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The Potentailly Injurious Effects of Forefoot Varus Posting

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  #1  
Old 27th November 2010, 06:11 PM
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Default The Potentailly Injurious Effects of Forefoot Varus Posting

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I made some comments at recent Boot Camps on the potentially injurious effects of forefoot varus posting on foot orthotics; we have had a number of threads in the past on forefoot varus. I have had a couple of emails about what I said, so it’s easier to post a generic reply here:

Forefoot varus is very rare, but when it is present, the rearfoot has to pronate to bring the medial side of the forefoot down to the ground. The traditional approach to dealing with forefoot varus is to use a foot orthotic with a medial forefoot post to bring the ground up to the foot so the rearfoot does not have to pronate.

The point I tried to make was that a forefoot varus post will have two very different effects depending if the foot orthotic was a rigid plastic or a semi-rigid/flexible material:

Semi-rigid/flexible orthotic:
For the forefoot varus posting to work, it is going to have to dorsiflex the first ray to end range of motion and then supinate the mid-foot joints to end range of motion before it can have any effect on the rearfoot pronation --> potentially injurious due to jamming at end range of motion

Rigid orthotic:
The effect of the forefoot varus posts is immediately transferred to the rearfoot to stop it pronating via the rigidity of the plastic --> does not have to move joints to end range of motion to effect rearfoot pronation.

Conclusion:
Using a forefoot varus post on anything other than a rigid plastic orthotic to treat forefoot varus induced rearfoot pronation is theoretically and potentially injurious

NB:
There are also effects of the medial forefoot posting on the windlass mechanism
There may be other indications for medial forefoot posting when its use is warranted.
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Old 27th November 2010, 07:44 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Craig Payne View Post
I made some comments at recent Boot Camps on the potentially injurious effects of forefoot varus posting on foot orthotics; we have had a number of threads in the past on forefoot varus. I have had a couple of emails about what I said, so it’s easier to post a generic reply here:

Forefoot varus is very rare, but when it is present, the rearfoot has to pronate to bring the medial side of the forefoot down to the ground. The traditional approach to dealing with forefoot varus is to use a foot orthotic with a medial forefoot post to bring the ground up to the foot so the rearfoot does not have to pronate.

The point I tried to make was that a forefoot varus post will have two very different effects depending if the foot orthotic was a rigid plastic or a semi-rigid/flexible material:

Semi-rigid/flexible orthotic:
For the forefoot varus posting to work, it is going to have to dorsiflex the first ray to end range of motion and then supinate the mid-foot joints to end range of motion before it can have any effect on the rearfoot pronation --> potentially injurious due to jamming at end range of motion

Rigid orthotic:
The effect of the forefoot varus posts is immediately transferred to the rearfoot to stop it pronating via the rigidity of the plastic --> does not have to move joints to end range of motion to effect rearfoot pronation.

Conclusion:
Using a forefoot varus post on anything other than a rigid plastic orthotic to treat forefoot varus induced rearfoot pronation is theoretically and potentially injurious

NB:
There are also effects of the medial forefoot posting on the windlass mechanism
There may be other indications for medial forefoot posting when its use is warranted.
Craig:

I use varus forefoot extensions in shank-dependent plastazote #3 orthoses for runners without any first ray symptoms. These work great for treating medial tibial stress syndrome and patello-femoral syndrome in runners. In fact, the injury may persist without proper use of the varus forefoot extension added to the orthosis. I really don't think it makes the orthosis plate material makes much difference. However, I rarely used varus forefoot extensions on foot orthoses for non-runners.
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Old 27th November 2010, 07:55 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

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I use varus forefoot extensions in shank-dependent plastazote #3 orthoses for runners without any first ray symptoms. These work great for treating medial tibial stress syndrome and patello-femoral syndrome in runners. In fact, the injury may persist without proper use of the varus forefoot extension added to the orthosis. I really don't think it makes the orthosis plate material makes much difference.
So do I, but I see that as a different 'kettle of fish' to the above scenario due to the so-called 'runners varus'.

