Important Historical Biomechanics Papers

Re: The Papers of Dr. Merton Root

"A functional orthotic must:...
3. Maintain the foot near the neutral position while standing, even in the presence of various structural abnormalities of the foot and leg."
Page 5: Neutral position casting techniques. Root et al.

 

Re: The Papers of Dr. Merton Root

Simon:

I stand corrected. It has been about 20 years since I looked at that book. Good find.:drinks

 

Re: The Papers of Dr. Merton Root

Which was one of Root's objectives.

 

Re: The Papers of Dr. Merton Root

Believe me, Mert Root corrected me many times in his seminars...I guess I just never got it.

 

Re: The Papers of Dr. Merton Root

Root theorized that the more everted the heel became, the more difficult it would be to control it. In fact, he said that if the heel was everted more than a few degrees, it would probably continue to evert to its end range of motion. He believed that in relaxed stance, the ideal foot would be in or very close to the neutral position at the STJ. So during relaxed stance, it is logical that an orthosis that restores "normal" function according to Root would place the foot at or near the neural position.

Simon, you only posted an isolated section of the book which again takes it out of context. So let’s look at the preceding section which says:
The purpose and Objective of the Neutral Position Casting Technique
The purpose of this casting technique is to provide a reproduction of the foot from which a functional orthotic can be made. A functional orthotic is a device which controls motion and position of the foot during locomotion. It re-established normal function within the physical limits of the patient.

A normal foot pronates at heel strike becoming a mobile adapter to variances of terrain and body position. It must then supinate, during propulsion, to become a rigid lever which is stable and bears weight without hypermobility. The orthotic should influence the calcaneus to create normal subtalar joint pronation and supination during locomotion. It should also influence the forefoot to create a fully pronated (locked) position of the midtarsal joint during the last half of the stance phase of gait. While allowing for normal motion of the foot, the orthotic should prevent:
1. Excessive motion of the foot
2. Inappropriate direction of the foot for each phase of gait
Page 2 of Neutral Position Casting Techniques

On page 5, you failed to quote all three points. They are:
1. Allow normal rearfoot pronation, then supination, during the stance phase of gait. This provides for normal leg rotation during locomotion.
2. Move the foot into a position where it provides its own stability during the last half of the stance phase of gait. A stable foot during propulsion lessens or eliminates abnormal shear forces which traumatize and deform the foot.
3. Maintain the foot near the neutral position while standing, even in the presence of various structural abnormalities of the foot and leg.

Jeff continues: Root was referring to static stance in #3 above. He also wrote in Normal and Abnormal Function of the Foot that static stance was actually a very brief moment of no motion, followed by periods of motion. In other words, he said that static stance isn’t really static.

The casting manual was published in 1971. Those who continue to try to apply a static concept of Root theory are missing the boat 40 years after Root wrote the very words above. So there you have it, in black and white, 40 years ago!

Jeff

 

Classic Anthony Huson: Functional Anatomy of the Foot

I have just added another one of my favorite works in foot biomechanics. Anthony Huson, MD, PhD, was the PhD supervisor for both Van Langelaan and Benink who produced some of the finest research papers ever done on motions of the pedal osseous skeleton. Dr. Huson has authored many papers but this chapter is one of my favorites and was instrumental in allowing me to have the background research so that I could write my paper on subtalar joint axis location and rotational equilibrium.

Huson A: “Functional anatomy of the foot.” Pages 409-431, in Jahss MH (ed): Disorders of the Foot and Ankle. W.B. Saunders Co., Philadelphia, 1991.

Since this high-quality scanned document is too large to load onto Podiatry Arena, I have uploaded it to my website.

http://www.box.net/shared/z9vvdj6lt8

 

Re: Classic Anthony Huson: Functional Anatomy of the Foot

I appreciate your sharing of some great work over the last few days, Kevin. However, they all require a password. Can you disclose this or PM it, please?

