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The myth of toes curling to grip the ground

Discussion in 'Biomechanics, Sports and Foot orthoses' started by scotfoot, Apr 28, 2022.

  1. scotfoot

    scotfoot Well-Known Member


    Members do not see these Ads. Sign Up.
    If you try and balance on one foot with weak intrinsic foot muscles you might well see the lesser toes adopt a "hammer toe" like arrangement to try to allow the toes to apply force to the ground. This is often misinterpreted as the toes being used to grip the ground, which is not the case, they're just collapsing due to weak flexor digitorum brevis.

    If a person can stand on one foot and the toes remain straight during balance then the next stage might be to lean forwards a little and put the toes under even more pressure. If they collapse into "hammer toe" now then the are still weak feet ( care needs to be taken to avoid loss of balance and falls when lean forwards on one foot, a table for support might be a good idea)

    I have found that as little as 6 weeks strengthening the toes ( moving them around the MTPJ without curling them) is enough to change the mechanics of the distal foot under load and stop "toe collapse".
    Here is a picture of toes collapsing under load, the toes are not gripping ; [​IMG]
     
  2. scotfoot

    scotfoot Well-Known Member

    A physiotherapist ,Tim Trevail @Trevail, has recently posted a good video of a person balancing on one foot on twitter which shows the lesser toes go in and out of a collapsed, hammer toe, position as they come under pressure.
    I have retweeted this video together with one of a stronger foot to illustrate the point made in the 1st post . My twitter address is @FarrellGerrard if anyone is interested .
     
  3. scotfoot

    scotfoot Well-Known Member

    Unless a person has a lesser toe deformity problem, having them stand on one foot and watching for toe collapse seems like a simple functional test for intrinsic weakness.
    If a patient is ok with standing on one foot then, with support available to prevent falls, you could move the test forwards by having them press forwards till the toes are maximally loaded and check for collapse ( done slowly and with ball of foot in contact with ground at all times ) . No collapse, all good, collapse into hammer toe then strengthening regime till toes remain straight during loading. Simple enough, surely .

    How to strengthen ? The theraband exercises used by Mickle in her study of toe flexor strength in older people should work fine. However, if a person has weak toes which give up the ghost under load, calf raises are likely not going to work because to load weak toes is to collapse them, with the long toe flexors coming more into play .

    Stronger toe flexors, better dynamic balance.

    If the foot resembles the foot on the left under load ( see below) it fails the intrinsics test .Thoughts ?
    [​IMG]
     
  4. scotfoot

    scotfoot Well-Known Member

    Recent research has demonstrated that footwear makes our feet weak, with toe flexor strength gains of 57% occurring within 6 months if people switch to daily activities in minimal shoes. However, the question this raises is; so what?
    How strong do your toes flexors have to be to allow the foot to function properly within the parameters of what you ask of them.

    There are lots of ways of testing toe flexor strength out there but no agreed level of strength to shoot for, so some might argue, what's the point.

    If you look at the posts above they describe a very simple, functional, test that lets the clinicians and the patients know if the feet are strong enough to be competent under load or if the toes will simply collapse into hammer toe. No need for ultrasound or complicated strength calculations ; no need even for the paper grip test which isn't even that informative anyway.
    Simply pressure, then if toe collapse occurs strengthen and if not then you can do further tests but things look ok .

    With guidance people can easily monitor themselves at home.

    Once you recognize that toe gripping is actually toe collapsing, toe flexor strength is much easier to understand . Weak toe flexors give poorer balance and general function. That's "so what".
     
    Last edited: May 1, 2022
  5. efuller

    efuller MVP

    Gerrard,
    I'm not sure what you mean by toe collapse. Is what you are calling toe collapse seen in the right foot in the picture above?
     
