Prescribing Orthoses: Has Tissue Stress Theory Supplanted Root Theory?

We have this which shows some of the kinetic influences: http://www.jfootankleres.com/content/5/1/20

In terms of validity studies of some elements of the theory and clinical assessment see: http://www.ncbi.nlm.nih.gov/m/pubmed/24959825/

Do we need to perform FEA analysis on every patient? No, but it helps our understanding when such studies are performed.

 

Daniel:

That question you are asking is something we have been discussing here on Podiatry Arena over the past decade. As Simon stated, we do have some research which validates the predicted mechanical effect of the medial heel skive modification but, unfortunately, that research is about it, even though the paper first describing this orthosis modification was published 23 years ago (Kirby KA: The medial heel skive technique: improving pronation control in foot orthoses. JAPMA, 82: 177-188, 1992).

Therefore, even though the medial heel skive is being used around the world by podiatrists and other foot-health specialists to improve the efficacy of their foot orthoses, and has been referenced multiple times in other peer-reviewed publications, there has been only one research paper produced that has investigated its mechanical effects on the human foot and lower extremity over the past 23 years. What does that tell us?

It tells me that we can't simply wait for researchers to validate all the things we do with foot orthoses, or other forms of mechanically-based therapy. We should not be withholding from our patients valuable treatments that have been shown to be clinically effective by our own experience and are theoretically coherent given our knowledge of physics, biomechanics, anatomy, physiology and prior research on the pathologies we treat. Our patients come to us in pain, demanding immediate results to relieve their pain so that they can again resume their daily activities without discomfort and disability. Do you think that patients care if the treatment suggested by their clinician has had Level 1 research performed in multiple medical institutions if this treatment made them better? No, they don't and they will not.

In my 30 years of treating tens of thousands of patients with foot and/or lower extremity pathology, I have never had a single one of these patients ask me about whether the treatment I was proposing had sufficient research to justify it's use on them. Why? Because patients just want to get better. Patients rely on their clinician's training, skill, and judgement to heal them and expect them to use whatever method they deem is safe and appropriate to accomplish that goal.

Therefore, Daniel, don't get caught up in the minutiae and lose sight of the bigger picture of what we can do, and should do, for our patients who are trusting us to give them the best medical care available for their problems. We should all strive toward the goal of achieving the highest level evidence for the treatments we use. However, we should also not let our striving for better research evidence get in our way of making our patients better.

 

Hi All,

I have been reading this discussion with great interest. As an orthotist working with patients with varying degrees of complexity with musculoskeletal and neurological problems i struggled to "believe" neutral theory effectively explained why i was seeing the problems that presented to me in clinic and its practical application didn't give my patients the desired outcomes that i believed were possible.

Rotational Equilibrium and SALRE theory were the first biomechanical explanations that i came across where forces and moments were used in explaining why patients develop problems and possibly why some of the treatments i attempted didnt work out so well.

As an orthotist, we currently look at body segments and consider the moments that are required to create rotational equilibrium through. This is particularly relevant for corrective scoliosis bracing, cruciate bracing etc.

As an undergraduate i remember asking my tutors why we had been taught to generate forces and moments to correct and stabilize body segments such as the knee, but we hadn't been given similar instructions regarding how foot orthosis worked.

I greatly respect the work done by many generations of people far more intelligent than I, to help us understand how the foot works but like all things i believe in continual improvement and evolution.

The purpose of my post is to share a video to get opinions on a rather unusual foot and what principles clinicians would use to treat her orthotically.

Brief history: 62 year old female with Ehler Danlos Syndrome. Suffered a significant ankle eversion sprain aged 35. She has extreme dorsal impingement pain and anterolateral ankle pain. She has normal muscle strength. I believe she has plastically deformed all of her plantar ligaments. She can weight bear for 2 minutes before needing to sit down due to her impingement pains. She can however uniquely stabilize her foot utilising her tib post, tib and and EHL (generating supination moments relative to the STJ axis). It then appears her peroneus longus stabilizes her first ray. She can only maintain this position for 2 minutes (but long enough to wash herself in the shower).

