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I am considering buying RS Scan gait analysis system. I would welcome advice on this system or on any others that Podiatrists have found useful.
Thanks
Bonnie

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Bonnie, Do you mean a pressure mat system? I wouldn't call this a gait analysis system but rather a a tool or component within a gait analysis system.
For me RS Scan go too far in suggesting a reliable relationship between evaluation of applied normal forces and orthotic design.
The data that you collect with a pressure measuring device be it insoles, short or long mat only tell you about forces applied to the mat and their time and location. They do not tell you anything about the biomechanics of the gait or the anatomy of the subject of interest.
Any extrapolation of data outside of what is known is assumption, this assumption can be made more reasonable if, combined with the pressure mat data, there are other parameters considered like biometrics, visual and video data, anatomical variations, biomechanical variations, history, tests and other technical data, e.g. accelerometer.
This, for me, constitutes a whole system of gait analysis and anyone of those on their own does not. How many of those system components you will require to reasonably asses your subject in terms of achieving a good outcome with your intervention is a matter for you to decide.
I would say a pressure may system is not essential but good education and knowledge in the relevant field is.

The pressure measuring device is very useful when used in the correct way otherwise it can be just an expensive toy to impress your customers.
I have an interest in a certain PMD so I'm not sure it is valid for me to give you advise on which system you should buy. I have always preffered capactive PMD rather than ink resistive PMD but if your buying an insole system then the choice is restricted


regards Dave Smith

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Descartes seems to consider here that beliefs formed by pure reasoning are less doubtful than those formed through perception.

It depends on what you want to do with it. Impress patients or get clinically useful information?

Problems with gait analysis systems.
Does the pain cause the gait or does the gait cause the pain?
Little published research on outcome advantages using systems.

Advantages
If you want to think a lot, you can learn a lot.

I wrote a chapter for Ron Valmassey's Clincal Biomechanics of the lower extremities 15 years ago. Some of the basic stuff in it is still useful.

Eric

Triaxial load cells are the way to go. This fella has all the answers with regard to that- https://www.eda.kent.ac.uk/school/st...ail.aspx?id=40

I'm going to be talking with a company in the next couple of weeks, who have a 2D system already, our initial conversations have touched on triaxial load sensing + 3D accelerometery. We'll see. 3d in-shoe is the way to go though.

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

Bonnie,

David Smith, Kevin Kirby and I had this paper published recently in JAPMA
http://www.japmaonline.org/cgi/conte...ract/100/6/518

Full text of Tom Mcpoil's review here:
http://ptjournal.apta.org/content/80/4/399.full.pdf

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

Hi Eic,
I query the statement "does the pain cause the gait or the gait cause the pain" as being a problem.

Does that matter, given that any gait analysis system, no matter how clever or complicated, can only capture certain aspects of gait? The common restrictive parameters for all gait analysis systems are that they only capture data taken at a specific time of day, and they all utilise a hard, flat surface (to walk on).

Joint stiffness is affected by diurnal variation - I''m talking about joint stiffness in the spine, hips or knees rather than feet, but joint stiffness anywhere will affect gait. There is an old Paper by Ian Haslock and Tony Unsworth which shows how circadian (24-hour as opposed to 12-hour) variation affects joints - I don't have the ref and having recently moved house I cannot put my hands on it for the moment.
Tony is a Prof in the Bioengineering Dept at Durham Uni. Ian is a Consultant Rheumatologist.

Hard, flat surfaces in gait labs are of little or no concern provided the subjects are walking on hard, flat surfaces all the time, but I feel the diurnal variation factor is really quite important.

I use a Tekscan mat system in my daily work. If a patient has an antalgic gait I would argue that there is value in having a record of that. The Tekscan is simple to use, works well given it's limitations, and costs are similar to the RS.
It will record weightbearing foot-shape, and aspects of gait fairly accurately, and is a good patient education tool.

Having met the RS team (including their MD) and talked to them at length about their product I'm rather inclined to agree with Dave S - they are very interested in providing insoles, and defending their system, and not so interested or even particularly well-informed about providing gait data.

Hello Simon,

I used Matthew's triaxial in-shoe 'force plates' a few years ago on a research project on wearable technology for monitoring various aspects of lower limb function. Have these been developed into a clinic-ready product yet? When I used them they were far from being clinically useful (I still remember a very lengthy process of locating the 'right' positions for the tranducers followed by a labour intensive process of manually crafting the insole for each subject).