  6. scotfoot

    scotfoot Well-Known Member

    Hi Eric
    Toe collapse under load is best illustrated dynamically . If you have access to twitter you can see what I am referring to in the posts of Tim Trevail that I have retweeted on my twitter page. Second post from the top.
    https://twitter.com/FarrellGerrard/
     
  7. scotfoot

    scotfoot Well-Known Member

    For those who are interested, here is a link to my twitter page- https://twitter.com/farrellgerrard . If you look at the second post ( April 24, 2022 ) you can see a short video of a man's foot as he tries to stand on one foot . The lesser toes of the subjects foot can be seen to go in and out of a hammer toe configuration or in and out of a collapsed position, same thing .

    From experience, if you take a subject who's toes collapse under load and strengthen them, they then remain straight under load. If you see a pt and their toes collapse under load then IMO you really should be trying to do something to correct this.

    Mickle et la demonstrated that the toe flexor strength of older subjects can be improved and brought up to the same levels as they would have had in their younger days.

    An open access paper has just been published on the very active role that the intrinsic foot muscles play during standing posture and it is worth noting that most falls in the elderly occur during simple weight shifting .

    https://doi.org/10.1155/2022/7708077


    Show citation Contributions of Intrinsic and Extrinsic Foot Muscles during Functional Standing Postures
    Sarah T. Ridge
    [​IMG],1 K. Michael Rowley[​IMG],2,3 Toshiyuki Kurihara[​IMG],4 Matthew McClung[​IMG],1 Jiaxi Tang,3 Steven Reischl,5 and Kornelia Kulig[​IMG]3
     
  8. efuller

    efuller MVP

    There is academic debate and there is marketing.
    In my opinion, asking someone to go to another website, off of podiatry arena, crosses the line from academic debate into marketing.

    Against my better judgement, I tried your link, in the past two posts above, and could not see the picture without registering for a lot of other things. If you want us to see pictures make them show up on the arena.

    So toe collapse and a hammertoe are the same thing. A hammer toe is dorsiflexion of the mpj and plantar flexion of the pipj. The short toe flexors insert on the base of the intermediate phalanx. Activation of the short flexors will cause plantar flexion of the pipj. Planter flexion of the pipj will cause dorsiflexion of the mpj. If you strengthen the short toe flexors you would expect to get hammer toes
     
  9. scotfoot

    scotfoot Well-Known Member

    You are entitled to your viewpoint which I reject .

    At what point did you become spokesperson for everyone on the arena?

    I don't own the illustrative video posted by Tim Trevail @Trevail which shows the toes collapsing under load ,he does and the only way people can see it is by following the link provided .
    Did you see his video ?
    Did you watch the toes collapse ?
    Do you think they are gripping the ground for better balance ?
    When was the last time you supervised a course of foot strengthening for anyone ?
    Do you even strengthen your own feet ?
     
  10. scotfoot

    scotfoot Well-Known Member

    As we evolved our big toes became adducted and our feet became "organs" of balance and propulsion rather than grasping appendages. Our hands, with their opposable thumb, very much retain their grasping, holding function.

    However, even when we invert and walk on our hands they do not grip the ground but instead the fingers remain generally straight and fanned out for better balance and weight distribution.

    The picture shows two youngsters doing hand stands on the sand .Their fingers are spread out for balance but can you imagine what would happen if they dug their fingers into the sand for "better balance ". The would have less area to balance on and would likely fall over .

    The idea that the toes curl on flat surfaces to give better grip is almost universal and, at the same time, preposterous. Research done with toe grip dynamometers in the belief that this measures an actual everyday physiological function is, IMO, extraordinarily ill-informed.

    From experience rather than guesswork, I can tell you that if you take toes that collapse under load and strengthen them by flexing the toes around the MTPJ ,against resistance, then the toes will no longer collapse . This is not something the subjects are even aware of till you point it out.

    IMO feet which have toes that collapse under load need strengthened, fee or no fee .

    upload_2022-5-15_10-3-12.png
     
  11. scotfoot

    scotfoot Well-Known Member

    IMO then, it seems obvious that toes which collapse into a hammer toe like configuration when under load mean that you have a weak foot ( using flexor digitorum brevis as a surrogate for the other intrinsic foot muscles) .