Would you agree, that if forefoot varus was present that the effect of a forefoot varus post would be very different on rearfoot pronation depending on the rigidity of the orthotic shell?
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Old 27th November 2010, 08:03 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

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Originally Posted by Craig Payne View Post
Would you agree, that if forefoot varus was present that the effect of a forefoot varus post would be very different on rearfoot pronation depending on the rigidity of the orthotic shell?
Craig:

I think a better way to put it (especially considering that many shank-dependent orthoses have very low "rigidity" but deform very little inside the shoe) is to say that the biomechanical effect of a forefoot varus post would be dependent both on the congruity and the amount of deformation of the orthosis under weightbearing loads.
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Old 28th November 2010, 07:27 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Craig Payne View Post
I made some comments at recent Boot Camps on the potentially injurious effects of forefoot varus posting on foot orthotics; we have had a number of threads in the past on forefoot varus. I have had a couple of emails about what I said, so it’s easier to post a generic reply here:

Forefoot varus is very rare, but when it is present, the rearfoot has to pronate to bring the medial side of the forefoot down to the ground. The traditional approach to dealing with forefoot varus is to use a foot orthotic with a medial forefoot post to bring the ground up to the foot so the rearfoot does not have to pronate.

The point I tried to make was that a forefoot varus post will have two very different effects depending if the foot orthotic was a rigid plastic or a semi-rigid/flexible material:

Semi-rigid/flexible orthotic:
For the forefoot varus posting to work, it is going to have to dorsiflex the first ray to end range of motion and then supinate the mid-foot joints to end range of motion before it can have any effect on the rearfoot pronation --> potentially injurious due to jamming at end range of motion

Rigid orthotic:
The effect of the forefoot varus posts is immediately transferred to the rearfoot to stop it pronating via the rigidity of the plastic --> does not have to move joints to end range of motion to effect rearfoot pronation.

Conclusion:
Using a forefoot varus post on anything other than a rigid plastic orthotic to treat forefoot varus induced rearfoot pronation is theoretically and potentially injurious

NB:
There are also effects of the medial forefoot posting on the windlass mechanism
There may be other indications for medial forefoot posting when its use is warranted.
Craig



I am not one too use a forefoot varus post very often, and yes I do agree that forefoot varus is a rare beast.

However, I have a few questions/ideas...

Do you think that your statement regarding Flexible orthoses may be paying too little attention to the properties of the shoe (as Kevin has eluded too) in which the orthosis is placed. A flexible orthosis in a shoe with a stiff shank should still allow transfer of forces from the FFVR post to the rearfoot. As we have all discussed in the shank dependancy thread. Additionally transfer of forces to the reafoot would also be promoted via the stiffness characteristics of the plantar fascia, spring ligament and potentially stretch reflexes in the plantar intrinsic foot muscles. I do agree that a rigid device will be more effective at transferring force, however I'm just not too sure about the statement re-flexible orthoses.

Additionally, Do you think that this argument leans a little bit too much in the direction of "position/motion", rather than tissue stress/ force alteration, and may be a little too simplistic? For example... When we are trying to reduce pronation about the STJ axis, we don't try to maximally supinate the rearfoot to stop pronation. We aim to apply enough force to the medial side of the joint axis to reduce excessive pronation FORCE. With this in mind, why do we have to maximally dorsiflex the first ray and maximally supinate the midfoot to effect any changes on pronation? . Correct me if I'm wrong, but it is my belief that force transmssion/alteration can happen before we see any changes in kinematics. Is this any different in FF varus?In a true forefoot varus, where the foot pronates to get ground ground contact under the medial forefoot, any pathogy will be caused by the forces encountered whilst getting to the endpoint of pronation, rather than being caused by the end pronated position itself. By adding a FF Varus post, you are essentially bringing the ground/shoe up to the medial forefoot. A forefoot varus post should enable earlier contact of the medial forefoot with the shoe/ground, thus reducing STJ pronatory acceleration and force. This may not change the total rearfoot excursion but would significantly alter the loading rate.

