Functional Hallux Limitus

Simon and Mark:

Performing a set (i.e. AP, MO and LAT) of weightbearing radiographs of this young man's feet is perfectly acceptable, in my opinion. In addition, as Stanley mentioned, performing a stress radiograph of the first MPJ in full dorsiflexion is also acceptable. Here in the US, performing these radiographs would not raise any eyebrows from most podiatrists or orthopedic surgeons. The radiation exposure for these views does not constitute a threat to this young man's health.

However, as Simon mentioned, one should not take x-rays that are unneccessary. If this boy had presented to me, I would have wanted a set of radiographs initially only if the parents desired me to do so or if I was going to be considering surgical intervention on the patient. Otherwise, I would have been treating the patient without radiographs initially but may have performed the radiographs later on if the symptoms did not go away soon with my initial treatment. I tend to take fewer radiographs than most podiatrists since I rely very heavily on clinical examination techniques in my practice, but I have no problems with my podiatric colleagues who perform far more radiographs than I do, as long as they are being done for a reasonable purpose.

In this young man, immobilization of the first MPJ with BK casting for tibial fracture could have caused the increased restriction of 1st MPJ motion on the affected side. Also, some people, mostly males, have such "tight ligaments" (i.e. increased ligamentous tensile stiffness) that they simply do not have the normal 70 degrees of 1st MPJ dorsiflexion even when they are teenagers. I think this is a little recognized mechanical phenomenom of the 1st MPJ that would be a fascinating study to explore the differences in 1st MPJ dorsiflexion, both weightbearing and non-weightbearing, between males and females at different ages. I think that males have much more tendency to develop hallux limitus due to their "tighter ligaments".

 

Hi Mark,

I'm sorry, I can't tell range of motion of any joint by looking at a picture. I must have missed that lecture.
What I do see is that the first ray is plantarflexed. Since the first ray cannot go through the ground, there has to be a compensation. The dorsiflexion has to be taken up at either the first metatarsal cuneiform joint, the cuneiform navicular joint, the talo-navicular joint, or the talo-calcaneal joint, or a combination of the above.
Uneven metatarsal heights in the lesser metatarsals are taken up at the metatarsal cuneiform joints, ad long as the range is available. As people age the range decreases. That is why we see submetatarsal hyperkeratoses in older patients. This is also a reason to take pre and post metatarsal pedographs. I had a patient come back several years after a metatarsal osteotomy accusing me of causing the "transfer lesion". I took a pedograph and compared it to the immediate post op pedograph, and showed her that the adjacent bone "dropped".
When the first metatarsal dorsiflexes, you know the story.
As an additional piece of the puzzle, I treated a marathoner about 25 years ago with hallux limitus. He had some X-ray changes. Most notably joint space narrowing. He had a long first metatarsal. He was too young to put in an implant, and this was before Danenberg's theory was conceived. I did a shortening osteotomy of the first (a Chevron osteotomy-2 "V"s) and removed the spurring on the first metatarsal and proximal phalanx. I took an x-ray several months later, and the joint space was normal. Back then, we thought that if we shortened the bone we would decrease the tension of the soft tissues around the joint. It does this, but it also allows the first metatarsal to drop down.

Regards,

Stanley

 

Kevin, Stanley et al.,

Thank you for your advice - much appreciated as always - and I will certainly bear this in mind when I see this patient back next week. Simon did pose an interesting question just prior to his petit mal episode where he asked why some patients go on to develop hallux limitus and others hallux valgus, however, I think Kevin has answered this in his last post where he observes that hallux limitus (and hallux rigidus) is more prevalent in young men than women. I suspect that ligamentous tensile stiffness is a major factor in determining whether deviation of the hallux occurs when there are pathomechanical factors, such as a medially deviated STJ axis, are present. In women, secretion of relaxin hormone obviously decreases tensile stiffness and will probably result in a reduction in the ability of the MTPJ to resist lateral force during propulsion. There are probably other factors too, such as the way an individual compensates when overloading the 1st MTPJ when aforementioned mechanical factors are present.

A subject worthy of a seperate thread.

Thanks again for all the advice.

