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The Pros and Cons of Computerized Foot Orthotic Technology

Discussion in 'Biomechanics, Sports and Foot orthoses' started by admin, Nov 12, 2004.

  1. admin

    admin Administrator Staff Member


    Members do not see these Ads. Sign Up.
    The latest O & P Edge has a lead story on The Pros and Cons of Computerized Foot Orthotic Technology

    The conclusion:
    What say you?
     
  2. davidh

    davidh Podiatry Arena Veteran

    I like taking plaster casts, using an orthoses lab who have cad-cam technology, and using my clinical skills :) .

    I don't like OTC's, the thought of an automated footbed system which will do the work for me, or anything which wil take the work away from me :eek: .

    Cheers,
    David
     
  3. Don ESWT

    Don ESWT Active Member

    Pros and Cons of Computerized Foot Orthotic technology

    I have had the Footmaxx Computer gait system since 1996
    My wife calls it the no nag, no fuss, no mess machine.
    It keeps all records and to order the orthotics it is just a matter of pressing a few keys.

    I still fabricate some orthotics for my Spina Bifida and Cerebral Palsy patients.

    The Footmaxx system took about 6 months to pay for itself.

    Don Scott
     
  4. Bruce Williams

    Bruce Williams Well-Known Member

    Computerized Foot Orthotic Technology

    Not all Foot scanners are created equal. I find it interesting that one respondent decries OTC's and foobed scanners, and that the following respondent sings praises of his FootMaxx system.
    In my opinion these are two different things. Knowing only that it is impossible to create a 3 dimensional orthotic device from a 2 dimensional flat pressure mat, I doubt that any systme that uses that technology is making anything but an OTC device that is "customized" to the patients foot type.
    I am now myself beginning to use the AMFIT scanner footbed, and find that it does indeed capture a 3D scan to create a 3D device. I find that it meets easliy my "technique" of non-weight bearing neutral position casting as well, and that I can add or subtract additions to the device as I see fit w/o having to trust the lab to understand what I want. I'm eliminating the middle man, even though AMFIT will still mill the device for me and then send it to me.
    Now, I am a bit of a control freak w/ my devices, so I'll make other changes to the devices as I see fit to perfect my prescription for my patient.
    But, at this point, I see great hope in certain foot scanners and footbeds, and I feel that as people learn to tweak their current plaster techniques to match the computerized digitizers, we will all eventually move forward towards a brighter future in podiatry.
    Sincerrely;
    Bruce Williams :)
     
  5. nicpod1

    nicpod1 Active Member

    Foot bed sanners make a lot of sense, if they can really capture the 3D image of the foot appropriately. I have been modifying my plaster-o-paris bandaging techniques for 'neutral' casts for some time now, so that I can obtain a weight-bearing 'neutral' cast and have been having better resluts with orthoses confort etc. especially in runners. So, a foot bed scanner system would be great for this, if reliable.

    However, I have also pulled out of one clinic I was going to continue working in because one of the physio's is going to use the 'gaitscan' system, which is bascially a static pressure plate that feeds the pressure info back to the orthotics lab electronically. The operator does not have to be biomechanically knowlegable in any way and merely fills in a questionnaire re. height, weight and general appearance of the foot!

    Basically, foot bed systems would be good if found to be reliable, but it eliminates the role of the Podiatrist..........and that's how this 'gaitscan' system was marketed to the Physio concerned!

    So, not only will running shoe shop workers be 'gait analysing' and 'prescribing' OTC's and shoes, but so will any old Joe with access to the appropriate equipment...............ooooops.....that's my degree down the pan again!!!! ;)
     
  6. davidh

    davidh Podiatry Arena Veteran

    My point exactly.
    Also, having billed the patient a realistic fee for my labour, I take pride in assuming responsibility for that patient, and the orthoses, and if there are problems, continue to see the patient until these are sorted, at no extra charge. "Quickie" orthoses may well work to some degree for some people - in most cases they are no substitute for the real thing.
    Regards,
    David
     
  7. Bruce Williams

    Bruce Williams Well-Known Member

    Computerized Foot Orthotic Technology

    Lets not forget that we are trained to "prescribe" orthotics, not just use any electronic device to scan an image of the foot and make a generic device.
    We are supposed to know more about the foot function and why certain things do and don't work w/ orthotic devices, no matter how they are constructed.
    I was just at the PFA meeting in Orlando Florida. The feeling there seems to be that even if the general public is getting exposed to foot orthotics in a non-professional way, i.e. shoe stores, running stores, etc, that the exposure is still good for us foot professionals. They will be more likely to seek our advice when those non-professionals don't do the job.
    Remember, it is supposed to be a prescription device! Make it to your prescription and it will outperform a non-professionals 9 times out of 10!
    :)
    Sincerley;
    Bruce Williams
     
  8. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    ....which makes it a scam..
     
