each design meets the needs of a wide range of users. Some adaptations might be standardized, while others have to be designed to user’s particular needs.

Level 4 A small range of completely standardized designs. At this level, even the most particular adaptation needs are met by standardized options. For this standardization level, either an extensive machinery park, or a very ingenious design would be required.

Level 5 One completely standardized design for adaptation to all needs of all people who need a prosthesis. Such a prosthesis would be unnecessary complex and costly for most of its purposes. However, this level could only exist in mass production.

Table “levels”: We can distinguish different levels of standardization. Each level increases the amount of standardization How to To read about a possible way to implement design for standardization in the third world, look in Appendix IV: “Manual - How to design prostheses”, paragraph “design for standardization”.


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Life Cycle Analysis Life Cycle Analysis (LCA) is an approach for the evaluation of the total environmental impact of the prosthesis. Since the whole life cycle of a product is considered, LCA is often called 'the analysis from cradle to grave'. In the situation described below however you will see that the materials of the prosthesis eventually find their grave, but the prosthesis itself keeps on living. Here we have tried to describe the life cycle of the prosthesis with the help of a scenario. We’ll use an example of a young boy of ten years old, who gets the possibility to get a prosthesis fitted. He will have to take a long journey, probably by bus, with his parents to the prostheses workshop. At the workshop the family is welcomed and the boy’s measurements are taken. The prosthesis is then skilfully made by the prostheses builders. Of course some tests will be done to see if the prostheses fit the boy well and if it’s comfortable. Quicker then expected, after only one day, the family and the child go back to their home. Before the boy had a prosthesis, the family of the boy had to look after him, but of course they couldn’t always be around and the boy was living in isolation, because he couldn’t go out to play and to explore the world around him. With the prosthesis the boy can improve his mobility and so won’t be dependent on others. His improved mobility gives him the opportunity to live his life as a worthy human being. In the beginning the boy will have to get used to his prosthesis and learn to walk on it and during his journey back home on the bus, he’ll learn how to bend his knees while sitting in the bus. On his first night back he’ll have to put off his flip-flops which are attached under his normal and artificial foot and later on take off his prosthesis before going to sleep. Standing up in the morning he’ll have to see if his prosthesis is clean and then put it on himself or (in the beginning) with the help of his parents. He will then immediately learn to squat down with his prosthesis and sit on the floor to eat breakfast. He will walk to school on his prosthesis and during the break be able to play on the playground with his friends. Of course he’s very enthusiastic. Later in the day he might have to go with his father to work in the rice fields. During and after work he’ll see what the possibilities of his prosthesis are. His prosthesis has of course gotten dirty and he needs to clean it up at home, otherwise his prosthesis might get damaged, following the instructions that have been given to him by the prosthetic workshop about “How to clean your prosthesis”.

SQUAT


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After a year the boy has grown and does not feel comfortable any more in his prosthesis. His father then gets the manual given to them by the prosthesis workshop about “How to adjust or repair your prosthesis”. They then decide that they have to make a bigger shank. They measure how big the new shank should be and go to the local repair shop to order this specific piece of wood or metal if needed. They then themselves or with the help of a friend or the repair shop, replace the old shank with the new shank. The old shank can then be used for cooking in their own home. The design of the whole prosthesis is in such a way that the disabled person itself or their family can improve and customize their prosthesis themselves, replacing old parts with new ones and keeping the prosthesis alive.


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Synthesis

Design Philosophy This is our design philosophy. It is a summary of the most important principles we think are important for the design of the prosthesis and the implementation in Sri Lanka. This Design philosophy can be found between the lines all through the synthesis. • The most important is that the solutions work (strong, robust, comfortable and with

good prospect) • Standardization of the design of shank and feet. “one design fits all” • A modular system for the socket. A range of standard sizes is produced. The

combination of these parts fulfils the needs of everybody. • The design has to give enough information (usecues) about how it could be

produced “at home” (the local bike repair shop or carpenter). This doesn’t imply that the design could not have a modern look. Example: A pink injection moulded foot with a wood texture could “communicate” that it also could be made of wood. This principle implies that the design also shows how it can be repaired at home.

• We give the amputees a cheap, basic prosthesis (which fits better than it looks). The people improve and customize their prosthesis themselves. Example: The prosthetic foot given is aesthetically minimal optimized (and thus cheap). This foot is easily changeable for a homemade one which looks more like the normal foot of the amputee.

• If we cooperate with a factory that already has a machine park (for example plastic processing) then you will have to use this “high tech” machinery. The same principle applies to the design. If you cooperate with people who have years of knowledge about for example a Jaipur foot, a lesser solution can not be proposed.

• We want to start up a trial when we arrive in Sri Lanka. We aim at an initial production of 300 pieces a year.

• Because of the many aspects on designing sockets and their production and fitting, we now present some general solutions. These can be optimized and standardized in Sri Lanka together with the professionals. Designs can be tried and adjusted immediately.

• Eventually we will come up with three Designs: o 1 mechanically and medical correct one: This one does what it has to do,

nothing more. Its producible and comfortable o 2 an aesthetic design : The idea’s are made in the Netherlands, the final

design in Sri Lanka o 3 luxurious versions: In the future, if the trials are successful, a new and

improved, more expensive design could be made. Its possible this prosthesis is designed by a different team


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List of Design Requirements Common An ideal artificial leg/ prosthesis should:

• Functional o serve its purpose well (help a handicapped person walk or function better) o be easy to put on and take off o be long lasting

water-resistant and wear-resistant o easy to clean

• Forces o be lightweight yet strong, but have a minimum weight of about 1 kg.

• Social o be as attractive as possible o be low cost

• Medical o be comfortable o do no harm o can be aligned without the help of well-trained professionals.

• Production o be easy and quick to make o be producible with local tools and limited skills o use local or easily available materials o be easy to repair and adjust as a handicapped person grows or develops

Shank • It has to be easy to adjust the length of the shank or to replace it.

Foot-ankle system The prosthetic foot should:

• Gait o allow a gait as normal as possible o allow for the swing of the pace o absorb any jolts to the heel o stabile while standing still

• Functional o allow squatting o walking over rough surfaces o not make any noise o be resistant to the tropical climate o be durable

• Social aspects o be made with the consideration taken of the social structure, cultural and

religious traditions and lifestyle of the person involved o be appropriate for wear with flip-flops o be appropriate to wearing no shoe at all, given the custom of taking off

shoes before entering a house.


