#249      36 min 37 sec
Tender connections: Fitting prosthetic limbs for comfort and cost

Mechanical engineer Peter Lee and prosthetist Jim Lavranos describe the challenges of creating low-cost prosthetic limb technologies in developing countries, and contrast this with how things are done in wealthier economies. Presented by Dr Shane Huntington.

"The socket is where the prosthetist comes into the action, because to make a socket you really have to customise it to the individual patient. And patient stumps then come with different shapes and sizes," -- Assoc Prof Peter Lee




Assoc Prof Peter Lee
Assoc Prof Peter Lee

Peter (Vee Sin) Lee is an Associate Professor and the Deputy Head of Department in the Department of Mechanical Engineering at The University of Melbourne. A/Prof Peter Lee obtained his BEng in Mechanical Engineering (1st Class Hons. 1991) and PhD (1996) in Bioengineering from the University of Strathclyde, UK, and continued his post-doc in the same university from 1996–1998. He was a Research Fellow with the Biomaterials Group at the Institute of Materials Research and Engineering, Singapore from 1998–2001. In 2001, he joined the Defence Medical and Environmental Research Institute, DSO National Laboratories, Singapore, as the Head of the Bioengineering Laboratory. He was appointed as an Adjunct Associate Professor from 2002–2008 at the National University of Singapore, Division of Bioengineering. He joined University of Melbourne as a Senior Lecturer in 2008, and was promoted to Associate Professor in 2011. A/Prof Lee is also a member  of the Engineering Ethics Advisory Group (EHEAG).

Publications

Jim Lavranos
Jim Lavranos

Jim Lavranos is a practicing clinician who manages a diverse patient case load requiring both prosthetic and orthotic intervention in the rehabilitation and definitive phases of management. Jim has extensive experience working in developing countries in a clinical, educational, research and administrative capacity. He has provided clinical and technical support, supervision and mentoring in Cambodia for VVAF (Vietnam Veterans of America Foundation) in their main Prosthetic and Orthotic facility and has provided similar services to Handicap International in remote locations in India. Jim has also been a key consultant and lecturer in the establishment of a Bachelor Degree in Prosthetics and Orthotics at Mahidol University in Bangkok, Thailand. All along he has assisted both humanitarian and non-government organizations in the evaluation and development of appropriate technology. Jim has an ongoing interest in research, having worked with Dr Lee, Dr Lythgo and Austin Health Physiotherapy staff including Helen Connor (Amputee/Orthopaedic) on the P-cast system, providing both clinical and technical feedback as well as input on direction and methodology. He has also shown a particular interest in partial foot prosthetics by working on functional prototypes and on silicon cosmetic designs with Dave Myers from the maxillofacial department, with the intention of pursuing testing in the near future.

Credits

Host: Dr Dyani Lewis
Producers: Eric van Bemmel, Kelvin Param, Dyani Lewis
Audio Engineers: Gavin Nebauer
Voiceover: Nerissa Hannink
Series Creators: Kelvin Param & Eric van Bemmel

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VOICEOVER 
Welcome to Up Close, the research talk show from the University of Melbourne, Australia. 

SHANE HUNTINGTON 
I'm Shane Huntington, thanks for joining us.  Most of us take the normal functioning of our limbs for granted and give them little thought in our day to day lives.  From our abilities to walk through the park or run for a bus, to threading a needle or playing the piano, our gross and fine motor skills allow us to physically fit in with the societies and built environments in which we live.  But due to accidents, disease, birth defects or other causes, a substantial number of people don't have normally functioning limbs and require prostheses to enable them to overcome physical limitations.  In countries living with ongoing conflict or even the aftermath of war or natural disasters, such needs can be enormous.  Demand can far outstrip the facilities and local know how to deliver prostheses to everyone in need.  The design and application of prostheses involves collaboration between many disciplines to optimise devices for specific patient needs. Today on Up Close we speak to two members of such a collaboration.  Peter Lee, Associate Professor of Mechanical Engineering at the University of Melbourne, and Jim Lavranos, Senior Clinician at the Orthotic and Prosthetic Unit of the Royal Children's Hospital in Melbourne.  Welcome to Up Close, Peter and Jim.

