MASS - Questions un-answered

No, I am arguing that it is more important to measure the foot than it is to measure the orthotic. Yes, both are important, but MASS is treating all feet as the same when we know they are different (supination resistance). One thing engineers do is look at is measurement error to see if their measurement is good enough. I'm saying that using your fingers in the patient's arch is good enough to tell the difference from an easy foot to supinate from a hard foot to supinate.

On the other hand, you don't need to know the exact stiffness of your orthotic under load from a bladder to estimate whether you should use 1/8th", 5/32nd" or 3/16th polyproplyene. What is your range of acceptable stiffness for an orthotic. So, are you using rate of return of orthotics to the lab as a measure that you have determined the correct stiffness? Don't you think there could be some error in that measurement? Do you include a prepaid mailer to be given to the patient that says if you are unsatisfied with these orthotics, mail them in and we will refund what you paid to your practioner. I'm not saying you should do that. I'm just saying you would get a different error rate. Maybe you should calibrate that.

Eric

 

Measurement of the axis does not add anything directly to the orthotic, but it does help in changing the prescription for the orthotic. Adding a medial heel skive to an orthotic does do something meaningful. Do you actually believe that a medial heel skive does nothing? What do you mean by mods? The skive is incorporated into the orthotic.

What do you mean by take into consideration? If you ignore the STJ axis, you are ignoring one of the axes of the foot. How do you know your redistribution of force is better if you don't look at it in terms of moments about joint axes. You apparently are not considering all joints of the foot. That last quote is a claim that you cannot substantiate.

Eric

 

Huh? This statement is such a contradiction I find it difficult to look at. For years the acronym MASS stood for Maximum Arch Subtalar Stabilization and today Ed and his team have conveniently changed the meaning to Maximum Arch Supination Stabilization. At what point did the subtalar joint axis not become important in the function of the foot and the design of the orthosis Ed? You clearly infer that all axes are important just after negating the importance of the STJ axis?

I propose the STJ axis became less important when 'posture' became the direction of your marketing and the change in the meaning of the MASS acronym. Supination around what axis?

Can I have more syrup with that waffle Ed?

 

Easy and Hard....a kind of two valued logic.
As opposed to a digital measurement.
Who said that we are calibrating anything the same....even left to right.
As I stated, we use Body Weight, foot flexibility and activity level for downward force and a measurement of orthotic resistance for upward force. It is kind of like a COP for the ORF at midstance.
The error in defect code measurement is mitigated by the size of the "n", about 300,000 since defect codes were installed.
No, they do not have a prepaid mailer. They have free Fed Ex boxes and a supply of two day billable stamps that allows all of my customers to peel and stick, call for a pickup as they usually do, and warrantees are treated as one day lab rushes at all times.
We deliver barefoot service....service that will knock your socks off. It is how our Professional Relations Department Makes People Better. They make our client's experience better.

So how do you calculate the downward force of the body to make a determination between " 1/8th", 5/32nd" or 3/16th polyproplyene"....and then how do you measure that the polypro is actually delivering the force you desire. Maybe you put it into the easy basket or hard basket.

Ed

 

There are three values. Hard, medium and easy. Hard gets medial heel skive, medium no skive, easy lateral heel skive. If you have three treatment options, if you digitized it to three significant figures, you'd still have to have a cutoff value at which you change the treatment.

Ed, could you explain what you are trying to say. Newton's 3rd law says that the upward force has to equal the downward force.

How is "it" kind of like CoP?

Large N doesn't help if there is systematic error.

Eric

 

Broadband was down at home all weekend. Sorry.:bang:

I'll make a full reply when I can, but one point leaps out at me based on the above points. Please don't think this a personal attack, it really isn't.

What you are saying above is that you are engaged in a massive clinical trial, the results of which superceed any other work done on the subject. We might argue the toss over how valid that is, and we will, but one point before that.

If this is the justification for your position then it makes any further debate impossible. It is essentially a tautological point. You're right because it works, it works because you're right. How do you know you're right? Because it works. And so proceeds ad infinitum.

This creates a problem in discussing this issue! Because from within this logical loop, any other concept is de facto wrong, and outside of the loop, anything within it is suspect.

I don't know if I am expressing myself clearly. Let me ask you this, and please think carefully about the answer rather than reflexing.

A now defunct UK orthoses supplier used to claim a 98.5% cure rate for plantar fasciitis based on their return figures (using bog standard poly shells).