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Socket A Socket should:

• Fitting o be comfortable / fit comfortably o provide a good fit with the stump / provide almost total contact with the

limb o allow blood circulation without being loose

provide continues pressure on the right places while not using the leg to prevent sliding. The prosthesis always stays on the same place. This pressure is as low as possible

while using the leg the normal pressures have to increase enough to provide stability. There has to be a good balance between the maximum pressure (this is the biggest force on a small surface and will probably be found on the patellar tendon) and the total pressure (sum of al forces * surface)

o allow a straight stump • Functional

o give an effective overall stability and suspension to the limb. o allow a “normal” gait

be correctly aligned (angular and linear). The angle between the upper leg and the shank should be correct.

not falling off while lifting the leg o allow squatting o allow to be easily taken off or put on.

• Forces o provide weight bearing support in the area of patellar tendon right below

the knee and medial tibial flares (popliteal shelf, the upper calf muscle). o not bear any weight on pressure sensitive areas o support the shear forces about the stump

• Pain o not cause any pressure sores o have enough air ventilation o not irritate the skin

• Adjustable / Grow o be adjustable to change according to stump thickness o be adjustable to support growing children o be able to support a large quantity of the Sri Lankan amputees o be adjustable all around the Island, with simple means


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Production and implementation • Production should involve the amputees. • The implementation should be low risk • The required financial investments should be low • The western input should be low, more input (e.g. time, energy and effort) is

asked from the country (its inhabitants, especially the amputees) itself • The prosthesis design is allowed to evolve. There is enough time for good

evaluation and feedback


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Experiments and evaluation From the beginning we we’re very exited to experiment with all kinds of solutions. We began with making our own Rocker-foot from wood to walk with and to test the feel of it. We were very satisfied with the outcome of this wooden model, which you can see at the right. We also made different kinds of sockets and simulated different ways of suspension, from which you can see a few examples in the pictures below. During our first visit to the Dijkzigt hospital we were given a prosthetic foot, which we later on attached to a piece of wood that functioned as a shank.

Picture: “rockerfoot”: While in normal gait the ankle can be held in the same angle all the time.

Picture: “suspension”: We tried different solution for the suspension.

Picture: “connecting the prosthetic foot and the shank”


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After a while we had thought of a suspension method, for which the lower leg had to be on a 30 degree angle with the upper leg, to be able to put sufficient pressure on the kneecap tendon to bear the patients weight. Here to the right you can see a picture of this idea. We eventually had to put aside this idea because of what we heard during our second visit to the Dijkzigt Hospital The orthopaedic surgeon at the Dijkzigt Hospital told us that this idea would cause contractures in the patient’s hip and knee (see picture “fitting a limb” on page 11). After our second visit to the Dijkzigt Hospital we were given a mould of an amputated limb, with which we could make designs, according to the measurements of the mould.

At the same time we thought of a leather design for the socket. This leather design is made from the materials leather and denim, with special padding for the bony places on the limb, which should be protected from any pressure being put on them. The leather socket also has two pockets for two wooden sticks, which suspend the limb. With amputees, the two sticks are attached to the shank.

Picture: “finding an angle”: Notice that angle α (see chapter “force diagram”) is about 65o, which has great mechanical advantages.

Picture: “leather prosthesis”: The leather prosthesis can be worn even with normal legs.


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During the experiments with this leather design, we saw that the limb would slip through the socket after a while. The wooden sticks were causing the socket to be stretched out, in such a way that the suspension wasn’t good enough. Even without the sticks the suspension did not improve. So we decide to wear the socket upside down. This (to our surprise) worked like a charm. In this situation the pressure that is put on the patellar tendon is along a wider surface, which causes a bigger pressure on the patellar tendon and a better force distribution (see the pictures to the right).

Picture: “production of the leather / denim socket”: The leather socket can be produced with simple tools, as is shown in this picture.

Picture: “wrong way”: The leather prosthesis can be worn even with normal legs, but what about wearing it upside down?


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Concepts Hereafter some concepts are shown. These are our results and recommendations for the design of the foot, shank and socket. Also, our concepts about production, implementation and knowledge transfer are present.

Concept 1: The rocker-foot This Rocker-foot concept consists of four parts. The main foot is made of wood and attached to the shank with the help of a connecting mechanism that is usually used for connecting kitchen sink components together. With this connecting mechanism there is no need to screw a hole in the wood, yet the connection remains very strong. A steel profile is shaped around the sole of the foot. On top of that there is an aesthetic foot, of which it is clear how it has been made. Our principle is that the person wearing the prosthesis or its environment can reproduce this aesthetic foot to look like the way they want it too look. At the bottom of the foot there is a standard flip-flop, which is removable.

Picture: “production of the rocket foot”: from left above to right under you can see how this foot could be produced.


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Concept 2: The socket by Inne redesigned Inne ten Have showed us and explained us his design. These are his results:

Advantages:

• Easy Production • Easy reproduction • Clear design • Good pressure points are used – principally right

Disadvantages:

• Not very comfortable • Not the most efficient force distribution • Easy to make mistakes while fitting • If the prosthesis bends through (cycling) loading, the prosthesis needs to be

taken off, tinkered back into the right shape and put on again

Picture: “Inne’s design”: Here you can see the main principle and production method of Inne’s design. In the upper left corner is shows how the prosthesis only loads the green parts, which can handle the pressure. At the upper right corner we see how the prosthesis can be fitted for every amputee. The lower pictures show the prosthesis while in use and their attachment to the limb.


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Force Distribution: As you can see on the right side, this design (as do all designs) requires an enormous force on the backside of the leg (see “Force Analysis”). This amount can be decreased with a bigger angle (now 30 degrees) or by a better a:b ratio (see chapter “Force diagram”). In this example the a:b ratio is 3. While the design of Inne takes the great force on the knee tensor in account, it doesn’t do the reaction force on the backside of the leg. Also, some additional attention is needed for the force on the shin-bone (tibia). In Inne’s design this force is in reality the resultant of two perpendicular forces from the vertical metal sheets on to the stump (see picture “resultant force”). Figure “MRI scan” shows a MRI scan of the knee. A MRI scan clearly shows hard and soft parts and tissue, like bone and cartilage and the ligaments. Soft tissue obviously deforms more under pressure than hard tissue. The red part drawn inside the scan shows the expected deformation if the tensor is loaded (on a 30 degree angle). Thus, instead of a straight shape of the prostheses (shown in blue) a piece with different thickness has a better force distribution (shown in red outside). Also, the patella is a moving part, so pressure upwards will cause the patella to move upwards. Therefore it’s required to load the patellar tendon (low and perpendicular to the surface) more than the patella itself (to high or to vertically loaded).