JIM LAVRANOS
Thank you.

PETER LEE
Thank you.

SHANE HUNTINGTON
Jim, I'd like to start with you.  You work down at the Royal Children's Hospital here in Melbourne.  What kind of conditions bring most of the patients to your clinic?

JIM LAVRANOS
Well the majority of our patients are congenital.  After that you're looking at traumatic patients and probably cancer patients.  So I think those three are probably the highest incidence.

SHANE HUNTINGTON
These are children of course?

JIM LAVRANOS
These are children ranging from obviously congenital, being when they first out, to 14, 15 when they end up with cancers of the bone and what not.

SHANE HUNTINGTON
Now what types of prostheses are there?  I mean legs and arms immediately spring to mind when we talk about this, but there must be a wider range of options for patients as well.  Can you talk us through some of the more unusual ones?

JIM LAVRANOS
Well I predominantly deal with limb prosthetics, which of course includes every level at the lower limb and every level of the upper limb. Other than that, the more obscure type of prosthetic devices tend to revolve around facial prosthetics, of course dental prosthetics, which we don't dabble in. That's an independent department on its own known as maxillofacial prosthetics.

SHANE HUNTINGTON
In terms of the limb prosthetics, I mean there must be a wide range of requirements there depending on the amount of the limb you're replacing.  Are they completely different depending on what part you're replacing?

JIM LAVRANOS
Every limb is unique and individual based on a number of factors.  Functional potential of the patient is number one.  Obviously amputation level is important because that dictates how many levels of mechanical articulation you require to replace the anatomical articulation that's gone missing.  So functional level is the primary concern and then of course there are the aesthetic and cosmetic concerns.  So based on an individual's needs we decide on what sort of ankle unit for example they require, what sort of knee unit they'll require, what sort of socket system they require in order to get them to function normally or as close to normal as possible.  Then also what sort of cosmetic cover, if they want one at all, is required for them to feel socially accepted, or at least in tune with what they consider their identity to be.

SHANE HUNTINGTON
Now we've seen some amazing results of a wide range of prostheses over the last few years, in particular the 2012 Olympics, you know we had one South African runner who used an artificial set of limbs, but competed with able bodied runners.  What are some of these big changes that are happening in terms of the technology that's available for people who are getting these prosthetic replacements?

JIM LAVRANOS
So I think one of the goals of research and development in prosthetics is to try to not only replicate range of motion which was what originally led to the design of prosthetic limbs.  So it wasn't just a matter of having an articulation that worked, it also had to do with ensuring that that articulation gave a sort of spring that the muscles would naturally give in your anatomy.  So I think one of the advances has been in storing and returning energy, as well as providing range of motion.  So when you're talking about these athletes who are using carbon feet, the idea behind the conception is to try to return as much energy as possible from the limb after it's loaded with weight and momentum and what not.  It's very controversial as to how much energy's actually returned by these things.  It's definitely not a positive output like your muscle can produce, but it will return anything up to 75 to 90 per cent of what you put into it, depending on the quality of the prosthesis.  So I wouldn't say it enhances human function as such, but it definitely gets close to it.

SHANE HUNTINGTON
Peter, if I turn to you now, we have to look at the other end of the spectrum where we don't have elite athletes with in some cases almost unlimited budgets to invest in these sorts of things.  You work in the area of developing countries where I can imagine a completely different suite of requirements and causes for amputation and the like.  Can you talk through some of those and how they differ from what we would see in a developed country?

PETER LEE
So in the developing country I think the problems are quite different when you compare to the needs and the function of the individual amputee, the immediate needs is to get person mobile so that you could sort out a lot of other issues like employment and work and making money.  That's the immediate need.  For that to happen a basic limb with durable components, able to restore the individual function, that's the main aim of the standard prostheses.