Do you believe that their poly shells (root neutral) had a 98.5 success rate?

If not, why not?

How are your claims different to theirs?

I will address your answer in more detail if I get time today.

Cheers
Robert


PS

Indeed:drinks

 

OK!

1) We can measure body weight, agreed, yet as has been pointed out, body weight has no correlation to supination resistance.

As your devices are designed to supinate the foot, how do you measure supination resistance and incorporate this into the calibration of the orthoses?

2) How to you measure forefoot flexibility and acurately incorporate the into the calibration of your orthoses?

3) How do you measure Activity Levels and how to you determine how this will affect your calibration variables?

Thanks,

 

Righty then

Very much! As indeed does your assessment of Forefoot flexibility I suspect. Unless you have a souped up cybex machine in every clinic!.

Here's the thing. If I make a WAG of forefoot flexibility it appears to be what it is, a WAG. If I make a WAG and then ascribe it a quantatative value (stiff, 2/5 or whatever), its STILL a WAG. Its just a quantatative assessment of a WAG.

Ta.

Righto.

Body weight is, as I said, not predictive of supination resistance. Evidence aside, i've had 15 stone patients I can supinate with one finger and 9 stone patients I can't supinate at all.

Forefoot flexibility depends on what that means to you and how you measure it. How do you measure forefoot flexibility quantatively.

Activity levels, I can't see this one. Say someone is a keen sportsman and calibrate for that. He then has a lazy week and does no sport, does that mean his insoles are incorrectly calibrated for that particular weeK?

So you are using a measureable variable which is not predictive of supination resistance (weight), a qualatative observation which is a WAG, and a varible which alters week by week.

What are you measuring? Only weight. The other two are not "measurements". They are estimates. WAGs in fact.

Actually, valid point. The study carried out on SR used a rig, but the clinical Supination resistance test should indeed not be thought of as a measurement. Point to you (although "silly" is a perojative term).

Ah, but I'm not. I'm comparing your "measurement" of the foot to mine. Is your method for "measuring" forefoot flexibility any more repeatable, valid or objective than the supination resistance test? What is this method?

I sort of covered this earlier today. Your data may satisfy you, but you cannot say that you don't want to share your data, then in the next that we should accept it! Do you accept that the lab which claimed a 98.5 % success rate based on returns had a 98.5% success rate with their Root neutral devices?

The "hard numbers" you mention, they are not "hard". None of them are. Your "measurement" of the foot is, as I say, based on three variables, only one of which is "hard". Your measurement of the orthotic is based on a measurement which is not predictive of how the dynamic foot works on an insole in vivo. Your return rate may be based on many, many factors besides how accurately an orthotic is matched to a foot.

I guess my point is that ascribing numbers to a subjectively observed variable, like forefoot flexibility, activity level or "insole tolerance" does not make it any less a subjectively observed variable.

I think measuring is a great idea. When it is indeed a measurement. Which is accurate and repeatable. Otherwise it is a guess in a measurements clothing.

I've not seen you show me any measurement tools yet, just ways to quantify your guessed and measurements of things which do not predict real function.

With such resources, I look forward to reading this research in Japma!! Not seen much just yet. What I have has not impressed. Can't keep the data to yourself and still expect to impress people with it. If you have it, bring it out! If you don't plan to publish it, how can you expect us to be swayed by it.

Ed. Open hands. I thought we had an agreement that sarcasm like this did not move the discussion forward! Why'd you do that?

Supination resistance (the clinical test, not the one with the rig) is, as I said, not a measurement. But neither from what I can see is what you are doing. So I echo Grahams question, what are the measurements of which you speak? How do you measure forefoot flexibility? How do you measure activity? How do you measure the behavior of an orthotic under varied load in vivo?

 

Here you go, there are various versions of this splattered across t'interweb.
http://www.castmyfeet.com/Portals/0/ProviderPDF/Prov_New3.pdf

From this site (extracted 13/12/2010):

"After you have determined a total range of motion, you may find that the number is on or near the border of one of the 1 - 5 Gib test ranges. A useful “rule of thumb” is to choose the smaller number of the two ranges because the shell will be made more rigid. In the event that the orthotics are too rigid, an easy lab adjustment can be made to make them more flexible*. If orthotics are originally made too flexible, however, they would have to be completely re-made. Some times, over-flexibility is not evident until after the warranty period is expired so it is wise to err on the side of rigidity. This is especially the case when foot flexibility is in the 1 - 2 ranges. We encourage you to consult our tech support department about any unusual or hard to judge situations.
*Heat adjustments to increase arch height should almost always be tried first before returning orthotics to the lab for adjustment. If uncertain, please consult our tech support department."