Sorry if this is a little hard to follow, I'm just writing these down as they come to my head
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Old 28th November 2010, 08:26 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Placing anything that dorsiflexes the first ray will inhibit first mtpj function. Again, here a varus wedge in a runner may reduce the tissue stress on the medial tibia or the pat fem but what tissues has it increased stress on?
Attached Files
File Type: pdf 1st Ray position and 1st MTPJ motion.pdf (116.2 KB, 73 views)
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Old 28th November 2010, 09:09 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

http://www.jbiomech.com/article/S002...081-X/abstract
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Old 28th November 2010, 09:39 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Craig Payne View Post

Forefoot varus is very rare, but when it is present, the rearfoot has to pronate to bring the medial side of the forefoot down to the ground. The traditional approach to dealing with forefoot varus is to use a foot orthotic with a medial forefoot post to bring the ground up to the foot so the rearfoot does not have to pronate.
As far as the STJ is concerned there is no difference between forefoot varus and rearfoot varus. It is all a matter of where the forefoot load is. If there is insufficient range of motion in the direction of eversion of the STJ to load the medial forefoot then you should use a forefoot varus wedge to increase the load on the medial forefoot. This is the old John Weed trick of trying to slide your fingers under the lateral or medial sides of the standing forefoot. If you can get your fingers under the first met, it is probably not bearing enough load.

Quote:
Originally Posted by Craig Payne View Post
The point I tried to make was that a forefoot varus post will have two very different effects depending if the foot orthotic was a rigid plastic or a semi-rigid/flexible material:

Semi-rigid/flexible orthotic:
For the forefoot varus posting to work, it is going to have to dorsiflex the first ray to end range of motion and then supinate the mid-foot joints to end range of motion before it can have any effect on the rearfoot pronation --> potentially injurious due to jamming at end range of motion

Rigid orthotic:
The effect of the forefoot varus posts is immediately transferred to the rearfoot to stop it pronating via the rigidity of the plastic --> does not have to move joints to end range of motion to effect rearfoot pronation.

Conclusion:
Using a forefoot varus post on anything other than a rigid plastic orthotic to treat forefoot varus induced rearfoot pronation is theoretically and potentially injurious

NB:
There are also effects of the medial forefoot posting on the windlass mechanism
There may be other indications for medial forefoot posting when its use is warranted.
Terminology time out:
Are we talking about intrinsic post or extension. Intrinsic post ends proximal to the metatarsals. Extension ends distal to the metatarsals. My discussion below is assuming extension.


Going back to the idea of load, it doesn't matter if the device is rigid or flexible. It matters in what position the load is applied. If you had a 10 degree soft foam wedge that compressed to be effectively 5 degrees it would still be more of a wedge than a non compressible 3 degree wedge.

I'm not sure I'm getting the difference between the rigid and flexible devices described. Whether or not the device is rigid or flexible a load will be applied to the metatarsals and they will move in response to that load. Just take a patient and seat them in a chair with the soles of their feet toward you. Take a rigid varus wedge and a flexible varus wedge and place a superiorly directed force on the met heads, is there any difference? (Do this with some "ground" under the wedges.

I'd agree with both Kevin and Graham about forefoot varus extensions. Yes, they will tend to increase load on the first ray and they will help medial tibial stress syndrome. You shift the stress from what hurts to some other location and monitor for symptoms in other structures.
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Old 28th November 2010, 10:41 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Graham View Post
Placing anything that dorsiflexes the first ray will inhibit first mtpj function. Again, here a varus wedge in a runner may reduce the tissue stress on the medial tibia or the pat fem but what tissues has it increased stress on?
Quote:
Originally Posted by efuller View Post
,I'd agree with both Kevin and Graham about forefoot varus extensions. Yes, they will tend to increase load on the first ray and they will help medial tibial stress syndrome. You shift the stress from what hurts to some other location and monitor for symptoms in other structures.
Eric
But this statement is the same for every orthotic device post, skive etc.

While I don´t use FF Varus posts that much, using one and then saying what other structures has it increased stress on, this type of question should be asked of all devices not just those with FF Varus extensions.
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Old 28th November 2010, 12:31 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
But this statement is the same for every orthotic device post, skive etc.

While I don´t use FF Varus posts that much, using one and then saying what other structures has it increased stress on, this type of question should be asked of all devices not just those with FF Varus extensions.