I welcome comments, observations and explanations relating to biomechanical approaches to managing this foot?

https://youtu.be/IBXDZsRcBf8

Best wishes

Simon

 

Simon, I hope your are well. One approach might be to cast her in this "stabilized" position- with the hallux dorsiflexed it is not dissimilar to the casting position advocated by G.K. Rose. I'd then go for a UCBL type device, maybe with a Carlsson skive to the medial heel and/ or a medial heel skive, internal oblique rearfoot post, high medial flange and a kinetic wedge and cluffy wedge at the forefoot. Also high top boots. Just one idea.

 

Where exactly is she having her impingement pain? Where is her STJ axis in relaxed stance position of the STJ? Is the anterolateral ankle pain in the sinus tarsi? And is it made worse by standing on a side slope (high lateral low medial)? Are you familiar with Kevin's rotational equilibrium paper and the picture in that paper that shows what happens at maximal pronation of the STJ?

I'm trying to identify the anatomical structures that are hurting. When you say dorsal impingement I immediately thought anterior ankle (not ant lateral). But it appears that there is plenty of ankle dorsiflexion range of motion in stance. The term impingement could also be impingement anywhere along the first ray. Or it could mean in the sinus tarsi.

Are you familiar with Kevin's supination resistance test? The optimal height of the medial arch of the device will be determined by this test. The medial arch of the orthosis will push the arch of this foot upward. The resistance, from the foot, of this push will determine how comfortable push in this location will be. For example, if you casted this foot in neutral position, with first ray plantarflexed, and added minimal arch fill, you would create an orthoses with a really high arch height. This could be really comfortable, or incredibly painful, depending how much resistance there is to force in the medial arch of the foot. The resistance to force in the arch is dependent on STJ axis position. A highly medially deviated STJ axis will have much more resistance to an upward force applied in the arch.

Eric

 

Eric
She describes her impingement pain over the dorsum of her medial mid foot. She wasn't able to isolate her pain specifically to a joint. Her anterolateral ankle pain was around her sinus tarsi. She also experience pain under her lateral malleolus and cramping pain when correcting her foot as in the video under her arch. Plantarflexion of her midfoot passively illicited pain (suggesting DMICS)

Her subtalar joint axis was not medically deviated but she had the most flexible midfoot I have ever examined. She had reduced dorsiflexion stiffness throughout her midfoot and with her hind foot immobilised she had 90 degrees of midfoot inversion hence my comment about extreme plastic deformation of her plantar ligaments as well as her spring ligament.

She has significant supination resistance in RCSP despite having a normal STj axis. You are correct in assuming her ankle ROM is normal.

My assumption was therefore that her eversion injury plastically deformed her medial plantar midfoot ligaments leaving her with a midfoot that was functionally unstable.

Simon

 

What position of the STJ did you assess STJ axis location. From the picture, it looks like you should assess STJ axis location in the maximally pronated position of the STJ. As you pronate the STJ the foot moves more lateral to the axis, making the foot appear more medially deviated. You want to know where the axis is relative to the foot when the patient is standing. If you found the axis location in neutral position, and the standing position of the STJ was much more pronated than neutral position, the axis could be much more medially deviated than you thought. This could explain why there was a lot of resistance to the supination resistance test. With this information I would give the high resistance finding much more weight than the average axis location finding. Then you could proceed with prescription that Simon Spooner gave you. I would go with a relatively low arch height in the orthotic as there is potential for arch irritation. Simon mentioned flanges. A flexible medial and lateral flange can apply some transverse plane moments that may add to comfort.

That video demonstrated a huge range of motion. However, the lateral ankle pain could just be a simple sinus tarsi syndrome that can happen with a foot with normal flexibility.

Eric

 

Just to show that you can discuss things (i.e. argue) with friends and still remain friends, here are two of my friends of 30 years, Jeff Root and Daryl Phillips, at the Pedorthic Association of Canada (PAC)- Prescription Foot Orthotic Lab Association (PFOLA) Conference in beautiful Vancouver, British Columbia.

