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Does the tibia drive the foot or does the foot drive the tibia?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by mike weber, May 20, 2010.


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

    I understand your very busy but you have created a butterfly effect/caos theory with a comment you made in the Pearls of Wisdom thread

    We have discussed it in the Auto-support thread

    and the ´leg stiffness thread

    and now Double limb support and leg stiffness thread

    Now that peeble you dropped in the ocean is about to be a huge wave.

    You would not have made this comment without research backing it up. It would be great if you could got it to it in further detail, or at least say the paper is in print can´t say to much but....

    Thanks I hope as it really effect the leg stiffness discussions and my brain hurts enough without this sticking point. Thanks



    ps for those who like music links to posts.

    the butterfly effect -reach

    the butterfly effect- take it away live
     
  2. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Re: Open letter to Craig Payne

    It from this:
    Contributions of proximal and distal moments to axial tibial rotation during walking and running
    T. L. Bellchamber and A. J. van den Bogert
    Journal of Biomechanics; Volume 33, Issue 11, 1 November 2000, Pages 1397-1403

    Here are my notes from the powerpoint I used at the weekend at NSW conference discussing this paper (that is now 10 years old!):
     
  3. Re: Open letter to Craig Payne

    Thanks Craig I´ll look into the paper
     
  4. dyfoot

    dyfoot Active Member

    Re: Open letter to Craig Payne

    Does anyone have a link to this paper??
     
  5. Griff

    Griff Moderator

    Re: Open letter to Craig Payne

    Here you go

    IG
     

    Attached Files:

  6. dyfoot

    dyfoot Active Member

    Re: Open letter to Craig Payne

    Thanks very much Ian.

    Cheers,

    Brad
     
  7. Re: Open letter to Craig Payne

    And found this which maybe or interst as well
     

    Attached Files:

  8. Jeff Root

    Jeff Root Well-Known Member

    Re: Open letter to Craig Payne

    Michael,

    First, my apologies for jumping in here without reading the referenced articles but I wanted to make a quick comment regarding your question. Try this little observational experiment. Sit in a chair with one leg extended in front of you and fully extend your knee. Lift your foot so it is slightly off of the floor and so that your leg is extended in space. Now supinate and pronate your STJ. There is virtually no internal or external rotation of the leg that occurs with open chain stj supination and pronation.

    In order for stj supination and pronation to produce leg rotation, the limb must be in a closed chain environment. Only when the leg is in a closed chain environment can stj supination and pronation produce rotation of the proximal segments (i.e. tibia, etc.). Without stabilization of the distal segment(s), the proximal segment(s) don’t really move much and there is no leg rotation visable.

    During closed chain pronation of the stj, the body could be actively pronating the stj through activity of the stj pronators and gravitational influences or it could be actively resisting pronation through activity of the stj supinators (i.e. it could be decelerating stj pronation). I’m sure Kevin could explain this much better than me, but I hope you get my drift. In addition, the muscles that drive stj motion are primarily located in the leg, so I agree with Craig. I know I should have read the links before commenting, but that's my take on it. I hope this little experiment helps ease your brain pain!

    Respectfully,
    Jeff
     
  9. Re: Open letter to Craig Payne

    Hi Jeff ,

    It´s more a question of Cause or effect or chicken and egg. In in you post you seem to be saying STJ motion cause change in tibia internal/external where as Craig was saying the tibia rotation causes STJ motion.

    Ie the question is STJ pronation does it cause internal tibial rotation or Internal Tibia Rotation is the cause of STJ pronation.

    The reason for this is the leg stiffness thread listed above if internal tibia rotation is the cause of STJ pronation and there is a link which has show that Knee flexion will lead to internal rotation of the tibia.

    So there is the potential for the knee being the most important joint in leg biomechancial regulation rather than the STJ which we have thought.

    So now you can see some of the headache. So we could control STJ pronation moments by reducing knee flexion moments.
     