 

Regarding the ligaments at the first metatarsal cuneiform joint, if you look at Johannes Sabotta's atlas, you will notice something very interesting. He has a picture of the first metatarsal joint with the peroneus longus removed. You will see that there is a separate part of the ligament directly under the peroneus longus tendon.
Remember that both ligaments and muscle/tendon protect joints, and when muscles fail, ligaments get damaged.
Just some food for thought.

Mark, before you slit your wrists for giving massive amounts of radiation, let me point out something.
Here in the States, things may be different than in Europe, but the safe amount of Rads/year for the foot is higher than anywhere else in the body at 75. Other parts of the body, like the chest, abdomen and brain are at 5.
Remember that we use intensifying screens that convert x-rays to visible light.

Since film is more sensitive to light than to x-ray exposure, film can be exposed with much less radiation if an intensifying screen is used. Conventional x-ray film has an x-ray exposure sensitivity in the range of 50 mR to 150 mR if exposed directly by the x-radiation.. When the film is combined with intensifying screens, the sensitivity ranges from approximately 0.1 mR to 10 mR, depending on the type of screen and film used.
http://www.sprawls.org/ppmi2/FILMSCR/#Exposure Reduction

If we were to compare what we do as podiatrists to what dentists do (and I am not even mentioning the Panorex), dentists using plain film take twice as many X-rays as we do at 5-1500 times the exposure on a part that is 15 times as sensitive. So you would have to take 150-45000 complete foot x-rays to equal one visit to your dentist.
You can put the knife away now.

Best regards,

Stanley

 

Hi Mark,

Does this patient have pain at the 1st MTP joint?

Maybe he has always been stiff at the MTP joint, even prior to his injury? ie thats just the way he functions inherently.

 

The latest Podiatry Today has this article:
Understanding The Biomechanical Effects Of Hallux Limitus
Paul R. Scherer

 

I have also seen this kind of restriction in the first MTPH joint in my practice and indeed most of them are young. And when I see it, most of this people do spring sports like basket or volley (I don't want to generalise it, but it has taked my attention when I saw it and I have linked it with the kind of sport they are doing). I think it is more a soft tissue protection of the body to the force acting and the ROM asked in/on the joint?!? But I don't know which sport your patiënt is doing so just a guess???

 

Kersten,

There may be a high incidence in the population, but if you partake in jumping, sprinting sports you are much more likely to put enough stress on the jonit to make it painful enogh to seek medical advice.

Eric

 

Most of this patiënts, with a structural hallux limitus and no RX confirmation of an exostosis, don't come with pain in that joint but with pain somewhere else. They don't have complains in that joint. I remember the last one, which is not so long, and he came with achilles pain, which can be linked with the structural hallux limitus. But he didn't had pain in the 1ste MPJ.

Kerstin

 

Dear all,

I am a ‘first time’ contributor to Podiatry arena, although I have observed many posts. I have indeed felt a little sheepish I must say, about placing a post, due to the fear of ridicule… however, here goes!

I am currently writing a case study on hallux limitus and have tied myself in knots. The patient in question is a female walker, who demonstrates 40 degrees of passive, non-weightbearing (NWB) dorsiflexion of the hallux (measured with a goniometer!). The rest of the clinical picture to me seems typical; i.e. STJ pronation beyond midstance, possibly (although not severe) a medially deviated STJ axis, abductory twist, gastroc/soleal equinus, slight IPJ callous, IPJ hyperextension, jack's test in relaxed stance - further reduction in hallux dorsiflexion, No arch re-formation,No external rotation of leg,No rearfoot inversion. C/o ‘’mild pain’’ in first MTPJ after long walk. The first ray does not seem to exhibit Kirby’s ‘’decreased first ray dorsiflexion stiffness’’. I decided that due to the NWB limitation and the presence of minor dorsal osteophytic proliferation, that this should be termed ‘’structural hallux limitus’’. Indeed, according to Simpson et als., (2011) classification for hallux rigidus (HR), my patient seems to be between grade 0, ‘’normal’’ and grade 1 HR. However, I explained in my paper the concepts offered by, amongst others, Fuller (2000), where he applied Newtonian mechanics to explain the osteopathy generated in the first MTPJ, as a result of initial functional impairment; which has subsequently lead to the structural impairment now seen in my patient. However, with all this in mind, I decided that there was still a functional element to the pathology and that my patient would benefit from the usual first ray cut outs etc., to restore some of the available function and perhaps slow down the rate of progression. However, an experienced colleague has argued that I should not be treating a functional HL when it is clearly structural. I do see his point. I have only found one reference to the ‘’co-existence’’ of structural and functional hallux limitus which is unhelpful. Can anyone advise me? What should I call it? Hallux Limitus, structural or functional, or both: that is my question!!!!