I agree! However, how to we determine that the alterations in moments and force on other joints won't create secondary pathology?
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Old 28th November 2010, 12:43 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

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I agree! However, how to we determine that the alterations in moments and force on other joints won't create secondary pathology?
Graham at the moment I don´t think we can, but maybe we can help reduce these secondary pathology with detailed history plans. ie we can only look back not predict the future.

eg 2 Patient present with problem that requires you to use external supination moments for the case of the example we say that they are the same even though it is impossible.

patinet A no history of lateral ankle sprains

patient B history of lateral ankle sprains

so if we only consider the stressed tissue at the moment then the chance of patient B returning with lateral ankle problems is much higher than patient A.

So just like late night Poker we play the percentages

does that make sense

A wise man wrote something this year that I went brilliant after reading( it was Eric) re GRF we can´t reduce it we can only move it from one place to another - maybe not in those words but that was the idea , it stuck with me, maybe I´m a few pages behind but I was of course.
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Old 28th November 2010, 12:59 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

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does that make sense
It Does!
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Old 28th November 2010, 03:20 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

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Terminology time out:
Are we talking about intrinsic post or extension. Intrinsic post ends proximal to the metatarsals. Extension ends distal to the metatarsals. My discussion below is assuming extension.
I specifically had in mind the widespread practice of using an extrinsic forefoot varus post on a flexible shank dependent prefabricated foot orthotic - how is that going to have any effect on the STJ? All I can see it doing is dorsiflexing the first ray.

Whereas an extrinsic forefoot varus post on a rigid plastic foot orthotic will have the effect of 'inverting' the plastic orthotic and affect the STJ.
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Old 28th November 2010, 03:49 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

While agree that what we call a forefoot varus seems to be rare or even extinct....what about the effect of significant tibial varum? The whole foot is shifted into varus, and when it pronates to the ground during compensation for that tibial varum a series of problems occur. If we use a rigid orthosis to limit that pronatory collapse at the rear foot via some kind of inversion prescription, then should we not also decrease the distance the metatarsal heads have to travel to reach the "ground" on the medial side of the forefoot?....ie add a flexible wedged forefoot post? so that we have in effect negated the condition of the tibial varum?
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Old 28th November 2010, 04:04 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
what about the effect of significant tibial varum? The whole foot is shifted into varus, and when it pronates to the ground during compensation for that tibial varum a series of problems occur.
You are assuming that the pronation is an issue. I believe Craig pointed out that pronation has a poor correlation to injury. Also, if what you say is true, how do Lateral wedges in cases of Tibial Varum reduce medial knee pain?
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Old 28th November 2010, 04:07 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

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While agree that what we call a forefoot varus seems to be rare or even extinct....what about the effect of significant tibial varum? The whole foot is shifted into varus, and when it pronates to the ground during compensation for that tibial varum a series of problems occur. If we use a rigid orthosis to limit that pronatory collapse at the rear foot via some kind of inversion prescription, then should we not also decrease the distance the metatarsal heads have to travel to reach the "ground" on the medial side of the forefoot?....ie add a flexible wedged forefoot post? so that we have in effect negated the condition of the tibial varum?
regards Phill Carter
Traditionally, in that situation you varus post the rearfoot as well. However, even in this situation a forefoot varus post on anything less than a rigid orthotic is not going to affect the rearfoot (unless its jammed up all the medial midfoot joints).
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Old 28th November 2010, 06:58 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Simon Spooner View Post
For Simon;

A study by Hall and Nester, shows that a decrease in 1st mpj dorsiflexion motion leads to Sagittal plane compensations at the Ankle Joints, Knee Joint and Hip Joints.
Participants walk with a rigid insole under the 1st ray to restrict 1st mpj dorsiflexion range of motion.
Ankle joint dorsiflexion showed an increase during late midstance, and a reduction in ankle joint plantarflexion during the propulsion phase, which led to increased knee flexion and decreased hip extension.
Sagittal Plane Compensations for Artificially Induced Limitation of the First Metatarsophalangeal Joint, A Preliminary Study, C Hall, CJNester, JAPMA, Vol 94; No 3; May/June 2004 – Level 2

good discussion
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Old 29th November 2010, 06:49 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

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Originally Posted by Bruce Williams View Post
For Simon;