  10. efuller

    efuller MVP

    Re: Open letter to Craig Payne

    Very good paper (van Den Bogert). I don't think that you can conclude from their data that the foot never drives the leg. I don't see any data that contradicts the conventional wisdom of what happens at heel strike (first 10% of stance.) After watching many slow motion videos and corelating that with force plates. In walking you have heel contact with the center of pressure close the STJ axis and very little pronation moment from the ground. As the ankle plantar flexes the lateral forefoot contacts the ground and the center of pressure is shifted lateral to the STJ axis and you will see pronation with internal leg rotation. The conventional wisdom is that the posterior tibial muscle is acting as a decelerator at this point in time. The COP is lateral to the axis causing a pronation moment and posterior tibial muscle is causing a supination moment and there is a net pronation (internal leg rotation) moment in the first 10% of stance. If you look at the power curves in figure 1 you see that the power is negative in the first 10% of stance which is indicative of the foot driving the leg.

    I didn't see a source on how much power flow was needed to make that conclusion.
    That said, the rest of the data clearly supports that the leg is driving the foot from then on. Which makes a lot of sense in that is where the muscles are. It would be very interesting to look at this study with STJ axis position of the subjects. I would bet that some of the variability across the subjects could be explained by that. There is one subject who has a pronation moment from the leg quite early in contact. I would bet that subject had a laterally positioned STJ axis.

    Regards,

    Eric
     
  11. Re: Open letter to Craig Payne

    Or is it indicative of the contra-lateral limb "spring" extending up to this point? Or just that ankle plantarflexion de-couples the shank from the foot? This would make sense given the shape of the trochlear surface. BTW trochlea is Latin for pulley...Hmmm I will think on that one over night.
     
  12. Re: Open letter to Craig Payne

    I would not say that the leg drives foot motion and foot motion doesn't drive leg motion. I similarly also wouldn't say that rearfoot motion drives forefoot motion and forefoot motion doesn't drive rearfoot motion.

    All these segment of the foot and lower extremity are interconnected by ligaments, tendons, muscles and fascia. When force is exerted on one segment by one of these tensile load-bearing structures, this structure also will simultaneously exert a tensile force on the other segment. For example, a tensile force will occur on the leg when the posterior tibial muscle contracts and a tensile force will be acting on the foot simultaneously by the posterior tibial tendon.

    In addition, unless the researcher has accurately calculated the the spatial location of the STJ axis at all times during the stance phase of gait, they can't possibly have an accurate assessement of the STJ moments from ground reaction force (GRF) to have made any conclusion as to how much GRF is driving leg motion or leg motion is driving foot motion. Until the STJ axis spatial location can be determined more accurately by researchers, this question will remain unanswered and I certainly would not be say that the leg drives foot motion and foot motion doesn't drive leg motion given our current uncertainties on such matters.
     
  13. Re: Open letter to Craig Payne

    So, we come back to the "flow of force"; on a molecular level how does a force get from one molecule to the next? If we have a muscle that contracts, how does the contractile force get from the muscle belly to the tendons insertion? How does the ground reaction force get from the plantar heel pad to the meniscus of the knee?

    Can power flow in a direction?

    I concur with the contention regarding mapping STJ spatial location, but in the absence of such data, what does the best evidence tell us?

    Lets imagine though two hypotheticals: one in which the foot is driving the leg and one in which the leg is driving the foot, and move back to our discussion of functional hallux limitus. lets say the foot is driving the leg, how do we explain the increase in foot pronation, delayed heel lift, increased knee and hip flexion? Now lets say the leg is driving the foot how do we explain the same kinematic changes?

    If it's "feed-backwards" then that supports the theory the functional hallux limitus causes foot pronation, If it's a feed-forwards then that supports the theory that foot pronation causes hallux limitus; if it's neither and all simultaneous, then what? Which is it?
     
