Is Forefoot Varus Posting Bad?

Forefoot varus is rare, yet some researchers always seem to manage to recruit enough subject for their research that have what they claim is forefoot varus. I suspect that they are not forefoot varus, but the much more common forefoot supinatus and they got confused. The reason that this is a problem is that they are totally different beasts. One is osseous and causes rearfoot pronation and cannot be reduced. The other is soft tissues and is the result of rearfoot pronation and can be reduced. Yet they look the same. They will both respond very different to foot orthoses … kinda think that the distinction between the two would be important in research projects don’t you? Also forefoot varus will respond very differently to rigid compared to flexible/semi-rigid foot orthotics.

To be clear, forefoot varus is a forefoot that is inverted when the subtalar joint is in its neutral position and the midtarsal joint is maximally pronated. As the forefoot is inverted, the rearfoot has to pronate to bring the medial side of the foot to the ground. To treat forefoot varies, you are supposed to use a medial forefoot post to bring the ground up to the foot, so the foot does not need to pronate the rearfoot to bring the medial side of the forefoot down to the ground. Right?

Consider the very rigid plastic orthotic with a forefoot varus post, when the foot is placed on top of it the forefoot varus post will invert the rearfoot (or stop it pronating/everting) through its effects on the rearfoot via the rigid plate of the orthotic.

Consider the less than totally rigid foot orthotic with a forefoot varus post. How will that affect the rearfoot pronation? The only way it can affect the rearfoot pronation is by dorsiflexing the first ray to end range of motion, then invert the midfoot joints to end range of motion, then it has a shot at affecting the subtalar joint. As the orthotic shell is not totally rigid, the forefoot varus post has to affect the rearfoot “through the foot”. Whereas if the shell was rigid, the forefoot varus posts work directly on the rearfoot by tilting the orthotic shell. It cannot do this with a less than rigid orthotic when the person is standing on it.

Is the use of forefoot varus posts potentially injurious?

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The Foot Posture Index

Measurements taken of the foot as part of a biomechanical assessment have been shown to be notoriously unreliable and not that repeatable. When the initial studies started to come out showing that, I wanted to disagree with them as “I” was reliable. That was until I became a participant in these studies and realised just how unreliable I was.

When it comes to determining the posture or alignment of the foot (for whatever reason you might want to do that!) what do you measure. The Calcaneal angle? The arch height? The transverse plane position of the midfoot? Whichever one you choose, you may end up with a ‘normal’ or ‘abnormal conclusion.

For the above to problems, Tony Redmond developed the Foot Posture Index. The index is based on observations and is based on a number of observations. The FPI has been shown to be reliable.

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Foot orthoses or gait retraining for patellofemoral pain?

Its long been held that excessive foot pronation causes the tibia to rotate excessively internally causing a misalignment of the patella and results in patellofemoral pain syndrome or anterior knee pain in runners. Therefore, based on this you use foot orthotics to correct the foot pronation to treat the problem. Two reasonably well conducted RCT’s shows that foot orthotics are successful at that.

However:
1. Almost the cross sectional and prospective evidence shows that foot pronation is not associated with patellofemoral pain (despite the fact that foot orthotics been shown to help).
2. Even though the foot and tibia are coupled, the research as to which is the driving force, shows that it is tibial internal and external rotation that drive foot pronation and supination. It is not foot motion that drives leg motion, it is the other way around (see this discussion). This is so counter-intuitive to what podiatrists, in general, have believed.
3. More and more physiotherapists are using proximal control exercises and gait retraining to treat patellofemoral pain without the use of foot orthotics, and the evidence shows that this is just as effective as foot orthotics in treating this problem.

What is going on? Is it proximal or distal that the problem is coming from? Should we really be using foot orthotics is the problem is proximal? Should physiotherapists be using proximal control exercises if the problem is distal?

I have been in a couple of conference debates with physiotherapists at both a physiotherapy and a podiatry conference. I have learnt a lot through that and I genuinely do believe that the solution to patellofemoral pain syndrome is proximal control exercises. However, I also believe that this proximal control will not work if the ankle inversion moment (or supination resistance) is above a certain threshold (which will probably vary from individual to individual). For example, if the ankle inversion moment is low (i.e. supination resistance is low), then the proximal control exercise should work easy to help and they may not even need foot orthotics. However, if the ankle inversion moment is high (i.e. supination resistance is high), then it does not matter what you do proximally, it’s not going to work as the foot won’t move. So, therefore the role of foot orthotic in patellofemoral pain could be to reduce the ankle inversion moment to below a certain threshold, so the proximal control can work. This theory makes sense to me and is consistent with the most recent evidence.

