Chasing footprints in time – reframing our understanding of human foot function

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Chasing footprints in time – reframing our understanding of human foot function in the context of current evidence and emerging insights
Anja-Verena Behling, Michael J. Rainbow, Lauren Welte, Luke Kelly
First published: 24 July 2023 https://doi.org/10.1111/brv.12999

 

^^^read this. Full text online at the link. And when you have read it, read it again.

"We need to stop trying to shoehorn 21st-century research observations into outdated and non-evidence-informed theories about human foot function. Based on the overwhelming evidence, we urge the scientific community to abandon the long-held mobile adaptor–rigid lever paradigm."

 

From paper "A transverse arch does not exist at the metatarsal head level, but rather at the base of the metatarsals in the midfoot region." Wrong !

As toe off progresses the adjacent met heads are drawn together mediolaterally and move apart anteroposteriorly accentuating the transverse arch and more than likely providing a more rigid structure missed in other experiments. Thus the "metatarsal parabola effect" provides a more compliant foot during weight acceptance and a more rigid one during toe off .

 

I will digest fully and maybe come back to the forum with some comments

 

Well......... That is probably my most erudite read this year - a tremendous bit of work. Did we note how the reference to Root at al was nearly none? I note and accept totally their canning of the mobile adaptor/rigid lever paradigm, and I note and accept the issue of midtarsal locking mechanism. Maybe the problem was/is that the use of the term "locking" implies an absolute? Whatever one says, you cannot deny that a foot with a subtalar joint pronated is more mobile than one with the subtalar joint supinated. Interesting how they have picked up on Ker's work on the spring. I knew Mike Bennett briefly when I was a PhD student, perhaps 33 years ago as he was besties with my first supervisor, Paul O'Higgins. A load to think about here - a fine peice of work IMHO (my wife says I do not have one). And I am glad that they did not rubbish the early guys, that had stuff all in the way of high tech tools. I think it is a great read.

 

I believe you are wrong to do so .

Here is a link to a thread that explains why I believe this .
https://podiatryarena.com/index.php?threads/the-transverse-arch-of-the-foot-venkadesan-et-al.112183/

The metatarsal parabola exists, about that there can be no argument. As the heel lifts during gait this parabola will impact foot mechanics , again no argument. A far a I am aware ,the extent of the impact remains entirely unstudied other than a couple of simple youtube videos posted by me. Actually, implying the videos are studies is stretching things a bit, they merely illustrate the obvious.

Also, although the Behling paper is a welcome and well written addition to the literature, it does not address the foot as an "organ" of circulation. The foot is an osseofascial pump and its anatomy is vital to this function.

Whilst it is perfectly true that the pressures generated by the heart are enough to move blood around the body at rest this changes during gait. During gait the osseofascial pump that is the foot does a huge amount of circulatory work thanks to its anatomy.

 

Lots of studies on metatarsal parabola and its influence on foot function. I wrote a piece on it for a textbook.

Demp did a fair job IMHO

Demp, PH: A mathematical model for the study of metatarsal length patterns. JAPA 54:2 1964 p.107-110

Demp PH: Mathematical medicine. JAPA 60:9 1970 p352-353

Demp PH: The metatarsal hyperbola and the pathomechanical forefoot. Currrent Podiatry 20:3 1971 p15-17

Demp PH: A numerical taxonomy for evaluating the angular biomechanics of the human metatarsus. Current Podiatry 24:5 1975 p.9-11

Demp PH: Biomechanical optimality and the mathematical measurement of diagnostic patterns in the human foot. Arch Pod Med Foot Surg 3:1 1976 p.11-21

Demp PH: Biomechanical foot roentgenometry. Yearbook of podiatry 1978-1979. Ed: TH Clarke. Futura Publ. Co. New York 1978 p. 64-70

Demp PH: An anthropometric index for screening foot dysfunction. Current Podiatry. 28:6 1979a p.11-13

Demp PH: A mathematical taxonomy to evaluate the biomechanical quality of the human foot. M.S. Thesis (unpublished) Polytechnic Institute of New York, USA June 1979b

Demp PH: A correlation of length, width, height and pathomechanical quality in the human foot. Current Podiatry 31:8 1982 p23