    Evidence is now emerging linking IFM weakness to a range of pathologies including PFP .

    Given the above, would it not be prudent for physicians doing physical examinations on people entering for example, the fire service, police, or armed services, to check that the toes function properly under load and recommend correction of any deficits found? None of this is particularly difficult.
     
  12. efuller

    efuller MVP

    Beware of the over simplification. It is not obvious that hammertoes are the result of muscle weakness. It is the contraction of the muscles that causes the toes to achieve the hammertoe position.

    PFP = ? patello femoral pain? Plantar foot pain? Plantar fascial pain?
     
  13. scotfoot

    scotfoot Well-Known Member

    Beware of over complication .
    The thread is not about hammer toes but the collapse of the toes when put under load . This is caused by intrinsic muscle weakness .I have witnessed toes which collapse under load stop collapsing and remain straight under load after strengthening exercises, both in my feet and those of others, over many years . I made this known to some leading podiatrists a decade ago but nothing has been done.

    Really ?
     
  14. efuller

    efuller MVP

    Can you explain the difference between a collapsing toe and a hammertoe. See your first line in post #11


    Yes, really. I have no idea what you mean by PFP.
     
  15. scotfoot

    scotfoot Well-Known Member

    Honestly ?

    I would ask you to revisit Tim Trevails website to understand what I mean by toe collapse or toe buckling but you don't seem to like the idea of this.
    You have seen my foot under load ,can I see yours ?
     
  16. scotfoot

    scotfoot Well-Known Member

    "10-second balance test may predict longevity - NBC Newshttps://www.nbcnews.com › health › health-news › 10-s...
    4 days ago — People who failed a 10-second balance test of standing on one foot were nearly twice as likely to die in the next 10 years, according to a ..."

    and

    "Participants in the supervised, progressive resistance training group significantly increased their toe strength (up to 36%; P<0.02), whereas there was no change in toe strength in either the home-based or control groups. This increased toe strength was accompanied by a significant improvement in perceived general foot health and single-leg balance time compared to the other groups (P<0.05)."

    Note; home base group included things like towel curls .
    Mickle et al 2016
     
  17. scotfoot

    scotfoot Well-Known Member

    Here is a link to a short youtube clip of toes 3,4,5 in collapsed positions during single leg stance . In my experience, the toes of people with stronger intrinsic foot muscles do not behave in this way .


    In my opinion, single leg balance would be a useful diagnostic tool for clinicians looking at musculoskeletal capacity particularly with regard to falls .

    A single leg balance test with a shift of COM towards the forefoot will single out those with particularly weak intrinsics.
    Most habitually shod subjects have very weak feet generally (50-60% of unshod ), but toe collapse seems to happen only in the weakest of the weak with COM forwards in single leg stance.

    Weak intrinsics have been linked to PFP ( patellofemoral pain ;)) with strengthening helping reduce symptoms , and to shin pain in professional marathon runners, with strengthening once again helping to eliminated the pain.
     
  18. scotfoot

    scotfoot Well-Known Member

    Hi Eric
    Re weak toes collapsing when under load, an interesting article has just been published on a BMJ site .
    I have included a link and one of the figures from the article .

    The author Dr Ana Morais Azevedo, musculoskeletal and sports physiotherapist, would appear to agree that the hammer toe configuration seen in Figure A, does not represent toes gripping the ground but collapsing due to insufficient strength when under load .

    Link to article
    https://blogs.bmj.com/bmjopensem/20... to,from increased postural balance challenge.

    [​IMG]

    Figure 1. Toe curling: A) Hammer toes and B) Claw toes during single-leg heel raises (Dancer: Sakis Michelis)
     
  19. efuller

    efuller MVP


    I'm not sure that one or the other is necessarily a sign of weakness. I made a toe model with just the long flexors and was able to create claw toes or hammertoes that depended on the starting position when tension was applied to the tendon. It can be explained by relative leverage of the point of ground reactive force and the lever arm of the tendon at the joint. (A paper that I should write at some point.)