My apologies in advance for any ignorance shown!

Thank you all very much in anticipation of your reply.

Koota.

 

If they only have 40 degrees of dorsiflexion, anything you do to mechanical encourage more than that 40 degree has a high probability of hurting.

 

The question is, which mechanical interventions have been shown to increase the dorsiflexion range of motion at the 1st metatarsophalangeal joint during dynamic function?

 

I have an issue with this which I'm certain have been raised before.

What is the threshold for determining the presence of FnHL?

If I were writing a case study, I would go to great lengths to explain that the dorsiflexion stiffness at the 1st MPJ is a continuum. How can there be a threshold at which the stiffness becomes "abnormal". Moreover, if there were a threshold, I would doubt that there would be any way to clinically measure such a threshold accurately.

So, hallux rigidus is just incredibly high dorsiflexion stiffness(unless surgically fused - although with enough force this could still be overcome) at the 1st MPJ created by a structural barrier.

FnHL is a high dorsiflexion stiffness at the 1st MPJ created by kinetic forces. I don't see why the two cannot co exist at different points over the entire range of motion of the joint.

 

I believe that Functional hallux limitus and structural hallux limitus are a continuum. Functional develops into structural from the high compression forces in the first MPJ. I believe that the high compression forces are still present in structural and that is one of the reasons that it structural hurts. So, if you can reduce tension in the plantar fascia, in the presence of structural changes, you can still reduce the painful symptoms.

In my own foot I have about 30 degrees of hallux dorsiflexion non weight bearing and when I stand barefoot, with muscles relaxed the tension in my plantar fascia is easily palpable and it's nearly impossible to lift my hallux off of the floor. My orthoses prevent the pain I get when I go barefoot. From personal experience, I know you can improve symptoms even though there is some structural component to the limitus.

Eric

 

I would agree with you Koota. If non weightbearing there is a structural limitation thats SHL.
If when functioning the ROM available NWB is not available/utilised/blocked (in your case 40 degrees) you could agrue that there is an element of Functional Hallux Limitus also.

 

Koota:

You have an excellent question and certainly I see no signs of "ignorance" in your assessment of the patient.

I just lectured on hallux limitus at Paul Scherer's "Learning in the Vineyards" seminar in Napa last weekend so let me see if I can help.

First of all, here are the definitions for structural and functional hallux limitus I gave in my lecture.

Hallux limitus: A condition in which hallux is unable to dorsiflex 65 to 70 degrees at first metatarsophalangeal joint (MPJ)
(Root, ML, Orien, WP, and Weed, JH: Normal and Abnormal Function of the Foot. Clinical Biomechanics Corporation, Los Angeles, CA 1977.)

Structural hallux limitus: limitation of first MPJ dorsiflexion both during non-weightbearing examination of first MPJ and during propulsive phase of gait

Functional hallux limitus: demonstrates limitation of first MPJ dorsiflexion only during weightbearing examination

By definition, your patient has a structural hallux limitus due to the lack of a full 65-70 degrees of dorsiflexion. But your patient also has a functional hallux limitus due to the further decrease in hallux dorsiflexion seen on weightbearing examination. If you wanted to be as precise as possible in your diagnosis you should say that the patient has a hallux limitus deformity with both structural and functional components since your patient not only has a restriction of normal hallux dorsiflexion in non-weightbearing exam but also has even further hallux dorsiflexion restriction during weightbearing exam.

Now what causes the restrictions of hallux dorsiflexion in both structural (SHL)and functional hallux limitus (FnHL)?

In SHL, the restriction of hallux dorsiflexion comes from an internal 1st metatarsophalangeal joint (MPJ) plantarflexion moment from the abnormal dorsal osseous protuberance (i.e. dorsal bunion) on the first metatarsal head which occurs when the dorsal base of the proximal phalanx of the hallux abuts against the abnormal dorsal osseous protuberance on the first metatarsal head which, in turn, effectively restricts normal hallux dorsiflexion during propulsion.