Demp PH: Biomechanical profile analysis of the foot radiograph based on mathematical modelling. Current Podiatry 32:10 1983a p15-17

Demp PH:Mathematical modelling in podiatric surgery. A new approach to biomechanical evaluation. J Acad Amb Foot Surg 1:1 1983b p72-73

Demp PH: A mathematical taxonomy to evaluate the biomechanical quality of the human foot. Mathl Comput Modelling 11 1988 p341-345

Demp PH: A mathematical taxonomy to evaluate the biomechanical quality of the human foot. Mathl Comput Modelling 12 1989 p777-790

Demp PH: Using conic curves to classify pathomechanical biostructure of the metatarsus. Mathl Comput Modelling 14 1990a p668-673

Demp PH: Pathomechanical metatarsal arc: radiographic evaluation of its geometric configuration. Clin Pod Med Surg 7:4 1990b p765-776

Demp PH: Numerical diagnosis of pathoanatomy in the human forefoot: A pilot study. The Lower Extremity 1:2 1994 p133-138

Demp PH: Geometric models that classify structural variation of the foot. JAPMA 88:9 1998 437-441

 

Read the paper. Came away with many questions, two most importunate ones:

1. How can this information be applied clinically, rear time?
2. How does this information integrate with the paradigm of the foot motion linked to postural deviations?

I would answer both questions as no real time application and no integration with postural distortions.

 

I had a look for some of texts referenced but can't find anything about adjacent met heads moving relative to each other, in the transverse plane, through toe off . Is this discussed in the literature?

Also, how is your study on IFM strength and PF going?

 

“Huson believed that the metatarsal rays are part of a non-constrained tarso-metatarsal mechanism in which each metatarsal ray has independent stiffness (resistance to dorsiflexion) and range of motion. He suggested that the second metatarsal ray is the stiffest and described it as a “fixed spoke”. The biomechanical modelling performed by Salathe et al. And the dynamic pressure analyses performed by Hughes et al., support this conjecture. Alteration of a metatarsal’s position in the sagittal plane will alter the relative protrusion of that metatarsal in the transverse plane (Barnet, Heden and Sorto). Stokes et al., and later, Hughes et al. Showed that during gait the metatarsals do not load and unload simultaneously with one another; they load and unload on independent time-scales. As each metatarsal is loaded, it is deformed and displaced dorsally (Salathe et al., Winson et al.) and its relative protrusion in the transverse plane increases (Heden and Sorto).

Conversely, as load decreases beneath each metatarsal, dorsal deformation and displacement is reduced and relative protrusion decreases. The resultant change in relative protrusion is dependent upon the length of the metatarsal and the amount of dorsal displacement of the metatarsal head (Janis and Donick). This is dependent upon the metatarsal stiffness and the load applied beneath it (Salathe et al); i.e. the position of the metatarsal at any given time is dependent upon the moments acting on it about the tarso-metatarsal joint axes. Thus at any given moment in time during the forefoot loading/ unloading cycle, the metatarsal arc may describe a different mathematical function. This function may be of the same general form as the static arc, e.g. hyperbolic, ellipse etc, or it may transform e.g. from hyperbolic to ellipse, to parabolic, to ellipse and back to hyperbolic. Further research is required to determine the accuracy of this “dynamic metatarsal arc” hypothesis”
From Spooner SK: The structure of the metatarsal arc. In: Albert SF and Curran SA: Lower extremity biomechanics, Theory and Practice Vol.1. Bipedmed, L.L.C 2013 pp. 125-126

Although this textbook was published in 2013, I actually wrote my piece about 20 years ago.

Not sure what’s happening with that study as the lead researcher had some personal issues and took extended leave.

 

And more recently, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7857307/

although their assertions re: rigid lever mobile adaptor appear at odds with the conclusions of the current study which is the focus of this thread.

 

Just read this paper. Awesome picking apart of some of the more prevalent fluff. Kinda just hope they'll stop teaching undergraduate degrees as Podiatric history instead of current, relevant and applicable biomechanics.
They missed SALRE out of their examples of better approaches to understanding foot functions which was a bit criminal good to see Dr K still get his flowers towards the end though