Thanks muchly,
Bel

 

Re: The Papers of Dr. Merton Root

Jeff, I'm fully aware of what the rest of the book says, and I thank you for sending it to me to replace the copy I had which was taken by a student and never returned. I was just pointing out to Kevin that your dad did indeed suggest that foot orthoses should attempt to maintain the foot close to neutral, albeit in static stance.

I kind of like the idea of the foot oscillating closely around neutral and avoiding extremes of excursion of the joint and viz. the STJ axis, since this should maintain the restraining tissues of the STJ within their zones of optimal stress (ZOOS).

 

Re: Classic Anthony Huson: Functional Anatomy of the Foot

This is one of my all time favourite chapters.

 

Re: The Papers of Dr. Merton Root

Simon,

I wanted others who might read this thread but do not have the book to see the full context of the quote as it pertains to functional orthotic therapy. For some reason, a lot of podiatrists think that an orthosis is supposed to "hold the foot in the neutral position”. I don't know why they think that but a lot of people have tried to attribute it to Merton Root. Obviously that's not the case. I know you knew that!

Best wishes,
Jeff

 

Re: The Papers of Dr. Merton Root

Jeff,

Is it time to get that anthology/ the complete works published? I'd at least like to have a glance at the unfinished symphony, even in a raw state.

 

Re: The Papers of Dr. Merton Root

Jeff:

Here is page 5 verbatim from the book:

I can very clearly see how someone could interpret, from these words written in the book (Root ML, Weed JH, Orien WP: Neutral Position Casting Techniques, Clinical Biomechanics Corp., Los Angeles, 1971) by Dr. Root and colleagues, that they felt that in order for a foot orthosis to be a "functional foot orthosis" is must maintain the foot near the subtalar joint neutral position during standing. Unfortunately, I can't agree with this declaration of Dr. Root and colleagues since many of the functional foot orthoses I make for my patients with posterior tibial tendon dysfunction do not come close to "maintaining the foot near the neutral position while standing", even though they improve the patient's gait function and symptoms. In addition, Dr. Root and colleagues' declaration also doesn't make sense considering the rotational equilibrium abnormalities seen in more severely medially deviated subtalar joint axes.

My question is if my orthoses are making the patient function better, and relieving their symptoms, why must my foot orthoses also "maintain the foot near the neutral position while standing", to be considered a true "functional foot orthosis"?

 

Re: The Papers of Dr. Merton Root

Kevin,

You don't necessarily always have to maintain the foot at or near the neutral position in static stance in order to eliminate symptoms. You have improved dynamic and static function within the physical limits of the patient or perhaps you have reduced pathological forces to the degree necessary to alleviate, at present, the patient's symptoms. Perhaps they will have problems (symptoms) at some point in the future and perhaps not. As I said earlier, Root also said that preventing the foot from functioning maximally pronated during propulsion is all that is necessary to eliminate symptoms or reduce pathology in some patients.

Jeff

 

Re: The Papers of Dr. Merton Root

Jeff:

These are not the questions I am trying to get answered. I am curious why you believe Dr. Root and his colleagues even included within their book that a functional foot orthosis must put the foot close to neutral position during standing when this certainly has no bearing on whether the orthosis is "functional" or not. In addition, in many feet, putting the foot close to neutral position with an orthosis while standing may actually lead to supination instability problems in that foot.

Why should the rotational position of the subtalar joint while standing on the orthosis be of any concern for the podiatrist or how would that parameter make or break whether that foot orthosis is a functional foot orthosis or not?

In other words, don't you think that #3....

just should have been omitted from their book since the equlibrium position of the subtalar joint while standing likely has little to do as to whether a foot orthosis is "functional" during the dynamics of gait?

 

Re: The Papers of Dr. Merton Root

This is where we run into the two definitions of normal problem seen in Dr. Root's writings. Definition one is essentially the foot is symptom free doing the activities that the patient wants to do. (Paraphrased) I can get behind that definition. And this definition applies to the situation quoted above.

