Prosthesis

Aditya Verma

Table of ContentsIntroduction2History of prosthesis3The Dark Ages (480 to 1000)3Early 1500s3Late 1500s4Engineering involved and their contribution4Technologies and Materials5Materials5Aluminium5Thermoplastics6Silicone7Technology8Ethical issues and impact on peoples lives9Conclusion10Bibliography10

Introduction Bioengineering applies areas of mathematics and engineering to replace, enhance and repair biological systems which work to improve the lives of people. It is one of the newest areas of study and one of the fastest growing areas in research and development. Bioengineers need to be able to work with other professionals, particularly in the medical field, so that they can work together to develop a product that will suit a purpose perfectly with immense detail. These developments rely on engineering principles such as material properties along with biological processes. New products currently being developed include:1. new drug delivery systems1. synthetic blood1. utilising 3D printing and printing body parts1. injectable, biodegradable cement to heal bone fractures1. retractable syringes to prevent needle stick injuries and the reuse of needles

Prosthesis is an artificial device extension that replaces a missing body part. Common devices include artificial arms, legs, eyes, hips and hands. This development has been used since Egyptian times, and recently new technology and materials have allowed people with missing limbs or body parts to live relatively normal lives. New technology has excelled in the biological industry making it relatively easy to obtain prosthesis. This has been a major breakthrough in modern times, as people surviving car crashes or returning from war can still take part in normal activities such as walking and picking objects up, shown in the picture on the above. Prosthesis fits into the wider area of bioengineering as it replaces body parts using mathematics and engineering concepts, which are used in the designing and production of the prosthetic limb or objects.

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As the rate of demand for prosthesis research and development contributing to bioengineering is increasing with each coming year, examples of an increasing contribution to this field is universities offering more courses regarding bioengineering, for example university of New South Wales bioengineering course. The universities which offer the course also allow specialising in certain fields allowing more in depth research into bioengineering.

History of prosthesisThe first observation in history of any form of prosthesis is back to the Egyptian times (2700-2625 B.C.) where archaeologists discovered the oldest known splint from that period. The earliest recorded written evidence is of an artificial limb which was made roughly 300 B.C. by Herodotus who wrote about a prisoner who escaped from prison by cutting his foot off which was held by chains and then later replacing it with a wooden substitute. This was the first evidence of an artificial limb in history.The Dark Ages (480 to 1000)The dark ages did not consist of very much advancement in prosthesis, record show prosthetic hand hooks and peg leg were found in this time. These prosthetic limbs would be needed for knights as an example who lost body parts during battle. Early 1500sIt wasnt until this era when a German mercenary by the name of Gotz von Berlichingen had a pair of technological advanced iron hands made after he lost his right arm in battle. The hands were able to move by relaxing a series of releases and springs while being suspended with a leather strap. Again this prosthesis was required due to battle injuries.image 2

The first injury outside the battle field was recorded in 1529 by a French surgeon named Ambroise Pare. Pare was able to use prosthesis for life saving operations in medicine to the wounded. After realizing its potential he began producing prosthetic limbs in a scientific matter using materials ranging from wood, steel and iron.Late 1500sin 1696 Peter Veruyn designed and developed the first non-locking below knee prosthesis which later became the first blue print for current day joints and corset devices.In 1863, Dubois Parmlee invented a suction socket polycentric knee and multi-articulate foot which was a big step forward for bioengineering nearing as the comfort was greatly increased making everyday life easier. In 1946, a major advancement was made in the attachment of the limbs. A suction sock for the above-knee prosthesis was created.The final big change in prosthesis was by Marcel Desoutter who set the standards of prosthesis in the 21st century with his creation of the aluminium artificial limb. Up till now people are still using this design to make prosthetic limbs.Engineering involved and their contribution There are several different classes of engineers whom are involved in the research and production of prosthesis. Prosthetics come from the minds of biomedical engineers. They start their projects by consulting with various professionals in fields which build up the engineering aspect of prosthetics, these fields are primarily composed of the medical field put are greatly influenced by the situation of the patient and the decisions the patient makes. The process beings by designing the parts on computer (CAD) and proposing it to the patient as well as the doctor to see if it fits the safety and necessary criteria. From there the design is produced to immense detail, from there several rounds of testing and modifications may be necessary before the final prosthetic limb is produced.