Ok..... so a device is too rigid and the solution given is to increase the arch curvature through heat adjustment. Right, so increasing the arch height doesn't increase the stiffness then? :bang: "I'll correct you because you're wrong". If you increase the arch height then the device will be STIFFER in this area not more flexible as intimated above. Moreover, I thought these devices were calibrated? If you start heat adjusting and changing the geometry at the arch, you will inevitably change the stiffness of the device and hence negate the calibration :bash:. Indeed, if the foot was cast in MASS in the first place and you then increase the height of the arch, doesn't this take the foot beyond the MASS position, which is perceived by some (Ed) to be the perfect position to cast the foot in? :sinking: So is MASS plus the right position for some? Or is it the calibration that is in-accurate? Either way, *Heat adjustments to increase arch height should almost always be tried first before returning orthotics to the lab for adjustment. because... "With Sole Supports, gauging foot flexibility
accurately is essential for obtaining a properly calibrated orthosis". k, thanks for that.

 

And BTW, according to Ed's website that I linked to in the above post, forefoot flexibility can be determined by rotating the forefoot on the rearfoot about a single axis passing longitudinally through the 5th metatarsal. As only frontal plane motion is discussed therein, we must conclude that Ed perceives motion in the other planes to be insignificant in orthotic prescription writing and that forefoot to rearfoot motion occurs about a single axis passing longitudinally through the 5th metatarsal. Nice work fella!

Oh! what a tangled (inter)web we weave
When first we practise to.....

 

So, everyone that has an arch that is easy to raise gets a mod to cause more pronation. Everyone in the middle gets no skive mod…..and everyone for whom it is hard to raise the arch you put a supination mod.

Firstly, this three-valued logic is quite subjective.
What happens to people on the borderlines? What are the borderlines? Nothing is really being measured.

It resembles our Gib test (a five valued subjective test) which is being replaced by a more accurate computer measurement of navicular differential between RCSP and MASS…..exactly because it suffers from the same inaccuracy. We constantly strive to improve our measurement technology…..

I guess that is an unnecessary step with such an dead on accurate method like two fingers.

BTW, when someone is unsure of the Gib test borderline, they are instructed to choose the lower number, which tells us that the foot is more flexible. That causes us to make the orthotic more rigid. We can always remove some plastic from the arch later….we cannot add plastic. This does that happen……although luckily for us quite rarely.

A Mod (short for Modification) is any number of lumps, bumps, tilts, flanges, grooves, skives, wedges, cushions, pads , indentations, placed anywhere on the orthotic. It is a method of moving tissue stresses around the bottom of the foot. These are not geometrically identical to the foot and therefore shift pressure and force from one place to another……..Literally herding the tissue stresses around the bottom of the foot. Take the stress from one hot spot by creating another. It creates local concentrations of forces. A basic principal of O and P is full contact to avoid hot spots. It is used on stump sockets. Soft tissue compression is also used in this effort.
These principles can be more effectively utilized on the plantar surface of the foot to spread out the forces, thus reducing hot spots while encouraging the foot into a more effective posture for gait. Mods necessitate arch fill. To make room for these lumpy bumps you must lower the MLA of the orthotic. Usually to the dysfunctional zone, described in my lecture. This is a zone of higher impact between the foot and the orthotic. To make mods tolerable, the arch is usually filled quite a bit by most labs leaving a huge gap between the foot and the orthotic. I tested this on the top Labs in the USA and found it to be almost universal. As the foot enters the pathologic zone, the ligaments tighten up, slowing the velocity of final impulse or impact, reducing its magnitude. The mods along with terminal shell contact, act to dampen the impact…..often reducing peak events below the tissue stress threshold of symptomatology while:
1. No significant change is made in kinematics.
2. Deformities continue their development.
3. Posture is unaffected.
4. No meaningful measurement of kinetic forces is performed.
5. Patients return for peel and move of pads.
6. It is masking symptoms without affecting function

This is the basic decision that each Podiatrist has to make for themselves.

