Is symmetry an important therapeutic goal?

Robert

Perxactly! to both well made points

If not most usuall

Dave

 

Kevin, Graham and all

I wrote

To contiunue this theme; (and this is pure speculation on my part)
Let's say we were to consider the undulations of the geographical topography as random frequencies transmitted to the human brain by the various senses. The brain must analyse and evaluate these signals and adjust the posture accordingly.

Consider that the brain has no sense of a baseline zero or neutral signal. These signal frequncies have infinite variability over a finite bandwidth within an unknown limitation. To be able to maintain balance within a gravitational field the brain makes jugements about input signals in terms of how one signal compares to another (not how it compares to neutral) and to those past extreme range of signals captured in its memories.

If now the human comes across some previously unencountered completely flat surface then this is like white noise to the human ear. I..E. there is a signal but all signals are the same magnitude across the bandwidth and so the overall mean effect is zero. In this case it may be very difficult for the body to maintain equlibrium since it has no refference. In this case it would be very convenient if the body could produce its own signal to reflect off the flat surface and then it could interpret those singals against othere references and equilibrium could be maintained. Now, if the body was completely symmetrical how then would it be able to produce this signal, rather like a sonar pulse, to maintain balance.

In fact if it were a little assymetrical and continually had to reajust its posture due to the effects of gravity, this then would produce a reference signal for the purposes of equilibrium. Therefore perfect body symmetry may be undisirable, immpossible and sub optimal. The close we approach the limit of assymetry toward symmetry the more we reduce the reference signal and perhaps somewhere there is a tipping point.

Dave

 

Dave

Thankyou. Fascinating stuff.:good:

Do you think the surfaces which are marginally sloped or cambered have a less asymetrical effect on the pivital function of the foot but a more asymetrical gross effect on the body above? Also, as these, not so flat, surfaces vary between themselves, do they really contribute significally to pathology over time?

When we attempt to "control" the foot with our orthotic are we not meerly changing the asymetry to stess another area of the body, therfore relieving the one that was hurting? Or, should we try and create a device which allows the foot to restablish the timing of events required for the pivot function of the foot to work as effectively as possible, and perhaps therfore, allow the foot to adapt, re: position and timing, on most surfaces?:dizzy:

 

If I were designiing a robot I would give it 6 indepnednt wheels like the Mars rover where one wheel froze up and the robot can still move around dragging the frozen wheel. The engineering problem of walking on two legs is really hard. I recall a science fiction book from the 1950's that had robots walking on two legs, but required a computer the size of a room to create speach. Boy, did that prediction of the future miss the mark. I'm still amazed my cell phone understands speach.

Now, if I had to design a robot that walked on two legs. The task that has to be desinged around is keeping the center of mass withing the base of support while walking. This can be done with or without equal length legs. You could design the robot with a pelvis tilt so that the leg lenght difference wouild not matter. Now, if your robot required a trunk above the pelvis, I would desing it so that there was a pivot at the bottom of the "spine." This pivot would enable the trunk to stay inbetween the base of support (the two feet) while not putting any undo stress on the base of the spine.

To get back to the thread. Thinking in terms of tissue stress, how does asymetry increase stress on anatomical structures. I can see how a leg length difference can put some stress on the base of the spine as it has to compensate for a tilt in the pelvis. The question could be changed to: how does asymetry increase stress on tissue?

Regards,

Eric

 

4 legs perhaps? Gives you redundancy. The only bonus i can see of having two is that it frees up the other two for manipulation and gives some height. MY robot has 2 legs and 4 arms and can ambulate on any combination.

Sorry. Off topic. Perhaps a new thread...

Robert

 

Dave:

The reason why I asked about the design of the legs of a bipedal robot was to emphasize the point that in animals, bilateral symmetry is often a design characteristic that may increase efficiency of locomotion and other metabolic processes.