 

Would love to have plain film, weight-bearing radiographs of the patients' foot, but based on the brief video, I'll give this one a shot. It's pretty obvious that her medial soft tissues, ie., spring ligament and P. T. tendon are stretched severely. She is probably beyond a P.T. tendon substitution surgery or surgical effort to tighten or replace the spring ligament. I would suggest an SMO type orthtotic to better control rear foot function and hypermobility secondary to the EDS.

 

Can she do a single foot heel rise? I would treat this foot for adult acquired flatfoot. In the video you can see she has significant forefoot supinatus because when she inverts her heel, the medial aspect of the forefoot comes off the ground until she supinates the "oblique" axis of the MTJ to plantarflex her medial forefoot. So either a functional AFO (Richie Brace) or an orthotic for adult acquired flatfoot would seem to me to be the best approach. I would recommend plantarflexing the medial column in casting and use plaster-of-Paris neutral suspension casting technique (not foam!).

Jeff

 

It was a pleasure listening to Kevin and Daryl. Kevin gave an excellent talk on the history of biomechanics of the lower extremity and Daryl did a wonderful talk on treatment of the diabetic foot. Daryl's should have been a plenary session lecture but unfortunately they could only work it into the breakout session. Hope to see more of you at the next PFOLA related conference. We are attempting to get something scheduled. Stay tuned!

Jeff

 

Good call on the possibility of an AFO. An SMO is in between an orthotic and the AFO and can worn inside a shoe, hidden from view. Expensive, but I believe worth a try or consideration.

 

Dear Dr. Kirby,

I feel that your post is covering an important part from the answer but there is another part which still are waiting for an answer. Unfortunately, at the moment I have to think at what I'm considering is missing in order to coherently define it clear. Unskillfulness, I'll try:

- indeed, the majority of the patients doesn't seem to be interested by the paradigm behind the treatment as long as the treatment has results. But on the PA many times I fill there is no consensus because the specialists doesn't assume the same reference system of objectivity in their discussions. Many years of experience add a powerful weight to an acknowledged professional but it still remains on the Levels IV of evidence [ http://www.researchgate.net/publication/12749180_What_is_evidence-based_medicine ] defined as "evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities". Is this true if we agree with this reference system ? Could exist a real change of a paradigm in this condition ?

-a lot of time people has believed they will help patients controlling pronation and now studies show that is not true and "...as the medical world progresses toward evidence-based practice, a scientific validation for orthotic function is required..." [ http://www.ncbi.nlm.nih.gov/pubmed/17507529 ]

- I don't understand why we still have PhD thesis regarding Root paradigm and don't we have any PhD thesis regarding the Tissue Stress Theory ?! Shouldn't the Podiatric schools from advanced countries assume this task ? How do you see a PhD thesis aiming to validate, at least partial, the Tissue Stress Theory ?

Respectfully,
Daniel

 

Simon:

So good to have you back here again on Podiatry Arena! Haven't seen you for quite a while and hope all is well. I'll never forget the time at a PFOLA meeting that I had three Simons sitting at the lunch table with me (you, Spooner and Bartold). That was quite an experience!

As for your patient, she looks fairly typical of the patients I am referred for foot orthoses and that I see fairly frequently. It sounds like the symptoms are being caused by Dorsal Midfoot Interosseous Compression Syndrome (DMICS) as you suggested and possibly sinus tarsi syndrome due to the excessive subtalar joint (STJ) pronation moments that this foot obviously experiences during weightbearing activities.

I think that both Drs. Spooner and Fuller have good suggestions for foot orthoses. Personally, with feet like these, I will use a 5 mm thick polypropylene shell, 4-6 mm medial heel skive, a 2-3 mm heel contact point thickness and will cast the foot with the medial forefoot slightly dorsiflexed so that the foot orthosis does not cause gouging in the medial arch of the foot. Minimal medial expansion plaster thickness is used along with an 18 mm heel cup depth, extra wide orthosis plate (to increase the orthosis reaction force medial to the STJ axis) with possibly a 2-3 degree inverted balancing position. Also, I will try and get these patients into hiking boots in order to stabilize the STJ superior to the STJ axis.