In FnHL, the restriction of hallux dorsiflexion comes from an internal 1st MPJ plantarflexion moment from an abnormal increase in tension force within the medial band of the central component of the plantar aponeurosis during early propulsion which effectively restricts normal hallux dorsiflexion during propulsion but will not restrict hallux dorsiflexion during non-weightbearing examination.

In your patient, my educated guess is that the patient has a FnHL that has, over time, caused a change in the morphology of the first metatarsal head that has, over time, also caused a SHL to occur. Therefore, your patient has both a FnHL and SHL deformity. Both SHL and FnHL commonly coexist with each other in the same foot with FnHL commonly causing the pathologic internal interosseous compression forces at the dorsal half of the 1st MPJ that, over time, lead to the morphological changes within the first metatarsal head that lead to SHL.

Please see accompanying illustrations from my lecture.

Hope this helps.:drinks

 

Dear Dr Kirby et al.,

May I thank you all most sincerely for your help…:drinks I was not expecting such a huge response from my post and I am truly grateful. I am a lowly MSc student who is immensely biomechanics naïve and trying to bring my, both limited and outdated knowledge, back from UG to M level; therefore, all your comments are extremely valuable. I am particularly enjoying reading about SALRE at the moment in relation to my case and have further questions… I do hope you don’t mind… ‘’you need to get out more!’’, I hear you cry… and I would agree. However, I have a deadline for this work and cannot rest until done!

After reading about SALRE, I feel like a fool and that I have missed something major! Upon examination of my clinical photos of the case, I have noticed that she has very slight physiological callous sub 5th MTPJ right foot and think that the FF may be inverted on the RF? I have also looked at the line I attempted to draw for the STJ axis using your palpation method and note that the axis appears average ‘ish’… I am now wondering what is occurring and have 4 things in mind:

1. She has an RF varus with a FF varus and therefore a high pronation moment due to the large lever arm created by the distance between the axis and the 5th metatarsal – certainly when compared to the medial tubercle of calc. (if this is the case, how do I measure/classify?)

2. A rearfoot valgus with calc tuberosity placed more lateral, or near the STJ axis; therefore causing a higher pronation moment because of reduced supination moment arm from calc tubercle.

3. RF valgus with FF varus, placing calc tubercle more lateral to STJ axis; therefore either increasing pronation moment or decreasing the supination moment.

4. After reading Fuller (2003), a partially compensated FF varus with a large pronation moment as there is large force on lateral side of FF and COP is relatively lateral to STJ axis that is, or appears to be, average. However, Dr Fuller adds that in this type of foot, the stress is not at the first MTPJ, but rather at the sinus tarsi.

My apologies guys… I know I must sound daft, but am in another knot with this one now:craig: I have enclosed some pics for your perusal… perhaps that might shine some more light on the issue?

Most kindest regards,

I am not worthy,

Koota.

 

oops! After looking at pics again... it can't possibly be 2 or 3 can it, as it seems that the calc tuberosity must be medial to the STJ axis and therefore the COP must be medial to it??? Arrrggh!

 

Am I barking up the wrong tree here, or is there going to be a high pronatory moment when compared to supination moment due to the distances of force from fulcrum (STJ axis)... and is it likely to be due to FF varus? I can't see any evidence of low gear propulsion with gait and footwear analysis... so is the callous sub 5th due to FF varus or is it more likely to be low gear propulsion? :sinking:
xx

 

Koota:

A callous sub 5th metatarsal head can be due to many causes. For example, it may be due to a high subtalar joint (STJ) supination moment from such causes a large degree of rearfoot varus, a large degree of metatarsus adductus or even a large degree of forefoot valgus deformity where the ground reaction force (GRF) acting on the foot is attempting the supinate the STJ and the 5th metatarsal head GRF is attempting to counterbalance and prevent STJ supination by causing a STJ pronation moment.

A forefoot varus deformity with inadequate STJ pronation range of motion may also cause a sub 5th tyloma since the STJ simply can't pronate enough to allow the medial metatarsal heads to bear sufficient weight on the ground. This could very well be the case in your patient's foot.