The engineers involved may vary from the situation and limb required, these include: electrical engineering medical engineering biological engineering mechanical engineering robotic engineeringTechnologies and Materials Materials The strength of a material refers to the ability to withstand applied stress without failure. As many components are used in a prosthetic limb, and they all rely on each other, each component's material must be able to withstand the force put on it by its use. Otherwise, the component may break down and cause the rest of the prosthetic to malfunction. Aluminium, a material widely used in prosthesis, is quite hard compared to its weight, which needs to be light to decrease the discomfort of the patient. Material strength is a very important factor in all areas of engineering, including bioengineering and other such as braking system and household appliances.Aluminium Aluminium is a light weight material, 2.7g/cm^3 specifically, and is used as an alternative to steel which is 3 times heavier, making it easier on the patient. The light weight is caused by the crystal structure of hoe closely bunched the atoms are. Aluminium still has the physical, chemical and mechanical properties of metals however it is quite malleable due to its polycrystalline structure. Polycrystalline materials are composed of crystallites which are held closely together through work. Certain artificial knees are fabricated of aluminium taking advantage of its light weight characteristics. Thermoplastics Image 7

Thermoplastics are used in prosthesis for prosthetic designs as well as structural components available in various thickness and colours. The bonds between molecules in thermoplastics are made up of lines of a few cross linkages. This allows them to be softened when heated and moulded into different shapes and unrestricting the possibilities. Once they are cooled they become solid again. This way they can be re-melted and remoulded by applying heat in the area to be re-constructed. This process can be repeated many times. This replaces other plastics such as thermosetting polymers or Plastic Polymer Laminates.Although these two plastics have advantages such as strength and stiffness, they are both difficult and costly to remould after the original shape is formed. The most basic types of plastics thermoplastics are polypropylene and polyethylene. These materials can be formed very stiff or very flexible depending on the use. This can be a great advantage when an annoyance occurs in or around the socket of a prosthetic structure because it can be reshaped and refitted on the patient. An example of a thermoplastic in prosthesis is Co-Polymer. The stiff thermoplastics are usually involved in the support factor of artificial legs. To decide where the thermoplastic is to be used, the patient must be taken into consideration. The prosthetic must offer comfort, strength for each individual because not one prosthetic development fits all people.Image 3

Silicone Silicones have a number of medical applications because are heat resistant, water resistant and chemically stable. In prosthesis silicone is crafted as a padding material in sockets. It can be made either very soft or firm depending on the intended use. For example, when using a soft silicone, the silicon is used as a type of suspension. This way, attaching a prosthetic limb to the skin will cause less irritation, due to the potential friction. Other materials such as Perlite can also be used in this application; however silicone is the most common because of its low expense and amazing qualities to resist most chemical reactions and its ability to be shaped as a result of its unique structure.image 4

Recently development in prosthesis materials have been through the use of carbon fibre to form a lightweight pylon. The carbon fibre is strong and reduced discomfort experienced by the patient from the light weight.The physical appearance is a factor which is considered for the security of the patient. Appearance is important with prosthetic limbs, the majority of prosthetic limbs are covered with a soft polyurethane foam cover to match the shape of a normal limb. This is then covered with artificial skin, usually made from pigmented plastic to make the limb look realistic. image 5

