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Theta Orthotics

Discussion in 'Biomechanics, Sports and Foot orthoses' started by dougpotter, Oct 6, 2010.

  1. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    robert you are right I am not following your thought at the moment...currently 3:30 am here and I have a busy day tomorrow...going to bed...thanks for taking me serious enoug to ask legitimate questions...brent
     
  2. At what stage during the gait cycle ?
     
  3. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    To all,
    You are correct that we have all been told many things about a new and improved way of designing orthotics, that is why there are more that 200 patents for foot control devices in just the US patent office, not to mention other countries, thousands of otc orthotics, and hundreds more orthotic labs...but you can be certain that NONE of them have ever quantified the functional part of their device...Until quantification of the functional variable involved is acomplished, it is mearly observation and NOT scientific investigation...thus the importance of my research weather you want to believe it or not...brent
     
  4. Sleep well. The questions will keep.

    To reclarify, you say that inclining the foot produces proportionate amounts of rotation in the leg, based on your observations. I say that this is untrue, that although there is a link, it is nowhere near so defined.

    I have cited research which shows that inclining the foot does not rotate the leg and can produce more, if you are interested, to show that whilst it does rotate the leg a little (with induced hyperpronation) it is certainly not a proportionate relationship.

    So my question to you is that if thing are as you say, why does ALL the available evidence show otherwise.

    Thats for starters. There are at least 30 other issues with what you claim, some of which my learned colleagues have already brought to the table. But these threads get so hard to follow when we keep flitting about and it is too easy to ignore the hard issues. So for me, I think we should stay with this one. For now.

    Sleep well.
     
  5. Thank god it´s not sunny today - with all the oil being thrown around I´d have 3rd degree burns if I went out.
     
  6. :D:D:D

    Behave!
     
  7. Griff

    Griff Moderator

    Brent,

    I appreciate you have many concurrent discussions/lines of questioning going on, but just wanted to add mine to the list. No hurry - just get to it when you can:

    How would you treat a peroneal tendinopathy with a Theta orthotic?

    I can wait until the morning - you sleep tight pal.
    Do you sleep on a bed of money by the way?
     
  8. A good question and If can add mine to the back of the line. As the tibial position is all important how would a theta orthotic treat medial knee O/A ?
     
  9. Form an orderly queue, no shoving at the back!

    The thing is, Brent, that you are not stating things we do not know, or that we have no data for. You are saying things that we have rather a lot of evidence that things are not so! Allow me to summarize the queue.

    The foot to leg coupling is a case in point. You can say that its a 1:1 ratio all you like, but the literature clearly shows otherwise. I've posted some, Simon has posted more. You cannot ignore this research as it directly contradicts what you say! How do you explain this discrepancy?

    Craigs point about the everting feet on inverting orthoses illustrates a second point. We have abundant, copious and vast amounts of evidence that (for eg) a 5 degree wedge will not result in a 5 degree change in position in vivo. So a 25 degree insole may be quantified, but that quantification will not make a like number of degrees positional change in the foot. So although you have quantified your device, this is will not extrapolate to a quantifiable effect on the foot. I quantified a device with the Theta method this morning. It was 4 degrees rearfoot, 25 in the arch and 0 in the forefoot. How much supination will that insole create? We have no idea. Measuring an insole gives little or no information on that insole's effect.

    Ian and Michaels points are somewhat more pragmatic. They highlight conditions where an agressive medial wedge will not be appropriate (and I know they can show references). If we take on what you say, we therefore see a discrepancy between what we know works, and doesn't , and the model you promote. One could add lateral instability to the list.

    Isn't biomechanics fun!
     
  10. Oh and as a PS. Six months ago, talking to Ed, I said

    Today, Brent wrote

    So the theta is more supinated than MASS because it has wedges fore and rear foot AND a high arch....

    DAMMIT! I KNEW I should have patented it sooner! Always too slow. Hands up who's impressed by my prophetic ability.

