Plantar fascia has no elastic fibers?

Martin:

Here's another nice article for you to read this weekend on the considerable stretching of the plantar fascia in vivo.

 

Hi Martin:

So stretch 1mm with 100 lbs.

So what is the original length? Resting state?

Perhaps the 1mm isn't "stretched" but perhaps it takes 100 lbs to observe it's actual length. It would be the difference between "slack" in the PF and actual stretching.

I have not read any study that proves (to me at least) that the "neutral" or "resting" or Primary length of the PF is actually shorter than at push off. The distance between the proximal and distal ends (as measured by various experimenters) may change, but this does not mean that the PF is stretching, does it? Much like a thin sheet of metal that is pliable - one can shorten it from point A and point B merely by bending it a bit, then lengthen it by "stretching " it. Does this mean it has elasticity?

I have to keep going back to my in vivo observations of PFs that I have resected - it's VERY tough stuff.

Steve

 

I think this is what I am trying to understand, ie be convinced by. One possibilty seemed to be how I speculated the flexors might suspend the fascia in a curve.

I tried to disprove this in the sauna last night.

Try this;

passively dorsiflex your hallux and keep a fingertip central to taut plantar fascia and stop dorsiflexion when bowing is reduced. maintaining restance to plantar digital area 1st toe actively plantarflex the toes. Are you able to reverse the curvature of the plantar fascia? Now try the same thing but with the 1st metatarso-phalangeal joint at zero dorsiflexion.

If anyone is able to notice any effect of the contour of the plantar fascia please post their obervation, in my foot I couldnt, so that is pretty good evidence to me that my idea is flawed.

Can you see any other mechanism which might allow inner longitudinal arch excursion without plantar fascia lengthenning?

Kevin and Simon must be right regarding some streching. However taken to extreme limits all of our living tissues are in constant state of intercellular stretching even bone at rest simply because of nature of cell migration and repair.

The mechanical testing of the resected cadaver fascia I have no issues with, agreed that the tissue is not living but given its microscopic structure (collagen fibres bound to ECM)I cannot see why this would differ a lot, agreed? If not why?

The methodologies for the stiffness studies I want to think about more, I think there may be some weakness there.

If you (+anyone else?) feel inspired lets critique methodologies, Kevin posted an in vitro study using fluoroscopy and Michael posted the other paper at start of thread.



cheers

Martin


The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Firstly a wish list for papers to be posted which I cannot get through my library.

Kitaoka, H. B., Z. P. Luo, et al. (1994). "Material properties of the plantar aponeurosis." Foot Ankle Int 15(10): 557-60.

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

At my knowledge level this seems like a really methodologically sound paper, thanks Kevin for that. It acknowledged limitations in differentiating plantar fascia properties from associated musculature and ligaments. I cannot see how it could have investigated its aim more painstakingly.

However there are some important assumptions in this paper to be checked.

Michael; This paper stated that the plantar fascia contains elastic fibres which contradicts the article which you originally cited.

Gefen cited (Bojsen-Moller, Fand Flagstad, KE, 1976). The abstract is added to the end of this post but doesn’t talk about elastic elements within the fascia.

Bojsen-Moller ‘s abstract stated: "The superficial fibres of the plantar aponeurosis are inserted into the skin of this distal area, and deep to them the plantar interdigital ligament forms a series of transverse lamellae connected to the proximal phalanges by a mooring ligament which arches from one fibrous flexor sheath to the next."