For more see:
Foot Orthoses for Knee Pain
Foot orthoses and patellofemoral pain syndrome
Foot pronation and knee pain
Does the tibia drive the foot or does the foot drive the tibia?

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The paradox of sinus tarsi syndrome

Sinus tarsi syndrome is somewhat paradoxical in that it can be caused by inversion, as in an ankle sprain damaging the structures in the sinus tarsi by stretching them; and it can also be caused by eversion, as in a pronated foot with high forces pushing the subtalar joint to end range of motion and causing compression forces at the bony end range of motion. The structures in the sinus tarsi and their role is very complex and poorly understood. A better understanding will better help direct therapeutic approaches. However, in both the pain is on the outside of the ankle joint. Generally, the inversion type responds well to physical therapy intervention and the eversion type responds well to foot orthotics.

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Posterior tibial tendon dysfunction

This is the primary cause of acquired flat foot in adults. Essentially the underlying pathomechanics is that the posterior tibial tendon and muscle just give up - they can no longer do their job. Why do they give up? My understanding and experience is that all that all those with posterior tibial tendon dysfunction have a medially located subtalar joint axis. If this is the case, then it means that the posterior tibial tendon will have a much shorter lever arm to the joint axis. This would mean that in these people the muscle would have to work substantially harder than if the tendon had a longer lever arm if the subtalar joint axis was closer to a more normal or average position. After a life time of having to work so much harder, no wonder the tendon and muscle complex just give up. This is becoming more common in runners who start forefoot striking.

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Functional hallux limitus

I am privileged with the honour of being invited to speak at many conferences. Most recently was at the Podiatric Surgeons conference. When I agreed to speak, I did not think to much about about the topic until I was back from another conference, then I had a OMG why did I agree to talk about that moment ? What the hell am I going to say?

One reason I enjoy speaking at conferences is that it forces me to organise my thoughts and "put them on the line", so I thought I would try and take our traditional understanding of first MPJ dysfunction (ie hallux rigidus; structural and functional hallux limitus) and the windlass dysfunctions (ie no windlass; delayed windlass; high force to establish; disruption during loading) and reconceptualise them in the framework of the mechanical engineering terms of 'stiffness'.

While going through the dot points, I got struck by something: All functional hallux limitus really is, is a temporary increase in the dorsiflexion stiffness of the first MPJ ! It got the thought processes going. (I have written about it here: Reconceptualising Functional Hallux Limitus)

Traditionally we have considered FnHL as being present or absent, when in reality it probably exists on a continuum. If we conceptualise it as a temporary increase in first MPJ stiffness, it then opens the possibility of grading functional hallux limitus (ie a low temporary increase in first MPJ stiffness to a high temporary increase in first MPJ stiffness). Maybe we can measure this !

Should we reconceptualise FnHL as a temporary increase in first MPJ stiffness? What say you?

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Hubscher manoeuvre

There has been some good discussion at Podiatry Arena on the Hubscher maneuver (terminology primarily used in the USA) or Jacks Test (used by the rest of the world!). A poll in that thread showed that 82% of those that responded to the poll used it as a clinical test.

A lot of the discussion focused on it value as a static clinical test used to predict dynamic function and, more important, as a tool that may or may not predict the clinical response to foot orthoses. IMHO, the Hubscher maneuver or Jacks test does have clinical use. When you do this test on different people they respond differently .... that has got to mean something for the way the function! At the end of the day, the disagreements are about what we think it means.

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The 5 great FALLACIES of podiatric biomechanics

Adam asks:
"I've been refreshing my comprehension of pedal biomechanics of late and wondered if you had an opinion on what the 5 greatest mis-truths of this discipline are.In other words what concepts most people think/ assume are correct, that haven't yet been tested by science or are likely to be."
Read the responses.

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The Mid Tarsal Joint

The midtarsal joints is one of those joints that is subject to so much ongoing debate, discussion, scientific and theoretical modeling. Chris Nester has attempted to, at least, get everyone speaking the same language with this new publication: Clinical and Experimental Models of the Midtarsal Joint Proposed Terms of Reference and Associated Terminology Journal of the American Podiatric Medical AssociationVolume 96 Number 1 24-31 2006. Discussion here.