SHANE HUNTINGTON
In these areas, the prosthetist who fits and guides the patient through this process, I can't imagine there would be a large supply of such clinicians available to assist with patients in developing countries.  Is that a significant limitation?

PETER LEE
Yes, so the skills of the prosthetists is the biggest problem at the moment, because in a lot of these countries, some of which you still get conflict happening, so sending people from places like Australia, United States into these places is quite dangerous.  The other thing is to train a prosthetist is primarily a three to four year training with a lot of clinical exposure, to be able to get the individual up to the skills able to make good artificial limbs.  So in [a] situation like this, it's not so much the components, because the components can be donated, can be provided through various means, but it's the people that are making the artificial limbs, that's where the clear lack is.

SHANE HUNTINGTON
Jim, let us focus for a moment on artificial legs.  Can you talk us through the process of a person going from coming into your clinic to actually being fitted with a prosthetic?

JIM LAVRANOS
So I think traditional procedure involves seeing the patient, discussing functional potential, functional needs and aesthetic requirements, then moving onto the processes of assessment and plaster casting, which is the initial clinical consultation. After that it moves to the technical realm where the casts are filled with dental plaster, made into positive models, and then you build whatever it is out of whatever material you want over the top of that positive model and assemble essentially the prosthetic from the components that you've ordered in from suppliers and distributors and whoever is out there designing and creating them.These days however there is I think an ever increasing movement towards CAD/CAM and scanning where they're completely eliminating the plaster process from the procedure and you're scanning and ending up with a 3D digital image, which you then modify on screen, which then gets carved out of a polyurethane block in a carver, or in the near future possibly just prints out a 3D socket.  So there is a movement towards that.  I think there is a lot of apprehension within the profession because a lot of the prosthetists do consider themselves artists and think they need to get their hands dirty in order for things to work.  So there's a culture shift and a paradigm shift that's on its way I would say.

SHANE HUNTINGTON
Let's talk about that for a moment, the issue of the sort of artist in the field.  Are there scenarios where you think you've fitted a leg for example appropriately to a person, but then comfort and other issues just sort of say, no, that's not right, even though you've pretty much designed it specifically for them. Does that come up?

JIM LAVRANOS
Yes there are many times where you've followed the rules and tried to I think accommodate the needs of an amputee's physiognomy, as well as their psychological state and found that it's a complete failure.  There is a large part of what you do in prosthetic management which involves subjective input from the patient.  So unless the patient is satisfied then essentially you have failed, which means a lot of fundamental principles need to be bent in order to achieve those goals.

SHANE HUNTINGTON
Now when we have a scenario where as you say many of your patients are coming in with cancer related amputations, how much does the need for the prosthetic drive the way in which the surgery of the amputation is done?  Can you optimise the surgery so that they are better able to use a prosthetic down the track?

JIM LAVRANOS
I think that over the past decade surgeons have opened up to consulting and discussing amputation levels with prosthetists.  Prior to that we all know what surgeons are like.  They tend to have a particular understanding of biomechanics that they think is ideal, but not always the case when it comes to fitting a prosthesis.  So yes, ideally it would be great if surgeons did discuss the options, because the surgery does play a huge role in optimising socket fit and optimising prosthetic function, because a lot of surgery, especially with the osteosarcomas, do get complex.  I think some of the surgeons are doing extremely cutting edge surgery in order to try to create a limb which is going to be prosthetically viable, but you do need that collaboration between the two professions in order to end up with an ideal outcome.

SHANE HUNTINGTON
I'm Shane Huntington and you're listening to Up Close.  In this episode we're talking about prostheses with mechanical engineer Peter Lee and prosthetist Jim Lavranos.   Peter, it sounds to me like outside of the pristine environment of the hospital surgical suites to where some of your focus is in the field, this issue of optimising the limb for later replacement when the limb is removed is something that would probably not be in the minds of many of those trauma surgeons that are dealing in war torn or natural disaster areas, is that true?