    The interesting thing about the hammertoe configuration is that the short flexors (intrinsics) attach at the intermediate phalanx and the long flexors attach at the distal phalanx. Thinking just about the attachments, the hammertoe contracture is evidence for the intrinsics being stronger than the extrinsics. Or it might just be the intrinsic muscles contracting first.

    From the article: " Toe curling at the height of the SLHR or as the test progresses can be a sign of gastrocnemius fatigue and overactivity of the long toe flexors." I would agree with the comment that toe curling can be a sign of gastroc fatigue. I don't like the characterization of the flexor activity being "overactivity". The long flexors have some leverage at the ankle joint and it would be normal recruitment of other plantar flexors rather than overactivity.

    Gerry you wrote: "The author Dr Ana Morais Azevedo, musculoskeletal and sports physiotherapist, would appear to agree that the hammer toe configuration seen in Figure A, does not represent toes gripping the ground but collapsing due to insufficient strength when under load"
    I don't see how the author attributed the "collapsing" due to insufficient strength under load.
     
  20. scotfoot

    scotfoot Well-Known Member


    But this is exactly my point Eric . Toes with active long toe flexors but weak or, in the case of your model, non existent short toe flexors, will give hammer or claw toes.

    The Author wrote "Why does dynamic deformity (toe curling) occur while performing SLHR? Toe curling (i.e., claw, hammer, mallet toes) presents as flexion and/or extension of the interphalangeal and/or metatarsophalangeal joints (Figure 1). If the person cannot keep the neutral position of the interphalangeal and metatarsophalangeal joints, by maintaining contact of the toes and metatarsal heads against the floor, this may be a clinical sign of a deficit in the strength of the intrinsic foot muscles and overactivity of the extrinsic muscles such as flexor digitorum longus and flexor hallucis longus. "

    Taken together with the left hand images in figure 1 this reads to me as "collapsing due to insufficient strength " since presumable the toes would be straight before they were loaded during single leg heel raise.

    Note
    The same dancer coach was used for both photographs A and B in figure 1 and so I assume he has a lot of control over the muscles of the foot since they can assume hammer or claw toes at will . My toes remain straight under load but I can also achieve a hammer toe position if I want by increasing the activity in the long toe flexors, provided the toes are not fully loaded .

    However, if the toes are fully loaded I cannot move them from a flat, straight position since the intrinsic kick in and will not allow it . I should imagine Sakis found the same thing I would also imagine he used a hand for balance so that he could take the weight on the ball of his foot for the photographs to allow toe maneuvering.

    I would love to know if this thread influenced the author at all.
     
  21. scotfoot

    scotfoot Well-Known Member

    Eric , further to your comments in post #19, I believe the following to be wrong -
    The short foot exercise and the doming exercise involve activating the short toe flexors, but not the long toe flexors, whilst keeping the toes straight and uncurled . You seem to be saying that the short toe flexor muscle of the lesser toes, the flexor digitorum brevis, when acting alone, would produce hammer toe contracture not a shortening of the foot with the toes remaining straight. If what you say is correct then these exercises, SFE and doming, would not be possible.

    I disagree with this since if the intrinsics are strong and engaged, and not themselves fatigued , toe curling will not take place.

    Where I chatting to Dr Azevedo I would respectfully point out that cognizance should be taken of the way that single heel raises are being done . If a dancer does these exercises whilst holding onto a bar then the toe flexor muscles, and in particular the short toe flexor muscles, will not be fully engaged ( these muscles would act to resist heel raises ) .

    However, if a dancer were to do single heel raises with no support then the intrinsic foot muscles would be far more engaged to give balance ( injury might also be more likely though, when doing raises to full height ).

    In a health individual toe curling during exercise is almost always a sign of intrinsic foot muscle weakness or fatigue and not extrinsic toe flexor dominance.
     
  22. efuller

    efuller MVP

    You did catch the "may" in the statement. The author does not have proof that a deficit in strength is present. We do know that contraction of the short or long flexors will create the hammertoe or claw toe appearance. The clawing of the toes indicates there is muscle strength.