  14. Jeff Root

    Jeff Root Well-Known Member

    Re: Open letter to Craig Payne

    I guess in some ways I might be saying it's both, or perhaps neither. Ok, now you're making my brain hurt! STJ motion isn't the cause of anything, it is the result of something! Muscles are the motors that drive the stj. Without the motors, there is no motion. The osseous segments are the frame or structural members that provide support and attachment for the muscles. Muscles induce motion by contraction. Other tissues hold the segments together. It is a system. So let’s look at each element of the system to see if we can put things in a context that makes sense relative to your question.

    You can internally and externally rotate the tibia (and leg) in the open chain without inducing stj motion. Conversely, you can supinate and pronate the stj in the open chain without inducing tibial or leg rotation. So from the standpoint of looking at transverse plane motion of the leg relative to the foot, we really need to look at ground reaction force and the role of friction because this has a direct influence on the resulting motion. For example, if I stepped on a pool of oil, it would alter my gait and the pattern of motion because it would reduce friction.

    The muscle motors are primarily located in the leg. But say for example, I step on a rock and suddenly invert my ankle and supinate my stj at heel strike. What drove the stj supination? It is the interface between the foot and the ground. I’m going top stop here for now because I just saw Kevin’s reply and I think he is kind of on the same line of thinking. Plus, my brain hurts!

    Regards,
    Jeff
     
  15. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Re: Open letter to Craig Payne

    This paper under discussion is now 10 yrs old. Somehow it slipped under my radar scope and I only looked at it again last yr after Chris Nester mentioned it at the APodC Conference. I now spend a bit of time on it at Boot Camps as it is an important and somewhat piviotal paper and is certainly being used by the 'anti-foot orthotic brigade'. We can't ignore it.

    The data clearly shows that the tibia drives the foot and not the other way around - Eric does raise a couple of issues and I have a few (eg the variance of the parameters). BUT, we can't just ignore the evidence and hope it goes away - we need a satisfactory explanation of how the data fits our modelling and understanding.

    So far, this year I have been on a panel or in a debate at 3 conferences with physiotherpists on the topic of patellofemoral pain syndrome (ie is it proximal or is it distal - and there is a lot of other compelling evidence that its proximal). I have been the one to raise this paper and offer explanation of how foot orthotics COULD influence things when the driving force is proximal ... fortunately the debates have been good as we end up with some sort of consensus on the proximal vs distal argument.

    ....I need to change the title of this thread!
     
  16. dyfoot

    dyfoot Active Member

    IMHO in closed kinetic chain, you can't internally/externally rotate the tibia without causing the STJ to pronate or supinate and vice versa.

    You can't move one without the other, so there is no way of saying one drives the other!

    It's a constsantly changing dynamic in the real world.

    Cheers,

    Brad Randazzo
     
  17. efuller

    efuller MVP

    Re: Open letter to Craig Payne

    Originally Posted by efuller View Post
    If you look at the power curves in figure 1 you see that the power is negative in the first 10% of stance which is indicative of the foot driving the leg.

    Power is change in energy and it does flow from one segment to another. In the first 10% of stance the power flow is from distal to proximal. So, it can't be from the contralateral leg at that point in time.

    Regards,

    Eric
     
  18. Re: Open letter to Craig Payne

    Research as this does not need to "go away" in order of us to make sense of it all. We just need to sometimes look at such research, especially when it does not make good mechanical sense, and try to determine if the researchers were actually measuring what they think they were. Generally, they were not measuring what they thought they were, in my experience in such cases.

    I have no doubt that foot mechanics drives leg mechanics for part of stance phase and leg mechanics drives foot mechanics for other parts of stance phase. Otherwise, subtalar joint (STJ) axis spatial location would make no difference to transverse plane leg function or to internal-external rotational stiffness of the leg during weightbearing activities (Benink, RJ: The constraint mechanism of the human tarsus. Acta Orthop Scand, 56: (Suppl) 215, 1985).