Technology image 6Technology in the development of prosthesis have improved over time. The technologies which are implemented are primarily consisted of different lever systems and the production of the prosthesis. Companies such as Hutnick Rehab are suppliers and developers of sensor technologies to give prosthetic limbs a sense. Current computer aided programs are making the process of developing a well fit prosthetic limb for patients much easier, CAD also provides very detailed designs that fits the patients body.Robotics has also advanced in prosthesis by engineering. Robotic arms and legs are now something we thought would only exist in a Sci-Fi film, but due to the advance in technology and engineering it is now that we can design prosthetic limbs which are controlled using the neurons from the brain. A myoelectric prosthesis uses electromyography signals or potentials from voluntarily contracted muscles in a users residual limb, this is used to control the movement of the prosthesis such as elbow flexing and closing of fingers. A prosthesis like this makes use of the neuro muscular system of the human body to control the prosthetic hand for example. This technology is still being enhanced but is still available.As technology advances the prosthetic limbs become easier to manage and lighter, the effort needed would be minimal giving the user much more freedom as if they had their body parts.Ethical issues and impact on peoples livesThere are many ethical and impacts on peoples lives that arise in the study and practice of bioengineering, especially concerning prosthesis. These issues include everyday life at home, in the working class world as a result impacting the values and beliefs of citizens. However there are positives aspects for peoples lives due to the introduction of prosthetic limbs for many people suffering from amputation or loss of body parts.Losing an important body part, such as an arm or leg, in most cases leads to a sort of disability. The outcome of being disabled may be people losing their jobs/sporting career, be diagnosed with depression or lose their sense of self belonging to the world. As a result of their quality and self-worth of their life is reduced. But with the introduction and advancement of technology from prosthetic research scientists are insuring amputees receive fare treatment among other individuals with artificial limbs, making sure they have the ability to accomplish day to day tasks to a certain extent. Of course people see the negative of this, stating they feel they will not be treated as fairly as they should. Image 8

People who have limbs replaced with prosthesis may encounter problems to the working world and still struggle to regain their normal place in the world. This is a discussion still argued on whether a person with artificial limbs should be allowed to work again such as sporting, military or other industries. The argument here is that people with prosthetic limbs would hold back the industry. But with recant advanced technology the opposite is happening, people with artificial limbs are able to excel more than the average person without an artificial limb, they are able to type twenty times as faster than normal humans with prosthetics hands, jump twice as high with prosthetic legs, and more. This advancement in technology and bioengineering has ethical issues as it gives specific categories of people a greater enhancement than others. Many dislike the idea that part of their body is a machine that natural even though it is better than nothing. There are also ethical issues regarding playing god and disturbing the natural outcome which are brought up by cultures which deny artificial limbs. But the benefits out way the positive greatly.Conclusion This report has explained what prosthesis and engineers contribution to it. We have found the materials properties and how we can use these in bioengineering for prosthesis.

Bibliography http://everydaylife.globalpost.com/engineer-designs-prosthetics-12210.html https://en.wikipedia.org/wiki/Prosthesis http://www.wired.co.uk/magazine/archive/2013/09/ideas-bank/now-we-need-to-talk-about-our-bionic-futurehttp://www.health.gov.au/internet/main/publishing.nsf/content/health-privatehealth-prostheseslist.htm http://www.amputee-coalition.org/inmotion/sep_oct_98/matinprs.html Image 1 http://www.designnews.com/document.asp?doc_id=245129image 2 http://io9.com/5951614/this-prosthetic-hand-was-made-for-a-16th-century-knightimage 3 http://www.nextstepbionicsandprosthetics.com/expertise-in-motion/bionics-and-prosthetics/products-and-technology.aspx image 4http://www.telegraph.co.uk/news/earth/wildlife/4966620/Mosha-the-elephant-gets-prosthetic-leg.html image 5http://www.scheckandsiress.com/pediatric-prosthetics.php image 6http://www.carbonfibergear.com/carbon-fiber-to-compete-in-2012-london-olympics/ image 7http://dismagazine.com/blog/29019/prosthetics-go-high-tech/ image 8http://www.gizmag.com/i-limb-ultra-revolution/27150/ note* all resources accessed on 17-09-2015

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