The cause of her medial dorsal midfoot pain is likely, as I said earlier, due to DMICS from the excessive medial column dorsiflexion moments that occur due to her medially deviated STJ axis. The HAV and bunion deformities don't help things since these deformities will decrease the first ray dorsiflexion stiffness further due to lateral positioning of the sesamoids relative to the plantar first metatarsal head. If the ankle pain is in the sinus tarsi then this is due to excessive compression force between the lateral process of the talus and the floor of the sinus tarsi of the calcaneus which I described in my papers on rotational equilibrium of the STJ axis (Kirby KA: Rotational equilibrium across the subtalar joint axis. JAPMA, 79: 1-14, 1989; Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001).

And, as Eric stated, the STJ axis is medially deviated in the video you provided due the extreme medial translation and internal rotation of the talar head and neck relative to the forefoot and rearfoot. I teach now that the STJ axis must always also be evaluated with the foot in a weightbearing setting, and not just non-weightbearing since, in some feet, the STJ will medially deviate even more when weightbearing.

Hope this helps and thanks for the kind comments. Hope you can find the time to continue to contribute here!:drinks

 

Daniel:

You are quite correct. We still need plenty of research to validate what we currently do and recommend for foot orthosis therapy. Unfortunately, here in the United States, the podiatry schools are busy trying to teach students and have little time or interest in trying to decide which theory is best. There are no PhD programs for that sort of things here in the US. Maybe the UK, Australia or Spain will be able to contribute to that knowledge basis with a Master level or PhD thesis or other research. I don't think either Root theory or Tissue Stress Theory has been researched adequately. All we can do now is speculate and theorize which is the best theory to use.

At least we are now having the academic discussion as to which theory is best, instead of just accepting the dogmatic approach that one theory is better than another just because one person, or group of people, say it is the best way to do things. That is a start in the right direction.

As always, Daniel, good questions. I like the way you think!:drinks

 

Here's a couple of pics of the SMO's I referred to earlier. More labor intensive, and therefore more costly, but they really work for flexible flat feet, especially with patients that have a collagen deficiency disorder. Notice the whole lower leg cast in the background. These SMO's utilize carbon graphite with an inner layer of a "gelatinous" material from the North Sea. Cool stuff...used in a lot of AFO's I've seen. Notice, also, the cutout in the carbon graphite for the 5th met base. These are very "transformable", ie., they can be altered without much effort or cost.

 

Just as quick follow up to earlier in this thread where I was accused of not knowing my flexors from extensors. The patient in question popped back in today, so I took another quick snap. Like I said, a lot of the time during stance her extensors are over-active.

 

For those interested, here is a pdf copy of my article recently published in Podiatry Today, "Prescribing Orthoses: Has Tissue Stress Theory Supplanted Root Theory?"

 

Dr.Kirby,
I’m supposing, depending on the reader understanding, the last image from your article could be interpreted as:
-the direction of orthosis reaction force on longitudinal arch of foot is oriented towards navicular,
-the apex of orthosis longitudinal arch is in the area proximal near to navicular
Taking into account some discussions on PA regarding the apex of Blake inverted orthosis how do you comment the above two possible interpretations?
Many thanks,
Daniel

 

Who is who Kevin i.e. is Jeff on your right or left?

Dave

 

Daryl has his glasses on, Jeff hasn't.

 

Hello Dr. Spooner,
The question was about kinematics (positions) and not about glasses !
So, the proper answer could be "Daryl is on the right side !"
Have a nice day,
Daniel

 

"Your right side" as we look at the picture or "your right side" from the perspective of the people in the picture when the picture was taken? Stating the Daryl had his glasses on avoided such confusion.