    What'll anyone bet me that the next hypersupinator device (MASS++?) will be along next year? Then, Brent, you will be faced with someone who's insoles are 450% more effective than everyone elses and 50% more effective than yours! After all if neutral is rubbish, Mass is good and 40 degree theta is better, then 45 degree theta (or MASS++) must be better yet!

    In ten years they'll probably be leaving talipes as is and calling everyone else abnormal!

    Only kidding Brent. Sorry, had to bring up my amazing nostadamus like predictive powers.
     
  11. Ask guru Bob about your propehetic powers ?
     
  12. Graham

    Graham RIP

    Introducing he Narcissistic Orthotic:

    For every level of Narcissistic injury the degree of "control" increases.

    Please follow the link below and fill in the NARC psychological assessment. Your level of Narcissistic injury will be computed and and the appropriate orthotic mailed to you express post.

    This opening offer includes a second pair of orthotics absolutely free, just pay separate shipping and handling.

    We guarantee the Narcissistic orthotic to be 401% better than any orthotic on the market. Because I say so:

    Dr Narcissist

    http://www.narcissismcured.com/narcissism.html?gclid=CO-rr4DfwKQCFQK8KgodU2gVDw
     
  13. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    I am back awake and I see that indeed you have come up with much better questions, and I wil see If I can get the time to address them throughout the course of the day.

    Please be just a little patient, not that I deserve special care, but as you know biomechanics is complicated enough to evade understanding for hundreds of years, by thousands of so called researchers like myself. Efforts to explain quickly with a type format is difficult, even when I believe I know how to explain the situation. Somtimes I understand the end result but not so sure the exact mechanics that brings both foot and leg to the observed end result. Robert one of the most complicated movements is STJ supination and the subsequent external rotation the leg. Clearly some of it I do not understand yet, thus continued investigation. Brent





    As I suggested earlier I was not complete in my first attempt to explain the relationship between supination of the foot and supination of the stj with respect to supination of the leg. You are correct that I have not read many of the articles your reference to "closed kinetic chain function". But at least when I do explain them they wont be prejudiced by previous argument.
     
  14. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Grahm, think I understand where you are coming from. If I wasn't threatened about my knowledge of biomechanics I might veiw such a claim juct like you have. I almost wish that I could deny my statement, but depending on the orthotic I compare my 40 degree rearfoot and 20 degree forefoot corrected orthotic with it may be much more than 400 percent. When I say every 5 degrees of correction up to 40 degrees rf and 20 degrees ff doubles the benefits, that is truly an estimate. I do have some physics however, that will substanciate this logrithmic progression of benefits. I apoligise for offending you, but it would be a lie if I suggested any different. Brent
     
  15. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    robert,

    Theta is the mesurment of the angle and does not pertain to any specific angle. Once I figured out how to measure it, It too 2 years for me to under stand where optimal correction occurs and fear not, as I did during the discover process, youi do not need to supinate the foot until nose bleeds occur. In fact optimal allingment interistingly is 40 degrees, but I would have never know that unless I had an accurate way of measuring it.

    my interpertatio of Dr Glasers reserarch is that he uses his casting technique to induce an more suinated position of the foot. based his lectures and some of his patients that I have treated, he achieves as much as 27 degres of angular correction, THETA, with his "MASS" technique.

    Even though he has correctly observed improved benefits with his technique, he has not quantified the end result, or orthotics. Labrotory technique can and does alter the correction he observes. I have observed orthotics produce by his lab , that he actually did the casting for, that had no more that 10 degrees of correction, which explained why the DR who wore it did not get any help. brent
     
  16. Graham

    Graham RIP

    I doubt it!


    Never offended. Often entertained. Too often disappointed!
     