Do they want to hide symptoms or change function?
Do they want to make a significant change in Kinematics…a visible change?
Do they want to slow deformity development or stop and possibly reverse it?
Do they want to effect posture?
Do they want to spend visit after visit peeling and moving lumps and bumps?
Do they really want to add new hot spots or go full contact?
Do they want the geometry of the othotic to be that of the foot with the soft tissues compressed or generic in shape?

Mods is like quantum physics. It is an ugly theory with lots of particles.
Mods involve a lot of guesswork, an art mastered by studying at the feet of the master.
No measurement told you to put the mod there and no measurement told you that it was a correct choice.

I think that the medial heel skive is just another mod to add to your “Bag of Tricks”.
It is interesting from one perspective. By placing the tilt or wedge inside the heel cup you avoid any change in MLA or foot posture. It is designed to avoid postural change….thus it is consistent with the model as it is applied.
Not to say it has no effect….just marginal effect when compared to full contact strategies.

I believe Mods are less effective than a strategy that is in full contact, that alters gait via its geometry and how that geometry supplies a spring force into the arch to attempt to change posture.

Changing posture will more fundamentally alter STJ axial translation and thus lower supination resistance. If you look at MASS thru the lens of SALRE.: Our full contact, postural approach to changing gait is far more effective than leaving the axis in its most damaging translational position, that is allowing the foot to assume its most pathologic posture, and then moving hot spots. Changing posture moves the STJ axis to a more efficient translational position where the balance of forces around the STJ axis and all other axes is improved. The foot is closed packed, tighter and a better propulsive lever. SALRE would predict that MASS is a more favorable posture than near RCSP where these tissue stress orthotics live.

Actually, the downward force of the human body should exceed at Midstance, the upward force of the orthotic allowing for orthotic flexion.

By measuring the force that the orthotic delivers to the body we can more easily adjust that force into a range that will not collapse beneath the body weight nor be intolerably stiff…..

It is like COP in magnitude, not in exact placement. Placement of forces varies throughout the gait cycle, but the orthotic is a fixed quantity at this point. Someday I can imagine a time when orthotics may deliver a dynamically changing force throughout the gait cycle, but they will still be most effective, I believe, at MASS posture in full contact. Mods will not likely be part of the equation.

When in full contact, there is no space for mods, they create hot spots, and they may be harmful causes of overcorrection when combined with MASS posture.

Since we are aiming for a range of forces that falls between parameters that are assessed by each patient in a subjective manner, warranty statistics do not have a systematic error. They have direct clinical relevance.

To answer how the measurements of supination resistance and weight are not related, but in MASS full contact calibrated orthotics body weight is important and relevant I would like to discuss the difference.

When a patient simply stands in RCSP the body’s total downward force is directly related to weight. Most or all of the force however is distributed on the weight bearing surfaces…the heel and forefoot in most cases. Therefore the additional force placed in the arch is not trying to counteract weight.
When the orthotic is in a posture considerably more Supinated than RCSP the downward force of the human body is moved from the ball of the foot and heel, to the entire plantar surface of the foot. The MLA becomes a weight bearing structure and therefore body weight becomes relevant…..BUT the posture when corrected, has a strong influence on the amount of force that is necessary to create a postural change due in part to how it moves many or all axes into different configurations. This changes moments.

Wouldn’t supination resistance be more relevant if you were actually trying to affect a change in posture? Why measure the resistance to change and then not make that change? Here’s how much force it will take to change the posture from RCSP to a more efficient posture but we’re going to leave the foot near RCSP….and just move kinetic forces around.

Ed

 

Is this because you recommend making the orthotic more "flexible" by increasing arch height using "heat adjustment" [this should make it stiffer] before returning it to the lab, to then make it more flexible by grinding material out of the arch? Laugh, I almost crashed my doughnuts out. http://www.castmyfeet.com/Portals/0/.../Prov_New3.pdf

Suggestions of making it up as you go along........

 

We changed the wording because we did not want to mislead the practitioner into concerning themselves with a singular axis but the meaning remains the same.

We capture the Maximum Arch that puts the foot in adequate Supination to achieve external rotation of the talus on the calcaneus which Stabilizes the Subtalar joint in the Sagittal plane for more effective propulsion.

We could have called it MASSSS but thought it better to keep the acronym simpler.

We could have chosen other words for the acronym but the meaning remains the same.

You are correct. As we realized the importance of posture and were able to see Single Axis theories like Neutral and SALRE as being an inadequate way of describing foot posture we changed the acronym to reflect our new understanding. We made no secret of that.