    Whether or not the toes claw or not is a complex interaction of moments at the MPJ, PIPJ and DIPJ. Someone who is very attuned to their foot muscles, like a professional dancer or someone who thinks obsessively about their feet, could coordinate their muscles to keep their toes straight. They may be plenty strong, just not used.
     
  23. efuller

    efuller MVP

    Or the assumption that the short foot exercise or doming exercise only used the short flexors, and not other muscles as well, was wrong.

    Toe curling will occur if there is not the perfect amount of contraction of the lumbricles, short flexors and long flexors. Contraction of the long flexors can produce hammertoes/claw toes. Contraction of the long flexors can aid in producing a plantar flexion moment at the ankle joint and are likely to be recruited when trying to do repetitive toe raises to the point of fatigue.
     
  24. scotfoot

    scotfoot Well-Known Member

    I feel you are over complicating things here . In closed chain the flexor digitorum brevis will always act to pull the joint between the 1st and 2nd phalangeal bones down to the deck. You will not get dorsiflexing of the 1st phalanx and plantarflexion of the 2nd since this would represent an increase in distance between the origin and insertion of the muscle involved .Generally, contacting muscles act to shorten the distance between their points of attachment.
     
  25. scotfoot

    scotfoot Well-Known Member

    Eric
    Some time ago a paper was published which, in part, looked at the effects of electrical stimulation on the structures of a loaded foot. The paper was Kelly et al 2014.

    If you know Luke Kelly you could always ask him what happened to the toes when stimulation was applied to the flexor digitorum brevis, one of the muscles studied . I would be interested to hear what he says .
     
  26. efuller

    efuller MVP

    By first phalanx do you mean distal, or proximal, of a lesser toe or do you mean a phalanx of the first toe?

    The flexor digitorum brevis (FDB) inserts on the intermediate phalanx and does not insert on the distal phalanx. So FDB, when contracting would tend to plantar flex the proximal interphalangeal joint (PIPJ) and do nothing, directly, at the distal interphalangeal joint (DIPJ). When you plantar flex the PIPJ the ground will tend to dorsiflex the DIPJ.
     
  27. scotfoot

    scotfoot Well-Known Member

    My understanding is that the tendon(s) of the flexor digitorum brevis are held on the bony plane of the 1st phalangeal bone(most proximal) by a synovial sheath . Depending on the exact anatomy, this type of arrangement probably means that the FDB tendon effectively has an additional attachment near the base of the 1st phalanx and so acts to plantar flex the toes at the MTPJ.
     
  28. efuller

    efuller MVP

    You have to be careful when interpreting the results of stimulation of a particular muscle. You would have to have to have an EMG in all of the other muscles verifying they were not simultaneously contracting when the muscle in question was stimulated. On the experimental set up, putting a fine needle into the FDB and stimulating would be painful and might cause the subject to contract other muscles.
     
  29. scotfoot

    scotfoot Well-Known Member

    Did you speak to Luke K ? He is the only person I know of who has done this piece of research.
     
  30. efuller

    efuller MVP

    Where I come from, we usually refer to the phalanges by distal, intermediate and proximal. Is it different in Scotland?

    Same logic as before. If you try and plantar flex the MPJ and the PIPJ and a muscle has no direct effect at the DIPJ the plantar flexion moment at the proximal joints will increase ground reaction force on the distal phalanx and the ground reaction force will tend to dorsiflex the dipj (like you showed in the left picture in post 18).
     
  31. scotfoot

    scotfoot Well-Known Member

    No idea and I don't see the relevance in the present context.

    Why not ask Luke K what actually happens when you fire up the flexor digitorum brevis . Your argument against asking him seems like fluffy obfuscation to me.


    "You have to be careful when interpreting the results of stimulation of a particular muscle. You would have to have to have an EMG in all of the other muscles verifying they were not simultaneously contracting when the muscle in question was stimulated. On the experimental set up, putting a fine needle into the FDB and stimulating would be painful and might cause the subject to contract other muscles."​
     
  32. scotfoot

    scotfoot Well-Known Member

    "Where I come from, we usually refer to the phalanges by distal, intermediate and proximal."

