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Pros and Cons of DC wedge orthoses

Discussion in 'Biomechanics, Sports and Foot orthoses' started by geelm, Sep 15, 2006.

  1. geelm

    geelm Welcome New Poster

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    Am just interested in the pros and cons of DC wedge orthoses. Obviously they are appropriate for medially deviated STJ axes. However, does their lack of heel cup have implications? Radiologically there is significant inclination angle between the calcaneus and cuboid. Are cuboid notches (vs valgus pads etc) really a satisfactory means of supporting the foot in this area? Additionally the lack of heel contour on a DC wedge appears to be a source of irritation.

    Thoughts would be appreciated
  2. admin

    admin Administrator Staff Member

    The DC wedge orthotic is a trade mark of TOL in Melbourne, Australia and would be unfamilair to all those outside Australia.
  3. pgcarter

    pgcarter Well-Known Member

    Maybe you are or have been one of my students?....if so.... you have had my views already......I have reverse engineered the concept and use similar shaped devices produced by my own "PC wedge" technique....and find them very useful in a variety of situations. Where you need significant lateral column support as well as rear foot inversion...."midfoot lift" rather than just inversion, you can give time split inversion, balancing pronatory force and forefoot wedging or offloading effects as required as well. The way the plaster work is done you have more individual control over the different shape components of the resulting orthoses than is easily achievable using either Mod Root or Blake style methods. As in all orthoses the final shape and dimensions and foot wear type used will determine if the patient tolerates them or not and if they work or not. No universal solution of course.
    In all quite useful
    regards Phill Carter
  4. Craig Payne

    Craig Payne Moderator

    When the STJ axis is more medially located, then the resolution of the sum of all the force vectors coming from a foot orthotic (the orthotic reaction force - ORF) has to be medial to that axis. When supination resistance is high, then the magnitude of the central vector of ORF also has to be high.

    There are a number of design parameters that can be incorporated into foot orthoses to achieve this. What TOL have done with the DC Wedge is three things:
    1. The massive amount of medial frontal plane wedging of the rearfoot moves that vector medially and increases it magnitude
    2. Plaster is added under that lateral heal to reduce all the forces that are lateral to the STJ (This is the opposite of the medial skive technique --- ie rather than remove plaster medially, why not add it laterally? ... the mean force vector will still be moved medially)
    3. No lateral heel cup is used (some force does come from a heel cup, ie the forces from the lateral heel cup will provide a small force that wll be attempting to pronate the foot, so why not eliminate that force?). I have NEVER had a problem with people sliding of these devices with the massive medial wedging and no lateral heel cup.

    The cuboid notch (I prefer to call it lateral column elevation) that TOL use on DC wedge devices is not really part of this attempt to increase and move medially the ORF and has other effects (ie it facilitates transer from BJ's oblique to transverse axis).

    As for the PC Wedge, what Phil is doing is somewhat different and is more aimed at trying to dorsiflex the calcaneus to control STJ motion, as well as invert it. There certainly is a big trend towards this and when you look around at a number of different design parameters and casting techniques, many of them are actually doing this (without not necessarily being explicit as this is the effect).

    BTW --- not sure what "DC" stands for - its either "Direct Control" (which the lab claims), but I wonder if it really "David Coull" (part of the TOL team).
  5. efuller

    efuller MVP

    The sum of all the forces is called the center of pressure. The vector from ground reactive force can be considered to act at the center of pressure. This would include orthotic reactive force as well as force distal to the shell. The center of pressure does not have to be moved medial to the axis, it only has to be moved to a more medial position. If the COP were moved medial to the STJ axis the foot would tend to supinate, and as the foot supinates pressure would increase laterally, until the COP is directly under the axis. Assuming no muscle activity. The total force on the feet, in static stance, is going to equal body weight. So, the force under the foot can be shifted from one location to another. A medial wedge will increase the pressure under heel and the pressure somewhere else will decrease.