I would forget about low gear and high gear propulsion since I think this concept is useless and, at best, is a poor method to understand the complexity of how the central nervous system chooses to propel off the foot during gait.

When you stand the patient in relaxed bipedal stance try a few tests. First, with your fingers, try to lift their first metatarsal head off the ground and then the 5th metatarsal head off the ground. My bet is that the 5th metatarsal head will be much more difficult to lift off the ground. This test actually allows you to "feel the force" that the plantar forefoot experiences in standing.

Second, do the maximum pronation test where you have the patient use their peroneals to see if they can pronate their STJ from their relaxed calcaneal stance position. If they can't pronate further and lift the lateral forefoot off the ground (keep the patient's knees fully extended during this test), then you possibly have a lateral metatarsal overload due to a combination of both a rearfoot varus and forefoot varus deformity. If they can pronate further from relaxed calcaneal stance position and lift the lateral forefoot off the ground, then they may be experiencing increased GRF sub 5th metatarsal head due to excessive STJ supination moments from a large degree of rearfoot varus, a large degree of metatarsus adductus or even a large degree of forefoot valgus deformity.

Third, on nonweightbearing examination, align the body flat on a table supine and then maximally pronate the STJ by placing manual force plantar to the 5th metatarsal head to see if their plantar forefoot can evert past the patient's transverse plane. If their forefoot eversion is limited to only 1-3 degrees everted past the transverse plane, then they likely have a rearfoot varus/forefoot varus deformity causing the 5th metatarsal head overload.

Hope this helps.:drinks

 

I went to school on the east coast, and they didn't explain this well. So help me understand this.
Are you saying there is a large GRF (which acts on the first metatarsal head), which results in subtalar supination moments (therefore in this foot type there is excessive stiffness of the first metatarsal cuneiform joint and talonavicular joint), and therefore there is an increase in the GRF sub 5 that is greater than sub 1?
If so, could you explain why there is a greater GRF sub 5 than sub 1 (as opposed to equal), or am I missing something?

Regards,
Stanley

 

Dear Dr Kirby,

Many many thanks for this ... I will perform the tests you have detailed and see what happens.

Again, I am most grateful for your help and advice.

Kindest regards,

Koota.:drinks

 

Dear Dr Kirby,

The maximum pronation test revealed that my patient is maximally pronated. She found it extremely difficult to evert her feet at all without bending the knee and flexing at the hip. She was certainly unable to lift the lateral forefoot off the ground.

With patient supine, maximal pronation of the STJ revealed that their plantar forefoot was not everting past the patient's transverse plane. I was able to manually assist however, and bring the forefoot approximately level with the transverse plane; but it would not move beyond this into eversion.

It was much harder, (nigh on impossible), to lift her 5th metatarsal heads off the ground.

So it looks like the lateral metatarsal overload is due to both a rearfoot varus and forefoot varus deformity?

I have been avoiding doing NCSP and RCSP… am I in error here… do you think these quantitative observations are worth doing?

Many thanks.

Kindest regards,

Koota.

 

Stanley:

What I am saying here is that when a foot has a large magnitude of external subtalar joint (STJ) supination moment acting on it due to the actions of ground reaction force (GRF) when standing in relaxed bipedal stance, the tendency for that foot will be to supinate at the STJ. When the STJ is trying to supinate due to a large external STJ supination moment, it will be the lateral metatarsal heads (i.e. 4th and 5th metatarsal heads) that will have the most GRF underneath them since the forefoot is, effectively, being inverted into the ground by the STJ supination moment.

However, since the 4th and 5th metatarsal heads are lateral to the STJ axis, GRF plantar to the 4th and 5th metatarsal heads will result in a STJ pronation moment which will act to counterbalance any STJ supination moment, and prevent further STJ supination motion. In other words, the greater the external STJ supination moment, the greater also will be the GRF plantar to the lateral metatarsal heads since it is these metatarsal heads which are effectively producing the STJ pronation moment which is preventing further STJ supination in relaxed bipedal stance.