  9. Lucy Hawkins

    Lucy Hawkins Active Member

    Foot Pressure Mats

    Hi All,

    There is a paper by the 'Foot Pressure Interest Group' which gives some guidance to the limitations of Pressure Mats. My memory is not perfect but the title is something like 'Foot Pressure Mats, The Best Thing Since Sliced Bread'. It makes clear there are limitations to these devices, a tool to be used but not surplanting the information derived from a proper clinical examination. They may guess at, but cannot measure, other physical factors which will influence a clinician. They may also have been programmed on the basis of some statistical analysis of footsteps from patients with differing conditions and some generic prescribing protocol, possibly based on a Rootian padagram. I suppose a doctor could carry out a statistical analysis of all prescription given to patients presenting with similar symptoms and arrive at a generic prescription for all. It would work some of the time.

    Good sales tool though, blind them with (pseudo) science and double the fee.

    Cheers
    Luke Hawkins
     
  10. Don ESWT

    Don ESWT Active Member

    Craig,
    From what I have seen of the Amfit System it is done by static stance, with a series of pin inflated to make contact with the skin. When they make contact data is sent to the computer and the podiatrist can then make a decision how to mill the orthotic. Turn around time is same day. Patient can obtain a technical print out. The system costs about $50,000.00AUD

    With the Footmaxx System the person walk over a pressure sensor pad. Once the data is taken it is emailed to Toronto Canada. The data is read by another computer system called METASCAN. From their the data is sent to Canberra where the orthotics are fabricated. Turn around time 72 hours. The patient can obtain a technical print out. The system costs about $15,000.00 AUD

    I do all the biomechanical, muscular and measurements prior to imput.

    The Athletes Foot scan is another type of system. NO othotics are produced but the person is shown a range of footwear appropriate to thier foot shape

    Treadmill with video, you get a pretty picture at the end for the patient you still have to cast the patient. Send the prescription to a lab or fabricate yourself.


    E Med or Efoot - sensors inside the shoe, is another scanning system used by UWS (University of Western Sydney - Campbelltown) since 1999.

    No system is perfect we have to imput the correct data and I made some mistakes using the Footmaxx system in the early years.

    Plaster cast functional orthotics have been in Australia since the late 1940's. My dad (UK Trained Chiropodist) was fabricating perspex (clear plastic) orthotic in 1949.

    Plaster cast fabricated orthotics can have mistakes as well technology based orthotics

    It all boils down to whether we are ethical in telling the patient of their options, and whether the patient is compliant.

    Where is your evidence of a scam??????


    Don Scott
     
  11. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    It is impossible to get the 3-d shape of a foot from a 2-d pressure system.

    We use 2-d pressure systems all the time, but you will NEVER be able to get a 3-d shape of the foot from one.
     
  12. Don ESWT

    Don ESWT Active Member

    Craig,
    I beg to differ,
    The Footmaxx does give 2D and 3D view showing pressure areas. It also shows medial and lateral heel, mets and hallux
    Please see www.footmaxx.com for more information. They use mathamatical calculations way above my understanding.

    A new system was introdued into Australia mid 2004 but I am not sure of its name.

    Don Scott
     
  13. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Sorry Don, you are very mistaken. All the pressure systems are 2-d....they however can display the pretty pictures of the pressure as a 3-d map/picture.

    This is very very very different to the 3-d shape of the foot. ... thats why its a scam because people are sucked into the 3-d picture for orthoses prescribing. I can tell you from our research and that of many others, there is no (or very very little) relationship between the plantar pressure pattern and the 3-d shape/structure of the foot.

    Despite that, it does not mean that plantar pressures/forces are not useful. We are close to finishing up and publishing some research that we presented prelim data at a conference 2 weeks ago in NZ ... the chair of the session summed up our work as being close to "finding the holy grail" when it comes to documenting what parameter(s) change with foot orthoses that are actually related to validated outcome measures ..... it was not rearfoot motion changes with foot orthoses, but was changes in some of the force/time parameters (Bruce has a fair idea what I am talking about) .... the Footmax system can't measure those parameters and can't give you the 3-d shape of the foot.
     
    Last edited: Nov 13, 2004
  14. Don ESWT

    Don ESWT Active Member

    Craig,
    Have you personally used the Footmaxx system?

    I am not privy to the internal workings of the computer system but algorithmic equations and a lot of CAD can transform 2D to 3D

    As I stated before where is your evidence of a scam??????????
     