Certainly in our bipedal robot, bilateral symmetry would be desirable also. One would want the legs to have the same dimensions, same moments of inertia and same power outputs to allow easy straight-ahead locomotion on flat surfaces. Of course, to avoid obstacles, to locomote over uneven surfaces or to move from side to side, our robot would also need to have the ability to have asymmetry of motion and function in each lower extremity to allow the robot to stay upright while performing these asymmetrical tasks. But when functioning on flat, level surfaces, I would think that gait symmetry in the robot would be extremely desirable to prevent wear and tear on the structural components of the robot, to promote gait efficiency and to allow smooth straight-ahead ambulation with a miniumum of corrections from the central processing unit.

As far as the bipedal human is concerned, bilateral symmetry is apparent, but is certainly not perfect. Fortunately, we do have a very powerful and wonderful central nervous system that allows immediate adjustments to our locomotion to allow asymmetrical function of the lower extremities depending on whether it is necessary or not for the task at hand. All in all, I believe that symmetry of function is a worthwhile goal of therapy for our patients especially if gait asymmetry is thought to be causing, or going to cause in the future, symptoms or pathology for the individual. However, the correction of the asymmetry with our therapy must not cause other symptoms or pathology in the individual since certainly none of us have enough knowledge about the internal forces and moments acting within the bodies of our patients to be able to predict when symptoms or pathologies will occur in all instances.

Hope this explains my position on whether symmetry is an important therapeutic goal more clearly.

 

Hi all

Is it possible that the moment we build something to function in a multi environment, as opposed to a single environment, that we then enter the scenario of building increasing potential for mechanical (or in the human case pathological) failure?

Is the capacity to function asymmetrically a trade off which with a robot we might more readily and easily manage, due to relative ease of intervention with none living tissue, but that in the human context the asymmetry can function with an element of failure with no obvious signs until "to late"?

Again, with the none living robot do we hit the issue that we can more readily design out issues that we cannot do with living tissue in humans?

Just questions as I follow the debate.

Ian

 

As I woke up on this rainy Saturday morning, I thought of another important point in regard to the comparison of a robot and a human. We don't necessarily want gait symmetry in our patients if this decreases the metabolic efficiency of locomotion or increases the pain of locomotion.

The robot doesn't likely have a capacity to analyze the power output of its electrical servo-motors to determine which locomotion pattern is the most energy efficient, but rather its central processing unit has been programmed to give it a certain locomotion pattern for different situations. It is also unlikely that the robot could continue to function well during gait if one of its structural components became significantly damaged or would change its locomotor pattern if one of its structural components was nearly at the point of structural failure unless the programmer had somehow compensated or allowed for that within the robotic design and within the central processing unit.

In the human, however, our central nervous system (CNS) constantly analyzes the metabolic efficiency of locomotion and will tend to, over time, choose the type of locomotion pattern that uses the least energy. For example, this might mean that someone with a structural asymmetry in their tibial torsion (e.g. decreased tibial torsion on one side) will tend to walk with an asymmetrical angle of gait because their CNS has determined that to use their external hip rotators or peroneal muscles with each step to abduct the foot with the low tibial torsion to the same position as the less adducted foot would require too much metabolic energy and would not be metabolically efficient.

In addition, the human has a CNS that normally will avoid locomotion patterns that are painful which will force the CNS to synthesize new methods of performing the locomotor task while minimizing the painful stimuli. For example, someone that has developed a stress fracture within their second metatarsal will develop an asymmetrical gait not because their forefoot can no longer mechanically support the weight of the body, but rather because the CNS will modify the gait pattern of the individual so that the ground reaction force plantar to the forefoot is minimized to reduce the pain of locomotion.

Therefore, metabolic efficiency and pain avoidance are also important considerations for the clinician that is trying to decide whether achieving gait symmetry is a desirable therapeutic goal for their patients.

 

The Inclined Posture by Dennis Shavelson, DPM
A clinical look at the need to treat unequal limbs.

