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Plantar fascia has no elastic fibers?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by mike weber, Jan 12, 2010.


  1. Members do not see these Ads. Sign Up.
    Hi all,

    I was looking at Podiatry Today this morning and read an peice on the treatment of Plantar fasciitis in runners. Link below.


    podiatry today article

    The below paragraph is taken from there

    The bit in red jumped out at me.

    There has been many discussions about the elastic properties of the PF and energy store process during gait. How can this occur if there is no elastic fibers or is the piece wrong and the PF does contain elastic fibers ?
     
  2. Re: podiatrytoday- plantar fascia has no elastic fibers

    I went off to Google and My thread came up as Number 3, but I did find this following article.
     

    Attached Files:

  3. Re: podiatrytoday- plantar fascia has no elastic fibers

    It appears Kevin has discussed this 1.5 years ago. I just saw it at the bottom of the page, Sorry for the double thread. http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=12196

    That being said why if there is evedence for the Elastic properties of the Plantar fascia would they write a line like that in a Paper with no reference, what I also find a bit odd is that they go on about positive from stretching the PF in this study seems a bit odd to me.

    DiGiovanni BF, Nawoczenski DA, Lintal ME, et al. Tissue-specific plantar fascia-stretching exercise enhances outcomes in patients with chronic heel pain: a prospective, randomized study. J Bone Joint Surg Am 2003; 85A(7):1270-7.

    a bit confused
     
  4. proud

    proud Member

    Re: podiatrytoday- plantar fascia has no elastic fibers

    Any discussion take place on here about the fact that histological studies are now suggesting that plantar fasciitis is not an "itis" at all but rather an "osis"....

    Such that of course intitially stretching and loading it will generally be uncomfortable but over time this tissue will adapt?

    I know there is solid research on this for patellar tendonosis and achilles tendonosis. Not sure what a different structure like the plantar fascia would respond to the loading strategies discussed in other relevant papers( Alfredson et al)...

    Just foor for thought.

    Regards,
     
  5. drsarbes

    drsarbes Well-Known Member

    Re: podiatrytoday- plantar fascia has no elastic fibers

    Hi Mike:
    There was a thread a couple years ago I recall - I stated that you cannot "stretch" the fascia for that same reason, no elastin. Of course the "bio-engineers" on the Arena argued that you can stretch anything, even steel!

    OK - well, you can't stretch the Fascia. I tell my patients this and I stand by it. You can stretch the AT all you want, but from what I see first hand, intraoperatively, the plantar fascia isn't intended for stretching.

    Steve
     
  6. Re: podiatrytoday- plantar fascia has no elastic fibers

    Heres one thread for you where it was discussed.


    One of Marts PF threads.

    here´s a journal paper for you. But it should be noted that wherever there is blood flow there can be inflammation, ever if there is no inflammation cells within the fascia. So it can be micro tears and inflammation at the same time or seperatley
     

    Attached Files:

  7. Re: podiatrytoday- plantar fascia has no elastic fibers

    Hi Steve. Did you have a chance to look at my post 2. Can you explain how the Plantar fascia stretched under load in that experiment ?

    Also does anyone have a histology paper of the make up of the plantar fascia I tried to find one but no luck.
     
  8. Re: podiatrytoday- plantar fascia has no elastic fibers

    Like all other materials, the plantar fascia can be stretched. In fact, scientific research from over 45 years ago has shown that the plantar fascia stretches under tensile loads (Wright DG, Rennels DC: A study of the elastic properties of plantar fascia. JBJS, 46 (A):482-492, 1964). Until one understands the concepts of elastic and plastic deformation in materials, and the concept of viscoelasticity, trying to understand why and how the plantar fascia will stretch when subjected to tensile loads will not be completely understood. I suggest a little reading is in order for all those involved in this discussion.
     
  9. Re: podiatrytoday- plantar fascia has no elastic fibers

    :good: Apply enough load and any tissue can be stretched. Apply enough load and you induce plastic set. Apply constant load and we get creep- http://www.youtube.com/watch?v=nxpblnsJEWM
    Tune!
     