PETER LEE
Definitely, because a lot of the limbs that are presented to the prosthetist in developing nations are due to landmine incidents or now this is primarily more traffic accidents.  There's still quite a lot the surgeon can do to repair the limb, to make it very suitable for prosthetics to fit them. But you can imagine the limitations that's being presented because in the landmine accident the leg's taken off not in ideal places or situation.  You get either too short a stump or sometimes even too long a stump that could give problems with prosthetic fitting.I guess to backtrack a bit, if you look at the entire prosthetic leg there are several components, so if we are talking about amputation below the knee you'll need a socket and the socket gets connected to a pylon and then to the prosthetic foot.  So the pylon, the prosthetic foot, these are standard components that are being made. So it's almost like buying a shoe and picking the right sizes.  But the socket is what we've been talking about where the prosthetist comes into the action, because to make a socket you really have to customise it to the individual patient and patient stumps then come with different shape[s] and sizes, different surgical environment can give different challenges to the prosthetist.  So that is the part that we are primarily interested in, because we see that as the major obstacle in providing good fitting socket in developing nations.

SHANE HUNTINGTON
Can you give us an idea of what the issue is with the historical version of these sockets, before we move on to what you're specifically looking at, and why that is not ideal for these replacements?

PETER LEE
So a lot of the socket development, the biomechanics part of it started really after the Second World War.  In the `50s and the `60s the United States researchers developed very concise methodology to make a socket based on biomechanical principles.  So these biomechanical principles are primarily developed based on where load can be transferred to the stump or to the residual limb.  At different part[s] of our limb you can imagine some parts can take load, some parts are very sensitive to load.  So what the socket tries to do is to move the load that is transferred from the ground during walking to the relevant part of the stump.  And in this environment several types of sockets then later develop, the most common one is the patellar tendon bearing type socket, where you try to put a lot of load at the patellar tendon where you know it's fairly tolerant to load, and then at some other places like the distal end or the fibular head, this is some anatomical jargon, but these are the places where you want load being taken off.Now so patellar tendon bearing socket has been used for many years, even up to today has been taught in prosthetic schools, but over the years there are different developments coming out.  One effort is trying to distribute a pressure of the load over the entire stump using new materials like silicon, where you've got [a] soft interface.  So these are some of the development that leads to what we call the total surface bearing type sockets.

SHANE HUNTINGTON
Peter, with regards to load, can you give us an idea of what the normal load should be for someone with a prosthetic and how you measure that, what it would feel like to us if we were, for example, feeling that load on a normal limb?

PETER LEE
So if you have a normal leg it's going to be difficult to imagine how load is being transferred to the amputee stump.  So if you imagine the moment your heel touches the ground at the heel strike, so you're going to get what we call a ground reaction force that's acting in front of the knee.  So you will create a moment at the interface between the stump and the socket and also forces in all different directions.  That is the load that we are particularly interested in, because that load gets distributed in the entire stump and transferred over the bony locations in the stump, and through the bony locations then they transfer to the entire body and that's how the stump takes that load.

SHANE HUNTINGTON
When we say load we effectively mean a force on the stump don't we?

PETER LEE
Yes, yes.

SHANE HUNTINGTON
This is essentially a force that is being applied by whatever surface we're interacting with that then is transferred to the body?

PETER LEE
Yeah, yes.  Whether it's standing, even jumping, walking, running, that force is being transferred from the entire prosthesis, so from the foot, the artificial components, to the pylon, to the socket, which are all artificial and when it hits the stump that's when your anatomical structure's got to take over.

SHANE HUNTINGTON
The region over which this force, this load is distributed, is it a smaller part of our remaining leg compared to what we would feel if we had a full limb?