    Ok fine, let's go with that.


    As you say "the flexor digitorum brevis (FDB) inserts on the intermediate phalanx".

    However, due to the fact that the tendon of the flexor digitorum brevis is held on the bony plane of the 1st phalangeal bone (most proximal) by a synovial sheath, the FDB does have an effective insertion point on the proximal phalanx which causes plantarflexion of this bone around the MTPJ .

    So the FDB plantarflexes both the proximal and intermediate phalanges . If the FDB is weak or fatigued, say for example by calf raises, then the toes collapse into the configuration shown in post 18. ( With regard to Dr Ana Morais Azevedo's new Phd, I feel that she and Dr Susan Mayes may be being led astray a little by incorrect "podiatry truths")

    If time permits over the weekend I will run up a simple model to demonstrate the above ( I already have the phalanges, Solero lolly pop sticks, but the synovial sheath might be a bit trickier to model !)
     
  33. efuller

    efuller MVP

    Let's make sure we agree with what we are seeing in post # 18. In the left picture the met heads are on the ground, there is plantar flexion of the lesser proximal inter phalangeal joints (PIPJ), a slight dorsiflexion of the MPJ's and dorsiflexion of the DIPJ (a relative dorsiflexed position of the distal phalanx relative to the proximal phalanx.

    Lets analyze the force created by tension of the EDB tendon that attaches to the base of the intermediate phalanx. A proximally directed pull on the plantar base of the intermediate phalanx will pull the phalanx backward into the proximal phalanx. (Now looking at only the forces acting on the intermediate phalanx.) Proximal phalanx will provide a proximal to distal force on the center of the base of the intermediate phalanx and this when combined with distal to proximal pull from the tendon will create a plantar flexion moment at the PIPJ. Drawing the picture is worth more than reading the words.

    Now lets look at the pull of EDB at the MPJ. The pull of the tendon will push both the intermediate and proximal phalanges back into the metatarsal head creating a proximal to distal force at the base of the proximal phalanx. (draw the proximal and intermediate phalanges as a single rigid body. These two forces (tendon and MPJ compression) will create a plantar flexion moment at the MPJ and in the absence of any other forces this should cause plantar flexion of the MPJ.

    However, the plantar flexion moment at PIPJ will increase ground reaction force on the head of the intermediate phalanx. Upward ground reaction force on the head of the intermediate phalanx will create a dorsiflexion moment at the MPJ. If this dorsiflexion moment is greater than the plantarflexion moment then there will be dorsiflexion of the MPJ with contraction of the EDB. The evidence for the ground reactive force on the distal toe is seen in the hyperextension of the DIPJ. This explanation of the forces explains what is seen in the left picture in post #18.
     
  34. scotfoot

    scotfoot Well-Known Member

    The model will relate only to; "However, due to the fact that the tendon of the flexor digitorum brevis is held on the bony plane of the 1st phalangeal bone (most proximal) by a synovial sheath, the FDB does have an effective insertion point on the proximal phalanx which causes plantarflexion of this bone around the MTPJ ."

    It's just to show that the FDB pulls the proximal inter phalangeal joints do onto the deck. I'm going to use the inside plastic bit of a half empty pen as the synovial sheath as I can't think of anything better at present. I might not get it done this weekend , but I am pretty sure of my ground .

    The thread is about feet with weak intrinsic muscles failing to function properly under load . Strengthen them and they perform differently, that has been my experience .
     
  35. terigreen

    terigreen Active Member

    That was very interesting. I always believed curling toes were to add stability.

    Teri
    Atlas Biomechanics
     
  36. scotfoot

    scotfoot Well-Known Member

    Here's that rough lollypop model, Eric, showing the proximal interphalangeal joint being pulled down by the action of the flexor digitorum brevis ,not being "popped up" .
     