Cheers,
Lee

That is part of my point. It is very hard to use gait analysis as a diagnostic tool because you don't know if a subject is walking a certain way to avoid pain or if they are walking in the gait style that caused the pain. Additionally, there is step to step variation, even on hard flat surfaces. So, if you were going to make any conclusions on the data, you should average multiple steps.

There is probably some useful data in gait analysis, but I'm not sure we have proven what is useful. For example, I just saw an article that showed that gait speed in folks over 74 was predictive for 5 year survival. Self selected gait speed might be useful clinically in the young as well.

I also think that joint power, as calculated by inverse dynamics, might be useful in some evaluations. However, a plantar pressure map may have limited applications. For example, assessment of plantar pressures in someone with loss of sensation. Beyond that, there is debate. Howard Dannenberg has done some interesting things with the speed of progression of the center of pressure. I'd be very interested in seeing if this correlates with joint power and, or, is consistent over time.

When they have an antalgic gait, what do you gain by recording it over just writing antalgic gait in the chart? Would measuring gait speed be a better measure?



That is the point. What do you do with the data, other than impress patients.

Eric

I'm not sure, they are down to about 2mm thickness now. If you have the thickness of the transducer and the diameter, how hard is it to get a material of the same thickness and stamp out some apertures to fit the load cells into? Regardless, 3d load sensing at the foot orthosis interface is the future. Do you have a reference for the publication following the research project you performed?

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

I don't conduct gait studies to impress patients. I use the data to educate patients, and to provide objective data about how that patient was ambulating on that day at that time.
The hospitals I work in are designed to impress patients.

My contention is that all gait analysis studies are limited as to the clinical usefulness of the data - some systems are simpler and less expensive to use than others and can provide useful objective data.
I remember Vicon as being the most complicated and expensive system (£500,000.00 at the time) out there.
Very impressive - told clinicians very little about how to treat a case.

David

The definition of flat feet is subjective. You can measaure standing arch height with a ruler. Doesn't require much technology. Ok, using a video camera is probably the best way to measure the amount of intoing.

Could you provide an example of how you educate a patient?

What do you do with the data that you produce about how a patient was walking at a particular point in time?

Eric

Useful for what?

Useful to convince people to part with money or useful in that it gives information beyond what you get from a usual clinical assessment that actually is useful in the clinical decision making process.

Call me cynical, but ask yourself some hard questions about what ever system you are considering ... will the information I get from this actually have the potential to change the treatment (ie foot orthotic prescription)?

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Craig Payne
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Follow me on Twitter | Run Junkie | Latest Blog Post: Foot pronation is not associated with increased injury risk in novice runners wearing a neutral shoe
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.

The data is stored. It becomes part of the clinical notes - there to be used again if needed, or there to be compared with a few years on. I should point out that my clinical practice is all musculoskeletal, that I only work in private hospitals (hence my reference to patients being impressed by the hospital, not a laptop, a mat and some wires) and pretty much all of my patients are referred, either by their GP or Medical Specialist (or Pod Surgeon). I don't think a vertical loading system would have as much application in general podiatry practice in the UK, although it would still be useful in some cases.

From Craigs reply I surmise that vertical loading systems are not flavour of the month on Pod Arena. I'm not sure if this is because they are often mis-sold, mis-used, or whether this is simply a backlash against the hype put out by overly keen GA system salesmen.

To paraphrase Dananberg (or maybe this is a direct quote, I can't remember - he made it a looong time ago.....
"This is the age of the chip".
These systems are now relatively inexpensive, easy and quick to use, accurate up to a point, and can provide repeatable and reproducible data. They also provide (unlike a video camera) easy data storage and accessability. I don't understand why anyone would still want to faff around with a video camera except for specialist applications like research or fast ambulation (running) outside.

I can assure you that the Tekscan mat is a useful piece of clinical kit. I only have experience with one other vertical loading system, the Musgrave mat. Good, but fussy to set up, and expensive when I bought mine. The Tekscan mat is less accurate, but accurate enough, and useful clinically for the reasons I've outlined above. I don't believe it is particularly useful in diagnosis, again for the reasons I've given.
In fact, and to repeat myself, I don't believe any gait analysis system is particularly useful in diagnosis.