Ed

 

But measuring forefoot to rearfoot motion about a single axis as you describe here http://www.castmyfeet.com/Portals/0/.../Prov_New3.pdf is OK?

 

The increase in arch curvature is usually less than 1/8” in its apex. The change in rigidity that is caused by that increase is quite small. But you would not know that because you cannot measure it…..we can. You are increasing arch height after a full contact heel raise test, to reduce impact force which is done by achieving full contact. The foot does not have to drop down and hit the orthotic because it is already touching it.

Often patients who feel some discomfort in their arches with MASS orthotics are not feeling it because the orthoses are miscalibrated, which is also possible, but more likely, in our vast experience with MASS technology (as compared to your zero experience with MASS calibrated devices) have complete relief when the calibrated shell is placed in full contact with the foot in MASS posture. Possibly, the practitioner did not supinate the foot adequately for many reasons. Maybe the patient was tightening their muscles during casting, maybe they were tired, maybe the patient had a painful midfoot due to their injury or condition and the doctor avoided moving the foot adequately. There are too many variables to consider. We simply test it with the heel raise test full contact test, heat adjust the orthotic slightly and in most cases it is fixed. This is how we learned how much drop in the MLA usually causes impact related symptoms. We find it to be about 3/16”. That much error in casting happens routinely with off weight bearing casting just due to the fact that soft tissues are not compressed.

Ed

 

Ed, how can you know what the change in arch curvature is when this is something you advocate that practitioners do before returning the devices to your lab. Frankly, you have no idea of all of the adjustments carried out by said practitioners. Moreover, lets pretend that you do know the change is less than 1/8 of an inch and that this doesn't make a big difference to stiffness, then why on earth do you advocate for practitioners to do this? Secondly, I do know because, unlike you, I can measure it. You forget that I do have finite element analysis capability and can manipulate arch height within orthosis to the nth degree and then run the analyses. So unlike you, I know exactly how changes in the shell geometry will influence the stress / strain characteristics across the entire foot orthosis- can you do this with you bladder? The full contact bit of this post is bull**** as well you know and irrelevant to the points I raise, as is the rest of your post which is clearly intended as a diversion to you avoiding the point.

Here's the reality: In your website here:
http://www.castmyfeet.com/Portals/0/.../Prov_New3.pdf

You advocate increasing arch height to increase flexibility, this is wrong. Both you and I know this is wrong. So just take the shame.

You also know that heat adjusting the arch changes the calibration- again, take the shame.

You also know that elevating the arch takes the foot beyond the MASS position- just take the shame, like a man.

Or tell me why I'm wrong with my points above, never mind the bull**** just address the points above. I'm a practitioner with a heat gun in my hand... You have no idea what I can or can't do with it.
P.S. Have a nice day.

 

We knew that foot flexibility was a factor so we devised a test that copied what the forefoot was doing during its postural collapse. The fifth metatarsal is stable on the ground all of the joints of the midfoot contribute, not just the STJ, to the postural collapse by rotating around the stable fifth met.

The Gib test has served our purposes well to this point but is being replaced because of more fundamental problems revolving around the difference between total ROM of the forefoot (which correlates somewhat well to foot flexibility in a functional sense) off weight bearing and actual closed chain dynamics.

Someday few practitioners will use it, but it works quite well until we can develop something to replace it....which we did with our new Geometric Laser Imaging System we call the G-laser (after me) and Postural Analysis. The Navicular Differential suffered from measurement errors that were large in comparison to the actual magnitude of the measurement. Computer Postural Analysis derived navicular differential is testing out to be a better measurement for flexibility because it illustrates what does happen in the closed chain during gait with the soft tissues compressed.

Don't think for a second that we are not continually critically assessing our current techniques and improving them. That is why we have 6 full time engineers on staff.
The bigger we grow the faster we innovate and improve.

Measuring one of the variables that effects downward force around a single axis is not the same as using one axis as the fulcrum of a two dimensional see saw to guide the placement of mods as a strategic focus. We don't have the practitioner draw the fifth ray axis on the bottom of the foot and try to balance kinetic forces around it. You are just misleading and confusing the reader. You should not practice to deceive. We don't.
We can explain WHY we do what we do....clearly and simply.....and doctors who use it, love it. We do it because, we have tried many different combinations of treatment protocols and to our knowledge and experience....this approach is the best at achieving our intention....We Make People Better. That is the brass ring.