A study by Hall and Nester, shows that a decrease in 1st mpj dorsiflexion motion leads to Sagittal plane compensations at the Ankle Joints, Knee Joint and Hip Joints.
Participants walk with a rigid insole under the 1st ray to restrict 1st mpj dorsiflexion range of motion.
Ankle joint dorsiflexion showed an increase during late midstance, and a reduction in ankle joint plantarflexion during the propulsion phase, which led to increased knee flexion and decreased hip extension.
Sagittal Plane Compensations for Artificially Induced Limitation of the First Metatarsophalangeal Joint, A Preliminary Study, C Hall, CJNester, JAPMA, Vol 94; No 3; May/June 2004 – Level 2

good discussion
Bruce
Thanks Bruce, I couldn't see the bit in this study where they measured the change in 1st MTPJ dorsiflexion with and without the insole though.
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Old 29th November 2010, 07:14 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Here you go, Bruce. See attached.

Conclusions: Foot orthoses that incorporate a
medial forefoot post do not have a consistent
negative effect of reducing first MTP joint
dorsiflexion during walking. J Orthop Sports
Phys Ther 2004;34:317-327.
Attached Files
File Type: pdf June2004-RR-Nawoczenski.pdf (148.8 KB, 36 views)
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Old 29th November 2010, 08:44 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

The discussion is interesting also!


Quote:
While all subjects were similar with regards to the
minimum criteria for inclusion into the study and the
orthotic design and footwear features were kept
consistent, there were highly variable individual re-
sponses to the different orthotic posting conditions.


Quote:
Anecdotally, subjects were
asked to report changes with their symptoms and
specify if they preferred using one orthosis over the
other. It was interesting to note that all subjects
reported improvement in their musculoskeletal symp-
toms with orthotic use, but they were evenly divided
on their personal wearing preference of ARCH versus
FF POST design.
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Old 29th November 2010, 09:17 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Simon,
Do you have this paper to share as well? Thanks.
I'll look thru Nesters paper today again.
Bruce
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Old 29th November 2010, 09:38 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Bruce Williams View Post
Simon,
Do you have this paper to share as well? Thanks.
I'll look thru Nesters paper today again.
Bruce
Which one Bruce, the Nester paper or the Nawoczenski? I attached the pdf of the Nawoczenski in my earlier post. Hint: they didn't measure 1st MTPJ kinematics in the Nester study, BTW.
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Old 29th November 2010, 09:39 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

should we not be thinking in terms of dorsiflexion stiffness of the 1st MTP.

ie by using the FF varus wedge we have increased the dorsiflexion stiffness of the 1st MTP and this will only become a problem if the forces required to overcome this increased dorsiflexion stiffness of the 1st MTP are too great for the muscles .

as an example achilles tendon which has greater resistance to the plantarflexion moment ( due to the longer lever arm of the foot) it´s creating , which is required in propulsion.

But if the gastroc/sol complex and tendon are strong enough to overcome this increased dorsiflexion stiffness of the 1st we may have no pathology.
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Old 29th November 2010, 10:18 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Simon Spooner View Post
Which one Bruce, the Nester paper or the Nawoczenski? I attached the pdf of the Nawoczenski in my earlier post. Hint: they didn't measure 1st MTPJ kinematics in the Nester study, BTW.
Neither,
Stefanshyn, Nigg I think you had a link to the abstract listed but did not have the paper linked, that one.
Hint: I make my own assessments of a papers validity.
have a swell day!
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Old 29th November 2010, 10:26 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Bruce Williams View Post
Neither,
Stefanshyn, Nigg I think you had a link to the abstract listed but did not have the paper linked, that one.
Hint: I make my own assessments of a papers validity.
have a swell day!
Bruce
Assess it all you like, they still didn't measure 1st MTPJ motion with or without the insole. So no-one knows whether the observed changes were related to a change in 1st MTPJ dorsiflexion. Kind of a fatal flaw in that paper, in my opinion. Particularly since the paper was called: Sagittal Plane Compensations for Artificially Induced Limitation of the First Metatarsophalangeal Joint. It would probably have been better to have been titled: Sagittal Plane Compensations for a 3mm Aluminium Mortons Extension on a Flat Insole. Yet since I don't generally use a 3mm aluminium Mortons extension in isolation when treating patients, I'm not sure how clinically applicable it was either regardless of it's misleading title.

