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A new research article on the mechanical response of feet to frontal plane orthosis wedging was just published in the Journal of the American Podiatric Medical Association. This paper was a joint project with Spanish podiatrists, Javier Pascual Huerta and Juan Manuel Ropa Moreno, which studied the feet of 53 subjects in response to 5 and 10 degree varus and valgus wedged foot orthoses in relaxed bipedal stance.

Javier and Juan are two of our very intelligent podiatric colleagues and deserve a lot of credit for their hard work and persistence in seeing this important multi-year research project through to its completion and publication in JAPMA. I would be happy to send a pdf copy of the article to anyone who contacts me privately.

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Sincerely,

Kevin

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Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
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Here is another biomechanical thought that we didn't include within the discussion of this paper.

We saw that the maximally pronated feet only inverted 4.63 degrees with a 10 degree varus wedged orthosis and the non-maximally pronated feet inverted 5.91 degrees with a 10 degree varus wedged orthosis. The mechanical analogy for this to imagine that the subtalar joint (STJ) in stance is like a spring with different stiffnesses. Maximally pronated STJs with medially deviated STJ axes have a "stiffer spring" to resist supination whereas non-maximally pronated STJs with more normal STJ axis location have a more "compliant spring" to resist supination.

Our research is mechanically consistent with the research by Craig Payne and co-workers' on the supination resistance device (Payne C, Munteaunu S, Miller K: Position of the subtalar joint axis and resistance of the rearfoot to supination. JAPMA, 93(2):131-135, 2003) in that some feet require much more force (whether it is from an inverted orthosis or a pulling force under their navicular) to supinate them than others.

Good to see the pieces of the puzzle start to fall into place into a coherent theory of how foot orthoses work.

__________________
Sincerely,

Kevin

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Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
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Kevin

Just to be silly for a moment - what are cow orkers and how does one ork a cow?

All the best Dave Dave

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

Very interesting research, doesnt this point to the fact a weight bearing casting/correction method is essential for determining the correct forces, ala Neil Smiths Vertical Alignment System
Regards Gavin J

Gavin,

No. Unless you want to make a device for a subject who stands still and never walks, this research is...irrelevant..... to the dynamic influence the orthoses has on each individual.

We already know there is no correlation between static measurments, observed static pronation and dynamic function. It would be reasonable to deduce that the static devices used in this research would also demonstrate a 0 correlation to dynamic function.

Graham

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Graham Curryer

None of us know what we are doing, but some of us know more about what we are not doing than others!::

No correlation at all? Zero?

Please Explain....

Cheers,

Paul D.

Graham:

Now, Graham, this is a rather myopic view of our research. If one had a more broad-minded perspective of our research, one could say that the foot orthoses constructed for these individuals acted on the plantar foot while in relaxed bipedal stance the same way that they would when these same individuals walked, by altering the ground reaction forces on the plantar foot. Then, if this assumption is valid, which I believe it is, then one could certainly make the inference from our research as to how varying degrees of varus and valgus wedging on an orthosis may or may not affect the kinematics and kinetics of the foot during gait.

If you read the disclaimer at the end of the paper, we do make mention of the fact that to compare this static study to what happens during gait, one must be very careful. However, to say there is "zero correlation" of what we see statically with foot orthoses to dynamic function, I think shows a lack of understanding how foot orthoses function to cause the kinematic and kinetic changes during weightbearing activities.

Graham, how do you propose that foot orthoses function to change the kinetics and kinematics of gait? From your comments, you must think that the kinetic and kinematic changes that occur with orthoses are purely neurological in origin, and not caused mechanically by altering the ground reaction forces on the plantar foot.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Interesting research. It would also be interesting to repeat this study with functional foot orthoses with 2mm/4mm/6mm/8mm medial skives at 15 degrees and compare those findings to this study. Any thoughts? Would a 6mm heel skive change calcaneal position in the frontal plane as much/more/less than a 10 degree rearfoot varus wedge???