I was born with one leg significantly short and when I was 17, 45 years ago, 6’2 and 220 lbs and athletically gifted, I was a great athlete but my back was always killing me and keeping me from the athletic field. I used lifts to solve my problem and I have been publishing and teaching about this almost universal problem ever since.

10,000 years ago, we decided to be civilized, pave our roads, built cities and wear hard unyielding shoe boxes. These facts paved the way for the profession of Podiatry . Before that time, the only universal negative was gravity.
We expanded the practice of medicine to include lengthening our lifespan and improving our quality of life.
Humans were gifted with an internal balance system to offset uneven terrain, angled terrain and the lumps and bumps of the terrain for the thirty or forty years that they lived quite well before those days.

In addition, our race is not symmetrical and many of us (the literature states up to 80%) have one lower limb shorter than the other giving us The Inclined Posture or TIP for short..
Clinically, one should only be concerned with TIP if the patient has not been able to compensate for the external negative forces applied against our inherited asymmetry.

The example I give is that there is a table that has two short legs in a corner and not being used, there is no need to compensate for its inclined posture.
However, if I have a table with two short legs that I keep books on and those books keep sliding off, I would suggest taking two of those books and placing them under the short legs and end the problem, PERIOD.

I am not concerned with how the leg is supported, what the connection is to the table, what the materials of the table are, etc. I am a clinician, not a researcher! I am a healer, not a technician.

If this is not scientific enough for you or if you wish to debate any of the above then stop reading here and go make fun of me on the functional foot typing thread.

If not, I would be more than interested in sharing my diagnostic tests, my treatments and answer all questions that you have related to caring for TIP.

I will stop at the first member post on this thread that says that I have to “prove it first” before they will lend an ear. YOU PROVE IT!

Dennis Shavelson, DPM,
DABPS
BS in BIOLOGY, Brooklyn College
Valedictorian Graduate NYCPM 1970
Podiatry Residency, Jewish Memorial Hospital, Marvin Steinberg, DPM, director Fellowship in Bone and Joint Pathology, Joint Disease Hospital, Henry Jaffe MD, lecturer
Associate Professor in the Department of Medicine, NYCPM 1981-88
Clinical Attending with offices in The Department of Endocrinology at “The New York Presbyterian Hospital, NYC, 1997-2002
Author “The Diabetic Foot” Chapter 8, The Principles of Diabetes Mellitis, edited by Leonid Poretsky, MD.
Medical Director, The FootHelpers Lab, NYC
Blah, blah blah

Please call me Dennis

 

How do you determine this clinically, i.e. that the pathology is due to this and not some other factor?

 

Simon:
off the top of my head, I'll just list 10
If you have
1. A unilateral foot complaint, i.e left sided heel pain
2. A larger deformity or unilateral deformity, i.e. a larger bunion left
3. A larger shoe size on one side
4. A larger forefoot width on one side
5. A unilateral postural comlaint i.e one sided or greater ankle, knee or hip pain
6. Lower back pain
7. A greater calf or thigh muscle mass on one side
8. An elevated pelvis or dropped shoulder girdle on one side in stance
9. A longer stride legth on one side in gait
10. A greater amount of abduction in the foot of one side than the other in stance or gait

If you have three or more of the above, functionally TIP is in play until proven otherwise.

Dennis

 

Hello Dennis,

Fascinating stuff, I love the subject and I would like to ask you some questions:

1. How do you measure LLD?

2.If there is not anatomical asymmetry but a patients shows most of the signs you describe, how do you explain that?

3. Also, I do not agree about your 80% for anatomical LLD. Studies; such as: Guichet JM, Spivak JM, Trouilloud P, Grammont PM Lower limb-length discrepancy. An epidemiologic study. Clin Orthop Relat Res.1991 Nov;(272):235-41.Click here to read; show the incidence of apparatus prescriptions for asymmetry correction filled was 2.16 per 100,000 population. The prevalence of people using a corrective apparatus was one per 1000 population. Other studies show similar numbers although real prevalence is unknown. Can you tell us about other epidemiologic studies that support your claim?

