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Lowering the lateral column in the cast for foot orthotics

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Craig Payne, Oct 21, 2010.

  1. Craig Payne

    Craig Payne Moderator

    Articles:
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    I have been a fan of elevating the lateral column when there is a clinical need to facilitate tansfer of weight towards a high gear propulsion.

    However, some do the opposite. For example I know at least one (HINT: Robert) flatten out the lateral column with the fingers following a foam box impression.

    Can someone (HINT: Robert) explain again to me the rationale for doing this.

    I really trying to get a better understanding of lateral column issues. Can you type it slowly, so I get a chance to get it! :rolleyes:
     
  2. LOL. Oooo you'm subtle. :rolleyes: I have a strange feeling you wanted ME to answer this point but I don't really know why. Must be something subliminal in the smilies.

    There are circumstances in which I will leave the lateral arch as is. Notably if there is a forefoot equinus, as part of a valgus forefoot modification or extension. But you are quite correct, I DO flatten the lateral arch more often than not. Several reasons. I emphasise this is only MY rationale, I'm not saying its "the right way".

    1. Whilst I may fight against it, my mindset is still based on my training, which is rootian. Rootian suspension casting dorsiflexes the first ray. So although its not a GOOD reason, habit probably plays a part.

    2. Similar to above, I started with POP then switched to foam. So when I started off, I was trying to make my foam casts like the corrected POP casts with which I was familier. They almost never had lateral arch.

    3. Although I understand the high gear / low gear thing theoretically, I've never been able to get much of a handle on it in practice. Tissue stress wise, my assessment is to find the knackered structure and try to reduce stress on it. In this sense I almost never think, "ah, a busted Plantar fascia, must be because they are propelling off the lesser mets".

    4. Most of my patients are children. Some very young. The smaller the foot, the less room one has to play with and the harder it is to manipulate segments. Generally what I want in these devices is very simple, to compensate for a lack of supination moments from lax ligaments or hypotonic muscles and block excessive ranges of movement. This is generally acheived by a purely medial device.

    5. It takes up less room in the shoe.

    6. The lateral column is lateral to the STJ axis (unless the foot be munted beyond recognition). Thus, higher lateral arch = more pronation moments from ORF than lower lateral arch.

    7. Although I think in internal kinetics rather than external kinematics, I am still guilty of intuiting in position. When I stand the patient up and consider (or hold) the position I want, there is rarely a lateral arch. Like number 1, not a GOOD reason, but I'm being honest about my shortcomings.

    All very woolley and subjective stuff I know. Do we have any inductive evidence on what the raised lateral column on the insole actually does?

    Kind regards
    Robert
     
  3. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    No. Thats why trying to get a better handle on it.
     
  4. There will be a role in Midtarsal joint kinetics and kinematics with a higher and lower lateral arch, if only we could work it out.!!!! Which may be more significant than the STJ Craig when you find the answers please tell - the black hole of biomechancis strikes again
     
  5. CraigT

    CraigT Well-Known Member

    Just to pick up on this one...
    Firstly- just for clarification- I am a fan of lateral column support in the majority of cases, and like suspension casting because the lateral column is preserved. Generally this mean the lateral column apex will be at the level of the cuboid.

    If you look at the sum of the forces that are lateral to the STJ axis, and look at them in relation to the axis, a higher level of support at the level of the cuboid may decrease the pronation moment as the lever arm would be shorter- ie- you are bringing the pronatory force closer to the axis. So this would mean the higher lateral column may not mean the pronation moments are greater. Does that make sense? (hope my terminology is clear)
     
  6. As in more ORF at the cuboid which although lateral to the axis shadow is closer to it than the lateral forefoot?

    Makes sense I guess...
     
  7. CraigT

    CraigT Well-Known Member

    Yup. Exactly.
     
  8. Jeff Root

    Jeff Root Well-Known Member

    Craig and Robert, good discussion. Robert, I disagree that Merton Root’s supine, suspension casting dorsiflexes the 1st ray. In fact, I think the reason that Root's neutral suspension casting technique has been so popular and successful for manufacturing functional orthoses is because you dorsiflex the lateral column but not the medial column of the foot. I have been thinking about this issue for many years now but it is the first time I have addressed it publically.