    Here's an easy experiment. Take a foot that stands with the STJ close to neutral position and have them stand on a 10 degree valgus wedge. Does the tibia internally rotate when standing on this wedge? If it does, then tibia function is being driven by foot function. If it does not, then foot function is being driven by tibial function. I already know what the experimental results will be since I did this experiment on 20+ subjects during my biomechanics fellowship over 25 years ago.
     
  19. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    The research publication under disucssion showed that you can.
     
  20. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Re: Open letter to Craig Payne

    But thats static stance.

    During dynamic gait when one leg is moving forward in swing phase, the pelvis is externally rotating; the femur is externally rotating, the tibia is externally rotating and the foot is supinating - that is the force/power coming from above.

    From below we have the resistance of the foot to supinating; we have the windlass supinating the foot; we have the muscles supinating the foot etc - that is the force/power coming from below

    --- what this paper is showing is that during dynamic gait that power from above is greater than that power from below during the majority of the stance phase.

    However, that is the AVERAGE response in the subjects - some subject specific results will be different.
     
  21. Re: Open letter to Craig Payne

    Defintely the position of the STJ axis and the GRF Vector angle and magnitude will effect things . So there will be external and internal moments which make changes.

    The big question is the internal moment of the STJ being driven by the tibia or the other way round.

    it´s a good brain workout.
     
  22. Re: Open letter to Craig Payne

    And if you got those 20 + to flex their knee you would also see STJ pronation.

    the link that we discussed in the leg stiffness thread...

    Knee flexion - Internal rotation of the tibia - STJ pronation.

    I´ve got 15 physios coming next week for a talk I´ll do some quick experiments.

    Marx brothers walking v´s straight leg and knee flexed v´s staight leg in relation to FHnL.
     
  23. Re: Open letter to Craig Payne

    can you expand the think that this knowledge is anti orthotics. I´m a bit confused by it.

    If we say that internal rotation of the tibia is driving pronation, therefore a device which causes a High supination moment of the subtalar joint ie medial skive should cause an external tibia moment ..... or

    As we have discussed we can change the surface stiffness to get a CNS response to regulate leg stiffness, this is controlled mainly by knee flexion and extension moments.

    So if we want to reduce pronation which we are saying in this example is caused by internal Tibia rotation ,we can use a device with less stiffness ie softer which will mean the CNS will regulate the leg stiffness by reducing knee flexion ,which will lead to a higher leg stiffness. The reduced knee flexion would lead to an external rotation moment of the tibia and a reduced STJ pronation moment.

    ... for those who are confused read the leg stiffness thread , unless it my writing skills then I say sorry and maybe Simon will add to it if I missed...

    Thought you might :drinks
     
  24. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Re: Open letter to Craig Payne

    There is a growing and strong school of thought that anterior knee pain/patellofemoral pain syndrome (PFPS) is not due to foot pronation (see this thread) and is due to proximal (ie hip and/or quadriceps control isses; eg see this thread). I have been into the lions den twice now to debate this and think I came out unscathed. We have the Vicenzino et al RCT that showed foot orthotics worked in PFPS, but also physiotherapy (ie the proximal control issues) was just as effective as the foot orthotics), so you are going to get just as much success using foot orthotics as you will working on the proximal control issues (they also showed that if you did both, there was not an added benefit).

    The Bellchamber paper being discussed in this thread is being used by the 'its all coming from proximal' school to help their argument that its not the foot and therefore you do not need orthotics for PFPS (despite that fact that two well designed RCT's conducted by physiotherpists showed foot orthotics work).
     
  25. Jeff Root

    Jeff Root Well-Known Member

    Re: Open letter to Craig Payne

    You can walk with a leg that doesn't have a foot, but a foot without a leg can't walk! :wacko: So what does that say about where the power (drive) comes from? :dizzy: And you can't move your center of mass forward unless you have interaction with the ground in order to accelerate your CoM.