Gefen stated “It was demonstrated that the fascia elongates more rapidly during weight acceptance and midstance of the contact phase of barefoot walking. A slower elongation during push-off and toe-off follows the initially rapid deformation. This behavior may be explained by the histological appearance of the plantar fascia, which is composed of both collagen and elastic fibers. The elastic fibers show considerable difference in thickness and are arranged predominantly in strands and bundle-like networks in the abundant interstitial tissue.2 During the contact phase of walking, both the collagen and elastic fibers change from a wavy to a straight configuration as stress is applied. Having a lower modulus of elasticity compared to collagen, the elastic fibers contribute their structural support in early extension of the fascia (around midstance), while the stretching of collagen produces restraining effects on the elongation occurring at the late extension phase (toward push-off and toe-off). “


Interesting that he descibes what amount to a tendon structure and function, I would like to see Bojsen-Moller’s paper because Gefen’s assumption is based on that

Gefen also stated


In the present study, the elastic stiffness of the plantar fascia during gait in vivo was measured to be at about 170±45 N/mm. This result resembles the stiffness of intact cadaver fascia specimens, measured by Kitaoka et al.8 to be around 204±50 N/mm, using a material testing machine and video tracking system for controlled loading and displacement monitoring, respectively. The discrepancy of about 20% between Kitaoka et al’s data and the present result for the fascia’s stiffness can be explained by the increase of the elastic modulus of the fascia (seen in other biological tissues as well) after more than one hour post mortem, as first observed by Smith in the early 50’s.17 The in vivo fascia demonstrated increased stiffness at the early stages of weight acceptance (Fig. 4), and this may reflect the action of the intrinsic muscles of the foot which contract to increase the arch’s stability for dynamic load-bearing.

I think we need to see what segement of the plantar fascia Kitaoka tested to see if they are comparing the same structures. . . . someone help with paper please.

I think that it has been mentioned elsewhere that the distal attatchement of the plantar fascia represents the most compliant region which is consitent with the description above.

Gefen stated “The plantar fascia was shown to undergo continuous elongation from arch-contact to toe-off, reaching a deformation of 9 to 12% between these positions.

I wonder if the elongation is occuring mainly through the plantar fibro-fatty pad in the forefoot and as it becomes increasing loaded during MS the vertical ground reaction force limits the deformation possible. Compression and shearing of the plantar fibro-fatty pad and tension of the mooring ligamnents intuitively seems likely the first AND PERHAPS ONLY zone to stretch.

When I look at the fluoro images it seems that the plantar fibro-fatty pad is not fully compressed until time F, this represents 12 mm of the total 14mm of calculated lenghtenning of the plantar fascia.







This might explain the increased prevalance of chronic plantar fasciosis with weight gain; with increased forefoot loading and loss of plantar fibro-fatty pad compliance the distal plantar fascia loses its compliance. Also with posterior group contractures the forefoot loading will be earlier and faster. (Perhaps our foot orthoses design should be offloading the forefoot !!!!!?????)

It doesnt explain the comfort people report with elevated heel height, but this may be more to do with pain generated largely by compression of the adapted enthesis which is currently my pet hypothesis.

When the plantar fascia seems stiff examining during surgery or cadaver studies, we are examining the non compliant part and then infering this for the entire structure. Functionally the plantar fascia really demonstrates a more complex distal region which becomes indistinguishable from fibrous fat, ligaments and other muscular attatchments.

I think this can be demonstrated with self exam. Apply a slight passive dorsiflexion to hallux and tightly resist bowing of plantar fascia pinning it under inner longitudinal arch with fingers of other hand, the hallux can be dorsiflexed considerably before the plantar fascia starts to unbow. This suggests distal compliance since plantar fascia is not being stretched proximally.

I wonder if this is what strapping might do; to force the distal segements to increase their tensile load by altering the vector of plantar fascia pull (keeps it more vertical by pinning to skeletal inner longitudinal arch )?

Steve; Gefen answered your concerns – “The plantar fascia was assumed to be in a position of its neutral length when the foot’s arch was in a very early stage of contact with the ground” – In non weight-bearing foot this would be akin to applying passive slight dorsiflexion moment at metatarso-phalangeal joints.