 

Nice ! Where is the "Like" button ?
Daniel

 

Daniel:

The arrow in the medial longitudinal arch (MLA) of the orthosis is meant to imply that the whole aspect of the orthosis MLA is pushing upward on the MLA of the foot. Don't worry about where the apex or arrow is in this one drawing. I was only trying to illustrate my point that the orthosis MLA is important in increasing the orthosis reaction force along with whole plantar aspect of the MLA of the foot.

 

Dave:

Left to right, Jeff Root, Kevin Kirby and Daryl Phillips.

 

I think this is a really important point and illustrates something I was saying in an earlier post; what comes first chicken or the egg, lax ligaments etc. and medial deviation or vice versa – probably a mixture depending on the patient and, without prospective studies, we will not know. However, acknowledging the changing position and thus point of deviation is key and, if I may be so bold, a step forward from the commonly discussed STJ axis location concept.

I think the ligament issue is not as you suspect. This patient has hypermobility due to her condition thus able to deform easily. If the ligamentous complex had been sufficiently traumatised, the coupling that occurs with dorsiflexion of the hallux would not be possible. Thus, it is the deforming force whilst the foot is fully loading that is the issue, it is simply accentuated by hypermobility and an unstable medial column / hallux valgus.

Unless I have missed something in a post, no-one appears to have commented on the equinus component. In the end position with the hallux dorsiflexed and the arch restored, the ankle is clearly in a plantarflexed position. Thus, there would appear to be a significant equinus which, combined with a hypermobile foot type allows significant deformity and dynamic deviation of the STJ axis. The lack of midfoot stability and HAV simply make this worse.

Although I do not feel there is ligament deficiency, the laxity means it is likely that treatment needs to be more than an orthosis and I would probably opt for a Ritchie brace but it would need to incorporate heel raises to counter the equinus.

 

"As I expressed above, I believe that the biggest contribution of Root was his vision of what could be — that we could not only understand the forces that were causing pathology, but also understand the abnormal motions (or failure of motions) to understand the creation of those abnormal forces, and then take it further and understand the etiology of the abnormal motions and/or the reason why normal motions did not occur. What I find lacking in any of the discussion of stress theory is much discussion of why abnormal motions (or failure of motions) occur. The only discussion of etiology of abnormal motions seems to be the projection of the subtalar joint axis onto the plantar surface of the foot. This writer will not underestimate the importance of the subtalar joint axis location but nowhere do I see discussion of the forefoot to rearfoot relationship, nor discussion of forefoot compensation for abnormal rearfoot motion. What I find lacking in the new tissue stress advocacy are principles that can better predict pathology. Clinical methods being advocated are directed to non-quantitative assessments, which I believe is a step backward from the vision of Root of clinical quantitative assessments. Of course, very high-priced biomechanical laboratories can crank out quantitative moments, but these are not clinical tools readily available to the average practitioner."

This is an extract of Daryl’s reply to Kevin’s article which Kevin posted previously. I agree with Daryl that the premise has to be to look for predictors not only of potential injury but negative effects of interventions that we provide.

I believe this is the way in which the varying paradigms are most likely to overlap and help guide assessment and management. If I see a foot that is clearly pronated with calcaneal eversion and talo-navicular drift, I can be fairly sure there is medial deviation of this axis. I can use structural alignment to help me understand positioning, tissue stress to evaluate the tissue involved and SALRE to help guide treatment.

If I have another foot with less rearfoot eversion but still has talo-navicular drift, I have a variation on function and this may be a patient with increased tibial rotation coupling with the midfoot. The effects of my treatment to increase supinatory moments may have differing effects both distally and proximally. I also suspect that supination resistance is greater in the first case assuming everything else is equal (body mass etc.)

If I have another foot that has an arch that is low but only in the sagittal plane, my STJ axis in in a different orientation and my management may have a basis in sagittal plane theory.
Depending on the amount of motion within the foot and the effects on function elsewhere, there is likely a combination of factors such that I may wish to increase the supinatory moments yet facilitate sagittal plane function to aid stability of the medial column and knee / hip motion.