    During the swing phase of gait, the foot pronates at the stj and the tibia internally rotates. At heel strike, frictional forces begin to act on the plantar surface of the foot. As a result, the tibia internally rotates faster than the foot because of these frictional forces. Part of the internal rotation of the tibia is the result of pelvic rotation. So during the contact period of the stance phase of gait, I would have to think that the inertia, greater mass, and relative direction of motion of leg and upper body would dictate the relative direction (net rotational moment ) at the stj. It would probably be necessary to look at each phase of gait individually or at each change in the direction of motion at the stj for a more accurate picture.

    For the record I‘m just thinking out loud here, so my confidence level is very low, at best! :confused: But personally, I find this to be a very interesting topic which is much more complex than it first appeared!

    Respectfully,
    Jeff
     
  26. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Re: Open letter to Craig Payne

    Here is the simplistic way I try to explain it. Lets assume that the external rotation moment of the limb is coming from the gluteals (which of course there is more to it than that); assume the gluteals are weak or have a motor control timing issue and there is greater internal rotation because of this --> patellofemoral pain syndrome (which is sort of what the research is showing); as part of that internal rotation the foot is driven into a pronated position - so the foot pronation is not causing the PFS (which is sort of what the research is showing). The physiotherpist then goes to work to strengthen the the guteals or improve the motor control or improve whatever they do up there. The RCT's tell us that this works. The RCT's also tell us that foot orthotics work as well .... what is going on?

    Lets assume there is high supination resistance of the foot or that the STJ axis is more medially located - the gluteals strength/timing gets improved, but what happens --> nothing as the moment needed to supinate the foot from the external rotation is too high for the gluteals to do their job (and remembering I am simlifying this for the sake of the explanation). If the supination resistance is low, the improvement in the gluteals will result in external rotation and foot supination.

    So what is the hypothetical role of foot orthoses here --- perhaps all they do is lower the moments, so the external rotation can overcome the supination resistance and supinate the foot. We know from the Williams et al and the McClean et al papers that foot orthoses create large and systematic reductions in the rearfoot inversion moments --> that will make it very easy for the proximal external rotation moments to supinate the foot.

    Does that make sense?
     
  27. Re: Open letter to Craig Payne

    Yes and I am thinking that the GRF ( Ground reaction Force) will also reduce Tibial rotation moments and with our device all we are doing is creating an (orthotic reaction force) ORF or changing the GRF vector which as you say may just make it easier for the proxiaml moments to function, a summation of forces if you will. Javalin is about about the hips and core maybe this is somewhat the same.

    If coming at this from a leg stiffness stand point this rotation are somewhat controlled by knee flexion/extension moments.
     
  28. Re: Open letter to Craig Payne

    Simon, Eric and Kevin were discussing this in the Double limb support and leg stiffness thread, I´m still trying to get my head around the power/energy return of the whole leg, but The achilles Tendon we have discussed in relation to knee flexion when considering leg stiffness

    Goes along with what Craig was saying. But it still comes back to the starting point or to use the analogy of the Butterfly effect, what is the peeble that starts it all.

    Respectfully,
    Jeff[/QUOTE]

    There are lots of very interesting papers that we have posted up in the leg stiffness thread, if you have a few quite days/hours. Very interesting indeed.
     
  29. Is this the paper you reffer to Craig ?

     
  30. Re: Open letter to Craig Payne

    Thanks Eric. The implication being that our best chance of creating changes in the kinematics via foot orthoses is in the first 10% of stance, which in walking is roughly the period of double limb support from heel strike to forefoot loading?
     