    I like the plantar lateral heel addition. I've been doing is since I heard about the medial heel skive and hurt myselft with too small of a skive. It also prevents medial longitudenal arch hieght reduction that can occur with a medial heel skive.

    The lateral wall of the heel cup pushes from lateral to medial and not vertically. So, if this force is plantar to the location of the STJ axis it will add supination moment.

    The shoe should be capapble of preventing the foot from sliding off of the device IF it has a strong enough heel counter. Some shoes do and others don't. If the material is slippery a person will slide. If not there will be increased friction. It may not be an actual problem, but it is a theoretical problem.


    Eric Fuller
  6. Craig Payne

    Craig Payne Moderator

    For those not familiar with the device in question, here is a pic of the prefab based on the same design.


    NB: Rearfoot wedging; release of lateral heel; and lack of lateral heel cup

    If anyone from TOL reads this, my address is below to send the cheque ... ;)
  7. PodAus

    PodAus Active Member


    You're spot on -

    DC=David Coull (never been a secret there...).


    DCW Contra-Ind.

    - Planatar Calc pain
    - Ankle Equinus / decreased Lunge Test (partic. if cannot accomodate HL)
  8. PodAus

    PodAus Active Member

    Oh, and geelm -

    lack of heel cup tends to DECREASE source of irritation
  9. One Foot In The Grave

    One Foot In The Grave Active Member

    I always assumed the latter.

    One definate pro of the DC Wedge in my experience is it's ability to control destructive pronators - like my husband who has, in the past, flattened polyprop blake devices within a few weeks of issue. His DC Wedges made of TL2100 (Carbon fibre mix) have withstood his feet and controlled them for years now...only the covers have needed replacing.

    With this type of foot, a far smaller degree of posting is required to achieve control so the device is ultimately more tolerable by the wearer.
  10. Craig Payne

    Craig Payne Moderator

    Destructive pronators ~= high supination resistance
  11. geelm

    geelm Welcome New Poster

    I agree that a lack of heel cup is not a source of irritation. However, the lack of curviture of the rearfoot wedge may cause discomfort?? With casted DC weges I have been asking the lab to add medial heel curviture and mark the area on the casts to negate this problem.
  12. Even though I have never ordered a "DC Wedge" orthosis from Australia, the concept of using medial rearfoot wedging in an insole arrangement to increase the STJ supination moment is something I have been using for the past 20 years with wedges made of adhesive felt and/or korex on shoe insoles/sockliners or on OTC orthoses.

    When you study the history of foot orthosis therapy, varus heel-wedged orthoses have been widely used for the last century. The varus heel-wedged orthosis has been around for a long time because it makes good mechanical sense but it was not until recently that a mechanically coherent explanation was offered in the literature as to how it produced its mechanical effect (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).

    Inverted heel orthoses were only more recently introduced by Rich Blake, DPM, against much objection from the STJ neutral dogmatists who were teaching biomechanics at CCPM at the time and that believed that the vertical heel orthosis was ideal for nearly all patients and thought that foot orthoses controlled the abnormal forces through the foot by "locking the midtarsal joint". Many of these individuals thought Rich Blake was "crazy" and, therefore, thought that such orthoses as the Blake Inverted orthosis would not work for patients or may even be harmful to patients. Then along came STJ axis palpation, STJ rotational equilibrium theory, medial heel skive technique, the Lundeen sectioned positive cast orthosis, and the DC wedge orthosis to prove the STJ neutral dogmatists wrong.

