D.i.y. Leg Prosthesis

Preface

Introduction to Cambodia

This article is the report of a graduation project for the Academy of Industrial Design Eindhoven. From November 1991 through May of 1992, I developed a leg prosthesis for Cambodian land mine casualties. The first several months were spent in the Netherlands learning the basics of development aid and prosthetics, followed by an educational tour to Cambodia.

As a result of the civil war Cambodia is heavily mined. There is a great need for leg prostheses. Western prostheses are not suitable for these patients; the situation is incomparable to Europe. Most prostheses available in Cambodia, however, are based on western principles. This study tries to find a solution from the Cambodian point of view. It is a study project and was not originally expected to be realized. Reactions, however, show that this could change. Therefore it is the intention to apply for a subsidy to develop this project further, so that it might be realized in the future.

I can never adequately thank the people who have helped me in the course of the past six months. Their support made the realization of this project possible. I owe great gratitude to the following persons: Mr. Ph. Vendeville, my graduation teacher. Without his vision and confidence in me I would never have begun the work. Mr. Ir J.M. van de Wiel, manager Westland orthopedie bv and Mr. L. de Groot, technical manger Westland orthopedie bv. It was through their supervision and stimulating advice that I was able to take on such a specialized project.

History Cambodia has been dominated by violence since the end of the sixties. Between 1974 and 1979 the country was oppressed by Pol Pot. His regime has had an unimaginably great influence on the standards of the Cambodian people. Only seven people survived the "Museum of Crime", the former center where the Khmer Rouge tortured their opponents. Nobody knows how many were murdered during those years.

Mrs. Brigitte Hogge and Mr. Abde Boueddhi, members of Handicap International. The entire organization received me very hospitably, giving me everything I could possibly use to study the situation in Cambodia. It was almost a holiday. Inne ten Have, Rotterdam, mei 1992

Consequence All major roads are destroyed. Cambodia has no infrastructure -- the consequence of the American bombings during the Vietnam war. Electricity is only available in certain parts of the capital a few hours a day; petrol is transported through the country by children on bicycles with jerrycans. It's still dangerous in the country; trains ride with two empty wagons in front, so that only the empty wagons are destroyed when the train hits a mine. Traveling on these wagons is for free; naturally these are loaded. The army sits in the back. Economy Economically the country has been broken apart systematically. There is not any form of infrastructure left; no foundations for development. The effects of the violence in Cambodia are obvious. Until the sixties it was a fertile country, economically based on rice and rubber cultivation and small scale craftsmanship, such as wood and metal work.

Prostheses This girl needs an above leg prosthesis; she has never had a prosthesis before. The prosthesist just made a new prosthesis for her, while her amputated leg hasn't healed long enough; the stump is soft and not able to stand the pressure. After one month she will be walking with her full weight on the small bone part already visible. One of the biggest prosthesis workshops of the International Red Cross was working for months without even one physio-therapist. All they did was fitting the prostheses on the patient.

There is hope to return to that old level again. After opening the borders a lively trade has been developed in foreign goods. Western products especially are very popular. Besides foreign products also relief workers and UN soldiers are floodingthe country, with the obvious consequences: A Cambodian craftsman earns a few dollars a month, a UN soldier on the contrary, about $100 a day. So begging often earns much more than having a job. Corruption thrivesand legislation doesn't seem to exist. As in the years before Pol Pot, there are enormous discrepancies between rich and poor Cambodians. Thingsare pretty bad in Cambodia. Aid Since 1979 the Khmer Rouge has been laying mines in Cambodia; about several millions by now. In the wet seasons the small plastic mines float throughout the country. Monthly there are between 200 and 600 casualties; the victims generally lose lower legs. A patient needs a good prosthesis during his whole life, and the lifetime of a leg prosthesis has been estimated at two years. The demand for leg prostheses will only increase for the foreseeable future. Non-Governmental Organizations (NGOs) try to tackle this problem by handing out as many prostheses as possible. It is difficult to involve the population in this process; there is no knowledge to build on, so it remains a western matter. The leg prostheses have often been made of cheap plastics. The advantages of plastic over prostheses made of leather and metal, are the short production time, the durability and the modern image of the material. Next to this there are the interests of western companies. For instance, there is an organization called "Cambodia Trust". This organization sends second choice leg prostheses from England to Cambodia and hands them out to the people in the capital. The problem is not dealt with seriously; people are led purely by short-term interests. Some organizations try more. Handicap International is an organization which produces leg from materials available in Cambodia. The prostheses are made in a simple way, in about ten workshops spread over the country. They are one of the few organizations trying to adapt to the situation in Cambodia. Despite this appropriate technology the result has a number of disadvantages. It still is no more than a translation in material; the patient still stays heavily dependent on the both the prosthesist, and the foreign funds.

The people involved only think in terms of existing solutions; the Cambodian context is a peripheral consideration. Because of the Pol Pot regime, the people of Cambodia are without knowledge; all the educated people were killed or fled. The survivors learned never to trust another. Their own interest is their only concern. It is not useful to import a western idea in this country. Aid workers give away prostheses for free while soldiers demand money from patients who want to reach the prosthesist workshops. The next day these patients take the prosthesis apart and sell the parts on the market. After all, the material is worth a lot and the prosthesis doesn't fit anyway. The joke of it all is: Everyone is pleased!