4. If there is not an anatomical LLD. What parameters do you measure for detecting functional LLD origin?

Regards,

Regards,

 

TIP is not a term that I am familiar with Dennis, could you please expound on this concept? Are there any peer-reviewed research studies or journal articles using this terminology? I don't believe that we need to further muddy the already standard and prolix lexicon and devise terminology not currently in usage in the medical field to define leg length inequality (LLI) or difference (LLD). Do we?

As a chiropractor I will say that a great number of the people who I examine do in fact have an LLI (functional) and very few over the years possess a confirmed LLD (structural). One of the reasons that I became so interested in the lower extremity and gait was the apparent link between certain types of foot dysfunction and an LLI that would not correct for long periods post manipulation.

As a chiropractor whose profession is decidedly focused on symmetry and removing dysfunction, almost to a fault in some cases, I wonder whether symmetry is as truly important as some of my colleagues would believe. I do see asymptomatic patients with an LLI and it is my practice not to manipulate such a finding. Because I am focused on the foot as well in practice I do attempt to differentiate between those who have a primary functional compensation from lumbopelvic misalignment and those with foot pathology as the cause. This is not always an easy task and reporting on this is at present weak.

I do not agree that 80% of the population presents with a functional LLI and certainly not an LLD. I agree with Javier here and feel his questions are valid and pertinent.

Despite your request not to engage you and say "prove it", I feel that you should defend these statements. There are myriad statistics out there to support another viewpoint regarding LLI and LLD Dennis.

As one of the few DC's who posts here you may find I am more 'open' to your theories at least regarding this subject. The tone of this post is only to question your assumptions and not intended to provoke a negative response.

I am listening and all ears Dennis.

Regards,

:drinks



As for

 

Javier:
1. In the future, you and your members will have to attach to me by visiting one of MY Arena’s because although I will visit now and again, my ability to juggle priorities prevent me from visiting as often as I have this last month..

drsha@foothelpers.com would be the easiest.

2. I can invent any terms, patent or trademark anything I want, especially if I think the by doing so, in the long run I would be making things more understandable and practicable universally. My difficulty in understanding your language and intention (I’m sure shared by others), justifies my point.
One definition of insanity is to keep doing the same thing over and over and over and over and over again and expect a different result.
Why don’t you try a different method of getting me to succumb to your will?

1. How do you measure LLD?

In appreciation of Mann and Inman’s Treatise on “The Joints of the Ankle”, I never believed that the subtalar joint was the center of the biomechanical universe (I now believe that to be The Vault of the Foot). Their work explained that at the junction of the ankle and the subtalar joint, motion of the foot in one direction was translated into motion of the superstructure in a different direction, kind of like the transmission to the wheels of a car and vica versa.
In podiatry school, the 3 second sound bite that solves all around LLD is that the long sided foot pronates and the short sided foot supinates (so similar to The Arena’s soundbites about axis/moment and the need for a medial skive).
The implication for me of the soundbite is that the short side is trying to get longer and the long side is trying to get shorter in primary functional compensation. So I have clinically investigated what bodies do to compensate long/short, functionally at the level of The Joints of The Ankle.

My diagnostic test is called The Functional Equinovarus of the Joints of the Ankle test or The FEJA Test
There are two parts to the test.

1. Relative Equinus of the Ankle Joint Left/Right
In Root Neutral position, forcibly dorsiflex both feet at the ankle joint as hard as you can (with or without the patient’s assistance).
If one foot is more dorsiflexed to the other, there is a relative Equinus on the foot that is more plantarflexed

2. Relative Varus of the Subtalar Joints Left/Right
In Root neutral, forcibly invert the subtalar joints of both feet as hard as you can (with or without the patient’s assistance).
If one foot is more inverted to the other, there is a relative Equinus on the foot that is more plantarflexed.

A positive FEJA Test would have one foot is relatively plantarflexed to the other and (almost always) that same foot is relatively inverted to the other.