It is not just the magnitude of the GRF plantar to the first metatarsal head which is critical, but also the distance of the first metatarsal head to the STJ axis that is critical in determining the STJ supination moment that results from the mechanical actions of GRF on the first metatarsal head. A first ray with increased dorsiflexion stiffness will tend to have a larger GRF plantar to the first metatarsal head than will a first ray with increased dorsiflexion compliance. The stiffer the first ray, the more the GRF plantar to the first metatarsal head and the greater the external STJ supination moment, all other factors being equal.

Hope this makes sense.

 

Koota:

Now that you have done these tests, then it is not really necessary to do the NCSP or RCSP tests unless you wanted to communicate that information to another clinician. You now know that her lateral metatarsal overload is due to, what in Root et al terminology would be described as, a combination of rearfoot varus and forefoot varus deformity sufficient to prevent the plane of the plantar forefoot from everting past the patient's transverse plane.

Here are the questions you should now be asking yourself using the concepts of tissue stress theory as your guide:

1. What are the patient's symptoms?

2. What exact anatomical stucture are causing these symptoms?

3. What are the likely pathological forces acting on that structure causing the symptoms (i.e. compression, tension, shearing force)?

4. What are the biomechanical and functional factors that are contributing to the symptoms?

5. How are you going to design a treatment plan to:

A. Reduce the pathological loading forces on the injured structure.
B. Improve their gait function.
C. Not cause any other pathologies to occur while accomplishing A and B.

Please, keep us informed of your progress. As you are learning, many others are also learning on this medical educational forum.

 

......

 

Dear Dr Kirby... many many thanks... I have been beavering away writing up the case using your advice... I am so grateful. I owe you a large pint! :drinks I have nearly finished, but it has been hard going... reducing 25,000 words down to 2,000!!! I think I'm losing the plot! :dizzy: I can't see how anything decent can be written about this subject in only 2000 words!! However, I now have good understanding of CoP and SALRE theories and have had my interest in biomechanics ignited!! My boss will be pleased...

Kindest regards,

M
x

 

Koota:

Send your paper my way to my private e-mail address. kevinakirby@comcast.net

I would be happy to give it a read over and make some suggestions for you.

 

The moment from ground reaction force can be calculated by using the concept of center of pressure. The center of pressure is a weighted average of ground reaction force and yields a single point that sum of all the forces on the bottom of the foot can be considered to act. So the force on the first met, the heel the fifth met, etc all contribute to the calculation of the location of the center of pressure. When the center of pressure is medial to the STJ axis there will be a supination moment from ground reaction force and when the center of pressure is lateral to the STJ axis there will be pronation moment from ground reaction force.

So, when the STJ axis exists lateral to the first metatarsal head, the force on the first metatarsal head will contribute supination moment, but whether or not there is a net supination moment from ground reaction force depends on the rest of the force acting on the plantar foot. There may be enough pronation moment from other locations to cancel the supination moment on the first met head.

Fuller, E.A. Center of pressure and its theoretical relationship to foot pathology.
J Am Podiatr Med Assoc. 1999 Jun;89(6):278-91.

 

Stanley:

By definition, an external subtalar joint (STJ) supination moment is a STJ supination moment caused by a force that originates from outside the foot and acts on the external surface of the foot. Ground reaction force (GRF) is, by far, the largest external force acting on the foot.

When GRF acts on the first metatarsal head, then the mechanical effect of that GRF will be variable depending not only on the three-dimensional location of the GRF vector but also on the spatial location of the STJ axis. If the vector of GRF acting on the plantar first metatarsal head passes medial to the STJ axis, then an external STJ supination moment is created. If the vector of GRF acting on the plantar first metatarsal head passes lateral to the STJ axis, then an external STJ pronation moment is created. If the vector of GRF acting on the plantar first metatarsal head passes directly through the STJ axis, then no external STJ moment is created, only STJ compression forces are created.

A "forefoot valgus deformity", by itself, does not determine where the GRF vectors acting on the plantar foot will be located since the magnitude and location of the GRF vectors acting under each metatarsal head will be largely dependent on many other factors. For example, the dorsiflexion stiffness of each individual metatarsal ray, the STJ axis spatial location, and the internal and external STJ pronation and supination moments are just a few of the possible factors which may affect whether a foot with a "forefoot valgus deformity" will have more GRF plantar to the first metatarsal head or more GRF plantar to the 2nd metatarsal head.