  15. Ian Linane

    Ian Linane Well-Known Member

    interesting claim

    Hi everyone. Having never used a scanner I found the following advert interesting particularly the latter element from a newspaper advert.

    See : www.heelspur.co.uk for more.

    "About the Laser Foot Scanner

    The optical Laser Foot Scanner is the most accurate way of measuring the foot for an orthotic.

    The old methods such as plaster casting were time consuming, messy and inaccurate. The NHS method of drawing around the foot and cutting an orthotic out of leather or plastic is at most, making a "pad" and at worse, a waste of time and risk's making the heel spur worse.

    The optical laser foot scanner accurately measures thousands and thousands of points on the foot's many contours producing an accurate end product of which to make a modern orthotic from.

    For the technical minded among us, the camera in the optical laser"picks up" 64,000 pixels every 2.5cm's of travel as it scans the foot.

    This information captured by the laser is then delivered to computers in the USA.

    After much correction of the foot "on screen" the computer feeds this information to a CNC milling machine which creates a model of the patients foot to an accuracy of plus or minus one ten thousandth of an inch!

    All this amazingly accurate measurement takes around 15 seconds per foot and is ultra-safe and obviously comfortable.

    Is it any wonder we're so confident in our orthotics and our guarantees to you our patient?"


    "We have a highly specialised 3D optical laser foot bed which takes 64,000 reading per 2.5cm of foot. With this latest technology our orthotics are accurate to 1/10,000 of an inch" :rolleyes:

    Any comments.
     
  16. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    I am very familiar with the Footmax system, which is why I would never use it. As I said above how can the pressure under the foot be used to determine the 3-d shape of the foot? ..... It can't (I know the marketing hype says you can :mad: ). In all our research, we have yet not been able to determine differences between a pronated or supinated foot type using plantar pressures (except at the extremes) - others have found the same.

    eg a low arch profile and a high arch profile, can have the exact same pressure profile under the forefoot. No amount of "blackbox" algorithm can sort that out to give a foot shape, despite the marketing hype.
     
    Last edited: Nov 13, 2004
  17. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Ian

    Optical scanners are different to the pressure scaners - optical scanners do accurately capture the 3-d shape, pressure scanners do not. There are many on the market and there will be more as this is where things are heading.
    The only problem with the scanners, is that they do accurately capture the body segment (eg the foot) down to the nth degree or fraction of a mm .... but they may be just accuratly reproducing the wrong position of the foot. eg we have long used STJ neutral as the right positon for a foot but:
    1. several studies have documented its variability in finding it between clinicans, so the "accurate" scan is just reproducing the variabily located position
    2. Getting a foot to STJ neutral with a foot orthoses is not related to clinical outcomes (I alluded to this is the research above)

    So what are these scanners actually reproducing :confused: .... they are accuratly reproducing what ever position we put the foot in .... we just do not know for sure yet what that position should be. It's not STJ neutral --- at this stage it appears as though the position the foot shoud be in is different for each individual --- ie 'subject specific' (its probably related to forces) ---- in the research alluded to above, we finishing up looking at clinical outcomes and related to foot position --- we thing we got the answer, but just need to do more than just the preliminary outcome work.
     
    Last edited: Nov 13, 2004
  18. Bruce Williams

    Bruce Williams Well-Known Member

    Craig and Don and all;
    I have to completely agree with Craig here. Don mentioned that the algorithm is way beyond his understanding. I admit, it is way beyond mine too. Unfortunately, this is oftne the case when someone does not want to be truly forthcoming on how they capture their data.
    I have experience using both F-scan and Mat-scan both of Tekscan. I predominantly use the F-scan in-shoe system, and can tell you that it is extremely difficult to know what foot type you are dealing with just by looking at the pressure data. I can give you an idea of which foot accelerates faster, and which foot stays in late midstance longer as well. I actually use some pressure map pictures that show very little medial arch pressure in a patient who is actually extremely flat footed. Everyone thinks it is a high arched foot, it is not!
    Re: the 3D pictures or images you can get from the mats, it just shows high points of pressure under certain areas!
    Craig is sincerely right when he states that you can't go from 2D to 3D w/ a flat device. You have to have either a laser that will scan the entire outline of the foot, or an AMFIT device that does something similar w/ the pressure pegs. All others are not true 3D.
    Craig is equally right about the positioning of the foot no matter what scanner you use. I am re-learning that now with the recent use of the AMFIT scanner. But, the neat thing about the AMFIT scanner is that I know what to look for as far as what the map shows should be a good scan. I can then re-scan much quicker than re-casting w/ plaster. Also, if you hold the foot in a proper position, the pressure pegs will hold the foot in such a position that you can improve certain veriables, ie. calcaneal incliniation, possibly the cuboid-navicular articulation, and see if the lateral and medial arch heights are where you want to them to be.
    Nothing is a panacea. It all comes down to knowing what you inherently want in your casts, no matter how you take them, and then positioning the foot properly and using the proper prescription to get the outcome you desire for the patient.
    Cheers!
    Bruce :)
     