WE NEED TO EXAMIN THE PAPERS AT THE START OF THIS THREAD TO MAKE PROGRESS . . . .HELP PLEASE.

blabbering as usual

cheers

Martin
The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com





Bojsen-Moller, F; Flagstad, KE: Plantar aponeurosis and internal
architecture of the ball of the foot. J Anat, 121:599-611, 1976.
Abstract
On the basis of its internal structure, the ball of the foot can be divided into three transverse areas, each with a different mechanical function: (1) an area proximal to the heads of the metatarsals in which the retinacula cutis are developed into a series of transverse bands, and in which the deep fibres of the plantar aponeurosis form ten sagittal septa connected to the deep transverse metatarsal ligament and through this to the proximal phalanges of the toes, (2) an area below the heads of the metatarsals in which vertical fibres from the joint capsules and the sides of the fibrous flexor sheaths form a cushion below each metatarsal head, and in which fat bodies cover the digital nerves and vessels in their passage between the cushions, and (3) a distal area which comprises the interdigital web. The superficial fibres of the plantar aponeurosis are inserted into the skin of this distal area, and deep to them the plantar interdigital ligament forms a series of transverse lamellae connected to the proximal phalanges by a mooring ligament which arches from one fibrous flexor sheath to the next. When the metatarsophalangeal joints are extended, the fibres of the three areas are tensed and the skin is anchored firmly to the skeleton. The direction of the fibres in the distal and proximal area promotes the transfer of forces exerted on the skin during push off and braking respectively, while the intermediate area is adapted to bear the weight of the body. A concentration of Pacinian corpuscles is found along the digital nerves in the weight bearing area below the transverse metatarsal ligament. The nerves for the second, and especially for the third, interstice are close to or in contact with the sharp proximal edges of the sagittal septa.

 

Here you go Mart...

 

Mart, I've not yet read the paper you quoted above, and have only scanned your post.

Might the variation in stiffness be accounted for by the loading rate and visco-elasticity of the plantar fascia. If loading rate is higher at the early stage of weight acceptance, and I would imagine it is, then this would account for the increased stiffness, irrespective of the intrinsic muscle action. Just a thought.

 

Steve

I still feel the need to find evidence for this; I agree that you are probably right. Does anyone have any better evidence than Gefen’s citation? It would be valuable to quantify what to expect between fresh, rigor morticed and embalmed tissue stiffeness.

Gefen stated

“The discrepancy of about 20% between Kitaoka et al’s data and the present result for the fascia’s stiffness can be explained by the increase of the elastic modulus of the fascia (seen in other biological tissues as well) after more than one hour post mortem, as first observed by Smith in the early 50’s.

I just finnished reading Smiths paper and all that he says about this is

”Annovazzi (1928) noted that the physical properties of ligaments change rapidly after general or local death. In my own experience ligaments become less readily extensible (Young's Modulus increases) and react elastically to greater loads (the elastic limit increases): the change becomes apparent within an hour of death and is progressive thereafter. The preparation of each ligament for examination was therefore always completed as quickly as possible, and no observations were considered valid unless they were made within 30 min. of death.

So nothing about the embalming process or any real evidence simply anecdote.

Interstingly he also mentioned;

“Histologically it (rabbit ACL) consists solely of collagen fibres and is devoid of elements showing the specific form and staining reaction of elastic fibres (PI. 1, figs. 1, 2).. “

ALSO

“The ligament (rabbit ACL) can be temporarily extended by as much as 20 % of-its original
Length”.

Now that is with histolgical evidence of lack of elastic fibres.

Cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com

 

I agree entirely but my gut has told me otherwise for a while which is why there is a nice window of opportunity to me explore this with others also being interested presently.

The evidence points to what you say but when I started to delve into some assumptions which the evidence used in its arguements it has started to look a little fragile.

I would really like to see what portions of the fascia were measured during in vitro studies because, if as I suspect, only the proximal segment was used this begs a look at the interpretion of the in vivo studies.

I am intersted to see where this ends up when the thread gets exhausted

cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Thanks Michael

Wow . . . .. what a beautiful exploration!

Could you find any reference to elastic fibres in this paper. I couldn't.

Looks like a flawed citation from Gefen's paper.