The other definition of normal is the biophysical criteria of normalcy that includes the STJ should be in neutral position in static stance and the axes of the MTJ should be maximally pronated. (I know John Weed taught these, I'm not sure that Mert Root has written them as well.) Knowing what we know now, these criteria are impossible.

Eric

 

The Papers of Dr. Anthony Huson

Here is a collection of foot and lower extremity biomechanics papers from Anthony Huson, MD, PhD. Dr. Huson has been involved in some of the best biomechanics research papers ever done on the foot. Those of you who want to gain a deeper understanding of foot and lower extremity biomechanics would do well to read each of these papers.

 

Re: The Papers of Dr. Merton Root

Kevin,

To answer your question why they put that in the casting manual, I don't know other than the fact that as much as possible, they thought an orthosis should try to restore ideal function. Since they believed that the ideal foot should be in or near the neutral position during relaxed stance, I would speculate that is why it's in there. I agree with you that it is not a critical goal for a functional orthosis, since during bilateral relaxed stance, forces are born by both feet and there is limited potential for trauma to the feet. I know Dr. Root would have agreed with this as well.

Dr. Root believed that it was very important for a functional orthosis to produce resupination of the foot in those feet that did not resupinate adequately because vertical GRF are greatest during propulsion. He believed that there was significant potential for pathology during propulsion and that a properly made functional orthosis, even if it did not create or restore ideal function, could significantly reduce pathological forces by reducing the degree of abnormal pronation during propulsion. This is especially true for individuals who lack stability in the MTJ, such as those with adult acquired flatfoot.

Jeff

 

Re: The Papers of Dr. Merton Root

Jeff:

Thanks for your response. Hope you and your family are having a great Thanksgiving weekend!:drinks

 

Re: The Papers of Dr. Merton Root

Eric,

Root et al stated that all of the biophysical criteria for normalcy are rarely seen and it was up to the clinician to determine how variances to these criteria might contribute to symptomolgy or pathology. The specific quote is on page 34 of Biomechanical Examination of the Foot which says:

A person could reasonably debate the specific criteria for normalcy. However, if those criteria were established by the authors at their option simply as a baseline for comparing one individual to another, then that is there option and you can either use the criteria as a basis for comparison or not. That is up to the individual practitioner. But in order to establish osseous conditions such as forefoot varus, forefoot valgus, plantarflexed 1st ray, metatarsus primus elevatus, rearfoot varus, rearfoot valgus, etc., there has to be a standard position for comparing feet and established criteria to serve as a baseline in order to determine the presence and the relative degree of such conditions. The biophysical criteria established by Root et al have far reaching ramifications since they establish terminology and conditions which have become the standard not only in orthotic therapy but in surgery as well.

Jeff

 

Re: The Papers of Dr. Merton Root

You're welcome Kevin. By the way, as a result of the podiatry arena I finally got around to ordering your three books last week. I'm looking forward to reading them. We are having a nice Thanksgiving but I have to admit that I really miss both of my parents at the holidays. Best wishes to you and your family as well!:drinks

Jeff

 

Re: The Papers of Dr. Merton Root

Jeff:

Hope you enjoy the books.

With my wife, two boys, daughter-in-law, three grandchildren and four dogs all at our house yesterday for Thanksgiving, it was a great time.

Too bad the 49ers didn't fare so well!:drinks

 

Wright, Desai & Henderson: Action of the Subtalar and Ankle Joint Complex during the Stance Phase of Walking

One of the classic pieces of research that came out of the early foot and lower extremity research centers at the University of California Biomechanics Laboratory was that done by Wright, Desai and Henderson in 1962 as a technical report published by the UC Biomechanics Lab (Wright DG, Desai SM, Henderson WH: Action of the subtalar and ankle joint complex during the stance phase of walking. Technical Report #48. University of California Biomechanics Laboratory, San Francisco-Berkeley, June 1962). I was given a copy of this very hard-to-find technical report by Dr. Wright, a foot and ankle orthopedist in 1985, when I briefly worked with him during my early years of private practice.