  19. Producing 3D Information from Flat Plane???

    Don:

    A two-dimensional (2D) pressure mapping system that is based on a single flat plane can not, in any way, produce a three-dimensional (3D) image of an object, such as a foot, no matter what an individual or company claims. This would be the equivalent to estimating the skyline of a city by measuring the weights of the buildings in the city at ground level. Unfortunately, for an arched structure, such as the foot, the lack of pressure in the middle of an arch does not give any information as to how high that the middle of the arched structure is.

    This does not mean, however, that the Footscan insoles are incapable of making some patients better since I'm sure there is a certain percentage of patients that are helped by these arch support type insoles, similar to how an over-the-counter insole may help some patients with their foot and/or lower extremity problems. However, to claim that a 3D image of a foot can be produced by a flat plane pressure mapping system of the plantar foot demonstrates, to me, that the person making that claim does not understand the basic mechanical process in determining the three-dimensional shape of an object.
     
  20. pgcarter

    pgcarter Well-Known Member

    Dear All,
    All this debate about 2D or 3D image capture still ignores the next and biggest wrinkle in the whole business: The captured static image, regardless of it's quality or multidimensional "correctness" gives only minimal (to zero) indication of the nature of the dynamic function of the foot.
    Why is it that so few podiatrists no longer make their own devices? and what is being lost by this erosion of skills?
    I still make all mine, although I have been forced to use labs when doing locum work.
    Scary when a practitioner such as a chiro or physio or myotherapist can do a w/e course and begin to prescribe devices on behalf of a lab.....just so long as they sell a pair.
    How can people justify the appointment fees as well as the size of the plain old mark-up on the cost of lab devices?. I used to be in retail and we never had margins like these. Unbelieveable!
    As always, full of questions and few answers.
    Regards Phill Carter
     
  21. kevin miller

    kevin miller Active Member

    All this debate about 2D or 3D image capture still ignores the next and biggest wrink

    Phill,

    Though this is no doubt true, how does it differ from a palster cast? The systems that "capture" data while walking capture the deformity. Laser scanners capture the deformity perfectly. The AMFIT scanner, on the other hand, uses pins under pressure to deform the soft tissue against the underlying bone. Since it is accurate to 1/10mm, its topographical scan may be used to determine osseous positioning. You may observe the relative calcaneal angle, met position in space, the transverse tarsal arch, etc. If you would like to see how the foot deforms under stress, simply take wieght bearing and non-wieght bearing scans. I personaly do lots of manipulation, so I use the scanner to determine if I have all articulations functioning properly, or which ones to which I cannot restore function. In short, there is an appreciable difference between two scans with a cuboid manipulation as the only variable. I submit that there is no other technique that can deliver this kind of data. Follow this with an F-scan to trouble shoot function, and you have the most powerful system I have ever seen.

    Regards,
    kevin m
     
  22. pgcarter

    pgcarter Well-Known Member

    Hi Kevin,
    I agree with you in that a plaster cast is just another way of capturing a foot image, it is a fairly cost effective way too. It does sound like you have developed ways to use the amfit as a pre and post test kind of thing. I have seen the amfit system in use in Surefoot ski shops, Whistler etc. I am sure having the opportunity to play with one a lot would provide some insights, but intellectual/academic value aside, these systems get to be pretty serious investments in Australia and our market size and fee structures don't always make these things very feasible.
    I suppose in the end I have a fairly strong belief in the value of practitioner assessment and the need for follow through all the way to the end. I believe that the process is likely to lead to better results if the same person does everything from start to finish. The machine that cuts the shell or the tech in the lab have never seen or felt the foot and neither brings anything extra to the process that really seems to matter.
    They both take things away from the process though, things such as the need for the practitioner to develop and maintain skills that provide insight into the shapes and effects of devices on various types of feet. The machine gives you the ability to reproduce a device identically, but then you've just got two that may or may not work. The lab tech may well be a plaster tech with no formal training and no insight into foot function.
    Sounds like you are trying to use the Amfit system as a part of a foot assessment process, not just a system to produce devices.

    In relation to Amfit, I particularly have issues with the blanks used. The high density but low stiffness composite that I have seen used give very little support to a foot through a range of positions.
    Like high density EVA shaped devices collapse with very little resistance until the under surface of the device is in contact with whatever is underneath it.(the shoe)
    Then it offers behavioural characteristics resulting from it's density, it becomes very hard then. This kind of material gives very little opportunity to influence foot function over a range of positions, which of course are necessary for natural dynamic function.