  31. Craig Payne

    Craig Payne Moderator

    Articles:
    6
  32. Re: Open letter to Craig Payne

    Eric, I just took another look at the paper and figure 1. Figure 1, the bottom graph shows a power time plot for one subject during running. Figure 4 shows the walking data for males and females and figure 6 shows the running data. According to the authors "positive power indicates distal control of the tibial rotation" Looking at figure 4 most subjects seem to show negative power during the loading response and to oscillate around the zero for about 60% of stance, then there are marked negative decreases in power- this according to the authors is indicative of proximal control of tibial rotation.
     
  33. efuller

    efuller MVP

    Re: Open letter to Craig Payne

    Power is change in energy and can flow form one segment to another. Energy can be potential, kinetic, or chemical or thermal. So one segment adds energy and the other segment loses energy.

    I think the article shows that sometimes the foot drives (imparts energy to) the leg and sometimes its the opposite. The measurement of joint power would help us answer the question of whether the late stance phase internal leg rotation (STJ pronation) causes the functional hallux limitus or the limitus causes the STJ pronation. This is not a general question, but a question for each specific step. The article clearly shows that some people don't fit the average profile. When we observe gait we sometimes see people who have external leg rotation and sometimes we see people who have internal leg rotation. Anecdotally, we see people who change from internal leg rotation to external leg rotation when they wear orthotics. We could measure power at the mid stance phase of gait and see if the motion is being driven by leg muscles. My bet is that gait is driven by the muscles after the forefoot has loaded.

    This info could possibly support the pain avoidance theory of orthotic function. (It's uncomfortable to lower your arch into a piece of plastic.) The CNS is "driving" which muscles are being used in the leg to create the motion that we see. When an orthotic is placed under the foot, the CNS changes how much it drives the muscles of the foot.

    One of the biggest ah ha moments occurred when I was doing the biomechanics fellowship at CCPM. A patient was back at her two week follow up and I was watching her walk with her orthotics in her shoes. I didn't remember how she walked before the orthotics so I had her take her shoes off. For two trips up and down the hall she walked just like she did with the orthotics in the shoes. Then she changed how she walked back to a late stance phase pronation type of gait. Clearly the orthotic was not working by "supporting the deformity". I believe that orthotics work, in part, by changing the CNS output. The orthotic may change the preferred movement pathway that is chosen by the CNS. Additionally, if that new preferred movement pathway requires additional posterior tibial muscle activation, a medial heel skive will reduce the moment needed from the posterior tibial muscle to create that new pathway.

    I probably should have posted this after Craig's comment about the orthotic naysayers using that article to say that orthotics can't work because the leg drives the foot.

    Cheers,

    Eric
     
  34. Bruce Williams

    Bruce Williams Well-Known Member

    Re: Open letter to Craig Payne

    my apologies for jumping in on this, but I disagree with the above statement Simon.

    I think that all Eric's statement shows is that the swing limb is not in effect at double limb support and that with both feet on the ground the power is from the foot not from the swining limb above, as Craig has explained so nicely in earlier posts.

    On the subject of proximal vs distal cures or tx's for PTFD ( Anterior Knee Pain) I would like to know how long patients will continue to do their exercises to treat their proximal dysfuntion vs how long patients will remain cured from just slipping on their CFO's and orthotics. Irene Davis longer term studies on this issue have shown a great increase in recurrence in this patient population when the have to carry on their own rehab protocols without regular checkups.

    cheers!
    Bruce
     
  35. Bruce Williams

    Bruce Williams Well-Known Member

    Re: Open letter to Craig Payne

    Eric;
    I think we will have some interesting discussion on this in another 2 weeks or so in Ohio.

    It is not painful to lower your arch into a piece of plastic... if there is pain then the plastic was designed incorrectly or it is too rigid to allow for motion during the period of gait when it causes pain.

    Also, the muscles are no more than supporting players stabilizing the lever that is the foot that the body must vault or pivot over at this time.