Ed

 

So the tests you advocate using are flawed. No brainer. Next.

Address the points Ed:
1) does increasing arch height of an orthosis increase or decrease it's stiffness?
2) does changing the arch height of an orthosis alter the arch load/deformation characteristics, viz. its "calibration"?
3) If a foot is cast in MASS and a device is subsequently made to this cast, does elevating the height of the arch through heat modification take the orthosis and/ or foot beyond the MASS position?

 

Is this an indication of a weapon of MASS distraction?

A new axes of evil?

No posturing now. Invade! Invade!:boxing:

 

I've chosen to remove this because it didn't add to the thread.

 

nor, this. I just want the points I've made above to be addressed.

 

After a person has been a final grinder at Mastery level for five years, they are sent to cPed school and then undergo extensive additional training. They are our technical support team….a free unlimited service to our clients. I dare say that these people have flexed more orthotics in one year than you will see in many lifetimes.
They also participate in a clinic that is open to the public, serving our local community with inexpensive orthotic care. This gives them considerable clinical experience as well. They do many of the heat adjustments and re-calibrations that come in on warranty. So they know how much a 1/8” change in arch height can change the calibration.

True, after the practitioner takes delivery they may do adjustments that we are unaware of….so what. What is your point.

In virtual reality, 3D virtual space FEA can calculate the correct flexibility, but if you cannot then measure (something you do not do), the physical object, you have no way of knowing if the assumptions that you made in virtual space apply correctly to the physical universe. No, you don’t know “exactly” until you can verify. Now make 300 pairs per day that way and carefully follow the defect codes and we can talk.

My engineers are also experimenting with FEA among many other things.

The full contact bit, as you call it is not BS at all. We have seen it work on thousands of cases with our clients, in our clinic and during my clinical practice. I would be hard pressed to change something that works based on your general opinion that everything I do is wrong just because you did not think of it, consider it, try it or evaluate it. If something works, we keep it until we come up with something better. That is just good business practice, good medical care and good science. We base decisions on data and what Makes People Better. Period.

No one said increase arch height to increase flexibility. We both know that increasing the arch height of the plastic to a significant degree will increase rigidity. The small change made has a more significant effect on impact than plastic resistance. Or another way to look at it is….we reduce impact and its associated discomfort but still keep the plastic rigidity within therapeutic range.

It depends on the Molecular weight of the plastic. Modulus of Elasticity. What temperature you bring the plastic to, how you cool it and the number of times you adjust it. After a certain number of adjustments are tried….and again this is an extremely rare occurrence, or else we would address it, we sometimes will remake the orthotic off a new cast with specific recommendations to the practitioner to improve his or her casting technique. That is why we require certification before a practitioner can utilize our lab. We make an honest attempt to standardize casting as much as possible. What other lab does that?

Exact is not an adjective I would use to describe any casting or calibration method to date. We are working on that too.

Wrong. That is why we test with the full contact heel raise test. The arch is only raised if a clinical determination is made that there is too much space between the orthotic and the foot in MASS Posture.

Shame on you Simon for NOT bringing a calibrated orthotic to market and then learning from your results.

Shame on you for blindly criticizing any attempt at calibration when you have not developed a viable system yourself. If you had one….it would be a commercial success…..like MASS..

Believe me, there is no Shame is trying to produce the best foot orthotic one can with the resources available. Science is moving forward and we are in the forefront of that change.

I did.

So, I suggest that you keep drawing lines on the bottom of feet, pushing up with your two fingers.

If you are so advanced with FEA, why don’t you take the full contact MASS approach (at varying resistances) in virtual space and your low flat tilted polypropylene generic shell with mods approach and see which is more effective.

I would ask one of my software engineers to do it but they are working on other projects. If you are using Pro Engineer or any standard format that is importable, you should be able to send me the file so I can view it for myself. I think it would be eye opening. And try to leave out the Bias.

Ed

 

Cute...
Very clever.
Ed

 

All answered in recent post.
Ed

 

Ed thank you for responding. I won't belabor the point on this thread as you appear to have your hands full already with Eric, Simon, Robert and Graham . I will repost this in the thread here:

http://www.podiatry-arena.com/podiatry-forum/showthread.php?p=184190#post184190

 

Science necessitates change. Change necessitates science. While MASS encourages change it does so with disregard for science. MASS therefore = CHAOS. CHAOS = probable unpredicatability.