Picture: “Force Analysis for Inne’s design”: Here you can see the big forces which are needed to support an 80 Kg weighing person. The formula’s used are below (Fx1 is the 2100 N arrow and Fx2 the 700 N arrow) Horizontal force 1385 = 800 / tan(30) Ftensor 1600 Solve Fx2: 1385 + Fx2=Fx2 * a / b Is a/ b= 3 then Fx2 = 692.5 N

Picture: “resultant force”: The two forces that act from the metal sheets on the stump, result in a force “backwards”.

Picture: “MRI scan”: The two forces that act from the metal sheets on the stump, result in a force “backwards”.


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Improvements • The patellar improvement. With an extra rubber piece on the metal sheet that loads

the patellar tendon, the pressure can be divided better when under load. • With some padding at the sides (vertical sheets) the pressure can be divided further. • A broad strip on the backside can be used, instead of using a thin thread • A western look can be obtained by making a nice aesthetic cover from foam or

polypropylene. The appearance is lifelike, but the underlying skeleton can still be made by the local carpenter.

• By having different sized inserts (“klickable” solutions) customized prosthesis can be presented. The measuring time can be reduced to minutes instead of days.

Picture: “padding”: The red areas are as broad as possible. Padding can be added here to improve comfort and to divide the pressure.

Picture: “add-ons”: With extra add-ons a more comfortable prosthesis comes into existence. The light blue pockets on the vertical sheets can be stuffed with padding according to the needs of the amputee.


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Concept 3: The textile / leather socket As we shortly described in chapter ‘Experiments and evaluation’ we thought of a leather design for the socket. This leather design is on the outside made from the materials leather and denim. On the inside special padding is placed for the places on the limb where the two wooden sticks will be placed to suspend the limb. (See Picture: “the inside” and picture “the outside”) The padding is meant to give the prosthesis more comfort and also for creating a large surface for contact. The bony places on the limb should be avoided from any pressure being put on them (see chapter “amputation”). For these places we made holes/ openings in the foam.

On the outside there are two pockets placed for the wooden sticks. The wooden sticks will be fastened to the shank of the prosthesis. If you would like to make the shank longer (for growing) you only have to change the length of the sticks. On the backside of the socket we made some holes to put a rope through.

Picture: “The outside”: The wooden sticks are in special pockets.

Picture: “the inside” There are several easy available materials used for the inside

Picture: “The backward side”: A rope is holding the socket together.


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During the experiments with this leather design, we saw that the limb would slip through the socket after a while. The wooden sticks were causing the socket to be stretched out, in such a way that the suspension wasn’t good enough. Even without the sticks the suspension did not improve. The reason for this is that the arrow ‘b’ is missing in this first design (see the right picture). In the chapter ‘Force Diagram’ we described why this arrow is so important.

We decided to wear the socket upside down. This (to our surprise) worked like a charm. In this situation the pressure that is put on the patellar tendon is along a wider surface, which causes a bigger pressure on the patellar tendon and a better force distribution (see the pictures to the left). Unfortunately we did not have enough time to make a new leather / textile socket with the sticks on the right side. Before going to Sri Lanka we’ll do this to optimize the design. The great advantage of the leather socket is that it can be adjusted easily to a persons stump.

Picture: “b is missing in this first design”: The cause of its ‘failure’

Picture: “upside down”: The leather prosthesis can even be worn on normal legs, but what about wearing it upside down?


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Concept 4: The polymer socket During our second visit to the Dijkzigt hospital we were shown some examples of temporary prostheses, which had an easy to shape polymer socket. We had already been thinking about polymers which would mold themselves to the shape of the body when heated and thought of the following concept.

Foams like polyfoam or Tempur (see appendix “Tempur”) could be suitable materials to use for the inner socket. The outer socket can be made out of carbon fiber, fiberglass, Polypropylene, wood, etc…

The back of the stump

Under high pressure deformable polymer, is heated, wound around and pressed onto the stump.

The rest material at the back and the bottom of the stump can be cut off, while the polymer is being fastened around the stump and glued to itself. This is now the inner socket.

The front of the stump

The outer socket is a standard shape, which is quite hard. It is pushed onto the inner socket from the bottom of the stump.

Attached to the bottom of the outer socket is a part, which is used to connect the outer socket to the shank.


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Concept 5: Knowledge transfer The transfer of knowledge is important in this project, because the local people should be able to continue or even extend the production of prostheses in the future. Information should be shared and applied in a way which provides the disabled person or the caretakers of that person with the appropriate knowledge. Books can be very helpful to share knowledge but learning from a book isn’t often the best way to learn something. A lot of methods, aids, and exercises can be learned more easily from other persons, through watching and through guided practice. But after a doctor, a limb maker or a village worker has taught the patient for example how to do certain exercises, or shown them an example of a home-made aid, printed instruction sheets with clear drawings can be a big help. Also depending on the interest and reading ability of the disabled person or its caretakers, it may be helpful to give them a few written papers of information about their disability. Sometimes they can make the difference between whether the recommendations are followed at home or not. For example a person with a artificial limb can get an instruction manual about how his/her prosthesis is produced and how it can be repaired, so when the prosthesis needs repairment or a modification, they themselves, a carpenter or a blacksmith in their own village can do the job. The Prosthesis workshop can build themselves a database of knowledge by keeping a big file box of papers and information sheets to give to disabled people, explaining not only what to do, but also why. It’s recommended that all the information, for example the exercises or the activities are adapted to the local situation. So three steps can be taken to help a disabled person or its family to understand how to make the prosthesis, how to do exercises that are needed and what kind of exercises to do:

1. First show and explain. 2. Guide them for a while in doing for example the exercises and to understand

why. 3. Then, give them the instruction sheet and explain the main points.

Next to giving information on rehabilitation and use of a certain aid to disabled people, also information needs to be shared about how disabilities can be prevented. A lot of times people aren’t concerned with disability until someone they love becomes disabled. After their loved one is helped, it’s possible to interest them in ways to prevent disability of other members of the family and community. Many of the preventive measures, just like the more general social measures, depend on increased awareness, community participation, and new ways of looking at things. These changes do not just happen. They require a process of education, organization, and struggle led by those who are most deeply concerned. Those who are most concerned about disability are usually disabled persons themselves and their families. Based on this concern, they can become leaders and community educators for disability prevention. Or disabled children and families can join together to form prevention campaigns. For example, village people put on short plays to inform the whole community about the dangers of mines.