  10. Re: podiatrytoday- plantar fascia has no elastic fibers

    So your saying that I was correct to question what I read in the Podiatry Today article when the author stated that the plantar fascia has no elastic fibers.
     
  11. Re: podiatrytoday- plantar fascia has no elastic fibers

    Mike:

    There is a difference between collagen fibers, elastin fibers and the term "elastic". To my knowledge, the plantar aponeurosis has no elastin fibers, only collagen fibers, and all of these collagen fibers are viscoelastic in nature.
     
  12. Re: podiatrytoday- plantar fascia has no elastic fibers

    I don't know what proportion of elastin and collagen fibres make up the average plantar fascia, but regardless of this, even if the plantar fascia has zero elastin fibres this does not mean that you cannot induce plastic set within it, i.e. stretch it permanently. All fibres will have an elastic and plastic zone- it just depends on the loading.

    Think about this: lets say we could take out individual fibres from the plantar fascia of each of the materials it is comprised of. Now lets put those fibres in a materials testing machine and apply a tensile load to them such that we get a stress/ strain graph for each fibre type, the graph for each fibre type will typically exhibit a toe region, a linear region, a limit of proportionality, an elastic limit (after which plastic set will be induced), a yield point and breaking point.

    Now do the same with the plantar fascia as a whole- we still see the same features in the stress/ strain plot.
    Somebody mentioned Robert Hooke recently- yeah, big up the Hooke- go read his work with springs!

    Basic materials science- if you wish to understand tissue stress, you MUST understand the stress/ strain curve.
    This book is a good read in this area:
    http://www.amazon.com/Kinesiology-Application-Pathological-Gary-Soderberg/dp/0683078518
     
  13. Re: podiatrytoday- plantar fascia has no elastic fibers

    Thanks that clears up a Couple of questions. I´ll keep reading, learning and asking thanks again and I check out that Book Simon.
     
  14. Re: podiatrytoday- plantar fascia has no elastic fibers

    Noting comes up when I click on the link.

    I´m guess it was Radiohead. I like the KORN version as well here for your listening pleasure.

    Korn cover of radiohead creep.
     
  15. drsarbes

    drsarbes Well-Known Member

    Re: cadaver studies of plantar fascia elastic properties:

    In my opinion it's a bit of a stretch (and in some cases a quantum leap) to compare nonviable cadaver studies to viable tissue properties.

    As I've said before - no blood supply and lots of formalin changes human tissue.

    Steve
     
  16. Mart

    Mart Well-Known Member

    Hi Steve


    A nice long reply for you . . . . . . on and on and ..... on (I am not in clinic today just getting over jet lag) :eek:

    I think you may be overstating this and to my knowledge this issue has never been studied. Whilst the embalming process will alter tissue properties we do not know how much. I have just finnished a couple of days preliminary investigation of effects of embalming of US appearance of foot and ankle. It is difficult to generalise too much because there is quite a large variability in how living feet image but I managed to sucessfully select pathologic specimins from a selection of undisected cadavers and examin them for impression of US and morphologic characteristics. What was striking for plantar fascia was similarity of cadaver to living US appearance.

    The anatomy prof who runs the lab I was working in (Dr Quentin Fogg, U of Glasgow) has wide interest in MSK anatomy and emphasises in his teaching the disparity between texbook appearance of soft tissue stucture, it’s labelling (convenient and pretty) which reality which can be demonstrated to be much more complex (and interesting).
    Case in point is concidering the plantar fascia and its relationship with FDB, ABH and FDMB.

    Before taking more care in thinking about these structures my mental imaging of them was based on anatomy textbooks, computer 3D images (primal) and crude quick dissections as undergrad; that the plantar fascia and adjacent muscle attatch into plantar calcaneal area, span the inner longitudinal arch and attatch into the forefoot. My impression is that FEA for plantar fascia simplifies the modelling process to this type of mechanical picture.