Wright, Desai and Henderson eventually published their technical report in the classic article published in JBJS a few years later (Wright DG, Desai SM, Henderson WH: Action of the subtalar and ankle-joint complex during the stance phase of walking. JBJS, 46 (A): 361, 1964).

Since it is likely that Dr. Merton Root and his colleagues were attending lectures at the UC Biomechanics Lab during this era and probably had access to this study, it is my belief that the graphs of "normal movements of the subtalar joint" from Normal and Abnormal Function of the Foot and the Compendium came from this study by Wright, Desai and Henderson. Note that this study was done on three subjects while in shoes, not barefoot and this probably greatly affected the results of their study on a few subjects.

I have uploaded this rare and very important technical report to my website for all of you who are interested. In addition, the subsequent 1964 article published in JBJS is attached below.

http://www.box.net/shared/z9vvdj6lt8

 

Re: The Papers of Dr. Merton Root

Jeff wrote

This is an important, even seminal statement and underpins any investigation to discover the cause of pathology. (IMO)

Having started a journey back into some of these old and original thinking ideas and theories is giving me a better idea of why much of the podiatry profession and its podiatrists tend to have the mindset they do i.e. foot posture, static and/or functional, indicates intrinsic and extrinsic pathology.

It appears to me that this mindset only started to change in the mid nineties and the paper in 1998 by Hilton B Menz indicates the turmoil at the time in trying to come to some general consensus of how to quantify all the different measures and models of foot posture and its correlation to pathology.

Luckily I started to learn in 1999 and grew up in my studies on the tail end of foot posture = pathology theory and, perhaps by good fortune, found myself reading the podiatry Jiscmail forum and being influenced by Kirby and concomitant thinkers i.e. using physics and particularly Newtonian mechanics to explain stress in tissues diagnosed as being pathological and by deductive reasoning come to logical conclusions about how to reduce those stress levels and reduce pathology without the need to dogmatically consider the foot posture paradigm.
Later I went on to study applied biomechanics at Strathclyde uni and this cemented the theories postulated by Kirby et al. I therefore grew up thinking this was a normal or usual way of thinking and did not understand why some podiatrists went off on strange tangents related to foot posture = pathology models e.g. Ed Glasers bottom block ans Dr Sha's Functional foot typing.

I have yet to read thru all the Root papers but I'm looking forward to and it occurs to me, reading thru the previous posts commented on and clarified by Jeff Root that perhaps Jef should re publish his dad's paper with annotation by Jeff Root clarifying exactly the thought processes behind Merton Root's thinking as he understands them. Just a small project!!

To finish, I must admit that even tho I try to use the model of tissue stress = pathology I still often find myself defining that in terms of foot posture. Can we escape foot posture modelling? should we? is it useful to try?

Regards Dave

 

Re: The Papers of Dr. Merton Root

How can something that is "normal" be also "rarely seen"? Seems like a contradictory idea to me that wasn't too well thought out. This statement simply doesn't make sense.

Normal: (definition)

2a: according with, constituting, or not deviating from a norm, rule, or principle
2b: conforming to a type, standard, or regular pattern

http://www.merriam-webster.com/dictionary/normal

 

Re: The Papers of Dr. Merton Root

The key words are all of! Therefore "conforming to a type (i.e. foot type) or standard (i.e. Root's "standard" criteria for normalcy) fulfills the requirements of the definition normal.

Kevin, what is a medially or a laterally deviated STJ deviated from? Average, ideal, normal or what? What data or criteria do you use? If you use average (which requires data) and the majority of the population tends to pronate more than they supinate, then a medially and possible pathological average axis is “normal”. Average is not necessarily functionally (biomechanically) ideal, is it? If so, then the ideal angle of hallux abductus would be how many degrees? What angle should the hallux be surgically correct to, given rectus is not the average? And poor vision would be the goal with corrective eyewear and eye surgery since we should correct to average, not ideal? Blood pressure, cholesterol, all these should target average, since the mathematical average is better?