Bojsen Moller, F. and K. E. Flagstad stated

On the basis of its internal structure the ball of the foot can be divided into three
transverse areas: (1) a proximal, with the subcutaneous transverse bands and the
deep sagittal septa of the plantar aponeurosis, (2) an area below the heads of the
metatarsals, with the submetatarsal cushions and the fat bodies and (3) a distal
area, with the insertions into the skin of the longitudinal fibres of the plantar
aponeurosis and, deep to these, the plantar interdigital ligament.​

The three areas seem adapted to three different mechanical functions. During
push-of the heel is raised and the anterior part of the ball is in contact with the
ground. The skin tends to slide anteriorly but is prevented from this by the longitudinal
fibres of the plantar aponeurosis, which insert exactly in this area, and which
transmit the forces to the calcaneus. The arcuate form of the mooring ligament of
the interdigital web limits the spreading of the toes and allows at the same time
individual extension of a digit."​

Whilst they talk about the adaptation into 3 different mechanical functions I wonder if they also have an integrated effect of plantar fascia tension?​

I want to go and read this some more after an obscession break​

cheers​

Martin​

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com​

 

Hi Steve

I have been thinking this through a bit more. Why would we assume that a cadaver tissues will be stiffer than a live ones?

"cos its obvious stupid"

well bodies stiffen after death because of rigor mortis which only affects muscle (ATP, actin and myosin etc right?)

why would facia or tendon stiffen?

temperature perhaps, blood supply? there is no significant blood supply.

Formalin - how will that affect fascia or tendon?

"I don't actually know but it must because . . . . its a nasty chemical which dries out skin when applied"

In vivo patella tendon stiffness (Hansen 2006) turned out to be measured similar to in vivo animal BUT STIFFER than cadaver.

Now I am really begining to queston the assumption that enbalming makes the plantar fascia stiffer.

HANSEN, P., BOJSEN-MOLLER, J., AAGAARD, P., KJAER, M. & MAGNUSSON, S. P. (2006) Mechanical properties of the human patellar tendon, in vivo. Clin Biomech (Bristol, Avon), 21, 54-8.

cheers


Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Hi Martin and others.

I found this article on the Finite Element Modeling of the human Foot and Footwear. Ive just flicked threw it but it does discuss the PF so thought I would post it up to see if it adds to the discussion.

 

Ok Read thru the above ariticle not so Much But did find the following paragraph, which I guess does not add so much.

 

Hi Michael

The start of the tread concerned if the plantar fascia contains elastic fibres or not. I think this also raises the questions of; if the plantar fascia is able to stretch "much" whatever that might mean (store significant potential energy?), if stretching exercises might stretch the plantar fascia therapeutically, presumptions regarding the accuracy of the stiffness of the plantar fascia in experiments and the nature of plantar fascia injury and how ther plantar fascia behaves distally.

So far I have learnt that one study cited a paper erroneously regarding presence of elastic fibres, ligaments without elastic fibres can stretch 20% of length without plastic deformation, and it is possible that the embamling process doesnt make plantar fascia stiffer as most might assume. Also some speculative ideas regarding possibilty that what is assumed to be evidence of alteration of stiffness of plantar fascia in early stance may be measurement of underlying soft tissue compression.

Not sure if there is much more can be trolled from the lit but seems like we have some questions/answers to add to "Podiatric Trivial Pursuits" cards

cheers

Martin


The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

That seems a good summary to me. Before this one gets retired off to warmer climates does anyone have a copy of

Ker RF, Bennett MB, Bibby SR, Kester RC, Alexander RMcN: The spring in the arch of the human foot. Nature, 325: 147-149, 1987.

Which Kevin put up I can´t hit a full text anywhere.

 

here's paper

View attachment The spring in the arch of the human foot.pdf


cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Martin:

Thanks for providing this excellent paper for everyone to read. It is one of my favorite foot biomechanics papers of all time and I use it as a reference frequently in my national and international biomechanics lectures.

Ker RF, Bennett MB, Bibby SR, Kester RC, Alexander RMcN: The spring in the arch of the human foot. Nature, 325: 147-149, 1987.