I don't think I have the full-text of the Nigg paper, we discussed a similar/ this study by these two workers previously, maybe it's in that thread.
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Old 29th November 2010, 10:53 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

This maybe of interst.

Quote:
Position of the First Ray and Motion of the First Metatarsophalangeal Joint

THOMAS S. ROUKIS, BS*
PAUL R. SCHERER, DPM†
CRAIG F. ANDERSON, DPM‡


The authors present a quantitative analysis of the effect that first ray
position has on motion of the first metatarsophalangeal joint. A goniometer
was constructed to measure the degrees of first metatarsophalangeal
joint dorsiflexion with the first ray in three positions: weightbearing
resting position, dorsiflexed 4 mm from the weightbearing resting
position, and dorsiflexed 8 mm from the weightbearing resting position.
First metatarsophalangeal joint dorsiflexion decreased 19% as
the first ray was moved from the weightbearing resting position to
4 mm dorsiflexed, 19.3% as the first ray was moved from 4 mm dorsiflexed
to 8 mm dorsiflexed, and 34.7% as the first ray was moved from
the weightbearing resting position to 8 mm dorsiflexed. The biomechanical
significance of decreased first metatarsophalangeal joint dorsiflexion
that results from first ray dorsiflexion is discussed, and proposed
bases for the pathomechanics of hallux abducto valgus and hallux
rigidus deformities are presented.
See full text below

also full text of Hall and Nester paper for those who want a read.
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Old 29th November 2010, 11:01 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

This is interesting from the paper Ian linked to above:
"The MP joint was a large energy absorber with average
absorption of 20.9 J during running and 47.8 J during
sprinting. In both activities, the MP joint absorbed substantial
amounts of energy yet did not produce or generate
any energy at take-off. The MP joint dorsiflexed as
the athletes rolled onto the balls of their feet and remained
in this dosiflexed position during take-off. There
was little or no plantarflexion of the MP joint during
take-off which would be required for energy production.
This corresponds to the finding of Mann and Hagy
(1979), who viewed the MP joint with high-speed film
during walking and found that the toes remained in
a dorsiflexed position during take-off and were, therefore,
unable to provide any sort of push-off.
Thus, it appears that the MP joint is a dissipater of
large amounts of energy. Athletes absorb energy at this
joint as they roll onto their toes and fail to provide any
plantarflexion or push-off at this joint as they roll off
their toes during take-off. It is possible that incorporation
of the toe spring (the raising of the forefoot of the
shoe) [SPOONER- Or pre-loading the hallux with a Cluffy wedge or Kinetic wedge]
in athletic shoes may be somewhat responsible for
this energy dissipation since it forces the MP joint to
remain in a dorsiflexed position during take-off. Although
it is generally believed that toe spring leads to
a more efficient stride due to a natural rocking onto the
forefoot, Cavanagh (1980) stated that there was no conclusive
evidence that this was true. In fact, the results of
this study may indeed suggest the opposite. It may also
be that athletic shoe mid-sole materials at the location of
the MP joint are too compliant. Athletic shoes are generally
manufactured with consistent mid-sole materials
from rearfoot to forefoot. However, the compliance that
is required for appropriate cushioning at the rearfoot
may be totally inappropriate for the requirements of the
forefoot."
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Old 29th November 2010, 11:48 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

So... if the 1st MTPJ is an energy absorber, then in the presence of hallux limitus / rigidus it's ability to absorb energy is reduced? Where does that energy go? (I may have asked that before in a previous thread ) but lets re-visit it.
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Old 29th November 2010, 11:56 AM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by Simon Spooner View Post
So... if the 1st MTPJ is an energy absorber, then in the presence of hallux limitus / rigidus it's ability to absorb energy is reduced? Where does that energy go? (I may have asked that before in a previous thread ) but lets re-visit it.
My theory = achilles tendon
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Old 29th November 2010, 12:08 PM
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Default Re: The Potentailly Injurious Effects of Forefoot Varus Posting

Quote:
Originally Posted by m weber View Post
My theory = achilles tendon
Why??
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