    Cheers!
    Bruce
     
  36. efuller

    efuller MVP

    Re: Open letter to Craig Payne

    So figure 1 bottom graph shows one subject who had a positive (foot drives the leg) result. In figure 4 the male graph between 0 and ~7% there is a small positive blip except for one or maybe two subjects. Interestingly the females don't have this. I still stand by the conclusion that in some people at some points in time, the moments applied to the foot move the leg.

    http://www.youtube.com/watch?v=hsUfo_jHQ60&feature=related

    (It was interesting that the "featured video" that popped up when I searched this was the barefoot professor. Don't watch it, but if you do is that a 5 fingers shoe [product placement] at the very end?)

    In that video there is some internal leg rotation after contact and visually it is hard see how that is not caused by the foot specifically STJ and MTJ pronation.

    Regards,
    Eric
     
  37. If the leg drives the foot, and the foot does not drive the leg, then these scientific research studies would not have shown the following changes in leg and knee kinetics and kinematics with foot orthoses:

    Decrease in maximum internal tibial rotation with foot orthoses

    Nawoczenski DA, Cook TM, Saltzman CL: The effect of foot orthotics on three-dimensional kinematics of the leg and rearfoot during running. J Ortho Sp Phys Ther, 21:317-327, 1995.

    Williams DS, McClay-Davis I, Baitch SP: Effect of inverted orthoses on lower extremity mechanics in runners. Med. Sci. Sports Exerc. 35:2060-2068, 2003.

    Woodburn J, Helliwell PS, Barker S: Changes in 3D joint kinematics support the continuous use of orthoses in the management of painful rearfoot deformity in rheumatoid arthritis. J Rheum, 30:2356-2364, 2003.


    Decrease in internal rotation/adduction of the knee with foot orthoses

    Stackhouse CL, Davis IM, Hamill J: Orthotic intervention in forefoot and rearfoot strike running patterns. Clin Biomech, 19:64-70, 2004.

    Williams DS, McClay-Davis I, Baitch SP: Effect of inverted orthoses on lower extremity mechanics in runners. Med. Sci. Sports Exerc. 35:2060-2068, 2003.


    Resultant knee joint forces and knee joint moments altered by up to 100% when posted orthoses are used in runners

    Nigg BM, Stergiou P, Cole G, et al: Effect of shoe inserts on kinematics, center of pressure, and leg joint moments during running. Med. Sci. Sport Exerc., 35:314-319, 2003.

    Williams DS, McClay-Davis I, Baitch SP: Effect of inverted orthoses on lower extremity mechanics in runners. Med. Sci. Sports Exerc. 35:2060-2068, 2003.


    In a study of 20 female adolescent subjects with patellofemoral syndrome, foot orthoses were found to significantly improve symptoms versus muscle strengthening alone

    Eng JJ, Pierrynowski MR: Evaluation of soft foot orthotics in the treatment of patellofemoral pain syndrome. Phys Therapy, 73:62-70, 1993.
     
  38. Maybe the next time any of you do a debate with the "proximal controls distal" people, I think your most powerful argument showing that foot structure can influence the moments required to internally-externally rotate the leg will come from Benink's PhD thesis from 25 years ago (Benink, RJ: The constraint mechanism of the human tarsus. Acta Orthop Scand, 56: (Suppl) 215, 1985). And, all of you who are interested in this subject should definitely read this excellent research...I have it posted the whole thesis on my website (you can e-mail me privately for the password)... or maybe Craig could post it here on Podiatry Arena in its entirety for me since it was too large for me to attach.

    In his landmark research, Benink found that those feet (cadaver preparations) with a greater plantarflexed position of the talus on the calcaneus (what he called tarsal index and which was determined from lateral radiographs of the cadaver feet) required a greater magnitude of external rotation moment on the tibia to externally rotate the tibia than those feet with less plantarflexed position of the talus on the calcaneus. I have always taken this fascinating research, which I first read in 1987, as being supportive of the theory that a plantarflexed talus causes a more medially deviated STJ axis and that this will cause more supination resistance (Kirby KA, Green DR: Evaluation and Nonoperative Management of Pes Valgus, pp. 295-327, in DeValentine, S.(ed), Foot and Ankle Disorders in Children. Churchill-Livingstone, New York, 1992) and also that a more medially deviated STJ axis will cause a greater external tibial rotation resistance (i.e. external tibial rotation stiffness).