    This is why I usually use a more rigid, but not that rigid material, such as 4.5mm copolymer. I currently see first ray mechanics, plantarflexion in late stance and timely and effective loading as pretty crucial to efficient foot function, and at the moment this seems to mean fairly aggressively shaped devices that offer dynamic support to a foot over a range of STJ and MTJ postions but are not too rigid. I seem to be unable to achieve these effects using EVA or cork/urethane compounds.

    Each to their own hey?

    Regards Phill Carter
     
  23. Ian Linane

    Ian Linane Well-Known Member

    Hi Phil

    Like yourself I assess, manufacture and review a person from start to finish. I do not consider this to be better or more virtuous it just happens to be where I have arrived. There are times when getting POP poured etc is a pain but there is a certain satisfaction arising from making and seeing the results. I invariably use a polycarbonate material rigid or semi-rigid (2.3/ 2.7/3mm) and, as my preference, default to fully intrinsically posted devices and occasional Kirby skives.

    For my money the most vulnerable part in gait is often just after heel lift when you see an sudden MTJ inroll. As a consequence I have always been a little supicious of the over emphasis upon rearfoot control.

    Occasionally I will so shape the arch of the foot that it supports the 1st ray a little longer after heel lift but does not interefer to much with its action. If it does then its back to the drawing board, at my cost, but this is not often.

    I am interested in what you mean by aggressively shaped devices and how you control 1st ray mechanics. How do you rectify your models etc?

    Mind you, marriage is certainly strained when you keep walking white powder from the workshop through the kitchen :eek: Sometimes I don't think I'm understood!!

    Cheers
    Ian
     
  24. Bruce Williams

    Bruce Williams Well-Known Member

    Ian and Phil;
    I'm curious as to what you both do re: 1st ray mechanics. Ian mentioned supporting the 1st ray longer into late midstance - early active propulsion (heel lift). In my mind this would cause dorsiflexion of the 1st ray at this time when the 1st metahead needs to be in contact with the ground. This often will make any pre-disposition for FHL (functional hallux Limitus) worse. I may not be understandgin what you are doing though.

    Finally, Phil mentioned materials and how he does not care for teh EVA. I have traditionally used polys or nylon polys for my flexible rigid devices. I prefer a device to have more give than less in most cases. I have however started using the EVA from AMFIT, and just distributed my first two devices yesterday.
    I have always found that it is much more the prescription and construction and casting for a device, much more so than the actual material that makes all the difference. I can use a simple device pre-made of aliplast plastizote and make it to 90% or more of what I cna w/ a poly device. I see no improvement w/ flexible carbon or nylonse etc.
    Now, I understand there will be some argument with this, and I know that some studies have shown higher energy return w/ different construction and different materials. But... I don't believe any examined before and after function, only energy return. I don't believe that these two variables are always compatible by any means.
    So, until someone can prove to me that a certain constructed material gives a huge improvement in energy and funcionality, I will be happy to use a well constructed/casted/EVA that is modified to my strict prescription.
    Cheers all!
    Bruce Williams :cool: :D
     
  25. Ian Linane

    Ian Linane Well-Known Member

    Hi Bruce et al

    I hope the following goes some way towards a thought process.

    I will try to address your query but realise that my view may well be severely questioned and will lack the intellectual credibility that many of you have. I am not a degreed nor hospital trained Pod and most of my biomechanical knowledge is self gleaned, no virtue in this, it is simply how I have arrived here.

    1. My perception is that our current 1st ray mechancis (indeed all our
    biomechanics) appears to be reliant on two things:

    - the assumption that planal congruity is the norm ( I am not saying
    this is wrong) which itself is based upon

    - acceptance of a false environment as the basis of measuring
    biomechanical function.

    2. The mobile human foot is, essentially, designed to be multi-
    adaptational (have I just made that word up?) for a multi-
    contoured surface which itself reacts to our contact with varying
    forces in any given part of a step from heel contact to toe off due
    to its undulating nature and the differing densities of that surface.

    Question: Do our current concepts of 1st ray or any biomechanics
    which may apply in a control trainer (false
    environment!?) have any relevance to someone who is a
    barefoot runner?

    3. How about if we take a view that a mild degree of forefoot
    Supinatus (which would possibly affect our concept of the timing of
    first ray mechanics) would be more biomechanically efficient in a
    true environment.

    Is it possible then to rethink how we shape the medial arch of the
    foot that accounts for the ability of the first ray (providing we are
    not unduly limiting joint movement) to roll over the device slightly
    later and perhaps resist late MTJ in roll. (With my significant heel
    eversion and marked MTJ in roll my first ray function is stuffed
    anyway. If nothing else the above may give it at least some
    function!)