    If you look at the contour of the plantar fascia saggitally in a semi weight-bearing foot it is bowed along the inner longitudinal arch and supported proximally by thick fat, it is not straight connecting forefoot to rearfoot in the simplified tie and beam diagrams. The FDL is surrounded by the plantar fascia on 3 sides, the FDL insertion is oblique along the entire length and on all 3 sides of the plantar fascia which functionally forms a tube around it. The FDL is really hundreds of small functional sub units which pull obliquely attaching not at the medial process of calcaneal tuberosity but along the entire length and circumference of the plantar fascia. Becasue the vector of their pull is oblique this is likley to impart much greater mechanical advantage than might be anticipated for small muscle and I am unaware if any calculation for the A/P forces generated have ever been studied.

    The fibrillar appearance of the collagen bundles in the plantar fascia seems primarily A/P and distally the specimin I looked at showed the deep surface of the plantar fascia had longitudinally arranged subunits of the FDL embedded intimately within the plantar fascia collagen bundles.

    From a mechancial point of view I think this infers that the stiffness of the plantar fascia during much of its loading during stance is a factor not simply of its isolated mechnical properties (embalmed not) but also includes the recruitment of the inserted musculature, the distortion of fatty tissue, the condition of the multitude of fine sheets of interposed fascial sheets which allow the layers to glide to name a few.

    I am unaware of the visoelastic characteristics of the isolated plantar fascia (Dave Smith are you reading this?) but would guestimate that during loading of the foot during gait the influence of the adjacent structures (if measuring stiffness of sum of entire inner longitudinal arch supporting units) must be considerable and that the endpoint stretching of the plantar fascia may primarily be protective for adjacent structures. If this is true it would manifest itself in alteration to the postion of the foot with increased recruitment of FDB and FDL. If I do a single limb stance heel raise and actively recruit toe flexors I can appreciate increased rearfoot inversion which is consistent with this possibility.
    That doesnt diminish thought the importance that the “tube” focuses its pull at the medial process of calcaneal tuberosity enthesis. This is correlated to clinical signs of injury, US evidence of change and FEA predicion of peak stress.

    In the end the mechanical properties of the plantar fascia in isolation may not be that influental to normal foot function but morphologic changes of its enthesis a reflection of more complex interaction. That, if true must be an important consideration in terms of what stretching regimen may amount to, what surgical release of plantar fascia is intended to acheive (where and why) and how foot orthoses may influence pain.


    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
     
  17. Steve:

    There is no question that the plantar fascia stretches under tensile load since it would be the only tissue within the human body that does not elongate under tensile loading forces.

    The better question should be, rather, will a stretching program cause permanent stretching or elongation of the plantar fascia? The answer to that is as follows: due to its viscoelastic properties, the plantar fascia certainly may be elongated if stretching is carried out regularly, but it will return back to its shorter length over time when it is not stretched. This time-dependent viscoelastic mechanism of the plantar fascia and other ligaments and tendons in the body is known as creep. The viscoelastic property of creep (all tissues of the body are viscoelastic in nature) very neatly explains the therapeutic results that plantar fasciitis night splints have on resolving the post-static dyskinesthesia that commonly is seen in patients with proximal plantar fasciitis.

    Here's a great study that all of those following along should read:

    Mechanical Properties of the Triceps Surae and Aponeurosis in Relation to Intensity of Sports Activity
     
  18. If you induce plastic set, it'll stay stretched (at least until it is remodelled by Davis's law). The question is how much load do you need to place upon it to induce plastic set?
     
  19. Simon:

    Probably about the amount of load to cause plantar fasciitis.:drinks
     
  20. Good call.
     
  21. Mart

    Mart Well-Known Member

    Kevin

    How about these possibities;

    1 the plantar fascia doesn't stretch uniformally thoughout most of its length but behaves more akin to a metatarsal which bends according to the tensile stress applied by inserted musculature and vertical ground reaction forces along its length. How else would you account for the fact that the plantar fascia is curved in the sagiital plane?


    2 the enthesis of the plantar fascia stretches not primarily because of a uniform tensile strain along its length but in a graduated way distal to proximal because of focus of forces from adjacent structures attatched to it.

    3 The morphologic changes associated with plantar fascia and plantar heel pain do not reflect plastic deformation (unless in acute tear) but a gradual adaptation to stress (fibroblastic activity) resulting in re-enforcemment of enthesis. This might be why the plantar fascia appears to appear inchanged after resolution of pain on US. The pain may be more related to increased compressive stress because of adaptive change in volume of plantar fascia and lack of corresponding adaptation of fatty tissue at that site.