Cheers,
Kent

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Cheers,
Kent

Performance Podiatry & Physiotherapy

My location

Hi Graham,

Do you have any references regarding this statement? The area of tests and assessment methods which are predictive of dynamic function is a big interest of mine and currently top of the list regarding my upcoming Masters degree thesis

Thanks in advance

Ian

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Hello all

Although I would not say there is no correlation between static measures and kinematic function, I would agree there tends to be a fair ammount of literature that notes that static measures are poor at predicting kinematic function as I have found doing some reading for my masters.

References are as follows Ian (some are a few yaers old but have fairly good methodology):

Hamill J. Bates BT. Knutzen KM. Kirkpatrick GM. 1989. Relationship Between Selected Static and Dynamic Lower Extremity Measures. Clinical Biomechanics; 4(4): 217-225

Hunt AE. Fahey AJ. Smith RM. 2000. Static Measures of Calcaneal Deviation and Arch Angle as Predictors of Rearfoot Motion During Walking. Australian Journal of Physiotherapy; 46: 9-16

Harradine PD. Bevan LS. Carter N. 2003. Gait Dysfunction and Podiatric Therapy – Part 1: Foot-based models and Orthotic Management. British Journal of Podiatry; 6(1): 5-11

McPoil TG. Cornwall MW. 1996. The Relationship Between Static Lower Extremity Measurements and Rearfoot Motion During Walking. Journal of Orthopaedic and Sports Physical Therapy; 24(5): 309-314

Halstead J. Redmond AC. 2006. Weight-Bearing Passive Dorsiflexion of the Hallux in Standing is Not Related to Hallux Dorsiflexion During Walking. Journal of Orthopaedic and Sports Physical Therapy; 36(8): 550-556

Cheers
Mark

Colleagues:

Here are some articles that do show a correlation between static measures and dynamic function:

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Ah Kevin!

,

Is this an elegant theorist calling the clinical evidence based kettle black?

o or one could say that at one miniscule of a second throughout the whole gait cycle that the foot orthoses constructed for these individuals MIGHT act on the plantar foot while in relaxed bipedal stance the same way that they would when these same individuals walked, by altering the ground reaction forces on the plantar foot. However, is there such a thing as relaxed calcaneal stance during dynamic function?

Then, if this assumption is NOT valid, considering that most assumptions are just that, it is very unlikely that you can infer anything from this research except that on the feet tested a wedge did this in static stance! Considering the variables associated with rearfoot/forefoot measurements, and there not so correlated effect on dynamic function, this type of research can only be assumed within the assumptions of an assumed theory.


G Another assumption. I have seen, using in-shoe pressure measurement, how various orthoses prescriptions affect multiple gait parameters. I "believe" that the primary effect of a device is mechanical (no evidence to support this assumption) but suspect that there must be some neurolgical effect. What is apparent is that varus heel and forefoot wedges dynamically would not produce the desired or consistent correction of foot function, especially in individuals who's static stance position appears to be similar,when timing of events & peak/total pressures etc are tested, as one would expect from the theoretical assumptions.

Some references I have, some repeated:

5. Sims DS & Cavanagh PR (1991): Selected Foot Mechanics Related to the Prescription of Foot Orthoses. In: Jahss MH (ed)Disorders of the Foot and Ankle: Medical and Surgical Management 2nd ed. Philadelphia: WB Saunders

6. Smith-Oricchio K & Harris BA (1990): Interator Reliability of Subtaler Joint Neutral, Calcaneal Inversion and Eversion. Journal of Orthopaedic and Sports Physical Therapy. 12(1) 10 -15.

7. Pierrynowski, M., Smith, S..B. and Mlynarczyk, J.H. (1996). Profficiency of Foot Care Specialists to Place the Rearfoot at Subtalar Joint Neutral Position. Journal of the American Podiatric Medical Association 86 (5) 217-223.

8. Menz HB (1995) Clinical Hindfoot Measurement - A Critical review of the Literature. The Foot 5:57-64

9. Hamil J, Bates BT, Knutzen KM & Kirkpatrick GM (1989): Relationship between selected static ansd dynamic lower extremity measures. Clinical Biomechanics 4 (4) 217-225

10. Knutzen KM & Price A (1994): Lower Extremity Static and Dynamic Relationships with Rearfoot Motion in Gait. Joournal of the American Podiatric Medical Association 84 (4) 171-180.