The side that is plantarflexed and inverted relative to the other is the short side until proven otherwise.

This combined with positive confirmatory tests (The ten tests that I listed for Simon) say to me that there is enough of a limb length in play to cause functional pathological compensation.

I don’t care structural, functional or even if there is a primary scoliosis producing a compensatory short limb. In my experience, the short side when treated with a lift or manual therapy or motion control therapy will eliminate (reduce) the need for pathological compensation.


2. If there is not anatomical asymmetry but a patients shows most of the signs you describe, how do you explain that?

If there is a negative FEJA test, that patient has successfully compensated the limb length and needs no care. If there is a positive FEJA test, my subjective opinion is that they need care to prevent sequelae.


3. How many times are you finding equal IM angles, HAV angles’s. CIA’s, etc?
Besides, most authorities consider an LLD to be ¼”- ½ “ or more and I am talking about smaller differences (That defines the difference between TIP and LLD.
I tell the patient that they are TIPped and need balancing.
You talk limb legth discrepancy, ASIS, umbilical blah blah blah.


4. If there is not an anatomical LLD. What parameters do you measure for detecting functional LLD origin?\
The FEJA TEST and
The Confirmatory Tests

See you in my Arena (or not), staying in yours is such a low priority for me? (sorry you can’t understand why?)

Wish you all, (except Kevin, hahahahaha) the best.

Dr Sha

 

drsha@foothelpers.com

This is an e mail address not a forum. Was this a typo?

Regards
Robert

 

The lower limb asymmetry is a very complex issue. Most asymmetries that we see, are positional, postural adjustments due to the body.
Referent to the short side foot supinates, and long side pronates. This is not entirely true, because I have seen many people who file such compensation to the contrary, the short side pronates and long side supinates.

what do you think?

In addition, to fold Level buttocks, there are also people who fold lower, correlates with the longest leg.

I think that we should give more consideration to the valuation of superior extremity when it comes to assessing the final treatment.

what think about the postural orthoses?

greetings
español » inglés Traducir
Proponer

 

Dr Sha

Been to your Foothelpers site, it seem a little short on focus on what type of system you actually are using.Which of the following is it?

1) The - Neoteric biomechanics system,(NBS) 2)Functional foot typing system (FFT) system, , 3)Foot centring theory system, 4) Functional lower extremity biomechanics system (FLEB) which also includes = SSERM + SPERM + FSERM + FPERM.
I imagine if I had flexible SPERM and a rigid PERM, I would probably be classified as a famous footballer (soccer) from the 1970's e.g. Kevin Keegan or Ian Wallace. They had Neoteric hair do's ie ginger curly perms.

Neoteric = new fresh and innovative- Biomechanics and yet its based on supporting the plantar vault in some predetermined position. An arch support - how new and innovative is that?

Where's the fresh innovation? is it the FFT system? 11 different (and new) ways to classify a foot. Are these classifications absolute? At what point does rigid become flexible? How is consistency of classification guarunteed between clinicians. How do the bits of felt apply the same forces to the foot as a UCBL type rigid orthosis and therefore prepare the customers foot for the real thing? Why not just use bits of felt then?

In what way do the shell designs and material properties vary to take account of the FFT classification? Do you use some kind of laminate system that is weight matched, calibrated and graded according to the varying stiffness of the customers foot?

Where is the biomechanics in your Neoteric biomechanical system? In what way do you actually take account of whats wrong with the customer rather than just classifying the foot type. IE how do you address the pathology with your system / systems 1 -4? Do you consider that the pathological internal forces will take care of themselves as long as you classify and address the funtional foot type and apply the FootCentring TM foot orthoses that are dramatically different from Root?
Suerly when a clinician casts a foot he casts it in the best position for resolution of symptoms. How is the cast dramatically different from a Root cast and is different always better?

So many questions, sorry about that but I was interested to know about the new system that you promote and the web site is a bit vague on what exactely the difference is and its not clear how they work in a new and innovative way.
Please could you explain

Cheers Dave