  17. Jeff Root

    Jeff Root Well-Known Member

    Dr. Jarrett,

    This is not true. First, there is no way selectively identify which part of an orthotic device is "the functional part" because it is generally impossible to independently test all of the individual parts of an orthotic device. Some of the parts of an orthotic device that contribute to the total functional influence of the device include but are not limited to the frontal plane contour of the heel cup (varus, valgus wedge influence), sagittal plane contour of the heel cup (sagittal plane influence on calcaneal inclination angle and talar declination angle), medial longitudinal arch of shell, lateral longitudinal arch of shell, transverse arch of shell, angle of intrinsic or extrinsic forefoot varus or valgus correction in shell, presence or absence of an extrinsic rearfoot post, influence of altering the amount of or the absence of frontal plane motion in an extrinsic rearfoot post, and the functional influence of the composition and stiffness of the orthotic shell. There is no way to isolate and individually test most of these functional parts or components of the device, with the exception of the rearfoot post or changing the shell material.

    In terms of quantifying certain aspects of a functional orthotic device design, this has been done. The measurable angle of the heel bisection of the positive cast of the foot and the resulting measurable angle of the plantar plane of the forefoot in relationship to the plane of the floor have been used in the manufacture of foot orthoses for fifty plus years. Clinicians have used these values to attempt to quantify the functional influence of their orthoses and have looked at measurable changes in RCSP, tibial rotation or changes in center of pressure as a means of evaluating the functional influence. For example, Rich Blake did a study that compared the change in the angle of the heel with various degrees of inverted orthoses as compared to a vertical, functional device.

    On the subject of shell influence and composition, what material are your devices made from. To me, they appear to be made of plastazote. Plastazote is widely used to manufacture accommodative orthoses because of its compressible nature. It is not typically used to manufacture functional orthoses because it is too compressible and as a result, lacks the durability (lifespan) and functional support required of functional orthoses. Is that what material you are using?

    Sincerely,
    Jeff Root
     
  18. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Not sure how to respond to Ian? michaels point , but to yours. Clearly I am suggesting something you either do not know or do not believe, therefore the controversy.

    When varus wedging is applied to the mla, rf, and the STJ is first supinated, the initial response in vivo may be adduction of the foot without external rotation of the leg. AS the soft tissue linkage between our hip, leg, and foot adjusts, the adductus resolves and the external rotation can be observed.

    Additionally as I suggested in earlier responses the STJ may not show a 1 to 1 relationship until you get above 20 degrees, the "natural" inclination of the mla described by Hicks. The 1 to 1 relationship between sub-first metatarsal wedging and external rotation of the tibia is much more direct as the supinatory force is directed through the medial column directly, and does not involve the more complicated relationship of the STJ.

    Please forgive spelling etc. as I am trying to hurry, partialy dislexic, have 60 year old eyes, and not an english major as Dr.Kirby suggested. Brent
     
  19. Griff

    Griff Moderator

    Just an answer would be fine Brent.

    Question was this: How would you treat a peroneal tendinopathy with a Theta orthotic?
     
  20. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Jeff,

    I understand you reluctance to accept that my Theta measurement doe not relate directly to orthoics function, as it truly has never been done before. When Dr grumbine suggested that the functional element of any foot control device was related to "specific angles" inherent in the design, he acknoledged he did not know how to define or measure them. Sorry to burst your bubble but I have.

    AS to material used for fabrication, the only concern is that it mantain the angle measured during weight bearing. I have use roadur plastic and non-compressable urethane rubber. You are absolutely correct that plastizote will not work, neither will a poly poly propolene plastic and it will compress during function. When two orthotics are designied with the same angular correction, Theta, but one form a compressable material and the other from one that does not compress, the patients will tollerate the compressable devide more rapidly but in the log run describe the non compressable devise as more effective. Brent
     
  21. Graham

    Graham RIP

    t
    Fabulous! How do you do this?
     
  22. Graham

    Graham RIP

    What Does Theta Mean?