  37. efuller

    efuller MVP

    As I said in an earlier post, starting position matters. A couple of things are wrong with your model. The "metatarsal is not bearing weight and your hand is allowing/?helping the metatarsal to dorsiflex. The metatarsal being up in the air increases the effective lever arm of the tendon at the MPJ. In reality the tendon travels much closer the bone. You need to put the same pulley mechanism that you have at the head of the proximal phalanx at the head of the metatarsal.
    Also if you start with PIPJ plantar flexed you will increase the lever arm of the tendon at the PIPJ and the increase in moment should be enough to plantar flex the PIPJ. Also the unusually long intermediate phalanx, compared to the proximal phalanx will alter the lever arm of ground reactive force on the head of the intermediate phalanx.

    Show us a video starting with the PIPJ plantar flexed, and the tendon closer to the metatarsal head and the metatarsal head forced into the ground. Body weight would normally keep the metatarsal head on the ground.
     
  38. scotfoot

    scotfoot Well-Known Member

    My understanding is that the FDB tendon travels in a synovial sheath in a groove on the plantar surface of the proximal phalanx . Near the MTPJ it leaves the phalanx to pass around the capsule surrounding the MTPJ . At a guess the angle of departure might be about 30-40 degrees or close to the angle in the model and that is why I am holding the met aspect of the model up .

    Looking at the number of views of the video it would appear very few are interested in this topic although, as previously stated in this thread, the PhD project (bottom of post) is underway.

    Dr Azevedo says in her blog that toe deformity under load may be due to an imbalance between extrinsic and intrinsic activity ; I agree .

    Whoever she also speculates -
    "These toe deformities during SLHR may also be associated with a lack of strength-endurance of the gastrocnemius. As the person repeats the SLHR endurance test, the flexor hallucis longus and flexor digitorum longus may compensate for a gastrocnemius with poor endurance. Toe curling at the height of the SLHR or as the test progresses can be a sign of gastrocnemius fatigue and overactivity of the long toe flexors. "

    I don't agree with this since experience has taught me that if you spend a few weeks strengthening the intrinsics, the toes don't collapse even under heavy load/ maximal long toe flexor activity. I am sure that is what she will find, and sure also that people will listen to her findings.

    "The author Dr Ana Morais Azevedo, musculoskeletal and sports physiotherapist, would appear to agree that the hammer toe configuration seen in Figure A, does not represent toes gripping the ground but collapsing due to insufficient strength when under load .

    Link to article

    https://blogs.bmj.com/bmjopensem/20... to,from increased postural balance challenge.

    [​IMG]
     
    Last edited: Sep 24, 2022
  39. efuller

    efuller MVP

    I don't understand why you think the angle of departure is that high? I'm not sure what you mean by angle of departure.
    The lever arm of the tendon, at a joint is the distance from the line of action of force is from the joint axis. In this case, the line of action of the tendon at the PIPJ is from the attachment on the intermediate phalanx to the distal end of your pulley. Your model correctly depicts a small lever arm at the PIPJ. However, your model has a huge lever arm at the MPJ. Thus, the pull in the tendon, in the model, creates a much higher plantar flexion moment at the MPJ than there is in reality.

    Let's make sure we are talking about the same thing. When you say popping up of the toes are you referring to picture A in post #38? In that picture the the head of the proximal phalanx is popping up and the motions that need to happen, to explain that reality, are dorsiflexion of MPJ and plantar flexion of the PIPJ and hyper extension of DIPJ. An artificially large plantar flexion moment from the tendon in the model will not allow that dorsiflexion motion. If you want your model to reflect reality, the tendon should be pulled with its line much closer to the metatarsal head and there should be much more force holding the metatarsal head on the ground.

    If you want see your model create what you see in the picture, start with the metatarsal head pushed into the ground and the MPJ slightly dorsiflexed and PIPJ slightly plantar flexed and the tendon close to the metatarsal.
     
  40. scotfoot

    scotfoot Well-Known Member

    Do you have a model and if so could you share it?
     
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