    All the above varus heel-wedged orthosis designs are doing the same thing: shifting the location of ORF from lateral to medial to either increase the magnitude of STJ supination moment or decrease the magnitude of STJ pronation moment. The important thing to remember is that the STJ axis spatial location will determine the prevailing STJ pronation/supination moments from GRF, ligamentous tensile force and muscular contractile/tendon tensile force and the clinician must design the orthosis appropriately to counterbalance the resultant abnormal STJ moments that are causing the patient's pathology and/or abnormal gait mechanics.
  13. Craig Payne

    Craig Payne Moderator

    That the battle I have with students - there are generic prescription variables (which rearfoot wedging is one; lateral heel release is one and no lateral heel cup is one) and there are brand names (of which the DC Wedge is one, that uses rearfoot wedging, a lateral heel release and no lateral heel cup). I guess its just a tribute to TOL's marketing that the use of the term DC Wedge has come into common use in Australia (...hey guys, I still waiting for that cheque :rolleyes: )
  14. And then there is an orthosis lab here in the US that uses a higher arched, non-rearfoot posted orthosis that has no varus-wedging in the rearfoot and then has the audacity to claim superior results to all other types of orthoses........when will they ever learn?!
  15. Don Bursch

    Don Bursch Member

    A Post Is Just . . .

    . . . an arbitrarily discreet point of contact with and leverage against the foot. There is no inherent magic to it -just one way to attempt foot control.

    The other way you disparage, the full contact in MASS position design used by Sole Supports, does not need a "post" because the control is spread evenly from rearfoot to metatarsals. Another way of saying it is the "post" of a Sole Supports consists of a cradle across the entire tarsus rather than just the medial heel. This is both more mechanically efficient and comfortable if done with correct flexibility to allow sufficient pronation.

    You can technically dribble a basketball with one finger, but the whole hand gives better control.

    Disclosure: I work for Sole Supports. However, I used them clinically for over 6 years, so was a fan before joining the company.
  16. Interesting statement, could you explain the theoretical proof for this please?
  17. Don Bursch

    Don Bursch Member


    We are working on the proof.

    We are starting with the same amount of proof Root had when everyone followed his suggestion to use posts.
  18. While your comparative may or may not be correct Don, you miss the point of my question. What I was asking for was for you to provide a theoretical explanation of why it should be "both more mechanically efficient and comfortable if done with correct flexibility to allow sufficient pronation" which is after all the claim you made. When you say "we are working on the proof" and then "we are starting with the same amount of proof Root had when everyone followed his suggestion to use posts" are we to conclude that you think Root had little/ no evidence for the use of posts and viz, that you have little/ no evidence for this statement also?
  19. Craig Payne

    Craig Payne Moderator

    Even with that, I try to break it down to prescription variables -- I also try to make a distinction between rearfoot posts and rearfoot wedges. I think what Don is talking about in their product is just a prescription variable that is very effective at dorsiflexing the calcaneus (because of the positioning for the foam box casting) ... if you take away the trade names (whether DC Wedge or MASS positioning) and the company names (whether TOL or Sole Supports) and look at the variables used ---- I think what Phil is doing (his "PC Wedge" ;) ) and Sole Supports are doing is just apply more of a dorsioflexory force to the calcaneus to control the STJ that way (where the force is apoplied still has to be medial to the STJ)
  20. No surprise here, Don. Everyone else that has replied back to me on Podiatry Arena in regards to Sole Supports insoles has also worked for the company. :rolleyes:

    Anyway, Don, no need to get your panties in a bunch, I wasn't even talking about Sole Supports insoles in my last posting. I was talking about a different foot orthosis lab in the US that uses high arched orthoses without rearfoot posts. Were you feeling guilty or something......because I did not name your company in my last posting?? :p

    However, now that you have also magically materialized out of the woodwork in support of Sole Supports insoles, it would be nice to see you try to reasonably answer Dr. Spooner's questions regarding the insole product that your employer makes. Are you a chiropractor also??
  21. Like I said before, Craig, I agree with you. However, one thing DC Wedge and Phil is not doing is claiming their orthosis design is superior to all others. Do you think that is appropriate or ethical for an orthosis company to make these claims?
  22. Don Bursch

    Don Bursch Member

    My point is one has to start somewhere with an idea, like Root did. It made sense to him that putting a post under the heel or forefoot would correct rearfoot/forefoot relationships and would prevent pathology. I am not aware of any research done proving the value of that strategy prior to recommending or implementing it.