 

Ah right. The Gib test. Indeed.

As I stated, I think measurement is a bit strong a word for the Gib test. Its pretty crude, as Simon stated the the midfoot does'nt work on that axis or indeed any single axis. Don't know if any research has been done on repeatability or validity for it but its not really a measurement regardless.

Nor, come to that, is activity level.

To be fair, I applaud the effort and the concept. I think that it includes a variable in prescribing which many don't consider at all! Whatever I might think about the methods used or the claims made I think that can only be good for the profession. What Ed is trying to do here (in our terms) is to get people thinking in terms of kinetics as well as kinematics. Fair play, this is a concept which many (most) people are not yet familier with.

But I do think that to claim that this is "measurement" and "calibration" is to overstate the case somewhat.

What we are looking at is supination resistance. Here is a serious offer for you Ed. What if you set aside a corner of your plastics lab, workshop or whatever, to construct a rig for MEASURING supination resistance, like the one Craig created, that can be commercially produced as a product for in office testing of supination resistance. I would be quite excited by a project like that. If we are all trying to measure the supination resistance (or residual pronation moment in my language), rather than struggle to extrapolate it from other variables, why not measure it directly? If you have the resources, that could be a goer!

 

Thanks for addressing the MASS letters thing BTW

 

Already got one under my desk. Did try and get it commercialised, there was some interest but it seemed to get lost with other ideas and projects. Phil?

 

What we are looking at is supination resistance. Here is a serious offer for you Ed. What if you set aside a corner of your plastics lab, workshop or whatever, to construct a rig for MEASURING supination resistance, like the one Craig created, that can be commercially produced as a product for in office testing of supination resistance. I would be quite excited by a project like that. If we are all trying to measure the supination resistance (or residual pronation moment in my language), rather than struggle to extrapolate it from other variables, why not measure it directly? If you have the resources, that could be a goer![/QUOTE]

Just A question: Is the goal, to apply supination resistance forces, to have a Kinamatic effect, and if so, how much? If not. At what point (before movement) does the orthotic have a positive effect, ie: how much force?

Cheers

 

WOW, mastery level grinding for five years you say? I've been grinding foot orthosis for twenty years, you have no idea about the numbers of devices I've personally manufactured during that time. And moreover, this statement of yours above is once again a diversion since it has little to do with the point in hand.

So you are saying that the arch height of the devices are only ever adjusted by 1/8 of an inch- right? You are also inferring that adjusting the arch height of the devices by 1/8 inch doesn't change their stiffness- right? I thought the whole point of sending the devices back to your lab was to change their stiffness? Since you wrote on your webpage:
"In the event that the orthotics are too rigid, an easy lab adjustment can be made to make them more flexible*. If orthotics are originally made too flexible, however, they would have to be completely re-made. Some times, over-flexibility is not evident until after the warranty period is expired so it is wise to err on the side of rigidity. This is especially the case when foot flexibility is in the 1 - 2 ranges. We encourage you to consult our tech support department about any unusual or hard to judge situations.
*Heat adjustments to increase arch height should almost always be tried first before returning orthotics to the lab for adjustment. If uncertain, please consult our tech support department."

Exactly. My point being that YOU state for the practitioner, before sending devices which are too stiff back to your lab that "Heat adjustments to increase arch height should almost always be tried first" So you have no idea about how your so called calibration has been altered. AND MY POINT IS THAT ELEVATING THE ARCH WILL MAKE THE DEVICE STIFFER NOT MORE FLEXIBLE. You clearly state above that when a device is too rigid they should attempt to rectify this before returning the devices to your lab by heating and elevating the arch of the device. This is fundamentally wrong.

Ed, I've run validation studies on the FEA models via physical testing, there is no problem with the validity of the models. So why do I need to manufacture 300 pairs a day? Once again, your point is about as relevant as a bicycle is to a fish.

Irrelevant.

Yes you did: "In the event that the orthotics are too rigid, an easy lab adjustment can be made to make them more flexible*.
*Heat adjustments to increase arch height should almost always be tried first before returning orthotics to the lab for adjustment."

I'll come back to the rest, later.

 

The thing about supination testing that I always find a bit limiting is that we take a " test/measurement" at midstance and then we say that this shows us supination resistance. It might but only at the split second of the gait cycle.