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The Mid Tarsal Joint

The midtarsal joints is one of those joints that is subject to so much ongoing debate, discussion, scientific and theoretical modeling. Chris Nester has attempted to, at least, get everyone speaking the same language with this new publication: Clinical and Experimental Models of the Midtarsal Joint Proposed Terms of Reference and Associated Terminology Journal of the American Podiatric Medical AssociationVolume 96 Number 1 24-31 2006. Discussion here.

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Does genu valgum cause the foot to pronate?

This one has troubled me for a while.

When teaching the pediatrics part of the course here, especially the genu varum and genu valgum, it always comes up about the effect they have on foot function. Genu vaurm affects the foot as it has to pronate to get the foot flat on the ground. According to so many podiatric texts, genu valgum also causes the foot to pronate as the center of body weight is medial to the subtalar joint -- this has always troubled me ... how can opposite alignments at the knee cause the same affect on foot function Is this just another one of those podiatric myths

As part of the lecture, I mention this troubling aspect --- sometimes, I get the students to do this exercise:
Stand up with feet wide apart (simulated genu valgum, due to wide base of gait) -what does your subtalar joint feel as though its doing? -- the answer is always "supinating" ---- so how does a genu valgum pronate a foot, like so many podiatric texts claim??

Now thanks to Bart Van Gheluwe we finally got some real data:

Effects of Simulated Genu Valgum and Genu Varum on Ground Reaction Forces and Subtalar Joint Function During GaitBart Van Gheluwe, Kevin A. Kirby and Friso Hagman
Journal of the American Podiatric Medical AssociationVolume 95 Number 6 531-541 2005
"The mechanical effects of genu valgum and varum deformities on the subtalar joint were investigated. First, a theoretical model of the forces within the foot and lower extremity during relaxed bipedal stance was developed predicting the rotational effect on the subtalar joint due to genu valgum and varum deformities. Second, a kinetic gait study was performed involving 15 subjects who walked with simulated genu valgum and genu varum over a force plate and a plantar pressure mat to determine the changes in the ground reaction force vector within the frontal plane and the changes in the center-of-pressure location on the plantar foot. These results predicted that a genu varum deformity would tend to cause a subtalar pronation moment to increase or a supination moment to decrease during the contact and propulsion phases of walking. With genu valgum, it was determined that during the contact phase a subtalar pronation moment would increase, whereas in the early propulsive phase, a subtalar supination moment would increase or a pronation moment would decrease. However, the current inability to track the spatial position of the subtalar joint axis makes it difficult to determine the absolute direction and magnitudes of the subtalar joint moments." (J Am Podiatr Med Assoc 95(6): 531–541, 2005)

What say you?

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Is the calcaneal spur in the plantar fascia?

In a Yahoo Groups Discussion on manipulation, a question was asked:

"What is the best treatment for plantar fascitis induced heel spurs... " to which I replied:

"Since when did heel spurs have anything to do with the plantar fascia?"

Needless to say there was some interesting comments that followed, mostly based on what people were taught as students, and NOT on a reading of the research evidence.At the end of the day, all the published evidence I have seen, is that the spur is not in the plantar fasica, so how can plantar fasica "traction" cause heel spurs?One poster (Peter Morgan) did back up what I said with this:

"McCarthy DJ, Gorecki GE. The anatomical basis of inferior calcaneal lesions. JAPMA 1979;69:527This is quoted as finding the spur in the origin of the flexor digitorum brevis. ALSO, they asserted "the origin of flexor digitorum brevis, quad. plantae, long plantar ligament, abductor hallucis muscle and abductor digiti minumi are all sites of potential spur formation."