    Root believed that applying a simultaneous dorsiflexion, abduction and eversion force with the thumb of the casting hand to the sulcus of the foot would fully pronate the MTJ but would allow the 1st ray to remain in the middle of its ROM (i.e. 1st ray stays in its neutral position). I have checked this and find it to be generally true. When you hold the foot in Root's recommended casting position, you will find available plantarflexion and dorsiflexion of the 1st ray in most patients. I think this is one of the benefits of the supine casting technique. The prone casting technique tends to result in less eversion of the forefoot of the resulting casts, so it may be possible that prone casting doesn't allow the 1st ray to be in the middle of its ROM as frequently, but rather in a more dorsiflexed relationship (just a hypothesis on my part). In the supine technique, the ankle and foot are slightly plantar flexed, which may enable gravity to bring the 1st ray down to the neutral position.

    Root's thinking was based on the concept that the mtj functioned as one unit or two joints with dependent motion. But as we recently discussed, what if the cc joint and the tn joint were not so dependent? What if you applied a pronation force to the lateral forefoot and if fully pronated the cc joint but not the tn joint? Hummm? Look at it in another way. What happens if we cast the foot and apply an identical force to the lateral and medial aspect of the sulcus? Would we end up with the cast of the foot in the same position as when we only apply a force to the lateral forefoot? No. So the question is, does the change in the ff to rf relationship using these two different casting techniques come about only because of dorsiflexion of the 1st ray, or does it possibly change the position of the tn joint. How accurate is it to think of the mtj as a single joint from a functional perspective? I think Simon and I both struggle with this same question.

    Anyway Robert, back to my original point. Merton Root stressed that the 1st ray should not be dorsiflexed during casting. This was a big issue to him.

    Jeff
     
  9. RobinP

    RobinP Well-Known Member

    Yes, it does I think, even to the simpletons like myself.

    Interesting....so in someone in whom you were trying to increase external supination moments, the cuboid pad would reduce the external pronation moments caused by the lever arm to the joint axis of the lateral forefoot and therefore enhance the nett supination moment?
     
  10. Only if the ´Cuboid´supination replaced another point which was further away or has the longer lever arm. If it does not "replace" the other point causing a pronation moment it will add to the pronation moment.

    I for one am looking forward to Simon, David and Kevin´s paper on orthotic function. Sure its going to give the brain cells a good workout.
     
  11. As we haven't written one yet on orthotic function, I'm looking forward to reading it too.;)
     
  12. Have I got my wires crossed I thought it was something about orthotic reaction forces :confused::eek:, What´s the official tittle or do I have to wait till JAPMA ( I assume JAPMA but could be wrong on that one too) comes out ?
     
  13. Next month.
     
  14. Um. This is embarrassing. I meant 5th ray, not 1st ray. Proof reading fail.

    As a gross (very gross) rule of thumb, I'm generally thinking in terms of plantarflexing the 1st ray and dorsiflexing the 5th. I've not forgotten I promised you a video of the technique I use for foam casting, I'll try to get than done tonight.
     
  15. Jeff Root

    Jeff Root Well-Known Member

    Robert,

    You really caught me off guard with that one. Now it makes sense. Thanks for clarifying.

    Jeff
     
  16. RobinP

    RobinP Well-Known Member

    For goodness sake Robert, don't you know that when something like that occurs you are supposed to swear black is white, belligerently defend your clearly ridiculous standpoint, try to misdirect criticism by starting a slagging match then say you are never posting on this site again because no one is respecting your view point.

    Instead, you admit to making a boo-boo like some sissie boy........the shame.

    [QUOTE/]
    As a gross (very gross) rule of thumb, I'm generally thinking in terms of plantarflexing the 1st ray and dorsiflexing the 5th. I've not forgotten I promised you a video of the technique I use for foam casting, I'll try to get than done tonight.[/QUOTE]

    Yes please

    Robin
     
  17. Well, sort of yes and no. We presume that we are increasing ORF under the cuboid, which is probably safe. If this pushes the foot over onto the first two mets for high gear then yes, it will decrease GRF under the lateral forefoot which is further from the axis, = net decrease in pronation moments.