If I have a patient with a tibial varum and only enough motion to pronate such that the heel remains inverted to the ground, I can be fairly sure that they will have increased lateral load (i.e. pronatory moments) with lateral displacement of the CoP. If I wish to offload lateral tissues, I need to be a little more cautious as it is likely some of the joints are nearer end range of motion. I do not wish to re-open the debate on how to manage this foot type – this is more an example of how applying the SALRE concepts can be applied to the positional concepts, perhaps help people transfer to a more rounded view point but also understand how structural factors will help determine moments.


If I choose to correct the position of a cast to utilise the motion an individual has available, use a shell of given density and apply a medial rearfoot post because I wish that patient to function less everted, I have still used a SALRE approach but have a less scientific explanation. However, if I can see that a patient is clearly towards the more significantly pronated foot type to someone less significantly pronated, I can start to consider if they are more at risk. I do not have to do much of an examination to work that out, I just have to do more to work out why they have that level of pronation and how best to manage.

 

Yeah...right, Simon. But since you're now a big fan of jpegs to support your position, (after previously dismissing the idea), let's add a few more to the "mix". RCSP, NCSP and orthotic corrected...using good ole Rootian precepts. Enjoy.

 

Surgical repair of the spring ligament is a fairly hot topic here in the States. Multiple ways to achieve this, including tendodesis procedures bringing a slip of the AT tendon down to the PT tendon and placing them under a periosteal flap of the navicular bone to form a "new" bolster for the talar head. Arthex has also created another approach to recreate the spring ligament:

https://www.arthrex.com/resources/a...rnalbrace-spring-ligament-augmentation-repair

Yes, the patient has a collagen deficiency disorder, therefore more aggressive treatment is necessary in order to correct the foot...whether it be osseous surgical procedures and/or soft tissue procedures, and/or more aggressive orthotic therapy...thus my pic of the SMO.

 

Matt, you missed his point. He has taken two pictures of the same foot and the muscle activity was different in the different pictures. His point was that you should not jump to conclusions from seeing a picture that captures a single instant in time. Two pictures proved the point that you should not make a conclusion from a single picture.

Eric

 

You nailed it Eric, you can't make clinical judgements based on a single photograph. You certainly can't make a clinical judgement based on someone standing off and on an orthosis. A single picture does not prove anything. In isolation kinematics is a very blunt instrument, just as kinetics in isolation is very blunt too. There seems to be this mis-understanding that tissue stress theory ignores structural mechanics- tissue stress theory is structural mechanics.

 

I did NOT miss his point, Eric. Simon's FOC...and he blasted others for putting pics up of patient's feet stating that "didn't prove anything". He made a serious faux pas and now he's trying to cover himself, and you're following suit by covering him. You TST guys run in packs.

 

Now, after 274 posts on this thread, do we have a conclusion to the question: Has Tissue Stress Theory Supplanted Root Theory?
Sincerely,
Daniel

 

I all things Biomechancially we must consider the fact that a brain is involved so when we start a discussion with a question N always = 1

So therefore we should conclude - That for some tissue stress theory supplanted Root Theory, for others not

 

The short answer is what Mike said.

The larger question is after reading the pros and cons what will you use.

I will summarize some of what has been said from my perspective. Many have said Root theory is not a finished product. I would agree with this because it is fairly hard to pin down exactly what Root theory is. There are different explanations of how an orthotosis works. Proponents of Root theory have said that in some situations they would use a lateral heel skive. I'm not really sure how they would justify that within Root theory. The logic for use of lateral heel skive comes from rotational equilibrium which is a basic part of tissue stress.

One of the criticisms pointed at tissue stress was that it was not predictive. I replied that there is a scenario where tissue stress could be predictive. For example, medially deviated STJ axes will be more likely to have pronation related problems. When I asked how neutral position theory could lead to predictive treatment, no one responded. I don't see how neutral position theory could be predictive of any specific pathology.