    This idea is consistent with formation of spur which is likely fibrocartilage at onset (responce to compressive stress) and if calcified has vertical trabeculation also suggesting compressive stress.

    cheers

    Contrary Mary

    The St. James Foot Clinic
    1749 Portage Ave.
    Winnipeg
    Manitoba
    R3J 0E6
    phone [204] 837 FOOT (3668)
    fax [204] 774 9918
    www.winnipegfootclinic.com
     
    Last edited: Jan 14, 2010
  22. Mart

    Mart Well-Known Member

    Hi Kevin

    Just finnished reading the paper, thanks for that.

    Interesting that “the force strain relationship of the human triceps surae tendon and aponeurosis remains at control level in a wide range of applied strains and that the strain amplitude or frequency should exceed a given threshold in order to trigger additional adaptation effects”.

    Does this suggest that ankle stretching exercise could only effect muscle compliance and doesn’t likely alter the tendon stiffness?

    I think that your comparison of tendo-achilles and plantar fascia is a bit of a stretch (prize for # of times this pun can be used in this thread?) because the tensile units are in series as opposed to parallel as in the plantar fascia.

    The more I think about it the less likely it seems that the plantar fascia elongates much, it seems more likely that its bowing is controlled by concentric muscular activity or passive stiffness of the muscle bundles throughout the strain of the entire complex musculo/fascial unit. If that is true then tissue adaptive response to tensile loading across the inner longitudinal arch is a completely different matter to the ankle.



    Cheers


    Martin


    The St. James Foot Clinic
    1749 Portage Ave.
    Winnipeg
    Manitoba
    R3J 0E6
     
  23. Martin:

    Don't really understand your point here: parallel vs series??

    I didn't say that the plantar fascia stretched or elongated a lot, I said it does stretch. Steve said it doesn't stretch. Normal stretching of the plantar fascia is probably something like 2-4 mm with each step, depending on body weight, by my estimates of tensile force and elastic modulus. Dave Smith's master's thesis was on this subject and he can provide his estimates also.
     
  24. Martin:

    Probably the plantar fascia stretches more like 1.5-2.0 mm with each step with someone of 150-200 lbs body weight from looking at Wright's original paper.
     

    Attached Files:

  25. Mart

    Mart Well-Known Member


    In the triceps complex ALL of the force created in the muscle is transmitted through the tendo-achilles because they are linked end to end (series) Diagram A below.

    [

    PF1.jpg


    I think that the plantar fascia forces relative to the FDB might be represented by diagram B

    PF2.jpg

    Blue arrow represents load during windlass for plantar fascia, likewise yellow arrow for FDB central aponeurosis. The green sub units will couple forces between plantar fascia and FDB aponeurosis (units acting in parallel). Distal force from windlass on distal plantar fascia will therefore be attenuated by pull of FDB subunits in more proximal section of plantar fascia. It might be argued that the opposite happens, ie that the distal pull on the plantar fascia from the FDL subunits increases the force more proximally on the plantar fascia. The bowing of the plantar fascia will be a function of activity if FDB subunits, the tension from distal plantar fascia windlass, passive stiffeness of FDB aponeurosis and muscle (plus complex similar interactions with ABH,ABDM, FAccess ect).

    I guess my point boils down to the idea that although we might appreciate an estimated youngs modulus for the plantar fascia, the deforming forces acting through it are likely to be inhomognous with time as opposed to the tendo-achilles which in a healthy tendon would be expected to be much more uniform.

    I find it interesting that the cross sectional area of the healthy plantar fascia appears to decrease towards the insertion which of course with FEA models explains why the strain is focused at the enthesis.

    If we consider a more coupled model which involves amoungst other things the FDB, and less appreciated the Flexor Accessorius then I would estimate the CSA of the entire "tie unit" much greater and perhaps the calculated strain at the plantar fascia enthesis lower.