    Similarly, we start with a strategy that makes sense from mechanical principles, have mostly empirical evidence at this time that it is effective, and have been trying to follow with more rigorous research to support what we see.

    So, theoretically we propose that full contact is more comfortable because it reduces the force per unit area against the plantar foot when achieving correction. We theorize that it is more mechanically efficient because the corrective force is applied directly to the subtalar joint at the midfoot, where there is more leverage to be applied against supination resistance. Along with this we have defined a model of correction that is much more supinated than usual: starting from a point of greater supination recruits more of the keystone effect of the supinated tarsus, further enhancing the mechanical efficiency.

    My initial post was in response to Kevin's remark about how ludicrous it was for a lab to do something other than the myriad ways in which the heel is commonly supported with posting. Just because the majority still do it does not constitute proof of the strategy or automatically relegate alternatives to the dust heap. And my point about Root is that no one seemed to care that his strategy was proven first before recommending it. It seems to me that research always lags implementation by a healthy margin. We are determined to get as much proof as we can, especially since we do not have the advantage of majority consensus.
  23. Now here is an interesting thought...

    Ed says I'm too negative and lets face it, he's always right, right? So I'm going to try and help those crazy guys from Sole Supports out here a little.

    Planal dominance theory basically states that the bigger the angle an axis makes to a plane, the more movement in that plane. Classical and modern studies of STJ axial position show the axis making relatively big angles to the transverse plane: average 42 degrees blah blah and relatively small angles to the sagittal plane: average 16 degrees, yeh right whatever.

    Tissue stress theory dictates that as the STJ approaches its end RoM stress is increased in the tissues. So by limiting the excursion of the STJ, stress can be reduced, i.e., Spooner's ZOOS.

    So if an orthosis succeeds in altering the functional RoM of the STJ by 1 degree in the frontal plane, this is a relatively smaller effect than if it succeeds in altering the functional RoM in the sagittal plane by 1 degree. Now this is only important if a kinematic change is important- which it is not always- Doh.

    So if we assume that Sole Supports (who I think make the best orthoses in the world) alter the sagittal plane function of the STJ and that frontal plane posts alter frontal plane function of the STJ (and that's all either of them do) then surely Sole Supports are a more effective device and moreover are the only brand to trust?

    Hope this helps Ed.
  24. Don Bursch

    Don Bursch Member

    I don't see how that in itself disqualifies the ideas expressed. I could just as easily dismiss you and your followers as people with a vested interest in the status quo. Let's not go down this road. Rootians are a vast group; we are kind of a small rebel faction.

    My mistake. So which lab were you referring to? My point remains whether in fact your subject was Sole Supports or another lab.

    Nothing magical, just decided to chime in for a change. Thanks for the insect analogy, too. Very professional. I very much doubt putting me down makes you more of an expert. I am a physical therapist.

    Ed does get enthusiastic, doesn't he? I guess that's what makes an entrepreneur tick. I agree we should not be making claims we can't back up so we are working on that. I have to admire him, though, for his courage to go against such a well-entrenched mainstream of thought. He's a bright guy with guts and he does tend to exaggerate a bit. But we don't want to throw out the baby with the bath water, right?
  25. All forces applied to the plantar foot act instantaneously across the STJ. So how is the force from a Sole Support "more direct"? You seem to suggest that sole supports apply a greater moment to the STJ, isn't the moment dependent upon the position, direction and magnitude of the force relative to the STJ axial position at any given instant in time? What you seem to be suggesting here is that the orthotic reaction force is constant and stationary? Where exactly at the midfoot? When does it apply a bigger moment? How are you measuring this?
    Last edited: Sep 19, 2006
  26. Now, Don, we can start carrying on a normal intellectual conversation since you said the magic words:
    I really have no problem with orthoses that are higher in the medial longitudinal arch, since I have been making orthoses, or having the orthosis lab I use make orthoses, this way for over the past two decades in patients that need that type of control. Rearfoot posts are very important in some patients, and are unneccessary in others. I believe you would have a hard time convincing very many orthosis experts that rearfoot posts are never necessary to achieve optimal foot orthosis control.