    A measure of the rate of decline in the value of an option due to the passage of time. Theta can also be referred to as the time decay on the value of an option. If everything is held constant, then the option will lose value as time moves closer to the maturity of the option.

    Sounds about right! :bash:
     
  23. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Doubt all you want, as that is the beginning of understanding. the refion of the foot at the apex of the mla forms a hyperbolic curve in the frontal plane, which creates a logrithmic effect on the angle and the vector of forces created, not a linial relationship suggested by a straight line.

    My only dissapontment with your group when first I found you on the internet, was that inspite of the importance you all seemed to place on human biomechanics, (unlike most of my american collegues) your minds did not appear open not open to anything out of the box. If our industry and profession had a handle on it all, we would not be having this discussion. Brent
     
  24. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Grahm,

    Thank you, my very favorite question. When I was taught Trig my very nerdy, nasal, and matter of fact professor, refered to any angle as Theta. When I tried to quantify these important angualar measurments, I refered to the angle as Theta, and continue to do so now 25 years later. AS you know Theta is a letter in the great alphabet and has sseveral meaning as you suggest, but in math it refers to any defined angle. Brent
     
  25. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    www.pcopco.com/orthotics.html www.pcopco.com/theta.html

    This is the most important element of my research all other biomechanical understandings I have learned relate directly to this critical measurment, just as Dr Grumbine suggestd but failed to define. Brent
     
  26. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Unfortunately, if the functional element of the orthotic is not identified and controled none of these studies have scientific relevence...brent
     
  27. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Re: Theta Ortoctics

    robert this is a goldmine of information because NOW for the first time you can explain why your orthoics may work better that others...nice...brent
     
  28. Brent you keep dancing around questions so I´ll bring up mine again

    20 degrees externally rotated tibia when and which stage of the gait cycle.

    and how would your orthotics treat medial knee OA.
     
  29. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Scientific investigation require the the causitive variable be identified and controled, if not any opservations or conclusion derived will be flawed and NO based on science. brent
     
  30. Graham

    Graham RIP

    I hate to say it AMIN man :cool: But this thread smells really bad and I'm feeling naucious!

    Can we get some science from this guy or can we ditch it over to the graveyard of Glasser, Shalveston, Rothbart etc?

    :butcher:
     
  31. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Generally I am not that good of a dancer, especially when I am not trying to do so...I treat medial OA of the knee with any amount of ff correction up to 20 degrees and rearfoot corretion above 20 degrees and below 40 degrees.

    Multiple injury during my youth resulted in severe OA of the knee, with almost complete loss of cartlige on both sides medially. I was virtually disabled with knee pain by age 31. My orthopedist suggested inplant as the only option. AS long as I wear a fully compensated 40 degree rf with 20 degree ff correction, I can pop, grind, and sublux my knee, but I am almost completely asymptomatic during ambulation, at least compared to what I was at 31. I am now 60. The treatment is however a long term progressively increasing process, and as I realigned function symptoms actually first increased in my knee, but I could not quit as the relief with my retro-calcaneal bursitis was significant. After just 2 weeks into the treatment with a 25 degree rf only orthotic it felt like the changes were actually positive. After 2 months I knew the changes were positive. After 2 years I knew I was significantly better but doubted I would every downhill ski, run, or be free of pain with ambulation. I would have never predicted the amount of recovery I now see with 40/20 now 30 years later...brent

    Obviously once joint pathology is extensive complete resolution of symptoms is unlikley. Having said that if my knee pain was even as bad as it was at age 31 I would be looking for the best of knee surgeons right now. Brent
     
  32. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Just ditch it and don't trouble you little brain...like robert suggested to me you can just slither away and not be troubled again...if you are "naucious" imagine how I must feel. Brent
     
  33. Jeff Root

    Jeff Root Well-Known Member

    Brent,

    Thanks for this reply, but you never answered one and only simple question. What material are the devices pictured on your website made from?