    I cannot substantiate this, pure speculation, but I am trying to justify (and play devils advocate) an arguement that the enthesis injury which most of us presume the result of purely tensile plastic deformation of the collagen at that site might be something else. :pigs:



    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
     
    Last edited: Jan 15, 2010
  26. Martin (Advocate of Lucifer):

    I like the colored drawings....but don't quite understand them. The bottom line is, that regardless of the magnitude of tensile force within the central component of the plantar aponeurosis, it will stretch or elongate during weightbearing activities.:drinks
     
  27. Mart

    Mart Well-Known Member

    Hi Kevin

    Thanks for paper, I wish Dave Smith would get involved in this thread.

    Wright and Rennels state

    “In a study made on one subject, an attempt was made to approxinlate in a
    living person some of the test conditions described. It is known that the arch of the
    foot is elongated by loading the foot. Because of the anatomical position of the
    plantar fascia, elongation of the arch entails identical elongation of the fascia. In
    this study, increasing loads were applied to the knee of a seated subject, and the
    progressive elongation of the arch of the foot was measured.”

    I think this premise is flawed. The plantar fascia is bowed and the elongation of the inner longitudinal arch might be better explained in large part by an alteration to the bow radius not plantar fascia stretching, this is what I percieve watching the behaviour of the plantar fascia on US with passive windlass and fits the idea in my previous post.

    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
     
  28. Mart

    Mart Well-Known Member

    The 1st diagram was intended as a key for the 2nd one; the red line is plantar fascia (central band of PA). I remain unconvinced by the magnitude of stretch. The youngs modulus calculation of Wright I have no problem with but the calculation for length I do - see last post. If I am right this will screw up the visco elastic model, which might better be explained by "spring muscles" than collagen motion in the plantar fascia.

    see what I am getting at?

    cheers

    Hornless 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
     
    Last edited: Jan 15, 2010
  29. Mart sorry to be a bit dence but what do you mean by "Spring Muscles"

    Edit: are you saying that the PF will not get longer but contract and return energy like a spring?
     
  30. Mart

    Mart Well-Known Member

    Hi Mike

    I am sure that you are not dense, my diagram probably doesnt make sense to you ( or Kevin and anyone else?)

    Let me try and clarify what I intended and relate it to what I see in dissection of FDB and interpretation of what I see on dynamic US.


    FDL dissection.jpg


    the photo above shows the subunits of the FDB attaching along deep aspect of the plantar fascia. They are represented in my diagram by the green lines, the red line is the plantar fascia and the yellow is the aponeurosis of the FDB (which is bipennate) which the subunits are attatched to.

    US FDL.jpg

    the US image above shows a a similar saggital view of the same structures, the arrows are coded with same colours.


    My arguement is;

    Wright and I think Dave Smith too estimated the stretch of the PF accoring to the increased distance measured on weight-bearing radiographic exam between the medial process of calcaneal tuberosity and the 1st metatarsal head.

    The premise here is that the plantar fascia is straight and any change in length must therefore represent stretching.

    I think this is flawed because

    the plantar fascia is is bowed (except perhaps in a very pes planus foot).

    If you look at your foot profile in sag plane and passively dorsiflex your hallux you can see the plantar fascia curvature reduce but still remains curved.

    I believe that the FDB subunits (amoungst other muscles) act as supporting "spings" which allow the plantar fascia to straighten with load. Hence my crude analogue earlier with the metatarsal. Clearly the plantar fascia is not stiff as the metatarsal but perhaps closer to that than the tendo-achilles.

    If this is true then the inner longitudinal arch excursion doesn't represent stretching of the plantar fascia unless the plantar fascia becomes entirely straightenned because the "springs" being muscle are more compliant.

    plantar fascia "stretching" then may be mostly resisted plantar fascia "unbowing"

    I did some crude experiments a while ago where I made a rig with a US probe mounted under a water bath so that I could study the behaviour of the plantar fascia in sag plane with weight-bearing. What suprised me was that although the plantar fascia straightenned somewhat it seemed to remain slightly bowed throughtout a simulated stance.



    hope that makes more sense.

    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
     
  31. That make more sense thanks. I will let others argue or agree with you and I think I will follow along.

    To make a simple eg. Take a A4 paper which is x cm long from edge to edge, when flat, now bend it in the middle the the edge´s come closer but the paper is the same length. Intersting how do you prove or disprove this one?
     