    I make about 90 pairs of custom foot orthoses per month and have been in practice now for 21 years. This makes lots of orthoses (over 10,000 pair) with the vast majority of them having rearfoot posts. I am interested, Don, how many patients have you treated with custom foot orthoses? If rearfoot posts are so unneccessary, then why have my orthoses, and the orthoses of most other podiatrists who are considered experts in foot orthosis therapy, have rearfoot posts added to them to allow their patients to function with less pain and disability.

    I would be interested in any research evidence that you have to show that rearfoot posts are not necessary to have improved gait function and improved symptom improvement in many patients.
  27. Don Bursch

    Don Bursch Member

    I have probably only done merely hundreds of orthotics since the mid eighties. I'll tip my hat to those with more experience for what it's worth (and it is worth something, I agree). Foot Leveler's sells more orthotics than any of us. So if quantity is the deciding factor of excellence, than we have a winner. Have you ever seen a Foot Leveller? Makes Dr. Scholls look aggressive.

    We have already mentioned in a number of posts our best research to date, which is the Hodgson et al article in the Journal of Sports Rehab. That article suggests that we are doing a much better job than posted orthotics in restoring function to the first ray. We have some other papers in the making through McMaster University addressing symptom relief, casting reliability and gait efficiency.

    The question is not whether rearfoot posts work or are necessary, but what are the best ways to achieve the goals of biomechanical correction, primarily in over-pronating feet where I would argue the majority of problems arise:
    1. Sufficient re-supination of the foot occurs af-
    ter midstance to stabilize or “lock” the tarsus in the sagittal plane to allow for efficient propulsion.
    2. The forefoot contacts the ground without imposed abnormal compensatory motion proximally or in the transverse, sagittal or frontal planes
    3. The first metatarsal is stably plantarflexed against the ground during forefoot loading
    4. The first metatarsal accepts 60% of forefoot loading force
    5. The first metatarsophalangeal (MTP) joint is free to dorsiflex sufficiently to avoid compensations in foot or lower extremity posture that would otherwise be necessary to allow sufficient dorsiflexion or forward gait progression.

    My feet are very flat and flexible; I never saw any functional change with the most aggressive posted orthotics I tried previous to SS. Now I realize my feet are not representative of the average, but I have to say the difference in corrective power I experienced was very impressive. My routine experience has been that my patients experienced a similar dramatic difference. We have to show this in studies and explain it. In the meantime, your observation of failed cases of SS use notwithstanding, many practitioners are changing to our way of doing orthotics. Everyone claims great results from whatever, and at least a third will get good results from placebo, so we realize we need to prove the science behind what we do. With all due respect, fame and expertise are a somewhat ephemeral and subjective thing, too.
  28. Craig Payne

    Craig Payne Moderator

    Thats where we going to have to disagree. I see nothing in that paper that shows that the orthoses were better at restoring function to the first ray. What they showed was that there were greater pressures under the first ray with the Sole Supports orthoses and thats all they showed. ONE possible theroretical explanation for that result is that first ray function improved and windlass worked better etc etc which could be why the pressure there was higher, but they did not show that. I can get pressures under the first ray higher by a lot of other means, some of which would be very detrimental to foot function.
  29. EdGlaser

    EdGlaser Active Member

  30. Dieter Fellner

    Dieter Fellner Well-Known Member

    since theory is defined as "any hypothesis or opinion not based on actual knowledge" and proof is defined as a fact or piece of information which shows that "something exists or is true" in such a case both Ed and Don have already many times satisfied this request.
  31. EdGlaser