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Lack of correct information often leads to misunderstanding. For example some people think that paralysis caused by polio is contagious, so they’re scared to go near a paralyzed person. A good education leads to a society where the disabled people are able to be a part of the community. The disabled people and their families can then maybe begin to organize a community rehabilitation program run by disabled people. Another way of sharing knowledge is through the radio. When a lot of people in development countries have a transistor radio, then it’s obvious that this is one of the simplest ways to reach people in a wide vicinity. Also, a picture could be with instructions could be printed on the prosthesis itself. Information about repair or use could then always be at hand. Also a print with which areas of the limb can de subject to pressure can be added.


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Concept 6: Implementation plan Apart from the list of requirements, this implementation plan is based on some basic ideas. First of all we have to try to let the system become self-supporting (see picture: “The Distribution”), as well in finances as in knowledge. We try to find finances by selling prostheses to the army (so, eventually, the army pays for all the disabled).

Picture: “The Distribution”: Apart of prostheses all the parties in the production process have their “special” extras. For Example: The environment and the high tech factory provide money for the smaller less advanced factories. These little factories are an important source of knowledge for the local carpenter or bicycle shop which wants to produce prostheses. Of course, the high tech factory also provides knowledge, but in this schematic only the most important functions are shown”.


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1: “At home” – year 0: preparation Objective: Collecting necessary data, get an overview over the total problem. Provide a starting point.

• Developing a decent design which can be used in this implementation • Collecting a knowledge base • Find finances • Develop an implementation plan • Write temporarily production and consultation documentation and a temporarily

knowledge transfer plan 2: “Sri Lanka” – year 1: setting up an trial Objective: Learn to cope with the people / situation.

• Discuss and evaluate the designs with the local experts. The manual as described in Appendix IV “Manual - How to design prostheses” can be used to as an introduction.

• Start a small factory or approach existing factories • Build a measuring prosthesis (see Appendix V “The measurement prosthesis” for

a functional description) • Fabricate some prostheses for “locals” (living in the neighbourhood) • Document all steps necessarily to teach the factory how to produce the

prostheses and how to consult the patients. Finish the production and consultation documentation and the knowledge transfer plan. (Also see Appendix III “Manual - Producing prostheses”)

3: “Sri Lanka” – year 2: evaluation Objective: Evaluation of the design.

• Retrieve information about the prostheses and their use from the subjects in step 2. Adjust the design according to the findings

• Evaluate the development of the factory over a year (is it grown, did it slow down production, did it start making other prostheses, etc)

• If the design is really good and the consultation handling too, the spreading of the design should already have begun. Look for this… it’s a good indication this implementation is going to work….

• Decide how to go on (worst-case scenario: stop the project, best-case scenario: speed up the project )

4A: “Sri Lanka” – year 2/3: implementing the redesign Objective: Spread the design

• Set up some factories and consultation centers spread over the whole country • Set up coordination / “helpdesk” centre for these factories; be sure all information

is available to all. • If needed, now new versions can be designed (for example for upper-leg

amputees or a version for bilateral (both legs) amputees). Consultation will than be more important. Appendix III “Manual - Producing prostheses”, chapter “consultation” describes this scenario.


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4B: “Sri Lanka” – year 2/3: trail for luxurious design Objective: Making money

• Design a luxurious version of the prostheses, meant for the Sri Lankan army (and eventually export)

• Find finances (which should be less difficult, because the design proved itself by now). Set up an import program and a distribution centre for the first prostheses (with this design) from Europe. This can be an extra task for the coordination centre (4A).

5: Sri Lanka – year 4: evaluation and merge Objective: Close the circle

• Evaluate the success of the luxurious design. • Set up a factory in Sri Lanka which is able to produce the luxurious design. This

can be an upgrade of the distribution centre (4B). • Make sure profit and parts are distributed to the smaller factories

Although this implementation plan seems to be a difficult and time consuming thing to do, it’s important to keep in mind that the main idea is to provide a self-supporting system. If the design is successful, it’s worth to experiment with this idea. Even if only steps 1 through 4a are implemented the project is already a success. In the project for “Design for All” we are focused on step 1 and 2.


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Conclusion We have thought about using one standard solution for the prosthesis foot. This could be the Rocker-foot (“concept 1”), which consists of three parts. A steel profile shaped to the shape of the sole of the foot. On top of that there is an aesthetic foot, of which it is clear how it has been made. At the bottom of the foot there is a standard flip-flop, which is removable. Still three different designs/concepts of the socket can be thought of. These are all reasonably good and worth experimenting with. The first design (called “concept 2” in the synthesis) is an adjusted and improved design, which was already made years ago by a designer, named Inne ten Have. We have lots of confidence in this concept because it’s well designed, having a good socket. We think it’s a shame that it hasn’t been used all these since it was designed. The second design (“concept 3”), which is made from leather and textile, has specially added soft pads and has the same bearing principle (in the socket) as the first design. This concept is aesthetically nicer than the Inne’s design (concept 2) and looks more comfortable. The disadvantage of this design could be that it will sweat more. The third design (“concept 4”) is a plastic prosthesis more based on western ideas and influenced by a video that we saw about a prosthetic workshop in Cambodia. We still have to see if the materials are available in Sri Lanka and if it can be produced there. Next, we presented some ideas about knowledge transfer and how the implementation could develop “concept 5 & 6”)


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References

• Ontwerpergonomie (sixth edition), Prof.dr.ir. R. den Buurman et al. Technische Universiteit Delft, Subfaculteit Industrieel Ontwerpen, March 2000.

• Biomechanica van het spierskeletstelsel, grondslagen en toepassingen (third edition), Prof.dr.ir. C.J. Snijders, Dr. M. Nordin, Prof.dr. V.H. Frankel Elsevier gezondheidszorg, Maarsen 2001

• Reader Beweging en Analyse, Haagse Hogeschool, May 1998 • The Tibial Prosthesis (second edition), Handicap International Training centre,

1985. • Prothesen-Kompendium, Prothesen für die untere Extremität, Otto Bock, • Prothesenpaßteile-Untere Extremität-, Otto Bock health Care, Germany 2002 • Materialien für die Orthopädie-Technik, Otto Bock health Care, Germany 2001

• Nothing About Us Without Us, Developing Innovative Technologies For, By and

With Disabled Persons, David Werner, Published by HealthWrights, 1998 • Disabled Village Children, A guide for community health workers, rehabilitation

workers, and families, David Werner, Published by HealthWrights, Published by The Hesperian Foundation, 1987

• Videotape, Phnom Penh’s Component factory and Battambang’s Prosthetic Workshop, 1998

Picture “information”: A selection from the gathered information.