11.McPoil, T.G. &Cornwall, M.W. (1996): The relationship between static lower extremity measurements and rearfoot motion during walking. Journal. of Orthopedic and Sports Physical Therapy. . 24. No.5. pp 309-314.

25.Cavanagh, P.R and Ulbrecht, J.S. (1994) Clinical plantar pressure measurement in diabetes: rationale and methodology. The Foot. Vol 4. pp 123 - 135.

26. Bosjen-Moller, F. (1979). Calcaneocuboid joint and stability of the longitudinal arch of the foot at high and low gear push off. Anat. Soc. GB & I. Pp165-176.

27.Bennet, P.J., Miskewitch, V. and Duplock, L.R. (1996). Quantitative analysis of the effects of custom-molded orthoses. JAPMA. Vol.86. No.7. July. pp 307-310.

28. Scherer, P. (1994). The center of pressure index in the evaluation of foot orthoses in shoes. In Book of abstracts, 4th anual EMED users meeting. pp 44.

29. Rose, N.E, Fiewell LA, Cracchiolo III, A. (1992). A Method for Measuring Foot Pressures Using a High Resolution Computerized Insole Sensor: The Effect of Heel Wedges on Plantar Pressure Distribution and Center of Force. Foot & Ankle. Vol 13. No. 5. June

31. Winter, D.A. (1995). Human balance and posture control during standing and walking. Gait & Posture. Vol.3. No.4. Dec.

32. Winter, D.A. and Scott, S. (1991). Technique for interpretation of electrodynography for concentric contractions in gait. J. Electromyogr. Kinesiol. Vol.1. pp 263.

33. Sutherland, D.H., Cooper, L. and Daniel, D. (1980). The role of the ankle plantar flexors in normal walking. The J. of Joint and Bone Surgery. Vol.62-A. No.3. April. pp354-363.

34. Murray, M.P., Guten, G.N., Sepic, S.B., Gardner, G.M. and Baldwin, J.M. (1978). Function of the triceps surae during gait. J. of Bone and Joint Surgery. Vol. 60-A. No.4. June. pp 473-476.

35. Simon, S.R., Mann, R.A., Hagy, J.L. and Larsen, L.J. (1978). Role of the posterior calf muscles in normal gait. The J.of Joint and Bone Surgery. Vol.60-A. No.4. June. pp 465-472.

36. Brandell, B.R. (1977). Functional Roles of the Calf and Vastus Muscles in Locomotion. Am.J.Phys. Med. 56: pp 59-74.

37.Sutherland, D.H. (1966). An electromyographic study of the plantar flexors of the ankle in normal walking on the level. J. of Bone and Joint Srgery. Vol.48-A. Jan. pp66-71.

38. Close, J.R. and Todd, F.N. (1959). The Phasic Activity of Muscles of the Lower Extremity and the Effects of Tendon Transfer. J. Bone and Joint Surg. 41-A: pp 189-208, March.

39. Eberhart, H.D., Inman, V.T., Saunders, J.B., Levens, A.S., Bresler, B. And McCowam, T.D. (1947). Fundamental studies of human locomotion and other information relating to the design of artificial limbs. A report to the National Research Council, Committee on Artificial Limbs. Berkley, University of California.

Regards



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Graham Curryer

None of us know what we are doing, but some of us know more about what we are not doing than others!::

Kevin,

It is rather disingenius to select specific research which may support an argument, although when reviewing the overall picture there is not a consistant body of work that does.

Also,

but does this "foot Posture" correlate to symptoms, and how do we assess the dynamic effect of an orthoses on foot posture, such as arch height, when we can only assess the dynamic function of a device in a shoe?

Does the arch fall or is the first ray elevated?

We get back to the difference between the assumption that a study supports a theory and our inability, or unwillingness, to test the assumption with the available tools.