David

Really?

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

Hello Simon,
From memory, there were a variety of issues beyond the simple tasks like stamping out cut outs for each transducer. I can't find the reference, but it was a poster presentation at one of the Salford biomechanics conferences (2005 probably) about the realprof project that I did with Chris Nester. Hopefully the technology has moved on and is more instantly useable in the clinical setting now. Matthew was a really nice bloke too and good to work with.
Cheers,
Lee

Yes - you'll no doubt have noticed that I deliberately didn't mention quantifying arch height, which it can't do, being a 2-D based system.

Ok, so how does it "show standing arch height clearly?

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

Think about a wet footprint on a tiled floor.
That would show standing arch height pretty clearly wouldn't you agree?
That's what the Tekscan shows, but it's a permanent record, not a wet footprint.

Of course - you already knew that..............

I´m a bit confused here -

Ive drawn a diagram .

Arch height to me is picture x measured in mm.

picture y represents the amount of foot that come in contact with the ground.

Which may mean the arch height is 3mm or 15 mm. So a wet foot print type of test only shows the amount of surface of the foot that come in contact with the ground right ? There maybe a lose correlation the height the arch height in mm the less foot comes in contact with the ground but clearly showing arch height ? Maybe it´s just me?

Attached Images

arch height.jpg (8.1 KB, 116 views)

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Mike Weber.



Crazy Mary

Mike,
We're kind of going off-topic here. I agree with your reasoning BTW.

Arch height is not too important clinically except to ensure that the contour of the orthotic fits. I do that with a cast, like most of us. I don't believe that either the Tekscan or RS Scan show arch height accurately. With Tekscan it doesn't matter, because all we want to verify in a foot which may have been referred in as being flat is "is there an arch". Tekscan or a wet footprint can show this - Tekscan can store the information.
With RS Scan it does matter, because that system is used to measure accurate arch height prior to prescribing orthotics. This is difficult to do with a 2D system, as has been discussed here before.

I also think that this is a misuse of the system. You can't get arch height from 2-d and you are misrepresenting the capabilities of the system. When people come to me with an arch and say they have flat feet, I just tell them they may be low average and they seem to accept that and that there problem is not that their feet are flat, it's that there feet hurt. I don't need a force plate to do that.


I usually point to the inside of their shoe to show that they are overloading an area.

I concede the point on a measurement of intoing, if you take multiple passes and average them. But do you actually treat intoeing. And if you do, don't most of the results come from external hip rotation, which is something that you would see better with video.

I do know this, I'm just questioning whether you need the cool looking computer screen to get the value that you say you are getting.

So, does the data change the treatment plan? How often have you retrieved data on a patient? A good analogy is an x-ray. It is sometimes nice to compare to prior films to assess progress.

My problem is the efficiency of use of health care money. I'm questioning the value added by the amount spent on gait analysis. I think a very interesting study would be to look at the use of inshoe pressure on the evaluation of pressure reduction insoles prior to the patient walking out the door. Modifications of the insole based on pressure data might prevent some problems. There might be some value there, but a lot of information can be obtained in other, less expensive, ways.


It appears to be pretty easy to put a picture into EMR. It shouldn't be much harder to put a digital video clip in as well. I have no experience here, but I do have experience with a force plate. It was hard to decide how much of the footprint data to save. How often do you go back to look at the data?

Agreed. So, your reasons are patient education and recording how they walk at a certain time? Were there any others? What I'm saying is that you may be able to do those tasks equally as well without the gait analysis system.

If you are asked to consult on a patient, you will add your expert opinion to the report. That is what referring people want from you. The question is what is added by the gait analysis system.

Eric

Eric

[quote=efuller;198180]


My problem is the efficiency of use of health care money. I'm questioning the value added by the amount spent on gait analysis.
In the grand scheme of things, and considering the money spent on (some) surgery and imaging I believe that conservative measures which may include the use of gait analysis systems offer good value for money.



So, your reasons are patient education and recording how they walk at a certain time? Were there any others? What I'm saying is that you may be able to do those tasks equally as well without the gait analysis system.
But why? The system is easy to use, non-invasive, fun for children, informative for adults, data collection is not expensive compared to, say, an MRI, or medication maintained foot-pain treatment. I can see no good reason not to use it.