 

Hi Kevin

From the same edition was a letter of commentary regarding the study. It nicely appreciates a difference in interpretation of running in a way I have not seen expressed elsewhere.

View attachment 1.pdf


Kinematically we might tend to differentiate walking and running according to presence of free flight. However an more meaningful alternative is to look at position of COM during midstance ie inverted pendulum vs spring. Here is shown how Groucho gait has no flight but is actually characteristic of running (spring) which has more meaning.


Cheers

Martin


The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Martin:

I have been lecturing on running vs walking biomechanics this way, via differences in COM kinematics, for about the past 10 years.

Here is a discussion from a few years ago we had on the subject of Running versus Walking.

 

Dear All,
Forgive me for going backwards in this debate, but I need some clarification.
1) We've all been taught that one of the treatment modalities for plantar fasciitis is stretching the plantar fascia. Is the consensus agreeing with this or not?
2) If, plantar fasciitis is a misnomer, and the condition should not be an 'itis' i.e no cardinal signs of inflammation, then have the other treatment modalities, such as application of ice, NSAIDs and hydrocortisone injections become out of place modalities? I am most concerned about hydrocortisone, because if this is of little help, it can also induce injury.

Just a small comment. In another life I worked in an automotive leather testing laboratory. We did millions of tensile strength/elongation tests of leather. The tests are similar, using similar equipment to the ones cited here. I do not want to disregard any science being put forward, but sometimes the scientific equipment can only measure to a certain magnitude, and sometimes there are many other reasons involved.
Sorry if this is not helpful.

 

Hi Mart, et al.

Well, as far as the elastic SPRING nature of the foot and the rubber ball effect of stored energy of running......
I can tell you from personal experience that without a certain amount of muscle strength, you cannot run, in fact, if you are unable to lift your body weight (tiptoe lift) with one foot, you cannot walk without a limp.

Stored energy and spring effect should make it easier to walk with each step unless you are expending all the stored energy from the previous step - i.e., uniform steps, pace, stride length, slope, etc.....hmmmmmmm.

I never did buy into the "controlled falling" definition of walking. We lift our body with each step with each foot unless we do not have a heel to toe gait.

Steve (the non biomechanic here)

 

Hi Gillian


As fellow Manitoban I thought I might respond to you :drinks

1 There is slight evidence in the lit for technique of "tissue specific stretching" at point of maximum tenderness for plantar heel pain in cases attributed to chronic plantar fasciosis. Otherwise there is no consensus regarding treatment because the etiology remains unknown and studies lacking.

2 no evidence exists supporting using injectible corticosteroid for plantar heel pain, not neccessarily because it is unhelpful simply that good studies have yet to be done to figure this out. Also role of inflamatory mediators, gene expression, effects of corticosteroids even nature of injury is not clear.

There are lots of threads on podarena which talk about this already

I would think that the instrument error in mecahnical testing of the plantar fascia is the least of the error concerns in the studies


way to go Manitobans!

cheers

Martin


The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

MART:
one more thing.

you said, "ligaments without elastic fibres can stretch 20% of length without plastic deformation,........."

my answer to this ---------

17.5% of all statistics are made up on the spot!

haha

Steve

 

I think you need to increase your daily dose of the Simpsons or Family Guy

:empathy:


cheers


Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Martin and Colleageus:

Here is my lecture, Biomechanics of Running, that I presented at Biomechanics Summer School 2004 at Heythrop Park, Oxfordshire, England, in August 2004, where I talked about the differences in energy transfer between walking and running. Thought you might enjoy the lecture since you have become more interested in the literature on the energetics of running versus walking.

 

Kevin,

I was in Oxford at that time and was lucky enough to hear you talk at Heythrop Park. If my memory serves me correctly it was in the above lecture on Running Biomechanics that you used a brilliant picture with reference to GRF (a fist coming out of the ground). 6 years on and I have never found a picture to use myself that has lived up to the memory of that one - any chance of a hint as to where you picked it up from??

Ian

 

Just for you, Ian.:drinks

 

Legendary! I thank you sir.

Ian