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Appendix

Appendix I: Individual motivations Boudewijn


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Farshad Farshad Soleymani, born in Teheran (Iran) on 18 April 1978, fled (from the long lasting war between Iran and Iraq) with parents in 1986 to The Netherlands. Leaving home to work or study abroad is an adventurous leap into the great unknown, especially if your destination is a remote country in the Far East which has been afflicted by numerous wars in the past 18 years. I see myself as a healthy young man with the possibility to put the skills I have learned during my Industrial Design study to good use right now and hopefully this summer, designing prostheses for disabled people in Sri Lanka. In July and August of the year 2000 I and a student colleague of mine went to the west coast of Mexico to work in a wheelchair workshop which was situated in a small village called Ajoya. The village, a cluster of run-down houses slowly baking in the hot Mexican sun, is buried deep in the Sierra Madre Mountains, where peasants are dirt poor and local drug-lords murder each other for control of the region's marijuana crop. And we knew we were heading to the wild Wild West before hand, but the work was too important to turn down. In Mexico, parents who can't afford to buy wheelchairs must carry or drag their disabled children around or some even leave their children always at home. Projimo, a community-based rehabilitation project run by and for disabled people, aims to empower local people by providing training and self-help medical manuals. With their meager funds unable to meet the overwhelming demand for their services, Projimo was delighted to welcome us two TU students. Our destination was Projimo’s 'Children's Wheelchair Project', where Gabriel, a paraplegic, runs the workshop. Using wood, metal, bicycle tires and basic designs, they build six wheelchairs a month. The wheelchairs are built from scratch, right down to putting the spokes on the wheels. The wheelchairs are then transported down the mountain to Mazatlan, where they're distributed to children for free. Having endured a 24-hour bus ride from Mexico City to Ajoya and been rudely welcomed in our new home by a tarantula, we set to work completing a project begun by Mauritz Zijp, a TU student who had worked in Ajoya a year prior to us. We redesigned and completed an 'evaluation measurement wheelchair', to be used during consultations. Before, children were measured with a tape measure, which is not precise enough. All of our evaluation chair's parts were adjustable and we painted it with bright colors to make it fun for kids.


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We then made a standardized form to be filled in during consultations. Previously, measurements were scribbled on scraps of paper, often illegibly. Consequently, mistakes were made during construction and children were hugely disappointed when their new wheelchairs didn't fit them properly. We also wrote a wheelchair design manual, detailing the TU's Method of Industrial Design. Our guidelines can be used in Ajoya and also in other poor countries where people want to start a wheelchair workshop. Ajoya proved to be a productive place to work. With no television or Internet, the only distraction was the occasional sound of government helicopters flying off to drop pesticide bombs on marijuana fields. Of course, drug-lords pay off the pilots to make sure they don't drop the pesticides on their marijuana crop. One night it was very hot, 35º C. The heat and a chorus of madly barking village dogs made sleep impossible. At 2 a.m., a masked gunman entered our home, pointed a pistol at us and demanded "Dinero!" Although the gunman wore a mask, I recognized his eyes. It was a young guy from the village. We knew that if we gringos reported the crime, local thugs might retaliate and we'd lose more than just some money. Everyone in Ajoya has been scarred by violence, it comes with the territory and you accept it. A few pesos poorer, we pressed on with our final project, designing and building a special seating wheelchair for children afflicted with Cerebral Palsy (CP). Chairs for CP victims must have adjustable seat angles and because CP children have great strength and can crack metal frames, we decided to use wood. Wood offered several advantages. It's supple, bending without snapping under pressure, unlike metal. And in poor regions, wood is usually available and inexpensive. Moreover, wooden wheelchairs can be built and repaired using hand-tools. We completed our prototype wheelchair, but some fine-tuning work remained. Despite the extra pressures of working in Ajoya, we both were glad we accepted the challenge and helped the needy. It was a life-changing experience, professionally, culturally and spiritually. It also made us value the law, order and quality of medical care we enjoy in The Netherlands. Because we had to adapt our ideas to the available materials and tools, we learned to be creative and the practical trial and error method we used taught us a lot of manual skills. Learning to speak Spanish turned out to be the foundation for a good working environment for us. We could learn the right manners of conduct and were able to have a nice chit-chat with the village people. The Mexican kitchen was very different from the Dutch one, which caused both our stomachs to irrupt. I was sick for one day with diarrhea and my colleague for almost a week. Adapting, acclimatizing and accepting were meaningful behaviours we learned to make our own. We saw how different the way of life is. We in The Netherlands seem to be in a hurry all the time and forget to find time to reflect. I don’t know what I’ll be doing in the future, but doing this project for Sri Lanka is at this moment very important to me. I will stay in Sri Lanka for approximately one month.


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Wouter In the motivation given below, I will describe why I am following this optional module and specifically why I choose for this design project. After I finished my secondary school (firstly HAVO, later VWO) I wanted to study medicine. The number of students who signed up for this course was far too much in comparison with the available number of places. After drawing lots I heard that I was not going to be studying medicine. Industrial Design and Development was an intuitive second choice. Nevertheless my interest for medicine is still increasing. I am specialising myself through means of optional modules, with subjects such as designing and developing products which have much ground in common with the medical discipline. During the first part of my study I followed two ergonomic modules. This year I followed several optional modules. An example is Bone Mechanics and Implants, which discussed the history of bones, the way in which a bone is build, several implants and their failure scenario’s. Another part of this module was a design project of a fall simulator to simulate in which way a femur will break. Biomechanics was about the appearing muscle activity in several parts of the human body during static and dynamic loads. Design for All continues this list of optional modules which also has much ground in common with the medical discipline. Comparable to Bone Mechanics and Implants, a part of the Design for All course is also a design project; the design of a prosthesis for people in Sri Lanka. It was especially this project that attracted me to follow this module. Why…..? Industrial Design and Development is creating products for people. But for me it is much more; Industrial Design and Development is creating useful products for people. What I mean with the word ‘useful’ is quite difficult to explain, it is a feeling I have that has very much in common with ‘doing the right thing, before doing things right’. This is the first design project that according to me can really contribute to people’s health. Besides the fact that this project contains the design of a medical product, I like the idea to design a product which is directly used by its consumer (patient), instead of designing a product for a (large) company of which the only purpose is to make a good profit. I believe it is clear enough that, therefore, I would like to give my internship (6 weeks) a medical aspect. If it is possible to combine my internship with this Design for All project I would like to do everything that is possible to design a good product for the amputees in Sri Lanka who really need a prosthesis. During the first six years of my life I lived in Saudi Arabia. In spite the fact that I was very young, I can remember very much about this period. Living in a country which has a complete different culture compared to the Netherlands will sometimes let you think completely different about certain things. What is really important in my life? Should I always think through a European window? A more practical reason to me to go to Sri Lanka is the fact that my girlfriend is going to Sweden for about half a year (August to January). It would be most convenient if I could go to Sri Lanka for my internship in that same time period (three months there). Yours Sincerely, Wouter