    Thanks,
    Jeff
     
  34. Sorry to burst yours, but so have many people. I can measure the angulation in 3 dimensions between any number of points on the surface of a foot orthosis and for that matter the angulation between points below the surface. As far as I can see all you have done is measured part of the geometry of an orthosis and decided to use 40 degree rearfoot posts and 20 degree forefoot posts. You haven't invented something new here. And you certainly haven't presented any data to demonstrate the validity of these magic numbers any more than why Prof. Kirby opted for 15 degrees in his medial heel skive. We can talk about the problem of interface variation later...

    But lest we get side-tracked, back to that 1:1 rearfoot to shank coupling ratio and back to that 1:1 orthotic to rearfoot coupling ratio that you claim.... and while you're there, tell me what you perceive was wrong with my trigonometric calculation last night?
     
  35. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    Jeff
    Urethane Rubber...brent
     

  36. You supinate the foot using Theta angle, right ?

    Well hate to break it to you but your doing the wrong thing, very wrong in fact wrong, wrong, wrong and well wrong.

    Evidence based medicine lateral wedge for medial knee pain .

    Brent I´m going to leave this thread now as it become more and more clear to me that my 5 week old son probably has a better grasp of foot biomechancis than you and I will say something that I should not.
     
  37. And their load/ deformation characteristics?
     
  38. Brent Jarrett DPM

    Brent Jarrett DPM Active Member

    So read my work agan this time with an open mind...I know it is hard to believe that 2 simple frontal plane measurments relate directly to this complicated biomechanical process, it was for me as well, but after controling theses variables in thousands of patients ver the last 25 +years I do believe.

    I don't expect anyone to change their thinking with the information I am presenting here...but if you can understant and implement some of my concepts you may be surpriced what you learn...brent
     
  39. Brent, I have to hand it to you! You have big balls.

    You dismiss the entire body of literature in a single sweep, because the angle of the arch was not measured. You dream big dreams, I will give you that!

    Let me bring you back to the rotation thing, since I've started on that point and it would be churlish to move on to another after you have answered my query.

    Coming back to this study:-

    The mechanical relationship between the rearfoot, pelvis and low-back.
    Duval K, Lam T, Sanderson D.Gait Posture. 2010 Oct 1. [Epub ahead of print]

    Which showed no external rotation of the leg with inversion of the foot.

    You said:-

    So (stop me if I've misunderstood) you are saying that this study showed no rotation because the foot was inclined by only 15 degrees and that this much is taken up by adduction of the foot with no rotation of the leg.

    Have I got that right?

    To which I would retort.

    1
    But this was not in vivo. The foot was fixed on the platform. Therefore no addution of the leg could take place within the first 15 degrees.

    2. Your figure of 20 degrees (which, BTW is completely arbitary but thats another point) refers to the MLA. The feet in the study were placed on a tilt table, so it was not the MLA which was inclined 15 degrees, but the entire foot. Your website describes the three locations for theta and states (for eg) that forefoot wedging goes from 10 to 40 degrees.
    On the tilt table, the angle of "wedging" in the 3 sections would be 15 degrees rearfoot, 15 forefoot and 15 plus arch height of mid foot. Only if the arch was completely flat (as in less than 6 mm, which is 5 degrees or so in a size 11 foot) in all cases would the MLA be less than 20 degrees to an absolute base plane (perpendicuar to the leg).

    Hicks (if we take his word for the 20 degree arch, which I don't) did NOT say that the normal position of the whole foot was 20 degrees inverted! And that is what this study did, Invert the whole foot.

    And, ref your assertions above, The studies done on coupling may not have measured the angle of the MLA wedge, but the casting method implies that it WAS there. The rear, and forefoot measurements WERE quantified. Even if not quantified none of the studies show a direct correlation between orthotic and angulation. The fact that they did not quantify one half of the variable (the MLA) is neither here nor there.
     
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