As Root said, variances can be seen without associated pathology and the system serves as a basis for comparison just as a medially or laterally deviated STJ axis is a comparative assessment. A person could have ideal blood pressure and cholesterol levels and still have a stroke or heart attack.

Jeff

 

Re: The Papers of Dr. Merton Root

Once I began to get confident in my clinical examination technique for determining subtalar joint (STJ) axis location, I examined approximately five hundred feet and hypothesized that the feet with the most normal gait function should also have the most normal STJ axis spatial location. In the subjects I examined, the feet that functioned most normally had a STJ axis that passed posteriorly through the posterior-lateral calcaneus and anteriorly passed over approximately the lateral sesamoid. This is how I determined what the "normal STJ axis location" was.

My definition of "normal gait function" were those feet that, during walking, pronated slightly during contact phase, resupinated or stayed stable during late midstance, supinated rapidly during propulsion and were propulsive at the end of stance phase (i.e. not apropulsive). I then published my findings in my first paper on STJ axis location (Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987).

How did Root et al determine what the eight biophysical criteria for normalcy were if these criteria for having a normal foot and lower extremity all only seldom occurred in the same individual?

I would think that abnormalities, rather than normalities, would only rarely occur. I come to this conclusion especially when considering that the definition of normal is "conforming to a type, standard, or regular pattern".

Maybe Root et al should have called their list "Ideal Biophysical Criteria for Normal Function" rather than "Biophysical Criteria for Normalcy"? Also, Root et al seem to use the word "seldom seen clinically" rather than the term "rarely". I can see how the term "seldom seen clinically" would be much more in line with not having all ideal structures present in the same individual, but still having normal gait function.

I suppose the big question was how Root et al determined what should be included as their "biophysical criteria for normalcy"? Was it by examination, unpublished research, theoretical reasoning, or by some other known mechanical concept? This was never described in any of their published works, to my knowledge. Do you have any idea of how they came up with these eight criteria?

 

Re: The Papers of Dr. Merton Root

Jeff:

Also, it would be interesting for me, and I'm sure many others following along, what specific reference was used (or was it a averaging of data from multiple references?) to come up with the illustration (shown as top illustration) for the subtalar joint motion from Figure 6-5, p. 133 from the following reference (Root ML, Orien WP, Weed JH: Normal and Abnormal Function of the Foot. Clinical Biomechanics Corp., Los Angeles, CA, 1977).

I have also included the results (shown as bottom illustration) from one subject from Wright et al for comparison (Wright DG, Desai SM, Henderson WH: Action of the subtalar and ankle joint complex during the stance phase of walking. Technical Report #48. University of California Biomechanics Laboratory, San Francisco-Berkeley, June 1962) that was one of the references that seems to have been used in "Normal and Abnormal".

Since there is no reference used in the legend for Figure 6-5, there is no way for any of us to know how the authors came up with the data to generate the graphs that illustrate normal lower extremity function in this figure, and many other figures, included within "Normal and Abnormal".

 

Re: John Hicks: My Favorite Early Biomechanics Author

I went looking for Hicks JH: The mechanics of the foot III as the series did not seem complete. 1 Author claims that - Hicks JH: The foot as a support full title is Hicks JH: The mechanics of the foot III. The foot as a support. Acta Anatomica, 25:34-45, 1955.

Just seems odd that the serious was broken or title not used.

Thanks again Kevin for posting these

 

Re: The Papers of Dr. Merton Root

Kevin,

I have said before on the Podiatry Arena and elsewhere that I don't like the use of the term "normal" and that I thought they should have used the term "ideal" in its place. Nice that we agree! In either case, it tends to be a value judgment since structural variation is relative and norms tend to change over time, be it global warming or the average height of humans.