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Appendix II: Exercises


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Appendix III: Manual – Producing prostheses WARNING: THIS MANUAL IS TEMPORARILY AND HAS TO BE FINISHED This page is the title page for a compact checklist manual for the prostheses builders who are involved in making a prosthesis for people of all ages. The next chapters are included: • Introduction • Consultation • Measuring • Evaluation These chapters are omitted, because we still have to improve the final design: • Producing the prosthesis • Running the workshop INTRODUCTION This manual will be a guideline throughout the design process of Prosthesis. People all over the world are in title of having a careless childhood and enough means to have a socially integrated life. People who can not walk will be soon living in isolation. Of course the family or caretakers will be around sometimes, but you can’t expect the caretakers being around all day. The problem of this situation can partly be solved. What if the person can improve his mobility with special aids like a prosthesis or even a wheelchair! With some basic tools, materials, a handyman and this manual it must be possible with some positive energy to build prostheses for everybody. If there is a will there is a way! Of course it is easily said than done. But at this moment somewhere else on Sri Lanka, people are making prostheses using these methods. The improved mobility of the amputees gives them the opportunity to live their life as a worthy human being. This manual includes some questionnaires that can be handy to consult the amputees needs. Always try to keep the amputee as the central subject. After all the information is gathered, it is wise to make a summary to get a clear picture of the wants and needs. We will call this a set of demands to fulfil. This set can be extended with wishes. The next step is taking the measurements of the limb. This can be done by the technician, physiotherapist and a physician if available, but with some patients, you will do fine too. Most measurements can be found with normal measurement tools. For a perfect fit, probably several tries for the shape of the socket are needed. (Also see Appendix VII). At this moment our goal is to make a standard design which will be fitted on the patient, with the idea that the patient won’t ever have to come back for a second one, because he/she or his/her surroundings can repair and adjust it themselves.


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CONSULTATION The fitting process When a patient is getting a prosthesis fitted at the prosthesis builder’s workshop, it is recommended to develop a trusting relationship between the patient (his family) and the team of prostheses builders. In the beginning also the patient’s measurements are taken to have a good check for when the prosthesis is being fitted. The measurements can possibly be documented in a standard fill in form. Close interaction and experimentation at that time with the prosthesis is needed to make a good fit for the patient. A very important part of the fitting process is to evaluate how the patient uses the prosthesis, which has been made for him, and if it fits correctly.

Consultation If in the future different designs are made of the prosthesis, which provide solutions for different needs, then a deeper consultation of the patient with information about the patient and his daily life patterns can become important. We have made an exemplary checklist of things which can be looked at, when a patient is being consulted. Shown on the next page. Checklist Consultation The information obtained by the questions in the checklist must be looked at carefully and used during the design and the production of the prosthesis. It is wise to make a summary to get a clear picture of the wants and needs of the patient. This is a set of demands to fulfil. This set can be extended with wishes. We think the general needs are: 1. Safety 2. Near family and friends 3. Movement 4. Discovering 5. Participation 6. Comfort 7: Self-respect


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Checklist “Consultation”: This checklist can be used for gathering important information about the disabled.

Checklist Consultation – Personal particulars Male / female _________________________ Name _____________ Last name _________________________ Street _____________ Town/village _________________________ Day of birth ________ Name parents/caretakers name brothers/sisters __________________ Kind of impairment? Abilities and disabilities (because of impairment) __________________ Condition of the lower extremities –

Power of disabled leg __________________ Power of normal leg __________________

What abilities does the patient still have? • What about the strength and possibilities of the non-effected limbs? • Is there a possibility to improve the affected body parts by (for example) training? • What about the mental situation of the patient, is the patient likely to learn and cooperate? • Can the patient stand up without using an artificial leg? What are the daily activities of the patient? Getting up in the morning _________ Breakfast _______________ Between breakfast and lunch _________ Lunch _______________ Between lunch and diner after diner _________ Bedtime _______________ Does he go to school? __________________________ Have some kind of work? __________________________ Does the patient have to be transported for that? __________________________ On what kind of terrain is the patient transported? ________________ Distance __ Can he fully join the school/ work program? __________________________ Does the patient have special plans for the nearby future? __________________________ Are there special wishes of the patient? __________________________ What are the patient’s hobbies? __________________________ What is the main purpose of using the prosthesis? __________________________ What locations does he go to? __________________________ What are the general activities at home? cooking/cleaning/gardening/repair Is the patient active or passive? __________________________ Which extra features does the prosthesis need? __________________________ About the family: How poor or rich are they? __________________________ • Can they support the costs of the prosthesis themselves or do they need the aid of funds? • What about special cultural habits in the patient’s environment? • What about the family’s and community’s acceptance of the patient’s impairment?


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MEASURING When the designer is making a prosthesis, he could use a chart of average human measures. The average prosthesis can’t meet with every person’s measurements. Of course, when you are making a prosthesis for a specific patient, you should take the measures of that patient. Measuring is a very important and delicate part of prosthesis making. For example children have very different proportions in comparison to adults. When the prosthesis has adjustable parts, the designer should call the patient’s attention to the adjustability of the prosthesis, because sometimes the patient’s are not aware of the possible adjustability’s of their prosthesis. Considerable help in determining the quality of the made prosthesis would be to develop a test procedure for prostheses. With the help of these tests, you could evaluate the prosthesis and if necessary add adaptations or change specific parts. Also possible is the use of a measuring prosthesis (see Appendix VII).