If the first ray has high dorsiflexion stiffness, and has a relatively large magnitude of GRF acting on the plantar first metatarsal head, and the STJ is lateral to the first metatarsal head, then, yes, GRF acting on the first metatarsal head will cause an external STJ supination moment. Other factors which may cause an external STJ supination moment would be when GRF acts on the plantar-medial heel. An internal STJ supination moment will normally be created by tensile force within the tendons of the deep flexor compartment, Achilles tendon and anterior tibial tendon and may also be created by compression forces within the sinus tarsi (i.e. floor of sinus tarsi of calcaneus exerting a compression force on the lateral process of the talus), and tensile forces within the deltoid ligament.

Hope that helps.

 

Eric,

Thanks for the response.
Getting back to the original question, which is why does a forefoot valgus cause a lesion sub 5 and not sub 1.
I was thinking that the moments add up to a supination moment through the first metatarsal. The thing I don't get is why would there not be a lesion sub 1.

Regards,
Stanley

 

Hi Kevin,

As I wrote in response to Eric,

Getting back to the original question, which is why does a forefoot valgus cause a lesion sub 5 and not sub 1.
I was thinking that the moments add up to a supination moment through the first metatarsal. The thing I don't get is why would there not be a lesion sub 1.

Regards,

Stanley

 

Some of the time the center of pressure will be under the STJ axis. When this occurs the force times distance from one side of the axis has to equal the force times distance from the other side of the axis. If the axis is very var lateral, the distance to the 5th met head will be small and so the force will have to be high lateral to the axis to reach equilibrium.

I remember being very surprised the first time I saw a foot with high lateral load and when I asked the person to evert they had plenty of range of motion in the direction of eversion. Up until that time I figured high lateral load was the product of a partially compensated varus. The partially compensated varus foot has no eversion range of motion available. But rotataional equilbrium and very far laterally deviated STJ axis can explain how you get high loads on the lateral forefoot with lots of eversion range of motion available.

Eric

 

Stanley:

A "forefoot valgus" does not always cause a lesion plantar to the 5th metatarsal head. In fact, many feet with a "forefoot valgus" may develop significant symptoms from excessive subtalar joint (STJ) pronation moments since forefoot to rearfoot relationship does not, by itself, determine the function of the foot. Lesions plantar to the 5th metatarsal head may also be caused by patients with a "partially compensated forefoot or rearfoot varus deformity" due their STJ not allowing them to undergo sufficient pronation motion to allow the more medial metatarsal heads to receive more ground reaction force (GRF) which would help to reduce the GRF plantar to the 5th metatarsal head.

John Weed, DPM, lectured to us 30 years ago as second and third year podiatry students at CCPM that a "flexibile forefoot valgus" would allow the foot to pronate since the "longitudinal midtarsal joint" had increased range of eversion range of motion of the forefoot on the rearfoot. Dr. Weed also lectured that a "rigid forefoot valgus" would cause the foot to supinate at the STJ since the "longitudinal midtarsal joint" had decreased range of eversion range of the motion of the forefoot on the rearfoot and that "rigid forefoot valgus" was commonly associated with a "rigid plantarflexed first ray".

In the patients with a forefoot valgus that I have examined over the past 30 years, that also have a callus plantar to the 5th metatarsal head, they have also tended to have a "rigid plantarflexed first ray" and not a "flexible forefoot valgus". These patients may also have a callus plantar to the 1st metatarsal head. My clinical experience is that less than 10 percent of individuals with a "forefoot valgus deformity" have a callus plantar to the 5th metatarsal head.

A foot with a "rigid plantarflexed first ray" will have increased GRF plantar to the 1st metatarsal head since, in effect, this foot has a first ray with increased dorsiflexion stiffness. The increased GRF plantar to the 1st metatarsal head will cause either a decrease in external STJ pronation moment or an increase in external STJ supination moment, depending on the spatial location of the STJ axis relative to the first metatarsal head (e.g. a more lateral STJ axis location combined with a first ray with increased dorsiflexion stiffness would cause an increase in external STJ supination moment).