Regards

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Graham Curryer

None of us know what we are doing, but some of us know more about what we are not doing than others!::

Graham:

Always good hearing your views. We, the authors of the paper in question, fully realized that we were doing a static, not a dynamic, study of the mechanical effects of foot orthoses on the human foot. In fact, here is the last few paragraphs of the paper that is our disclaimer regarding our research.

We do have another paper that will be published soon in JAPMA that studies the dynamics of gait with varus and valgus wedges (Effect of 7 Degree Varus and Valgus Rearfoot Wedging on Rearfoot Kinematics and Kinetics during the Stance Phase of Walking). You can then protest, Graham, that this dynamic study had absolutely nothing to do with people that stand all day at work on foot orthoses.

I am still waiting for you, Graham, to publish just one research study so that I can critique your work also. I won't hold my breath.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Kevin,

Don't, I am just one of us Canadian clinicians without any resources other than an inquisitive mind!

regards

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Graham Curryer

None of us know what we are doing, but some of us know more about what we are not doing than others!::

Graham:

And a good clinician at that! I appeciate the dialogue on our paper and don't mind the challenges since they are certainly healthy.....in a Curryer sort of way.....

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Kevin,

A likewise my friend

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Graham Curryer

None of us know what we are doing, but some of us know more about what we are not doing than others!::

In this issue of static measures versus dynamic function there are many static measurements that will have no predictive value in dynamic function. That does not mean that the few that are picked out do not show a corelation with dynamic function. You have to look at the individual measurements.

Regards,

Eric

Graham,

Thank you very much for your comments of our paper recently published. I appreciate the critics that help us to improve the quailty of our research.

You are right when you said that there is no correlation between observed static pronation and dynamic function... However, the paper studied the "static correction" of the device, not the observed pronation... Those are different things. Till date, I do not know of any study that has proven that the static correction of foot orthoses is not correlated with the dynamic correction of foot orthoses. No one of the studies you cited have proven that.

I have only read three articles that measured correction of frontal rearfoot angles in static stance and dynamic:
1. Genova JM, Gross MT. Effect of foot orthotics on calcaneal eversion during standing and treadmill walking for subjects with abnormal pronation. At least, I think there is no evidence of that subject. J Orthop Sports Phys Ther. 2000 Nov;30(11):664-75.
2. McCulloch MU, Brunt D, Vander Linden D. The effect of foot orthotics and gait velocity on lower limb kinematics and temporal events of stance. J Orthop Sports Phys Ther. 1993 Jan;17(1):2-10.
3. Novick A, Kelley DL. Position and movement changes of the foot with orthotic intervention during the loading response of gait. J Orthop Sports Phys Ther 1990; 11: 301-312.

No one of these papers measured the degreee of correlation (or lack of) between static and dynamic correction with foot orthoses. By reading the articles I can tell you that the first one obtained a correction of 4.8 º in static stance (orthotic + shoe) and a dynamic correction 2.2º of peak eversion. McCulloch et al. obtained a 3.3º correction in static stance and 3.35º in peak calcaneal eversion. Finally, Novick and Kelley obtained a static correction of 2.39º and dynamic correction between 3º. However, I repeat, no one of these papers measured the degree of correlation between static and dynamic correction with foot orthoses.

We recomend (in the discussion of the paper to observe the results cautiously because of the static nature of the research. However, till we found evidences that the "static correction" of foot orthoses is absolutely no correlated with dynamic "correction" I would not say that this article is "irrelevant".

Thak you very much for your comments, again, we appreciate the critics that help us to improve the quailty of our research.

Kind regards

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Javier Pascual Huerta
Departamento de Podología
Universidad Europea de Madrid
Madrid, Spain

Cuando una ortesis no hace daño deberíamos alegrarnos y no exigir además que sirva para algo.

Thank you Javier

Despite my rather brutal critique it is still great to see research being published from the Podiatry community.

I wish you all the best in your future research endevours.

regrads

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Graham Curryer

None of us know what we are doing, but some of us know more about what we are not doing than others!::

Javier:

Thanks for your reply on our paper. You are an excellent role model for other podiatrists from your wonderful country. Keep up the good work!

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************