  32. Put a strain gauge into a plantar fascia in a cadaver gait simulator.
     
  33. Mart

    Mart Well-Known Member

    This is the same idea, the curvature of your sheet of paper (plantar fascia) is suported by springs (FDB sub units) as the springs are stretched the distance increases but the paper doesnt lengthen (stretch) until it is flat . . . . when perhaps it tears at point of least CSA ie the enthesis.

    If this is true then what use stretching? It seems from one study to help symptomatically but is this really an alteration of visco-elastic properties? Perhaps. It seems to me that the plantar fascia specific stretching is unlikely to have the 2mm excursion which Kevin mentioned. This is the intuitive reaction Steve has and me too, I am trying to find an explaination for that intuition, Steve has more interesting things to do ;) than me.


    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
     
  34. Mart

    Mart Well-Known Member

    Crude as it was, when I was poking around my plantar fascia with accupuncture needles I did look at the effect of passive hallux dorsiflexion on the position of the needle and could not see any motion in AP direction with US. Granted that the adjacent fat pad might have "splinted" it but I was expecting to see some motion.

    Anyone want to volunteer to have absorbable sutures embedded into the plantar fascia, then we can get "gold standard" measurements using US?

    I was thinking we could form the "extreme foot self experiment group" which would be akin to those crazy extreme sports guys who tight rope walked between the Twin Towers ect. . . . . .. . . .. maybe not

    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
     
  35. Mart

    Mart Well-Known Member

    Crude as it was, when I was poking around my plantar fascia with accupuncture needles I did look at the effect of passive hallux dorsiflexion on the position of the needle and could not see any motion in AP direction with US. Granted that the adjacent fat pad might have "splinted" it but I was expecting to see some motion.

    Anyone want to volunteer to have absorbable sutures embedded into the plantar fascia, then we can get "gold standard" measurements using US?

    I was thinking we could form the "extreme foot self experiment group" which would be akin to those crazy extreme sports guys who tight rope walked between the Twin Towers ect. . . . . .. . . .. maybe not

    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
     
  36. This would just show whether the two sutures move apart or not, not whether the plantar fascia stretches. Given your hypothesis, we need to differentiate whether the curve of the fascia "flatten" or whether the plantar fascia stretches- to do this you will need a strain gauge.
     
  37. Martin:

    You are going to lose the battle on whether the plantar fascia elongates some under tensile loads, Martin. I know this because all structures and materials elongate under tensile loads.

    I do see, however, you point about the bowing of the plantar fascia and certainly this is an important consideration when we are trying to estimate's its change of length in vivo without a strain gauge attached to the plantar fascia. All the studies I know that looked at plantar fascial tension showed it did have tension in it, which means, by definition, it stretched a little.
     
  38. Mart

    Mart Well-Known Member

    good point, I hadn't thought that through carefully enough; make that "extreme and FUTILE foot self experiment group"

    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
     
  39. Mart

    Mart Well-Known Member


    Hi Kevin

    I have no quibble with the idea that the plantar fascia stretches (some) but I am trying to get my head around why to me (and Steve) and I think many others that there is no "perceptual" stretching either when examining live feet or cadavers.

    This may be lack of sensitivity in my finger tips or poor judgement but I still believe it represents lack of compliance which is perhaps what we should be talking about. I feel that my spring supported curved wire has some merit because so far I have unsuccessfully tried to disprove the notion and it seems to make sense.

    If I am right it would mean that elasic recoil was little to do with the mechanical properties of the fascia. I agree that is a bit of a "stretch" given lack of evidence though.

    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
     
    Last edited: Jan 16, 2010
  40. Martin:

    The plantar fascia is relatively stiff so will stretch little with tensile force applied across it. However it does stretch. This is the whole point about my discussion: you will need to apply about a 100 pound load before you will see it stretch 1 mm (at least using Wright's data). However, since Wright only used a part of the fascia during his experiment, the fascia, from heel to digits, probably stretches more than this. As far as elasticity, Ker et al's paper shows that the plantar fascia can add stiffness and return energy to the arch of the foot, which means that it must also be able to stretch and then recoil in order to release this energy into the foot.

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