I don't know exactly how Root et. al. came up with their biophysical criteria for normalcy, but I do know Dr. Root theorized that the ankle, STJ and MTJ would be stable when this ideal relationship existed. I also know that he theorized that sagittal plane deviations in one or more metatarsals (i.e. pf 1st or 5th, ff varus, ff valgus, 1st or 5th met elevatus, pf 2nd) might result in compensation at other joints, including the MTJ and STJ and that such compensation can sometimes lead to other pathology (i.e. bunions, knee pain, etc.).

Jeff

 

Re: The Papers of Dr. Merton Root

Kevin,

Sorry, I can't help you here. Do you ever have contact with Bill Orien? Perhaps he can answer your question.

Jeff

 

Re: Wright, Desai & Henderson: Action of the Subtalar and Ankle Joint Complex during the Stance Phase of Walking

Thank you Kevin for sharing this classic paper on foot kinematics. I had to track the JBJS article in the stacks of the University of Toronto medical library in the late 1980's. What I would have given for the internet back during that time.

 

Re: Wright, Desai & Henderson: Action of the Subtalar and Ankle Joint Complex during the Stance Phase of Walking

Don't worry Peter, it's only us old guys that know how hard it was back in the old days. I had to walk uphill both to and from the library stacks....in the snow....when I was trying to find papers in the 1980s.

 

Re: Wright, Desai & Henderson: Action of the Subtalar and Ankle Joint Complex during the Stance Phase of Walking

It wasn't so bad going to the stacks and copying papers when the stacks were just down the hall. What was really painful was typing out the citations when writing a paper.

 

Re: John Hicks: My Favorite Early Biomechanics Author

Just reading 3 Weight Bearing Mechanisms Of The Foot. I'll have to read it a few more times before I take it all in. Its certainly increased my understanding of foot function.

Thanks Kevin for pointing out these papers and making them accessible.

 

Classic Bojsen-Moller: High Gear and Low Gear at Push Off

Finn Bojsen-Moller has written some classic articles on foot biomechanics over the years and here is one that I think everyone should read.

Bojsen-Moller F: Calcaneocuboid joint and stability of the longitudinal arch of the foot at high and low gear push off. J Anat, 129:165-176, 1979.

 

Re: Classic Bojsen-Moller: High Gear and Low Gear at Push Off

Thanks, Prof Kirby, I always remember Bojsen-Moller for his wonderful explanations of why toe function shouldn't be messed with, pretty important in shoe design for children. Thanks from Anette Thompson in South Africa.

 

Re: Classic Bojsen-Moller: High Gear and Low Gear at Push Off

Here are two more papers by Finn Bojsen-Moller that are very good and you should all consider reading.

Bojsen-Moller F, Flagstad KE: Plantar aponeurosis and internal architecture of the ball of the foot. J Anat, 121:599-611, 1976.

DeZee M, Bojsen-Moller F, Voigt M: Dynamic viscoelastic behavior of lower extremity tendons during simulated running. J Appl Physio, 89:1352-1359, 2000.

 

Re: The Papers of Dr. Anthony Huson

Estimated Prf Kirby.
I´ll need some long lifes to reed all you´ve posted in Podiatry Arena and other some more for understandig it totally... %[
In admiration, best regards from Spain
Julián Talavera, UEM, Spain

 

Re: The Papers of Dr. Anthony Huson

Julian:

Welcome to Podiatry Arena.:welcome:

The reason for posting these "classic" papers on foot and lower extremity biomechanics here on Podiatry Arena (and making them available on my website) is to provide those of you, who were not aware of the works of these authors, an opportunity to expand your knowledge base. Many times, especially for younger clinicians, there is insufficient exposure to the many older important papers that have shaped our current thought processes. These papers will provide additional insight as to the function of the foot and lower extremity.

Good luck with your studies!:drinks