THIS WAS PUBLISHED IN 1979!!!! -- why do people still talk about the calcaneal heel spur as being due to traction of the plantar fascia. Now, I finally found one of the other more recent references showing the same thing:

"Heel Spur Formation and the Subcalcaneal Enthesis of the Plantar Fascia TSUKASA KUMAI and MIKE BENJAMIN Objective. To describe the structure and significance of subcalcaneal heel spurs associated with the plantar fascia. Methods. The enthesis of the plantar fascia was removed from 17 elderly cadavers by sagittal saw cuts either side of the medial tuberosity, radiographs were taken, and the tissue was processed for routine histology. Sagittal sections were stained with toluidine blue, Masson's trichrome, or alcian blue, and sections were matched with the corresponding radiographs. Results. Spurs develop on the deep surface of the plantar fascia but their formation is heralded by degenerative changes that occur within it. According to differences between small and large spurs, we propose that there are 3 stages in their development: (1) an initial formation of cartilage cell clusters and fissures at the plantar fascia enthesis; (2) thickening of the subchondral bone plate at the enthesis as small spurs form; (3) development of vertically oriented trabeculae buttressing the proximal end of larger spurs. The spurs grow by a combination of intramembranous and chondroidal ossification. Conclusion. Contrary to popular belief, subcalcaneal heel spurs cannot be traction spurs as they do not develop within the plantar fascia itself. They are thus fundamentally different from heel spurs in the Achilles tendon. We suggest instead that they develop as a consequence of degenerative changes that occur in the plantar fascia enthesis. (J Rheumatol 2002;29:1957-64) "

That was 3 yrs ago. There are other references, I just don't have them handy. Is it not time to "put this one to bed"? What say you? Discussion

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Is the calcaneal spur in the plantar fascia?

In a Yahoo Groups Discussion on manipulation, a question was asked:

"What is the best treatment for plantar fascitis induced heel spurs... " to which I replied:

"Since when did heel spurs have anything to do with the plantar fascia?"

Needless to say there was some interesting comments that followed, mostly based on what people were taught as students, and NOT on a reading of the research evidence.At the end of the day, all the published evidence I have seen, is that the spur is not in the plantar fasica, so how can plantar fasica "traction" cause heel spurs?One poster (Peter Morgan) did back up what I said with this:

"McCarthy DJ, Gorecki GE. The anatomical basis of inferior calcaneal lesions. JAPMA 1979;69:527This is quoted as finding the spur in the origin of the flexor digitorum brevis. ALSO, they asserted "the origin of flexor digitorum brevis, quad. plantae, long plantar ligament, abductor hallucis muscle and abductor digiti minumi are all sites of potential spur formation."

THIS WAS PUBLISHED IN 1979!!!! -- why do people still talk about the calcaneal heel spur as being due to traction of the plantar fascia. Now, I finally found one of the other more recent references showing the same thing:

"Heel Spur Formation and the Subcalcaneal Enthesis of the Plantar Fascia TSUKASA KUMAI and MIKE BENJAMIN Objective. To describe the structure and significance of subcalcaneal heel spurs associated with the plantar fascia. Methods. The enthesis of the plantar fascia was removed from 17 elderly cadavers by sagittal saw cuts either side of the medial tuberosity, radiographs were taken, and the tissue was processed for routine histology. Sagittal sections were stained with toluidine blue, Masson's trichrome, or alcian blue, and sections were matched with the corresponding radiographs. Results. Spurs develop on the deep surface of the plantar fascia but their formation is heralded by degenerative changes that occur within it. According to differences between small and large spurs, we propose that there are 3 stages in their development: (1) an initial formation of cartilage cell clusters and fissures at the plantar fascia enthesis; (2) thickening of the subchondral bone plate at the enthesis as small spurs form; (3) development of vertically oriented trabeculae buttressing the proximal end of larger spurs. The spurs grow by a combination of intramembranous and chondroidal ossification. Conclusion. Contrary to popular belief, subcalcaneal heel spurs cannot be traction spurs as they do not develop within the plantar fascia itself. They are thus fundamentally different from heel spurs in the Achilles tendon. We suggest instead that they develop as a consequence of degenerative changes that occur in the plantar fascia enthesis. (J Rheumatol 2002;29:1957-64) "

That was 3 yrs ago. There are other references, I just don't have them handy. Is it not time to "put this one to bed"? What say you? Discussion

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Foot Posture Index

I have just had a look at the logs for this web site - these tell me what keywords people are using in search engines like Google ---- 'Foot Posture Index' is currently used by a lot .... hhhmmm - I talked about that on January 17. For more on the Foot Posture Index, check that date - there are some links to our work and the work of others on this Foot Posture Index that Tony Redmond developed.

More on the Foot Posture Index

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Foot Posture Index

I have just had a look at the logs for this web site - these tell me what keywords people are using in search engines like Google ---- 'Foot Posture Index' is currently used by a lot .... hhhmmm - I talked about that on January 17. For more on the Foot Posture Index, check that date - there are some links to our work and the work of others on this Foot Posture Index that Tony Redmond developed.