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EVALUATION If possible, you should try to make a periodical evaluation. Of course, you can not expect people to travel a lot for this evaluation. But maybe there are users of the prosthesis in the neighbourhood. Asking them sometimes about their experience with the prosthesis can be rewarding. Either it tells you about the amputee’s feelings about the prosthesis or it can show you important improvements or adjustments to the design. Hereafter a short “checklist for aftercare and evaluation” is given, in order to obtain a good view on the problems that have occurred during use of the prosthesis.

Checklist for aftercare and evaluation Male / female _________________________ Name _____________ Last name _________________________ Street _____________ Town/village _________________________ Day of birth ________ Name parents/caretakers name brothers/sisters __________________

Situation • For how long have you been using the prosthesis? _______ years • Did you use the prosthesis like suggested during consultation?

Repairs • Did the prosthesis have to be repaired by others?

• Which parts of the prosthesis has been defect? (Note down in detail: when cause and frequency)

• By whom was it done? self - family/friends - local workshop • How long did you have to do without the prosthesis? • What kind of defects have you got at this moment?

Intensity of use • Frequency per week hours per day wearing / walking? Do others use the prosthesis? • After how long do you need a rest? • What kind of problems have you got with the prosthesis?

Problems with dimenions Fit of the socket good - too tight - too loose Gait good – acceptable – looking funny – unpleasant - pain Length of the shank too long – good – too short Cushions comfortable – useless – too much friction - sliding Comfort and safety Do you have problems or pain, caused by wearing the prosthesis? no - yes If yes, where? __________________________________________ Do you have problems or pain, caused by walking with the prosthesis? no - yes If yes, where? __________________________________________ When do you need help from others? going uphill – sit / stand – dress /undress - other Have there been accidents during use of the prosthesis? Do you walk on a road with busy traffic?

yes - no If not, why not? unsafe - too far away - not necessary


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Appendix IV: Manual - How to design prostheses WARNING: THIS MANUAL IS TEMPORARILY AND HAS TO BE FINISHED Introduction This is a manual which describes a method for designing prostheses. It shows a method for designing all kinds of things as in taught in the Netherlands. Of course, designing is an activity which can be done in many ways. If you have your own way and if the results are good, just go on with doing what you are doing. But if you are stuck, you can try some tips described here and see if it helps. Designing in a group There are several design methods that can be used for designing a new prosthesis. For example there is a method used by small businesses. This method is characterized by the early production of a prototype. The design is refined through repeated prototype/ Evaluation/ Prototype cycles. The designer learns about the problem through the generation and evaluation of sequential prototypes. During this process the prosthesis builder, who is the designer, should analyze all the information that he has obtained from the patient. During this he could look for functional and optional solutions for all the particular needs of the prosthesis and the patient. This is a very useful method We industrial design and development students have learned, at the Technical University of Delft in the Netherlands, to use the following design process while designing. The design process exists of different phases described in the next schematic overview. ANALYSIS --------Evaluate------- PROBLEM DEFINITION --------Evaluate ------- IDEA --------Evaluate-------- CONCEPT (s) --------Evaluate-------- ASSIGN MATERIAL/ OPTIMIZE --------Evaluate-------- FINAL DESIGN --------Evaluate-------- ASSEMBLY PLANNING --------Evaluate-------- ASSEMBLY --------Evaluate--------- TESTING --------Evaluate--------- After each step you can evaluate the quality of the content. When you are not satisfied you can take a step back. Sometimes you can even take more steps back in the process. Design is an iterative process. ANALYSIS This is the process of looking for information about the topic/product of the design process, to understand the problem at hand.

Case An important analysis is the analysis of use. Try imagining all kinds of different situations the prosthesis and the patient could be in. For example, you should consider in your design how the patient stands up from his/her sitting posture.


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PROBLEM DEFINITION A problem definition is a short summary of the problems that must be solved in order to obtain a satisfied product. It is recommended writing it down for example like a few questions.

Case Our problem definition: After writing the problem definition you will need to obtain a list of demands. When you design a product think before you start of the most important demands that your design needs to fulfil. The demands can be determined by • The future user (think of consulting the patient) • Product analysis The obtained demands will be your reflection guide during the design process. When one of the demands is not fulfilled, take a step back into the design process and try to also fit this demand into your design.

Case: In our case we used product analysis, literature study and talking with experts in this field.

LIST OF REQUIREMENTS In this list you can collect all the requirements and a list of wishes for your prosthesis IDEA The IDEA phase is drawing or writing as much as possible ideas and solutions according to the problem definition. By generating a lot of different ideas, the chance of a good design is more likely. Alternatives for specific elements of the design enable you to combine these elements into a total quality design.

Case: Important while making ideas is to do not think at the first idea “This is it!’. It can be helpful when you collect more ideas so they can be compared. The drawings are just simple sketches and don’t have to be very accurate. Next we draw several solutions for the different design parts. We did this at random. Evaluating our first ideas did not give us a satisfied feeling. The process of decision making and evaluation of our designs will maybe be too fast in our case, because of time pressure. We know that when we’ll be making the prototype we will learn more and meet new problems. A concept should show that a design has got potential and is ready for the next phase, which is the phase where your design gets optimized.


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Choosing the best concept: A very quick and effective method to choose one your best concept is via a method, which we’ll call the ‘Date Method’. How does it work? The different concepts (two or more) will be compared with each other. For example there are three concepts for the prosthesis. Compare criterion 1 of concept 1 with that of concept 2. Assign to the concepts for de different criteria - ,-/+ , + or ++. Then do the same with concept 1 and 3 and concept 2 and 3.

After comparing the plus and minus we can see which concept has got the most potential for a good design. The method can be more honest by letting other people do it. OPTIMIZATION During this phase we’ll take a more careful look at the concept and try to optimize the design by assigning the material, the construction method and the measurements to our design. In this process you can for example find a new, maybe better solution for your design. And that’s ok. Like it has already been said, it’s allowed to take a step back in the design process! Of course it can happen that you just don’t know how a solution of yours will work out. Well during your evaluation, during production or even during assembly you can find out if your design will fulfil the set demands or cause problems. These problems can then be solved in the workshop.