    EdGlaser Active Member

    Clarification of our position on rearfoot posts and wedges

    You say that you use and have experimented with higher arches but the juxtaposition of the two sentences above makes me seriously doubt it. Early on, we of course, experimented with combining the Sole Support, full contact, MASS position calibrated model with earlier technologies, like rearfoot posting…….. with universally poor results and in some cases I believe, they were harmful and precipitated injury and imbalance. I was not even considering publication at that time, so I was just applying biomechanical principles that I was taught in school with more aggressive arches. Several cases, consistently failed to produce positive results so the idea was abandoned. It also just made sense that combining MASS position with posting would yield a far too aggressive attempt to control pronation and may even over supinate the foot.
    Anyway, bottom line……if you say you experimented with MASS position and found that combining it with posting is possible, and even helpful……then you have never even gotten close to MASS position in any of your experiments. MASS position is NOT "neutral" position with minimum arch fill. Where did you describe this particular position and the technique to reliably and repeatably achieve it, in your publications? I can’t find it,
    You take this weird point of view…you state:
    1. MASS position is the wrong position to put the foot in. It is over-supinated and hurts people.
    2. You have used similar positions for years when appropriate but never published it or talked about it or even know about it.
    3. Oh and if the MASS position does turn out to be correct…You invented it but don’t even offer it at the lab where you are medical director.
    4. If you combine this MASS position with posts and patients have benefited more than MASS position alone….then I know that you have never used the MASS position because the combination is absurd.

    Now let me explain my position on posts and skives clearly: They are the best you and many docs had, and in many cases still have to offer because there was no MASS position discovered yet. Posted and Skived orthoses are every bit as effective as prefabs and maybe a little better at blocking the last tiny bit of pronation that causes “tissue stresses”. Posts are CONTRA-INDICATED in Sole Supports or any orthoses that places the foot in the MASS position because the orthotic is already as aggressive as a foot orthoses can be without causing problems associated with over correction. As research will continue to come out showing positive biomechanical changes with Sole Supports technology, I predict that the MASS position will supplant “neutral” as the correct position to put the foot in for optimal foot function. I have had lots of personal experience with posted and skived orthoses before I invented our product. I would say your experience with my technology is rather limited and statistically insignificant.

    The worst reason to do anything is because everyone else is doing it. See the quote that begins this article:


    There is an article in this month’s Podiatry Management although I cannot seem to link to it easily online by Dr. Paul Sherer entitled, “Root Biomechanics: Does It Still Hold Water?” I think he describes neutral position as a great “guess”; the understanding of which was arrived at by “trial and error”. That’s also how I came up with MASS position. A theoretical hypothesis, followed by invention and experimentation, then evaluation and modification.

    BTW, congrats on being named one of the 175 most influential Podiatrists in America in the same issue of Podiatry Managment: Well Done.

    We are not saying that they are not necessary….just that their minimal effectiveness has been supplanted by a more obviously correct approach of full contact in the MASS position with calibrated orthoses and that rear-foot posting, the pillar of traditional biomechanics, is not compatible with the more effective new approach and therefore needs to remain in the armamentarium of those that do not yet have our technology in their market or have not bothered to be certified in it…..which is silly…. The DVD is FREE just by emailing mshelby@solesupports.com and is approved by the CPME for 2 CME credits in the USA.

    Ed Glaser, DPM
    CEO Sole Supports, Inc.
  32. EdGlaser

    EdGlaser Active Member

    I thought that this thread was a discussion of DC wedges but you could not resist attacking Sole Supports. I thought we were past this.

  33. With you until the point where you say "Ed and Don have already many times satisfied this request". Could you point to where they have "many times" satisfied the request for theoretical proof ? In other words can you show where they have proven their hypothesis. Semantics is fun Dieter.
  34. Seem to recall an article titled something like: "no-one stays neutral on negative casting" published (I think) in Biomechanics magazine some years ago- couldn't find it in their archives as they only go back a couple of years. I think Eric Fuller and maybe Kevin Kirby contributed to this article. Perhaps someone would be good enough to give a synopsis of the content as it may be relevant to this discussion.
  35. Steve The Footman

    Steve The Footman Active Member

    I do not think it was Kevin that brought up the issue of sole supports.