    4. How about a flexible polycarbon device that captures the shape of
    a medial arch when the foot is in Talar congruency and the forefoot
    rolled to the ground. Beyond having the medial arch the base plate
    of the device is completely flat. On top of this is placed a material
    such as that used in the Tempur mattress. This material is graded
    in different density from rear to forefoot and medial to lateral. The
    whole of the rear foot is low density. From Navicular and 1st ray
    moving laterally in a graduated skive from 3/4 mm to 1 mm we have
    medium density as far as the 4th ray. From the 4th ray to fifth ray
    we have low density of 2mm.

    Although the cast has been captured in Talar congruency with the
    forefoot rolled over, the actual foot can maintain something of it
    Supinatus as it rolls over the arch and slowly compress into the
    forefoot material with its graded density. It can still get
    plantarflexion of the 1st ray but in slightly supinated position.

    Does this help mimic something of the different terrains that the
    foot is designed to move over? Does it move us away from spurious
    claims about precision devices when our basic assumptions are
    based upon a false environment?

    Cheers
    Ian
     
  26. pgcarter

    pgcarter Well-Known Member

    Dear Iain,
    I have often thought about the "natural" foot on natural surfaces with more compression under body wt than most of what we walk on today, and how when you walk on sand much more of the foot bears load than when you walk on concrete.
    I would love to be able to do some research on Youngs modulus of a bunch of materials and look at hysteresis etc...I'm fairly sure what we use for footwear and orthoses is not very like what we evolved on.
    However we seem to want to extend the service life of the implement to 3 or so times it's evolved span also, so different parameters probably apply.

    My view of 1st ray stuff is fairly simplistic. Get it down and plantarflexed, get it loaded and keep the D/F range at the 1st mpj available and used.
    In order to do this I tend to think the proximal end has to well up in the air as a starting point from which to plantarflex.
    As far as plantarfascial impingement goes I don't seem to have trouble as long as the anterior angle of descent of the device under the 1st met shaft is steep enough then the distance horizontally from the 1st met head to the calc med tubercle is decreased and therfor tension on the plantarfascia is decreased. Craig talks about less force to engage the windlass, same beast I think but different label.
    Regards Phill.
     
  27. pgcarter

    pgcarter Well-Known Member

    Dear Bruce,
    I haven't actually played with Amfit, so am far from expert.
    But I suspect you will get fair results with relatively low arched feet but once you want to try and effect the function of a high arched foot at C-C / MTJ/ T-N joint I suspect you won't be able to reach that high into the air with significant influence on function without being to rigid/hard also during mid stance. Your point about travel in the material of the device I also like....you want resistence over a range of positions, not very little and then suddenly a lot, which is what I think happens with EVA a fair bit.

    When I used the word "aggressive" I meant relatively high device under T-N joint with posterior focus rather than trad Root mid foot focus, with what I call a steep anterior medial plaster addition in order to create the best (steep) plantarflexion angle for the first met shaft.
    With not a lot of science I tend to think about the ranges of motion available in a particular foot and how to create efficiency and avoid end of range function.
    Regards Phill
     
  28. Bruce Williams

    Bruce Williams Well-Known Member

    Phil and Ian;
    Thanks for your replies. I think I understand where you are coming from a little better now. I like the idea of different materials proposed by Ian, though I doubt it is probalbe, nonetheless very interesting and intrigueing.
    Re: AMFIT and a high arched foot, well I will just have to see. I think the device is able to capture whatever foot architecture that it is given, so I don't know why it wouldn't work w/ high arched feet.
    Finally, lets all remember that the feet are not a traditional tripod. The foot will support itself in some form, good or bad. In other words, we can only help to improve that function with an exacting prescriptino that brings out the best in foot function, not just by posting or forcing the foot to do what we may have been taught it was supposed to do.
    cheers
    Bruce W
     