If you are asked to consult on a patient, you will add your expert opinion to the report. That is what referring people want from you. The question is what is added by the gait analysis system.
Of course. That is what I do. Usually though I'm handed the case to sort out - a "diagnosis" is sometimes handed to me too, sometimes it is wrong.
The gait analysis system records objectively what I see when I walk the patient. The Tekscan is not as accurate as the Musgrave, which I believe is much better as a predictor of tissue damage or ulceration, in diabetes or compromised circulation (as per Cavanagh).

You asked about in-toeing. It's highly satisfying to compare a footprint five years later which shows the foot is now straight. In most cases of course this is simply normal hip derotation. I take no credit there. But I contend that orthoses may stop some of the deforming forces as the foot tries to accomodate to the ground....(new thread).

You also asked about how often I referred back to the data. Not often, but that's not the point. The point is that the data is there for me to refer back to, instantly if need be, at any time. I refer back to perhaps one or two cases in a three month period.

I also carry a stills digital camera nowadays for my medicolegal cases. Those pictures may not be strictly necessary either, but I promise you that the instructing lawyers appreciate having them as part of the content of a courts-ready medicolegal report.


David

You could perform an arch index, but that would require quantification, and as you were at pains to point out, you don't quantify. Moreover, the relationship between something like Staheli's arch index and the actual height of the arch is questionable. http://www.ejbjs.org/cgi/reprint/69/3/426


So, do I agree that the static stance print that you get from the activation of sensors in a pressure mat, or a wet footprint test "show standing arch height pretty clearly"? Not really, no. "Of course - you already knew that............."

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

Craig,

Useful is a great word and a well --- useful, principle to aim for.

To answer the question 'what useful information can you glean from a pressure measuring device (PMD) that you cannot get from other clinical evaluation techniques?'

These could be defined as corporate or universal usefulness

1) A permanent precise record
2) Comparable data from a inter and intra clinician repeatable technique
3) Confirmation of standard references and the variation from that standard reference.
4) Standard references that are precisely communicable
5) Standard references that are testable and falsifiable.
6) Quantifiable data

To answer the question ' Does this information change your prescription values and orthotic design?'

This could be defined as personal or singular usefulness - in other words these are relative to my / a person's acceptance of the truthfulness or reliability of the interpretation (human and machine) of the data output.

1) Yes
Saying more than that requires me to validate each statement and that would take hours and could only be successfully concluded when/if you accept my initial assumptions and axioms. NB I do have a 1 day training seminar on that subject.

For example I would say that FncHL is indicated when the peak of the force time curve applied by the hallux occurs later than that of the 1st MPJ. I.E. hallux force is increasing while 1st MPJ force is decreasing. Confirmation of FncHL would result in a definite orthotic design.

Regards Dave

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Descartes seems to consider here that beliefs formed by pure reasoning are less doubtful than those formed through perception.

What, like a kinetic wedge? http://www.asbweb.org/conferences/2003/pdfs/163.pdf http://www.health.uottawa.ca/biomech...s/isb19_kr.pdf I know you're talking timing, Dave. But do we have any data which shows a change in temporal measures with such a modification? Nice little study for you.

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

I am not disagreeing with you, I just want those who are considering buying any system to ask those questions rather than buy them for the "bells and whistles".

__________________
Craig Payne
__________________________________________________ ___________________________________
Follow me on Twitter | Run Junkie | Latest Blog Post: Foot pronation is not associated with increased injury risk in novice runners wearing a neutral shoe
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.

Leaving Tekscan alone for a minute, you don't think you can show standing arch height (not quantified of course) with a wet footprint? Just to clarify, because I don't want this taken out of context, I discussed this in terms of showing whether a foot was flat or not.

Yeah, really. Your contention being that you can infer the height of the medial longitudinal arch from a qualitative viewing of a 2D pressure mat read-out. Tell me how you do this?

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

Please see the last line of my last post.

I think I've put enough info on this thread to show how I use a pressure mat.
I hope some find it useful.

You said regarding a foot pressure mat: Now that last line of your post was a question: No, I don't think you can show standing arch height clearly with a wet foot print or a 2d pressure mat output, which is why I started asking you about this. So enlighten me as to how you do it....

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."