This increase in STJ supination moment or decrease in STJ pronation moment will tend to cause the STJ to supinate unless it is resisted by some other STJ pronation moment. If the 5th ray has normal to high dorsiflexion stiffness, then it is more likely that the GRF acting plantar to the 5th metatarsal head will be of higher magnitude than normal and may more likely cause a plantar 5th metatarsal head callous as a result. In other words, the ground reaction force that causes the 5th metatarsal head callous is one of the most significant forces which also helps to resist further supination motion of the STJ during weightbearing activities.

Surgical elevation of the 5th metatarsal head intended to rid the patient of their 5th metatarsal head callous may reduce the GRF plantar to the 5th metatarsal head in this foot but may then cause the patient to develop peroneal tendinitis/tendinopathy since now the peroneal muscles will need to contract harder to provide the STJ pronation moment that has been reduced by surgical elevation of the 5th metatarsal head. Using the relatively basic physics principles of rotational equilibrium at any joint of the human foot and lower extremity will allow the clinician to better grasp the external and internal forces which determine the moments, motions and pathologies that affect the human foot.

 

:good:

This is something that all students(and many practitioners for that matter) would do well to grasp and a reason that using this type of terminology is confusing for anyone wishing to learn about biomechanics

 

The idea of FHL is a helpful clinical paradigm, but perhaps this patient has other biomechanical problems.

Also, I think we could include retrotalar pulley as a possible cause for FHL. Here is the abstract, sorry I don't have article to upload.


J Am Podiatr Med Assoc. 2010 May-Jun;100(3):220-9.

Functional hallux limitus or rigidus caused by a tenodesis effect at the retrotalar pulley: description of the functional stretch test and the simple hoover cord maneuver that releases this tenodesis.

Vallotton J, Echeverri S, Dobbelaere-Nicolas V.


Source

Swiss Ortho Clinic, Lausanne, Switzerland. drvallotton@swissorthoclinic.ch


Abstract

Functional hallux limitus is a loss of metatarsophalangeal joint extension during the second half of the single-support phase, when the weightbearing foot is in maximal dorsiflexion. Functionally, it constitutes a sagittal plane blockade during gait. As a result, the mechanical support and stability mechanisms of the foot are disrupted, with important consequences during gait. Functional hallux limitus is a frequent, though relatively unknown condition that clinicians may overlook when examining patients with complaints that are not limited to their feet, for they can also present other symptoms such as hip, knee and lower-back pain. The purpose of this article is to present a critical review of the literature on functional hallux limitus and to explain a previously described and simple diagnostic test (flexor hallucis longus stretch test) and a physiotherapeutic manipulation (the Hoover cord maneuver) that recovers the dorsiflexion of the hallux releasing the tenodesis effect at the retrotalar pulley, which according to our clinical experience is the main cause of functional hallux limitus. The latter, to the best of our knowledge, has never been described before.

 

Hi all,

Great post so far! I use first ray cut-outs for functional hallux limitus quite extensively and have found it very benificial. Although i do not see this clinically, I was told that a 1st ray cut out causes the shell to pronate within the shoe. Is this case?

What is everyone's opinion on this?

Regards,

Jo-Pod

 

hello every one,

To get back to the forefoot valgus, we can't predict motion or pressure just on a measurement. It is very important to evaluate the whole patient (motions, flexibility not only in the joints but also muscles, positions,...) and when we have done that we need to do a gait analysis to see how the patient compensates on some of the measurements. The measurements gives us just an idea of what we should expect but it is not always the case. It really depends on so much things why they do or don't do. And this gives us the information how we will tread the patient.
Like Kevin has try to explain, you first need to examine the patient and then you make your conclusions.

The first ray cut out doesn't always mean you get pronation, it depends on how you have correct your orthosis, it can mean that you just want that the firts ray is be able to plantar flex so the first MTPJ can dorsi flex.

sincerly,
kerstin

 

The shell may or may not evert in the shoe depending on where the center of pressure of the foot orthotic interface is. When the center of pressure of the force from the foot is medial to the line from the following two points, the posterior contact point and the anterior medial aspect of the orthosis. Having looked at many a center of pressure line, my guess is that the heel will lift off of the orthosis before the center of pressure gets to the medial side of the "tipping" line. There may be some exceptions, but I would bet that most feet won't evert the orthotic. If you are worried about it you can add a rearfoot post to move the posterior contact point more medial.

Eric