  29. kevin miller

    kevin miller Active Member

    Ian and Phil,

    Phil is correct. I do use the AMFIT device as a diagnostics tool. However, I do so because I have many of the same concerns you have just expressed. If my goal is to restore function; by that I mean to allow the foot to adapt to surfaces with variable topography, then bringing the ground to the foot as with an extrinsic post will not suffice. I must try to get the foot to move back to the ground. Then, to actually function normally, I must limit sagital plane motion to a degree, while allowing as much frontal plane motion as the foot needs. Therein is the crux of why I use AMFIT. The scans can tell me if I have the bones in a functional position. Instead of grinding a negative out of an EVA shell, I grind a positive and pull a flexible thermoplastic graphite composite over that. The surface of the resulting insert is almost invariable volume reducing in nature. Due to this characteristic, the graphite becomes more rigid in the sagital plane than the frontal….just what we asked for. (AMFIT adopted my technique for fabricating with carbon. They call the device the “Stealth”. The problem is that most people send them a scan that is similar to what they would get from a foam box or plaster. That is, without the topography in the scan I mentioned. As a result, they are force to use a more rigid carbon to prevent failure of the device. This makes the device too stiff in the frontal plane and negates the reason I developed the process in the first place. The key then, is the scan.) The truth is, however, the individuals who seem to get the greatest benefit for this effort are runners (these devices work well in track spikes) or people with high activity levels. The rest do fine in EVA with the same volume reducing topography. The exception is patients with midtarsal instability; those on who you can demonstrate passive sagital plane motion of the forefoot with respect to the rearfoot. These folks do much better in carbon no matter their activity level.

    You can make a positive from the AMFIT device that will allow you to fabricate full length carbon devices as well. If you have a terribly dysfunctional diabetic foot with met head ulcerations, it is possible transfer pressure distally and over a greater surface area with these due to the properties of the flexible graphite.

    Regards,
    Kevin M
     
  30. kevin miller

    kevin miller Active Member


    Phil,

    On the contrary. The very reason I use AMFIT is to establish better talonavicular and cuboidonavicular control. Using the scanner you can even see rotational relationships in the midfoot that are impossible with x-ray. Plus, the scan - of the corrected foot - is used to manufacture the orthosis. Even if you send the scan to AMFIT for manufacture, they send you back exactly what you asked for because the data is digital. They couldn't change your prescription if they tried. I cannot say this about plaster. I think you would really enjoy the system if you had an opportunity to work with it.

    Regards,
    Kevin M
     
  31. pgcarter

    pgcarter Well-Known Member

    Hi Kevin,
    Which material are you using for feet like this?, I have only seen one kind of Amfit blank.
    Regards Phill
     
  32. kevin miller

    kevin miller Active Member

    Phil,

    JMS Plastics carries a product called TL-2100 made by performance materials. It is a carbon fiber weave impregnated with a thermoplastic acrylic. I think Performance distributes TL through someone in Germany as well. If you are interested, use the semi-flex. If you try it and are having breakage, let me know and I'll give you a hint. It is not the easiest product to work with because its thermolinking temp range is very narrow. You have to pull it down within 3-5 seconds to get nice, deep heel cups. I use a carbide wheel to grind it because it will eat a garnet sleeve for lunch. The good side is that it heats better in a cheap convection oven that it does in the more expensive types. I also think it is the most biocompatible material an the market....period. After I developed the analysis techniques with the AMFIT machine, it became obvious that the common orthotic materials were not up to the task. I spent lots of money looking for a product like TL-2100. I found several materials that might work, but they were all thermosets, not thermoplastics. Long story short...TL, specifically the semiflex, is the only product I have found that will give the performance I described in earlier posts.

    AMFIT picked up my process. They call the product "The Stealth", but they use a semi rigid TL-2100, not the semiflex. I asked why and was told that people were complaining of breakage. This is because they were sending in wieght bearing scans that result in a flat orthisis. The semiflex becomes strong when radii are imposed on it. Even a simple met pad and increased lateral arch will make it satrong enough to hold a 230lb man. The moral is, most people do not use the AMFIT machine to its potential. It is simply a tool....like a hammer, one man may build a bird house while the other builds a ranch house.

    regards,
    Kevin M
     
  33. pgcarter

    pgcarter Well-Known Member

    Dear Kevin,
    I am familiar with TL2100. Now it is clear why you can get results that work for you. My initial remarks apply specifically to the behavioural nature of EVA and things like it, such as Amfits original blanks. I was basically saying that you can't do these things with those materials, you have indentified another material that will allow you to exert influence over the foot across a greater range of positions.
    Regards Phill Carter
     
  34. kevin miller

    kevin miller Active Member

    Phil,

    Sorry I got a little off track. I made a statement in passing that a volume reducing contour on EVA produces the results we are looking for on a higher percentage of pts that a flat surface with posting. However, for higher functioning pts and athletes, the TL works much better. I think I got sidetracked because we were discussing the advantaged of the AMFIT digi. It is how I get the maximum volume reduction without discomfort to the patient.