    However this presumes that the orf under the cuboid comes from the forefoot. One could as well suggest that such a mod would merely decrease ORF from the arch of the orthotic, in the same frontal plane as the cuboid. In which case it is decreasing supination moment (from the arch) and increasing pronation moment (from the navicular).

    Hypothetically, if you made an insole with a higher lateral arch than medial, would you expect it to supinate the foot by decreasing the lateral forefoot load? Probably not. So at what point would the lateral arch cease to decrease pronation moment and start to increase it?

    OR is it the case that the lat arch MUST decrease supination moment by decreasing medial arch ORF but can also decrease pronation moment by shifting the COP nearer the axis? In which case its effect depends on whether the decrease in pronation moment is greater than the decrease in supination moment . There is probably a graph with a tipping point there somewhere...

    Then of course we must consider the sagittal plane. If the Mid tarsal joint was completely flaccid, one could have a flat foot from the simple act of the calcaneus pivoting until the proximal part of the lateral arch hits the ground and stops it. In which case blocking the movement early, with a lateral wedge may have merit.

    Its late and I'm now babbling. I suspect that the answer is the one we always come back to.

    It depends.

    Regards
    Robert
     
  18. Yes please

    Robin[/QUOTE]

    LOL. Damn, I forgot the rules! Of course one must dorsiflex the 1st met. I've treated 5,000,000 patients that way over the last 91 years and have a 100% success rate. Its the eta beta pi / X model. There is also research to prove it but its secret research so you'll just have to take my word for it. hahaha, You insufferable bore, I don't have to listen to this, off on holiday, bye. FU.

    There, the life of a pod arena salesman in one paragraph.

    Yes, I can see how me advocating dorsiflexing the 1st met in a thread about why I like to dorsiflex the 5th could come over a bit silly! :wacko:

    Sorry for the confusion.
     
  19. Foot orthoses can physical effect:
    1) the geometry at the foots interface with the supporting surface;
    2) the load / deformation characteristic's at the foots interface with the supporting surface

    These two factors are linked.

    If we lower the profile of the orthosis at the lateral border, we will decrease the stiffness of the device in this area: the lower the curvature the lower the stiffness, until the orthotic contacts the shoe in this region. It's not quite as simple as that as span length will influence the stiffness too. But for an orthosis that is shank independent in this region, for a given span length, a lower curvature will be more compliant than a higher curvature.

    In general, the less stiff the orthotic, then the greater the potential deformation of the orthotic and the greater the potential deformation of the foot that will occur on top of the orthotic, before equilibrium is reached. Therefore, one might predict an increase in rearfoot plantarflexion and/ or an increase in forefoot dorsiflexion in the lateral segments of the foot about an MTJ axis which was perpendicular to the sagittal plane in association with an orthotic which is more compliant in this region; a lower lateral arch profile in the orthosis might result in this.
     
  20. Jeff Root

    Jeff Root Well-Known Member


    Congratulations Robert, you are now the father of the dorsiflexed medial, longitudinal beam paradigm!
     
  21. Because its a flawed concept.
     
  22. Graham

    Graham RIP

    No it's not! It's common scence:drinks
     
  23. Don't knock that paradigm, just because you are not willing to try it....
     
  24. Could be. Could be just that I'm a bit simple...


    Yea me!

    Don't worry gents, When I'm rich and famous, everyone is using the DMLBP and all other models are discarded, I'll not forget you. :cool::cool::cool:
     
  25. Yes it is. A bit early for panto season, but he probably is behind you.
     
  26. Common scence. Half common sense, half common science.

    Cool word!!;)

    The Pod arena panto! Now there is an idea. Bags I chuckles the clown.
     
  27. This will be bad form to post a picture you found but who gets to play these guys.
     

    Attached Files:

  28. From left to right and top to bottom

    Micheal Weber, Mark Russell, Graham, Dave Smith

    Craig, Kevin, Twirly Ian

    Jeff, Simon, Me.
     