PETER LEE
So the load has been transferred to the stump is highly complex, because it gets transferred from the skin to the fatty tissues to the bone.  This is where you can craft a socket to direct this load.  This is where the whole concept of making the stump socket fit is all about, you know how do you transfer this load from the environment to the entire body?  The other thing you have to bear in mind the stump is not built to take load.  The stump is there because [of an] unfortunate situation that one requires an amputation, and like our foot structure has evolved to take load.  So what we are trying to do is to make the stump take load with the help of a good designed socket.

SHANE HUNTINGTON
If I was to calculate how far I could drop you in height before your leg actually broke I'd be doing that calculation based on your bone density and your bone strength.  But you're talking about a situation here where the bone is the last thing to get involved.  This seems very different and presumably it's something where the actual strength or the ability of a person to take a force or an impact is substantially reduced.  Is that correct?

PETER LEE
Yes.  Because the stump of course over the years starts to accommodate and to a structure that take load.  This is where your socket, however you design it, will eventually get the stump engaged and changes over the years to be able to take load.  But you're absolutely right, because here if you look at your feet there's not a lot of fatty tissues there.  You've got your fat pads, and these are shock absorbers, but you also get very tough skin.  But in a stump you're not going to get this.  For example, in an above knee amputee you need a femur sitting inside a bulk tissues which is highly mobile, it's almost like a stake in the fluid bag.  Yeah, so you can imagine if you apply load on the bag you'll just get moved around.  So you have to find mechanisms to be able to lock the femur from moving too much, and therefore create an environment to be able to transfer whatever load is being given to the stump to be taken up by the entire body.

SHANE HUNTINGTON
I suspect most people when they think of the difficulties in a prosthetic leg, they're thinking more of the joints and the movement of the joints around the heel, the knee if it's above the knee line.  The socket isn't something that normally would come to mind, but when you describe these issues around load I can only think that depending on the activity where that load is borne by the stump would be different.  How do you accommodate for that changing load parameter depending on what the person is doing at the time, whether they're sitting or standing or kneeling?  All these factors must affect that.

PETER LEE
Yes.  So this is where the whole entire field of stump socket interface comes about, because you can imagine the load that an amputee experiences is very dynamic.  So from walking to running to even just standing.  So the socket at the moment is currently non-dynamic.  So you get a hard socket, you fit it onto the stump, so the only thing that's changing is the stump and you know your loading environment.  So you can imagine that there's a lot of mismatch between the socket and the stump.  So people have used soft material to try and minimise this mismatch, but more and more we think that a good socket design can actually handle a majority of this mismatch depending on the type of environment the individual is going.  And one of which is to try to get as even a pressure distribution over the entire stump.

SHANE HUNTINGTON
Peter, you and Jim have been working on a new system for socket design, a new way of going about this.  Tell us about how this is different from the existing versions you've discussed?

PETER LEE
Right, to say that it's an entire new system is not entirely true, because in the `60s a surgeon by the name of Murdoch decided to look into trying to make socket fitting more consistent.  One of the issue is this patellar tendon bar the indentation on that section of the socket has raised some inconsistency from prosthetist to prosthetist.  Then also the entire casting process can be different.  For example, prosthetists can take a cast today and take a cast tomorrow, the two casts can be different depending a lot on the skills of the prosthetist.  So he then decided to say can we do something about this? He developed a tank, the tank basically gets filled up with water and separating the amputee's stump and the water is a plastic diaphragm, and from which your apply pressure.  After which he tried to capture that shape and use that shape to reduce the amount of inconsistency from prosthetist to prosthetist.  Eventually he will then use a lot of the other traditional methods in making the socket, to complete the shape of the socket.  This whole idea of casting under pressure has evolved over the years, and what we've done is we took a more drastic step.  We used a similar technique and produced a socket shape and attempt not to make any changes to the socket shape.  So in other words there's no skills input into the entire process, and then use this socket shape and fit in on the amputee and see if it works.  If it doesn't work, why?  If it works, why?  So that's been the primary background of the research.