    Regards,
    Kevin M
     
  35. pgcarter

    pgcarter Well-Known Member

    Dear Kevin,'
    I'm not entirely sure what you mean by"volume reduction" can you give me a longhand version?
    Thanks Phill
     
  36. kevin miller

    kevin miller Active Member

    Phil,

    The AMFIT machine, as you know, has pins that are pushed up under pneumatic pressure to capture the contour of the foot. They deform the soft tissuue, varying with the ammount of pressure the practitioner uses. The computer is accurate to 1/10mm. So accurate in fact, that you can observe ossoeus positioning on the scan itself. This is why I use it to tell me if I have all bones adjusted properly. The "instant met pad" feature can be used at this point to create a volume reducing post. This is not just a met pad, however. The algorithm identifies the apex of the met arch and extrapolates it 360 degrees creating sort of an off-set pyramid that captures the proper curvature of the met heads, the met angle, the "saddle created" by the cuboidonavicular articulation, etc. This feature is why it is imperative to correct the foot with manipulation before scanning. The pins will capture a malpostioned foot just as it will a corrected one. This is superior to other methods and attempting to extrensically post an orthotic because it is truly tri-planar. For instance, in the case of FHL, you don't have to post the FF to bring the ground to it, you simply force the 1st ray to the ground via the cuboid. You may ask how in the world could you get enough material on top of the orthotic to do this without hurting the patient. 1) You only need an extra 3.5 - 4.5 mm on top of the contour the pins captured. What is more, there is no guess work about where it needs to go. A perfect tri-planar post. 2) If you will recall from dissection, there is a band of fasci perpendicular to the plantar fascia that extends from the plantar fascia to the tarsals separating abd. digi. mini. and flex. digi. brevis. It just so happens that the shape created by the machine will compress on this struture.....which also happens to be partially responsible for supporting the lateral column during wieght bearing. In summary, because of manipulation, very accurate capture of the corrected position, and very accurate placement and design of a volume reducing post, you can get maximum foot control with little or no break-in period.

    I hope this explanation helps.

    Regards,
    Kevin M
     
  37. pgcarter

    pgcarter Well-Known Member

    Thanks Kevin,
    It would appear that by volume reduction you kind of mean "creating the least bulky orthosis for the best possible effect, so that it will easily fit in shoes". If that's what you mean I agree entirely, it's what I attempt all the time.Sounds like Amfit has more potential based on how it is used.
    Regards Phill.
     
  38. kevin miller

    kevin miller Active Member

    Phil,

    Sorry for the confusion. By volume reducing I mean reduction in volume of the foot. The term comes from O&P fabrication. Usually refering to "reducing the volume" of a cast for prosthetics, though it is often applied elsewhere. Reducing the volume of the cast then reduces the volume of the limb to which the appliance is afixed. I think I confused you when I spoke of the vertical lig. attached to the plantar fasc. Allow me to clarify.

    If these lig. have undergone [plastic deformity, then they cannot help support the lateral column. Volume reduction "takes up the slck" in the plant. fasc. as well as these ligaments, helping them do their job without a direct post, say under the cuboid.

    Regards.
    Kevin M
     
  39. Sean Millar

    Sean Millar Active Member

    vertical casting

    I would like to add discussion in this forum regarding the vertcal casting system. this system was researched by Craig Payne et. al. and results pulished in the AJPM. 2001; Vol35, No3. 65-71. the results suggested the device could provide good repeatability in casting. I have also worked breifly with the Amfit system, and found the vertical casting system more predictable and satsifactory in its outcomes.

    I have used this vertical casting system for over 12 months.

    In summary the device works by, standing the client in place on the device. The foot draped in plaster then the rf and ff adjusted to place the client in NCSP (as we know it). Or in the position that you feel is functional benifical.

    To test this process, initally I used the calc. bisection to measure the NCSP (x # deg). then cast the patient on the device. The Bisection line transfered to the cast (y # deg) measured the same as the NCSP (x= y# deg).
    Therefore I felt the result I was getting was accurate.

    More importantly , my clients compliance improved markedly. As far as i am aware every set of orthosis made on system are still insitu. The clients report increased comfort levels compared to previous orthosis (mine and others). the wearing in time is down to 4 days maximum. all patients have reported significant reduction in symptoms >70%. Further, the modifications need to be made are also greatly reduced ( i recall 3 modificatioins in 12 months).
    I have found there are significant benifits to this system and feel that further research is warranted.
    To put the icing on the cake, this system is also aimimg to be CAD/CAm enabled within 12 months.
     
  40. Ian Linane

    Ian Linane Well-Known Member

    Hi all,

    Interesting to read this view on casting etc. I have always found that a good pair of hand made FFO's, fully intrinsically posted, brings rapid pt compliance. Even adaptive phase muscular adjustment is more tolerated because the device is comfortable. It is quite unusual to have to make modifications and if these occur it is normally a widening of the heel cup or the addition of a FF extension etc (never done, even if I think it a good idea at the time, until I see the need for it on review).

    Bit old fashioned admittedly.

    Cheers
    Ian
     
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