  29. Bruce Williams

    Bruce Williams Well-Known Member

    Jeff is correct here as it is clearly written in the text not to plantarflex the 1st ray. I referenced this in an online post early this year for Podiatry Today on digital casting techniqes.

    I disagree with Jeff regarding the lateral column casting technique, but I have not fully come to a comfortable understanding of how and why and sometimes when it is best not to plantarflex the lateral column during casting.

    I've talked about my change in technique many times in the Arena, but to recap I will Plantarflex or actually supinate the lateral column instead of plantarflexing or pronating the medial column of the foot. Ive tested this many times and what I have found is that if you do this, in most instances, the 1st ray will not be able to Plantarflex anymore while the 4th adn 5th rays are maximally plantarflexed.

    My reasoning is that this internally rotates the cuboid with the 4th adn 5th rays so that it sits under the navicular, engages the anterior calcaneal beak or the CC joint. This stabilizes the medial column/1st ray and puts it where it is supposed to be most of teh time, IMHO.

    I agree with the Craigs' on the increased ORF at the CC joint not usually increasing the pronationg moments but instead increasing the supination moments in many or most instancces.

    Where I am not fully comfortable with my reasoning is that I am also an ardent user of FF valgus posting due to the Kogler study and my own in-shoe experiences. I'm not sure that the two, casting the lateral column PF'd and the valgus FF post, don't compliment each other. I have had issues where it has caused discomfort to my patients, especially in more neutral feet. In flat feet I usually have to use a very high degree of FF valgus posting along with Medial skives adn often a heel lift of at least 3 mm.

    good discussion!
    Bruce
     
  30. Bruce and Craig T if I can pick up this point. As I said before if the longer ORF point is removed I can see it if it´s not ,but maybe reduced is size and then you add another ORF point then the external pronation moments must have increased.

    What I beleive is happening in that the higher lateral arch is increasing the tension in the PL tendon from cuboid to 1st which is then planatarflexing the head the 1st and having positive effects with the windlass mechanism.
     
  31. efuller

    efuller MVP

    I generally like elvating the lateral column, when there is range of motion available. However, I like doing for a different reason than changeing to a different gear of push off. I don't like the hi gear/ low gear idea even if it makes scence to some. (The reason that I don't like it is that high gear low gear thing assumes constant angular velocity, which is a bad assumption.)

    The reason that I like lifting the lateral side of the orthtic was the cadaver study that showed lower plantar fascial tensions with lateral forefoot wedges. The theory is that in the medial slip of the plantar fascia tension is increased when there is force under the first met. The goal of the lateral forefoot wedge is to increase pressure under the lateral forefoot to decrease pressure under the first ray, especially as the heel lifts.

    I will usually try to avoid filling in the lateral column in casts. I'm making the assumption that I've dorsiflexed the lateral column to a point of increasing stiffness when I've taken my negative cast. (As you dorsiflex the MTJ there will be a point when ligament tension starts to increase to resist further dorsiflexion. I used to call this the end of range of motion, but you can ge a little more motion if you stretch the ligaments. I don't know how dorsiflexed the MTJ is when I use a foam box. Is the pressure from the foam enough to fully dorsiflex it?

    There are a couple of foot types to think about when looking at the amount of dorsiflxion of the lateral forefoot on the rearfoot. There is the lateral cavus foot. The one with no contact under the lateral arch with the wet foot print test. These feet often have calluses/ pain in the forefoot that I attribute to higher pressures under the forefoot. (P = force/area and there is decreased area of contact, so higher pressures under the forefoot. See Cavanagh Morag paper.) In these feet having a lateral arch distributes the force over a larger area.

    The other foot type to think about is the one where the lateral column dorsiflexes relative to the rearfoot. Most feet will stop at a position where the plantar rearfoot is parallel and in line with the plantar forefoot. There are some feet where, when you watch gait from behind, you can see the heel lift, then the lateral foot and then the toes lift off the ground. This is also better seen with pressure analysis. I'm not really sure what I should do with this foot. I usually try to keep the cast straight. If I have one of these casts that I've forgotton to keep straigth I will carve out positive cast to make it straight.