More on the Foot Posture Index

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Foot Posture Index

This was originally develeoped by Tony Redmond as a means to overcome some of the limitations of previous methods of quantifying posture of the foot.
We have two recent publications in which we used it in:
Static Stance Response to Different Types of Foot Orthoses
The Reliability of the Manual Supination Resistance Test

Another 2 papers from the University of South Australia has just appeared look more at the FPI validity:
Criterion Validation of Four Criteria of the Foot Posture Index
Reliability of the Foot Posture Index and Traditional Measures of Foot Position

My opinion on the Foot Posture Index (FPI):
We use it a lot in research. We use it a lot as part of the inclusion criteria for our orthotic studies (eg we may only recruit those with a Foot Posture Index greater than, say, 6 --> this probably indicates that these people would have probably got foot orthotics if they had symptoms related to a pronated foot --> anything >4-5 on the Foot Posture Index is a pronated foot). The the end of the day, the Foot Posture Index is good for what it is designed for. Like a lot of tools its not good for what it is not designed for.

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Foot Posture Index

This was originally develeoped by Tony Redmond as a means to overcome some of the limitations of previous methods of quantifying posture of the foot.
We have two recent publications in which we used it in:
Static Stance Response to Different Types of Foot Orthoses
The Reliability of the Manual Supination Resistance Test

Another 2 papers from the University of South Australia has just appeared look more at the FPI validity:
Criterion Validation of Four Criteria of the Foot Posture Index
Reliability of the Foot Posture Index and Traditional Measures of Foot Position

My opinion on the Foot Posture Index (FPI):
We use it a lot in research. We use it a lot as part of the inclusion criteria for our orthotic studies (eg we may only recruit those with a Foot Posture Index greater than, say, 6 --> this probably indicates that these people would have probably got foot orthotics if they had symptoms related to a pronated foot --> anything >4-5 on the Foot Posture Index is a pronated foot). The the end of the day, the Foot Posture Index is good for what it is designed for. Like a lot of tools its not good for what it is not designed for.

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New stuff published in JAMPA:

The latest issue of JAPMA came out yesterday ... three things caught my eye ...
The first one had to catch my eye cause I wrote it :-)
Static Stance Response to Different Types of Foot Orthoses

This one furthered our knowledge on the effects of variations in the position of the subtalar joint axis (...and Karl, if you ever read this .... at least they think there is an axis there :-)
Relationship Between the Subtalar Joint Inclination Angle and the Location of Lower-Extremity Injuries

The final one was this:
In Vivo Forces in the Plantar Fascia During the Stance Phase of Gait: Sequential Release of the Plantar Fascia This one got me excited .... one of the main findings was the subtalar joint was unable to resupinate as the amount of fascia release increased, indicating a direct relationship between the medial band of the plantar fascia and resupination of the subtalar joint during late midstance and propulsion which is so consistent with the work we are soon to publish that shows the force to get the windlass established is much higher in those with plantar fasciitis. Maybe plantar fasciitis has nothing to do with a pronated foot, but has to do with a lack of resupination due to the high forces going through the windlass .... watch this space.

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New stuff published in JAMPA:

The latest issue of JAPMA came out yesterday ... three things caught my eye ...
The first one had to catch my eye cause I wrote it :-)
Static Stance Response to Different Types of Foot Orthoses

This one furthered our knowledge on the effects of variations in the position of the subtalar joint axis (...and Karl, if you ever read this .... at least they think there is an axis there :-)
Relationship Between the Subtalar Joint Inclination Angle and the Location of Lower-Extremity Injuries

The final one was this:
In Vivo Forces in the Plantar Fascia During the Stance Phase of Gait: Sequential Release of the Plantar Fascia This one got me excited .... one of the main findings was the subtalar joint was unable to resupinate as the amount of fascia release increased, indicating a direct relationship between the medial band of the plantar fascia and resupination of the subtalar joint during late midstance and propulsion which is so consistent with the work we are soon to publish that shows the force to get the windlass established is much higher in those with plantar fasciitis. Maybe plantar fasciitis has nothing to do with a pronated foot, but has to do with a lack of resupination due to the high forces going through the windlass .... watch this space.

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