Case: Design for Standardization This section shows a structural way that could lead to make a design for a standardized prosthesis. The first step is always, to make it clear for whom you want to design. Since it is not possible to design a prosthesis to meet the needs of all people in the world, (most of them can walk), you have to select a relatively small group of people that share the same basic needs. The smaller the group you select, the more particular their shared needs will be, and by that, the easier it will be to standardize the prosthesis. On the other hand, if you choose the group too small, you will need a lot of different designs to cover the needs of ´all people who need a prosthesis´. Accordingly, the use of many different designs would not improve your workshops efficiency either. In this context, we can distinguish between different levels of standardization: Level 1 Every prosthesis designed for a particular user. Except from the standard buying parts you use to build these prostheses, there is no standardization at this level. Level 2 A wide range of particular standard designs. Each design meets the needs of only a small range of users. Although, at this level, the prostheses can be highly standardized, the standardization level of your workshop as a whole is not very high. The wide range of different models will take a lot of time changing the production, and causes low routine to build the prostheses.


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Level 3 A small range of partly standardized designs. Each design meets the needs of a wide range of users. Some adaptations might be standardized, while others have to be designed to user’s particular needs. Level 4 A small range of completely standardized designs. At this level, even the most particular adaptation needs are met by standardized options. For this standardization level, either an extensive machinery park, or a very ingenious design would be required. Level 5 One completely standardized design for adaptation to all needs of all people who need a prosthesis. Such a prosthesis would be unnecessary complex and costly for most of its purposes. However, this level could only exist in mass production. It is important to get yourself insight in the possibilities and restrictions of your own workshop. Which level of standardization would fit your situation best? Probably, if your workshop is averagely equipped with some basic machinery and your production rate is not more then a few prostheses every week, somewhere around level 3 would be a good aim. We say ´somewhere around´, because there are no clear borders drawn between the levels. For example, you might have one design closest to level 4, to serve a wide range of particular needs by highly standardized solutions, and two designs that together cover the remaining small range of needs (level 2). The standardization level of your workshop as a whole would then be somewhere in the middle, around the third level. When you make it clear for yourself, what kind of standardization would work out well for your workshop, you will be able to divide all prostheses users into smaller groups in order to decide what combination of designs would be best to cover all needs for all users. Choose the groups in such a way, that within each group, the users have similar needs. A survey like this can help you to make a logical division. You can make this as extensive as you prefer.

FINAL DESIGN A final design will give you all the information you need to prepare a plan of assembly. Mostly this is used to discuss the design of the prosthesis with the people of the workshop or others involved with the assembly. It’s important to put all the design specifics on paper and not to keep it in your head, because at some time you will have to discuss your design with another person, for example the person who will make the design (or a part of it) for you. Don’t be ashamed for your drawings. Case: In our case we made a prototype of our design although we had a shortage of time, also because of the more exploring aspect of our process. Assembly (and plan of assembly) A plan of assembly contains all the steps that must be taken in order to build the design with the aid of tools. Assembly is the manufacturing of the design following the plan of assembly.


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Exceptions to the rules In general the next factors can be the cause of not going through the whole design process step by step: Time limits (the delivering date is coming soon....) Money (there is no money to pay the designer) Skills of the designer (the skills of the designer are not adequate for the job) Lack of information (there is a lack of information about the topic) Explorative design - “learning by doing” If you are experienced, sometimes some steps can be skipped.

Case: *brainstorm: brainstorm is a creative stimulating process to obtain new ideas. You sit around a table or elsewhere comfortable. A good brainstorm needs at least four members to join in. One of the members will make the notes (facilitator). Start with formulating a question according to the problem that needs to be solved. The group can start to put forward ideas. There are some rules for putting forward ideas. 1. Never disrespect an others idea. 2. It doesn’t have to be true what you’re saying. 3. Try to associate on the idea of others. 4. Don’t be afraid to put forward strange ideas. 5. See if the facilitator can keep up with the group, otherwise slowdown. After a certain amount of time it is wise to change the brainstorm question into another. Another question will give a new perspective on the problem. After several rounds eliminate the useless ideas and analyze the ones with potential. Combining of ideas is also a strong tool.

Test and evaluation Testing and evaluation of the prototype. Conclusions and suggestions Try to summarize your results and to make some suggestions about future things that have to be done. For example: Future experiments, adjustments or maybe a suggestion to make another version of the design for other users.


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Appendix V: The measurement prosthesis In order to build a prosthesis specially to the needs of a specific patient, it’s very important to determine all the specific measurements. For this reason, it could be very useful to have a so called 'measurement-prosthesis'. With such a prosthesis it’s possible to accurately determine the measurements of a patient. The shank of the ‘measurement prosthesis’ is easily adjustable and the right measurement can then be read, because there is a measuring scale on the shank of the prosthesis. After putting the ‘measurement prosthesis’ around the stump and adjusting it to the specific stump, the measurements can be read with the help of a few measuring tapes that are attached to the ‘measurement prosthesis’ and which can be put around the stump. After that the measurements need to be well documented of course. The socket of the ‘measurement prosthesis’ also needs to be adjustable in height.

Picture “current way of measuring”: This will be the principle, that can be used to design a measuring prosthesis. Today many limbs are measured the same way.


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Appendix VI: Tempur Tempur® material is a breakthrough in sleep technology that will forever change the way you sleep. The original formula was developed in the early 1970's at NASA's Ames Research Centre in an effort to relieve astronauts of the incredible g-forces experienced during lift-off. Fagerdala World Foams of Sweden, spent almost a decade and millions of dollars researching and experimenting with the NASA material before discovering a way to produce a consistent and durable product. Tempur material relieves pressure because its cellular structure is completely different. It's made up of billions of high density, viscoelastic, memory cells. The cells are spherical with windows, and the key is…they're temperature sensitive. The high density of Tempur material makes the Tempur-Pedic Swedish Mattress so durable that it's backed by an incredible 20-year limited warranty. In warm areas, they get softer and pliable. In cooler areas, they stay firm. The cells will literally shift position and reorganize to conform to your body contours. The cells shift so we don't have to. Imagine a mattress that's firm where you need it and soft where you want it. It's like having a mattress custom designed to fit your body. Acting like a very thick fluid, Tempur material doesn’t compress in the classic sense, it displaces to accommodate the load. Tempur, like other fluid or fluid-like materials, is also reactive to heat and pressure. It becomes significantly softer and flows more readily when the material is warmed close to body temperature than the material which remains at ambient temperature. This variable degree of viscoelastic stiffness results in the material molding to the body. Body weight is so effectively distributed over the body contact area that gross pressure is markedly reduced to therapeutic levels. Although there are obviously variances in interface pressure at different parts of the body, the pressure is distributed so evenly that there are minimal pressure spikes.


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Appendix VII: Patents

prosthesis for tibial amputees focused on the 3rd world

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