SHANE HUNTINGTON
How long does it take to make a socket using this particular pressure based system?

PETER LEE
Really fast.  So to reiterate the whole process.  What you do is you're presented with a patient, you take a plaster cast and then before the plaster cast sets you ask the patient to put his stump into the tank and then you just let water in.  So this water, you just connect the pipes to the normal water mains.  There's enough pressure.  Once the water starts filling up, the stump's kept dry because you have a plastic diaphragm in between, and you start to see the stump and the amputee being pushed up and out of the tank.  That's when you turn off the tap and then you actually could release the water and try to get the amputee standing.So in order to make sure that the amputee is not cheating, is actually putting weight on the tank, we place a sort of a bathroom scale on the good leg and make sure that only half his body weight is on that good leg.  So that the whole uniqueness of this pressure casting is we are casting with the patient underweight bearing condition, and once the cast is set, hardened, we release the water, take the stump out, remove the plaster cast and reproduce exactly the shape of the plaster cast as the socket.The whole casting process takes about five minutes.  After which we go back to make the socket in the traditional manner.  Yeah, so it can be really fast.  Much faster than the traditional casting methods.

SHANE HUNTINGTON
I'm Shane Huntington and my guests today are prosthetist Jim Lavranos and mechanical engineer, Peter Lee.  We're talking about improving people's access to artificial limbs in developing countries here on Up Close.  Peter, when you take this new version of things, the pressure casting, into the field how easy is it for a novice to use, someone who doesn't have this three to four years of training that you referred to earlier?

PETER LEE
This is really the key question, because of how easy is it to use in a developing country setting?  All these years that most of the research has been done in very high tech research lab[s], with motion capture system, pressure measurement systems, but the field testing has not really been carried out using the pressure cast system until in 2010 we've got a project funded by the CASS Foundation and the Rotary Club in Richmond, they funded a trial, one and a half year clinical trial in VIETCOT which is the Vietnamese Centre for Orthopaedic Technologies in Hanoi.  So in that trial, we just completed it about six months ago, allow us to test the whole pressure cast system under field condition with people who are not as highly trained as clinicians here.  So in that environment we could see for sure how easy the take up rate is, how successful can the systems like this be [unclear].

SHANE HUNTINGTON
One of the real questions here would be how the pressure felt by the person's remaining part of their limb actually compares in these PCAST systems to traditional socket.  You have measurements on this.  How does that look?  Is it way off, is it telling us that they shouldn't feel comfort here or are they reasonable given the difficult circumstances these people are finding themselves in?

PETER LEE
Well during the trial that we did in VIETCOT in Hanoi, the process is we fitted the participants and we asked participants to take the limb and use it for a period of four months.  Following that four months period we'll come back and we'll do a couple of measurements, biomechanical measurements where we look at how well the person's walking, by taking all the temperate distance measurements, like for example stride length, step length and there's also physiological type measurements where we ask subjects to walk as fast as they can over a certain period for six minutes and then track how was the distance that they have undertaken.  Then also what we call satisfaction survey.  So with all these three components we put them together and then we determine if the individual is performing as well as their old sockets or even as well as people who are in the norm of say for example an amputee of this age and of this type.  So with the 53 participants, 14 of them fail due to minimal usage, and eight of them was lost to follow up.  So we have about 31 recorded success.  Now this is about 70 per cent successful first time fit sockets, so these are the first socket that the patients receive and they walk away and they say that it's fine.  So a 70 per cent success is almost the same as the developed country in cases. So with these figures give us a lot of confidence to move ahead and say that, now, if we are able to produce fairly standard protocol and simple protocol to make the socket better, now we introduce rectification process.  We are making the person that's making the socket sort of an artisan, but not a high level artisan.  So can we actually improve the successful fit?Now of course in the process we also take the stump socket interface pressures using pressure sensors that we can insert in between the stump and the socket.  Now interestingly all this data are just coming out, we're starting to see that a lot of the pressure distribution are not much different from socket that is made by a trained prosthetist.  There's still a lot to understand how the PCAST actually work, now that we know it works, so making it work better could be exciting for us.