    However back to the DC inverted idea. I am not sure why podiatrists seem to think that orthotics work in a vaccuum. Removing the lateral flare on an orthotic does not remove lateral pressure on the foot. All it does is shift responsibility for that pressure from the orthoses to the shoe. In fact the shoe heel counter may do a much better job of it by exerting pressure above the subtalar joint axis. I think that the reduced cupping of the heel may cause extra slipping and shearing stress inside the shoe. Not sure if the whole idea reduces the 'customised' part of the orthoses.
  36. Good point, Steve. Even though the DC inverted orthosis does not have the lateral heel cup that would give a more inferiorly-positioned, medially directed force on the lateral aspect of the plantar calcaneus, it can still rely on the lateral heel counter of the shoe to exert this force over a broader area. In the medial heel skive (MHS) or Blake Inverted Orthosis (BIO), the traditional high lateral heel cup of the MHS and BIO (16-20+mm) is necesssary to prevent lateral heel cup irritation caused by the plantar heel "falling laterally down the slope" of the inverted heel of the MHS and BIO. However, if the calcaneus is effectively prevented from shifting laterally on the orthosis plate by the lateral heel cup of the MHS or BIO device, then this same medially directed orthosis reaction force (ORF) acting inferior to the STJ axis, which prevents lateral calcaneal shifting, will also cause a subtalar joint (STJ) supination moment.

    In fact, mechanical modelling of this interaction reveals that the more inferiorly located (i.e. more plantarly located) that this medially-directed lateral heel cup ORF is on the foot, then the longer will be the STJ supination moment arm for this force. However, this "lateral heel cup supination effect" can not be said to occur with the DC inverted orthosis since it doesn't have a lateral heel cup. Instead, the DC invertd orthosis will have a be more superiorly located (i.e. more dorsally located) heel counter reaction force acting on the lateral calcaneus, thus decreasing the STJ supination moment arm length, and potentially reducing the STJ supination moment from the device, when compared to the MHS and BIO that do have a lateral heel cup.

    This DC inverted wedge vs MHS and BIO orthosis design difference involves some very interesting mechanical concepts that I have been contemplating for the past two decades. I personally think the DC inverted orthosis is a very cleverly designed device and I think it has great potential to be a very effective orthosis device for many patients with mechanically-based pathologies caused by increased magnitudes of STJ pronation moments.

    When I finish the writing project I am currently working on, I will try to devote a little more thought to these concepts to see if I can come up with any more ideas regarding potential positives/negatives for each of these effective anti-pronation, varus heel cup orthosis designs.
  37. markjohconley

    markjohconley Well-Known Member

    one plane control all that is needed?

    if stj axis is triplanar .... if you control? / influence? one of those planes haven't you controlled? / influenced? all three?
  38. What if the amount of work required varies from plane to plane? That is, what if changing to STJ functional RoM by 1 degree in the sagittal plane is easier to achieve than altering the functional RoM by 1 degree in the frontal plane? What if sagittal plane "wedges" are more efficient than frontal plane "wedges"?

  39. Agreed. Also of significance here is the co-efficient of friction between the orthosis top-cover and hosiery, and, the hosiery and foot. Me, I don't like slippy-slidey top-covers like the one in the picture earlier in this thread as it means I have to increase the posting angle to get the same mechanical effect.
  40. Steve The Footman

    Steve The Footman Active Member

    Another thing that is often ignored is the sliding across the orthotic that occurs in gait. Regardless of whatever the shoe looks like, if the heel is sliding lateraly across the orthotic it will be causing eversion of the STj within the shoe. This may increase if there is a slippery top cover, if there is no heel cup, or if there is no lateral flange. The DC orthoses I have seen have been deficit in all of these features. They simply look like a flat varus wedge at the rearfoot.

    Moreover, unless the orthotic is only being used to stand on, a static exam outside the shoes are unlikly to capture what is happening during gait.

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