    It is also interesting to note that Benink's PhD thesis apparatus was done on the same apparatus that VanLangelaan used for his PhD thesis (Van Langelaan EJ: A kinematical analysis of the tarsal joints. Acta Orthop. Scand., 54:Suppl. 204, 135-229, 1983), with both of them having Antony Huson, PhD as their advisor. We all owe Drs. Huson, VanLangelaan and Benink a great debt for performing and publishing these two very important research projects.
     
  39. Jeff Root

    Jeff Root Well-Known Member

    Re: Open letter to Craig Payne

    I agree with Bruce. I love you man! (picture that being said in a drunken tone). :drinks If orthoses work by inducing pain, I would be making orthoses with spikes on the dorsal surface of the arch. Ok I wouldn't, but Ed would if you could make a profit from it! I'm still patiently waiting for Ed to answer my question as to why an orthosis should be designed to support the arch higher than its normal anatomical position during the contact and midstance periods of the stance phase of gait. Apparently we haven't had a cold day in hell yet, so I’m left here waiting. :bang::bang: In fact as you can see, I'm beside myself!

    One function of the medial arch is to help absorb shock by decelerating motion. The bottom of an arch, by the very definition and nature of an arch, is to span a space by transferring load to its load bearing members which are called posts (see: http://en.wikipedia.org/wiki/Arch). The arch of the foot is dynamic in that its apex raises and lowers. At the extreme lower end, the soft tissue of the arch develops increased ground reaction force which also acts on the osseous arch members to decelerate motion or to support the osseous structure. This is what happens in "collapsed" arches, which in many cases aren't actually collapsed, but rather are lowered arches. A rockerbottom foot, now there is a real example of a collapsed arch, because it reverses in direction.

    Part of what an orthotic shell does, is to support the arch by transferring load (vertical grf) to its load bearing members which typically are the plantar, distal edge, the plantar heel post or heel contact point if no extrinsic rearfoot post was used, and in some cases, to the plantar, lateral column of the orthosis if the patient has a low lateral longitudinal arch and the plantar, lateral surface of the orthotic shell resets on or periodically makes contact with the surface of the shoe as the device flexes.

    Look at the wear and abrasion pattern on the plantar surface of orthoses. This tells you a lot about how the device is functioning because you can evaluate the wear pattern and see where it makes contact with the supporting surface. Depending on the structure of the individual foot, there is typically minimal or no abrasion on the plantar surface of the device under the medial arch. This indicates that the device is stiff enough to transfer load to its load bearing members. If the plantar, medial arch of the device has abrasion it indicates that the shell is flexible, or you have a patient with a very low arch structure and shell is striking the shoe in this area.

    As the foot pronates, the arch naturally becomes lower. The orthotic shell receives an increased level of ground reaction force under the arch of the foot. The shell then increases its contribution to support of the osseous structure, which decreases stress on the soft tissue. The shell deflects (lowers) and then returns energy to aid in resupination of the foot. Acrylic orthoses would never fracture if this were not true.

    Support of the medial arch is just one aspect of the mechanical influence of an orthotic shell. While functional orthoses do provide support of the medial arch of the foot, that is not their only or necessarily their primary function. It is however, one way in which functional orthoses act to reduce pathological forces.

    Respectfully,
    Jeff
     
  40. Jeff Root

    Jeff Root Well-Known Member

    Re: Open letter to Craig Payne

    Sorry, should have read "rests": and the plantar, lateral surface of the orthotic shell rests on or periodically makes contact with the surface of the shoe as the device flexes.
     
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