SHANE HUNTINGTON
Now Peter, you're a mechanical engineer but you must interact with chemical engineers and the like as well, and you have all this data coming in from the sensors and various things.  Is there not an option down the track, and certainly this wouldn't be an option in the developing world, but in general to make these prosthetic limbs more real time adjustable to need.  Is this something that's being considered?

PETER LEE
Yes, I think the whole concept of an adaptive socket is exciting. The whole advancement in lower limb prosthetics has been triggered by advancement in materials.  In fact a lot of which are aerospace materials. And even sensors, you know miniaturised sensors, computer controlled limbs, I think there are a lot of potential.  So this is where it gets very exciting because we have a low cost technique, but I think it's a low cost technique that could help us understand socket fitting better, that allow us to make it high tech as well.  For example, introducing new materials, new sensors to the socket, we now have a methodology.  The next question is how do you want to take this further?  I think there are two routes.  One is using it for developing nations, but the other one is using it as a platform for research to further understand how load is being transferred from the socket to the stump.

SHANE HUNTINGTON
Jim, back to you.  With regards to children of course, they're growing very rapidly.  How often do you have them back in your clinic to have their artificial limbs replaced or extended or changed to fit in with that growth?   I could imagine some kids this would almost be every few months.

JIM LAVRANOS
Absolutely.  Changing the length of prostheses and also foot sizes probably happens throughout their entire childhood and adolescent years.  In terms of socket fit, which is of primary concern and what needs to be changed in order to optimise the function, we are probably looking at making a new socket every six months to a year, depending on how fast a child grows or when they break it, because they do.  Kids are very adventurous.  So they tend to destroy things quite quickly.So yeah, probably within the year sockets need to be replaced, but throughout that year there are constant adjustments and constant modifications to the overall prosthetic dimensions.

SHANE HUNTINGTON
I could imagine with the kids you work with, you get pretty honest feedback with regards to comfort.  What are the limitations?  If you have a good socket fit, are there still limitations in terms of the extent to which a person can wear the artificial limb for a day?  Is there just a physical limitation in their bodies that says we just can't tolerate this for more than six hours or something like that?

JIM LAVRANOS
Every child, every individual is different when it comes to tolerance level of using a prosthetic limb.  We understand and encourage them to go for full time use, which is very acceptable and happens throughout the adult years, patients are using the limbs for 14 to 16 hours a day.  Kids do the same.  As soon as they find that it's their only channel to mobility then they tend to tolerate a lot if it's an ill-fitting socket, if not great.  They adapt very well.  It doesn't take much for them to adapt to a difference in a socket fit when you've changed them after the first year, second year, third year, tenth year.  There are also no limitations across activities.  Kids will do everything from walking to running to crawling to jumping to wading through water to attempting to swim with a buoyant device.I think the limitations are really a part of how they're brought up, what sort of input stimulus they receive from their parents, as well as the clinician.

SHANE HUNTINGTON
Jim, with all these advancements that people were hearing about as well, you read the news about people moving computer aspects with their mind, all these sorts of things.  I mean are the expectations of parents and families coming into your clinic changing accordingly and hoping for something more than the traditional prosthetic limb?