It does not take into the effect of windlass on the amount of supination resistance - which may stay the same, go up or go down. Muscle function also changes during dynamic v´s static etc etc

If you going to build a ring and Ed always saying how much ´splash´hes got why not look at dynamic rig which can look at supination resistance which takes into account the stage of the gait cycle the foot is in.

This would give us useful information.

This tissue is stressed
This tissue is stressed at this point of the gait cycle -

for sake of discussion we say the forces providing stress come from pronation

Supination resistance is x newtons at this stage of the gait cycle

this info will give us much more to work with and help much much more with orthotic prescription variables in my option.

The rig already been built and with a little time most people could build one themselves for static measurements.

 

Great question. The orthotic has a kinetic effect as soon as there is a reaction force between the foot and the orthotic. In measuring supination stiffness of the foot with my jig I look at the load/ deformation data. I'm playing around with accelerometers to detect when motion occurs. The simple answer to your question is that there is no single answer, it will vary between individuals.

 

To do dynamic testing you don't need a rig, you need a pressure mat or ideally a force plate and a method of recording the 2 dimensional or ideally 3-dimensional kinematics of the navicular/ arch of the foot. This is the dynamic navicular stiffness (dynamic medial longitudinal arch stiffness) test I was discussing the other day. Mike, think about how leg stiffness is measured, then you'll see how it can be done, I'm sure.

 

Thanks, but why not? The variation is only how much pronation/supination resistance and how far med/lat the axis is, which will determine force required. I get, an orthotic dosen't have to move the foot, and only have a kinetic effect to relieve symptoms from tissue stress. Take the stress away from the tissue and bingo! But... how long does the symptom relief last? From my experience, (28yrs) I see a lot of people returning, after 5 or more years with orthotics that worked originally, but now have the same pain again. You look at the orthotics and think...your feet aren't even moving when you stand on them and look no different. How did they work in the first place! Re-cast and make an orthotic that puts the foot in a better position (God forbid...closer to neutral!) and it's happy days.

If you say you've got a device that measures force, well I've got a device that applies force. There's a formula there, and I believe the whole things measureable and outcome predictable.

If anyone on this site has the brains to pull off a project as big as that ,you'd be the one. Not to stray from the thread. I like the idea that Ed has come up with a formula for pushing the feet into a foam box in a certain way, calabrate the orthotic material thickness (based on weight not resistance, which is wrong IMO) that only focus's on the MLA and no other segment of the foot, must be working cause he seems like he's killing it-No pun intended. But...is it the way of the future? I don't believe so, because of the force problem which manifests itself in other ways because of so many other factors, ie: muscle tightness, fascia, ligament, bone...

I just spent about 50K going to a Pedorthic conference in Olando Florida to see what interest there, may be, in that thingymajig... you know the one, but I don't think many people got it. Hey...why would you want to apply medial or lateral force to the plantar surface of the foot (3 segments, individually or all at once, heel height and pitch), take a mold of that position to produce an orthoses?

One Uni. One College and One Pedorthic traning College got it and wanted to use it as a traing tool for students to teach the Kinetic and Kinematic effect an orthoses will have on the foot before it's made. I believe you would be best to do it. At my expence (obviously!)

Please don't take the offer the wrong way. It's not an offer to get all cuddly and warm, cause I know, from reading most of your posts, you aint the Christmas card sort of a guy.

There's a formula there, it just needs the right tools to calibrate it.

Cheers

 

What you say sounds interesting. But its so hard to follow what you are saying I can't be sure!!:hammer:

Here's fun. It would not be excessively hard to design a supination resistance rig in which one could control the force vector, and the area to which force was applied as well as the amount of force. I wonder if that would derive some interesting data if combined with planal dominance measurement

 

Why don't you send me your proposition privately so as I might better understand what it is you want me to do? My thing applies and measures force too, btw.

skspooner@blueyonder.co.uk

 

Totally doable. I see no reason why it can't. A pressure mat on top of the foot foams as your correcting the feet...done!

 

Axial position only predicted about 30% of the variance in supination resistance in Craig's study (if memory serves), which means a further 70% is due to something other, body weight, x1, x2, ...xn

What you need is the model that says supination resistance = mx1 + x2 +... xn +c, in other words,the multiple regression model which predicts supination resistance and accounts for as much of it's variance as possible (high rsquare).

 

Can already do that too. I was talking with the uni here and they were going to help with the development and research, but they basically wanted me to sign everything over to them. So I pulled out.