Quality

Conclusion

The quality of the prosthesis is mainly in the fit. To increase the durability of the fit, the stump socket is made of relatively hard material. "Once good, always good". A skilled prosthesist can make a good socket: Special areas of the leg can be burdened with pressure, others can't.

We need a totally different kind of prosthesis for Cambodia. The patient must be able to help himself because there are so few prosthesis workshops. The value of the prosthesis should not be in the material. The patient does not have the money to buy, and is too tempted to sell.

It demands a skill and precision which are lacking in Cambodia. Besides, the form of the stump can change over time. It is almost impossible for the patient to adapt the prosthesis to the changing circumstances. The present prostheses are short-term provisions instead of structurally adjustable solutions. The person involved can not master his own prosthesis.

A lot of children in the third world die because of diarrhea. A doctor came up with a medicine in the form of a children's song:

The problem is clear when broken prostheses are taken as a starting point: Then the lack of quality reveals itself.

If you suffer diarrhea, drink sugar and salt, dissolved in water. This song has probably saved more people than any program. Patients have to be able to stand on their own legs.

Leg prostheses last in the west for about two years. In Cambodia some have to stay in use longer; the patient with the prosthesis in the photo was walking with his full weight on this metal edge.

Design for a New Prosthesis

Pressure bearing areas

Analysis

The present development in prosthetics for leg prostheses looks for the largest possible bearing surface on the leg stump, to make the local pressure as small as possible. In Cambodia this is not sensible as this threatens to make the prosthesis difficult for the patient to understand: One has to look for a balance between a small area simple to be indicated and a large comfortable area. The preferred area is the knee: The knee can be well loaded with pressure, the knee is often still healthy, knees look a lot alike and remain of the same form.

The crux of the whole matter is that the prosthesis workshops are very difficult to reach; as a rule patients pay only one visit to the workshop. The durability of the prosthesis is therefore essential. The present prostheses are short-term provisions instead of structurally adjustable solutions. The person involved can't master his own prosthesis. The problem is clear when broken prostheses are taken as a starting point: Then the lack of quality reveals itself. Concept The durability of the prosthesis should not be found in the material but in the patient. The patient has to become a prosthesist: Seeing that the whole problem can never be mastered, the prosthesis has to be restricted to key subjects. It is the intention to make up principles, which show the direction in which the safest or best solution can be found, not to give a prompt solution. "Make it their problem."

Left: Good pressure bearing surfaces. The patella tendon of the healthy upper leg muscle can become well trained The muscles in the leg are easily trained too. Right: Bad pressure bearing surfaces. Bone will get irritated and hurt. The soft parts aren't fit for pressure.

Spiral

Manufacture of the New Prosthesis

The patella tendon is a familiar pressure bearing area in below-the-knee prostheses, but too small as a sole pressure bearing point. It takes a lot of pressure to fix the prosthesis on it. It is unacceptable to run the risk of slipping out of the brace.

The prosthesis is very simple to make: A metal strip 0.1 by 5 by 100 cm is put lengthwise against the inner side of the lower part of the amputated leg. Below the knee the strip is folded at an angle of 40° forward, then around the knee. At the outer side of the knee again straight downwards.

By enlarging the surface of the brace, bad pressure bearing areas can also be loaded. The crest of the tibia (shin-bone) and the head of the fibula (splint-bone). The solution lies in spirally winding a metal strip around the knee, from the inner side upwards to the outer side. The metal strip only covers good pressure bearing areas. The knee sides are relatively flat; no more than a piece of cloth is needed for a good fit. A string or strap keeps the whole thing in place.

The improvement of prostheses is based on experience in practice. Innovation starts in the workshop, not behind the desk. The patients' comments make new ideas a success or not. Evolution instead of revolution. For the new design all pressure was put on the knee; therefore also the prosthesists could wear this prosthesis. This turned out to be of great value. All the support is given by this brace; the ends form the two front sides of the three sided lower leg. To keep the stump extremity in position a second strip at the back is needed. With two strings or small straps the prosthesis is practically ready.

The foot

Result

The design is based on a existing foot prosthesis. A realistic foot is not the first thing required; in Cambodia one can always get hold of a closed shoe and shoes normally stay attached to the prosthesis (In a temple people will take off their prosthesis). By explaining the parts of the foot, the patient gets an insightinto the structure of the prosthesis.

Advantages: • The patient becomes the prosthesist, and thus independent; • It is a safe standard product; • The prosthesis is light; it will not fall off the leg, but grips around the knee; • The prosthesis is very cheap and can be produced in ashort time; • It is made of local materials and local technology; • Repair and adjustment is possible without coaching.

The foot is assembled from four elements: 1. an inflexible metal plate provides stability; 2. a rubber layer provides flexibility; 3. a shoe makes the foot look better; 4. a screw through the shoe, plate and rubber into the wooden lower leg part determines the turning point and the elasticity of the foot.

This approach results in a good foot prosthesis with a very long lifetime.

There is one disadvantage: • The patient can not 'show off' with this home-made and cheap looking prosthesis.

Discussion The aim was to make the patient independent of the prosthesist. It is required of the patient to control his own prosthesis; this is beyond the task of the prosthesist. In order to offer help as structured as possible the starting point is to offer principles, like the rules of a game. The fewer the rules, the clearer the game. The temptation to complete the prosthesis here and now must be resisted: That is the patient's problem. The self-made prosthesis is better than a foreign one. The patient understands what he has done and can readjust the prosthesis as needed: Where it hurts, lower the pressure. Inne ten Have, May 1992 -- [email protected]