JIM LAVRANOS
So expectations are always changing and parents obviously have access to the web and all those resources and information that really make everything, all the R and D, as well as everything that's already existed out there accessible.  I think in terms of prosthetic devices moving forward, as Peter did mention a lot of the systems are still based on a programmed algorithm, rather than in absolute control by the patient themselves.  Obviously what patients are really looking for, what amputees are constantly looking for is neural interaction, something that they're able to control intuitively, rather than having to learn the functioning of the component and then turn that into a secondary ability.So I think that's one thing that they're always after.  The other which is lacking and which will be probably be lacking for a very long time to come is sensory feedback.  Prostheses don't offer sensory feedback.  Hands don't have feeling, feet don't feel impact.  You feel it through your stump.  So that is something we're also looking forward to, and I think with regards to socket design, I think the big call card is eliminating the socket completely, using processes like an osteo-integration where they put a big rod into your femur or your radius or whatever and then it sticks out of the skin and the you just click your prosthesis onto it and avoid the whole complexity of material surrounding a stump and trying to apply forces to the bone through soft tissue and muscle.  So that is what they come in questioning about, and a lot of it isn't on offer, and even if it is it's very expensive and highly experimental.  So it'll probably be a few years before we're able to move in that direction.

SHANE HUNTINGTON
Jim, can you speak a bit too the costs of this process.  You mentioned the idea of a child having a refit every six to 12 months.  I could imagine there are also a range of different standards of prosthetics available.  What sort of costs are we talking about here and is it something that will really be limited in terms of what you get by the amount of money you can spend on it?

JIM LAVRANOS
So at a baseline level where the components are fairly simple and you're making a fairly straight forward socket, then a prosthesis can cost, well, below knee prosthesis up to about $3000 and above knee prosthesis $6000 to $7000.  Outside of the base line of course you can go for your high specification components, which of course cost a lot more.  You can spend $5000 on just a foot if you really wanted to.  A lot of the knee units, a lot of the micro-processor knee units which have currently been released, a lot of the micro-processor ankles, a lot of the micro-processor terminal devices in terms of hands cost $30,000 to $60,000 just on their own before you even started putting together a prosthesis.  It doesn't take into account too labour and all the other materials and components that you're using.There still is a drive in the R and D and across distributors to produce products that fit into funding schemes, because they're the ones that have a huge throughput.  When we talk about the cost in developing countries, and it's quite a contrast, we are talking in terms of appropriate technology.  With the PCAST system we were using appropriate technology, as opposed to the options you have in a public system or a private facility in a developed country, where in terms of the socket you can use anything from fibreglass to carbon fibre with resins, silicon liners, suction systems, all that sort of thing.  The socket in a developing country is a straight down the line thermo-plastic polypropylene co-polymer with a low temperature thermoplastic inner liner.  Really simple, really easy to use.  You put it in the oven, you drape it over the top, it butt welds together.  You're done.  The cost of the components are also low because they're also manufactured out of the same materials, polypropylene, especially the pylons and the adaptors.The feet are locally made out of natural rubber plantations that they have available.  So everything is designed and fabricated in the country, which means the cost of a prosthesis is under $300, $400.  At the same time you lose out on the customisation of a device, because you've only got one set of components which is great, especially when you're talking about low income countries where everyone's pretty much using the same thing.  You need to have some sort of universal ability to chop and change, but as I said, it does offer less options.

SHANE HUNTINGTON
Peter Lee, Associate Professor of Mechanical Engineering at the University of Melbourne, and Jim Lavranos, Senior Clinician at the Orthotic and Prosthetic Unit of the Royal Children's Hospital here in Melbourne.  Thank you both for being our guests on Up Close today and talking to us about prosthetic limb construction in particular for developing countries.

JIM LAVRANOS
Thank you.

PETER LEE
Thank you.

SHANE HUNTINGTON
Relevant links, the full transcript and more info on this episode can be found on our website at upclose.unimelb.edu.au.  Up Close is a production of the University of Melbourne Australia.  This episode was recorded on 16 May, 2013.  Producers for this episode were Kelvin Param, Eric van Bemmel and Dyani Lewis.  Audio engineering by Gavin Nebauer.  Up Close is created by Eric van Bemmel and Kelvin Param.  I'm Shane Huntington, until next time goodbye.

VOICEOVER
You've been listening to Up Close.  We're also on Twitter and Facebook.  For more info visit upclose.unimelb.edu.au.  Copyright 2013, the University of Melbourne.


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