So, I'm curious if there was anyone on the fence about which theory to choose before this thread has changed their mind about the relative value of either paradigm.
Any comments?

Eric

 

Eric,

Do you own a copy of Normal and Abnormal Function of the Foot?

Jeff

 

Rotational equilibrium is a part of basic biomechanics. It is not unique to "Root Theory" or "Tissue Stress Theory". Root et. al. did right about rotational equilibrium and other aspects of joint mechanics. I have to assume that you do not own a copy of Normal and Abnormal Function of the Foot based on the number of the statements that you have made here on the PA that misrepresent "Root Theory".

If you have access to a copy of Normal and Abnormal Function of the Foot, please read pages 75 through pages 77, starting with General Principles of Skeletal Stability. For those who don’t have it, here are a few excerpts:

1. Ligament tension resists the tendency for motion to occur at each weight bearing joint. The forces interacting at each joint are in near equilibrium, but in the absence of perfect equilibrium, some motion will occur and gradually stretch the ligaments.

2. Joint stability is also essential during locomotion. Bones of the foot must move, but, while moving, they must also bear weight and must not collapse under the weight load.

3. A large portion of the forces that acts upon a bone contributes to stability of that bone within the normal skeletal framework. Only a small portion of force tends to produce motion of the bone at a joint, but even small amounts of force will cause skeletal instability unless those forces are resisted by muscle tension.

Force that acts upon a weight bearing bone of the foot is divided into two components. One component of force tends to stabilize the bone against the surrounding bones by creating compression between the bones at their joints. The other component of force attempts to create osseous instability by moving bone at its joints. The component of force which enhances stability is called compression force, and the component of force which enhances instability is called a rotational moment of force.

4. Therefore, muscles must resist any rotational moment of force that would either disrupt the integrity of the joint or cause the joint to move excessively.

5. In the pathological foot, the participation of muscles and ligaments in the support function is increased considerably. Muscles are overworked and may become fatigued or traumatized. Ligaments may become deformed (lengthened) because they must support greater forces for a longer period of time.

6. When the foot is in its neutral or slightly supinated position at the subtalar joint, all bones of the medial arch angle less with each other than when the foot is pronated. Clinically, this means that a neutral or slightly supinated position of the foot improves its weigh bearing efficiency. In a pronated position, the foot is a less efficient weight bearing organ.

It is unfortunate that so much time and effort is spent debating the role of "Root" versus "Tissue Stress" theory when that time and effort could be better spent creating a new model of function that incorporates elements of both. I honestly believe these labels are retarding potential progress. In tissue stress theory you must take into account structure and in Root theory, tissue stress can be seen as an underlying component as I have just demonstrated.

I just shelled out $300 to purchase McGlamry's Comprehensive Textbook of Foot and Ankle Surgery because I'm interested in the biomechanics of surgery and in how structural and functional conditions are addressed surgically. We can't have biomechanical principles for orthotic therapy that are inconsistent with those used in surgery, can we? The same pathology can sometimes be treated surgically or non-surgically. The pathological forces that create the symptoms or condition being treated are the same, regardless of which treatment approach is undertaken. Therefore, we need to develop terminology, techniques and theories that apply in both realms. This is called pathomechanics, not Root theory or Tissue Stress theory.

Jeff

 

Hi Jeff

Sorry to jump in but where can one obtain a copy of your fathers book (volume 2)? I picked up a brand new copy of volume 1 a few years back on Amazon but have yet to find a reasonably priced copy of Volume 2

Cheers

Ian

 

Ian,

After John Weed passed away, my father gave the remaining books and publishing rights to John's widow Marilyn Weed to help her out financially. The new, paperback copies that are being sold on Amazon are the ones she had printed and is selling now that the hard cover edition ran out. Before she reprinted the book, some were asking ridiculous prices on the internet but I think she charges a reasonable price. Send her a message via Amazon if there is any issues ordering it and let her know that you communicated with me about the book.

Thanks,
Jeff