    If I see a cast where I feel that I did not fully dorsiflex the forefoot on the rearfoot, I will add some fill. I've had some people complain of a lump running from medial to lateral under the foot when standing on the orthosis. I attribute some of those to a cast that is putting too much pressure under lateral midfoot because the lateral arch of the orthotic is too high. Other cause of the lump feeling can be the need for a plantar fascial groove.


    A lot of comments that make you think in this thread.

    Eric
     
  32. efuller

    efuller MVP

    The total force on the foot has to be equal to body weight. As you increase force in one area, it has to decrease in another area. With the cuboid pad/ lift of lateral orthotic that force could come from medial to the axis or lateral to the axis. So, I don't know if the effect from the increase in height in this location is entirely predictable.

    Eric
     
  33. RobinP

    RobinP Well-Known Member

    Perfect
     
  34. Bruce Williams

    Bruce Williams Well-Known Member

    Michael;

    I agree with you regarding the PL tendon. I think that diagram is best in Root's book as well?

    I suppose ORF may not be appropriate here completely? It is a positional thing both from the casting perspective of the forefoot and STJ and quite often the Ankle Joint I think too. The rest is wedging in most cases at the medial heel, lateral FF, distal toes plus metapads if you like them, reverse morton's extensions, cutouts etc.

    Yes they all contribute to the ORF's but it is also dependent on what the more proximal joints (ankle, knee, hip) and the contralateral limb is doing as well.

    Cheers
    Bruce
     
  35. Bruce Williams

    Bruce Williams Well-Known Member

    I think Eric's post may reinforce my statements earlier regarding the potential differences between casting position or cast mold and posting the device.

    I don't think they are the same depending on how you modify your devices.

    The Kogler study used wedges not orthotics. I think that is a big difference!

    I think as well that you can cast with a higher lateral arch but still utilize a FF valgus posting on the device. I'm not saying you should all the time, but I think in a flatter foot it may be very beneficial.
    Bruce
     
  36. MR NAKE

    MR NAKE Active Member

    E=MCX2
     
  37. This the one you refer to Bruce ? Kogler, G.F., Veer, F.B., Solomonidis, S.E., and J.P. Paul: The influence of medial and lateral placement of orthotic wedges on loading of the plantar aponeurosis full text below

    anyone got a copy of these below?

     
  38. S Cook

    S Cook Welcome New Poster

    With Fettig/Feehry/Denton mods being used for a raised lateral arch, is there any literature that explains the theory behind the desired effect (which, from experience is to transfer to "high gear axis")? If anyone has anything on these mods i would love to read. :drinks

    Cheers,
    -Sam.
     
  39. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    Herein lies the problem. There is nothing. You won't getting any better information than what has come through in this thread.
     
  40. efuller

    efuller MVP

    Michael, Bruce,

    I don't see how a cuboid pad or raising the lateral arch of the orthosis has any effect on peroneus longus tension. Tension in the tendon is created by contraction of the muscle belly. Some muscles when they reach the end of their physiologic length will exert passive tension. (Think Achilles and dorsiflexion of ankle.) Placing something under the cuboid does not stretch the tendon. Supination of the STJ and dorsiflexion of the metaarsal will stretch the tendon. And the metatarsal motion does not stretch it very much. I've looked at the excursion of the tendon with full range of motion of the first ray and it's about an 3-4mm. There's about 10-12mm excursion with full range of motion of the STJ.

    The old Hicks' paper showed that tension in the peroneus longus tendon did decrease tension in the plantar fascia. So, I do agree that peroneus longus can have a positive effect on the windlass.

    I disagree with the vector diagrams in Normal and Abnormal function of the Foot that try to explain the function of peroneus longus. If you look at the course of the tendon, it does not really pull the base downward at all. It pulls the base proximally and in conjuction with a distal push from the anterior facet of the cuneiform a force couple is created that will create a plantar flexion moment at the first ray. (Think hamstrings with extended knee and direction of pull of the hamstrings. A force couple causes knee flexion.)

    Eric
     
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