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Functional Hallux Rigidus ???

Discussion in 'Biomechanics, Sports and Foot orthoses' started by mike weber, May 25, 2010.


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    Hi folks.

    Had a lttle bit of an intersting one today.

    Doing some assessment stuff, noted slight Structural Hallux limitus non weightbearing on weightbearing exam No Hallux dorsiflexion available.

    So is there such thing as a functional Hallux Rigidus ?

    and papers written on it ?
     
  2. drsarbes

    drsarbes Well-Known Member

    is this a trick question?
     
  3. Probably, Steve. Probably...;)
     
  4. No

    Allright Steve work with me. or anyone else

    If you have a functional Hallux Limitus the joint will still dorsiflex but it will take increased force.

    But if the joint become rigid ( 1st time Ive noted this) it will not dorsiflex with any force I could muster, infact the patient started to lean back.

    so Limited motion v´s none.

    Explain to me why you thought it was a trick question.
     
  5. Cos it was not rigid. It was just that the amount of force needed to dorsiflex it was greater than the amount of force you could exert on it. Very, very stiff, but not rigid.

    Although this did get me to thinking. I think the terminology IS bad. The concept of functional hallux limitus implies that in function there is a limit to the amount of hallux dorsiflexion available. While this may be true the nature of FnHL as we understand it runs a little deeper. We discussed a while back how it may be fallacious to describe FnHL as either present or absent, that it is perhaps more accurate to talk about degrees on a scale. If we take the Rotational equilibrium definition of FnHL as

    "the condition which exists when the internal plantarflexion moment exceeds the external dorsiflexion moment"

    It sort of makes one think more in terms of kinetics than kinematics.

    Would it be more accurate to think of FnHL in terms of stiffness or resistance rather than purely the degrees of movement?

    Lets take a simplistic example. Two feet. One has a floppy 1st met and unstable ankle, the other a much stiffer 1st ray and more stable ankle. Lets say that the internal Plantarflexion moment is 50 for the first and 10 for the second.

    Now lets say that the external dorsiflexion moment is 60 for both, enough in both cases to dorsiflex the toe in gait.

    Obviously foot number 1 will have a far stiffer joint and far higher internal compression within the 1st MPJ than foot number 2. Perhaps to the point where it causes pain. Yet they are neither truly limited in that they both have the same range. Not FnHL then?

    Functional hallux stiffidus anyone? Or am I just rambling now.
     
  6. No I think it was Bruce Williams who got me thinking in terms of Dorsiflexion stiffness of the MTP joints when discussing windlass. But there must be a point of 100% stiffness and maybe this 1st MTP Joint was not but close enough that I would say rigid.

    But the point you make is a good one.
     
  7. Mike:

    In our current terminology, anything less than approximately 10 degrees of dorsiflexion range of motion of the hallux nonweigthbearing is considered a hallux rigidus. A foot with hallux rigidus will always become more stiff when hallux dorsiflexion is attempted in weightbearing due to the large increase in magnitude in passive hallux plantarflexion moment from the plantar fascia during forefoot loading. This foot would be considered, in other words, a hallux rigidus deformity.

    If, however, the patient had 35 degrees of dorsiflexion range of motion of the hallux in non-weightbeairing, which, with weightbearing, had no available range of motion of the hallux, then this foot example would be considered a functional hallux limitus.

    Therefore, for your case report, no new terms are needed to answer your question. However, in the future, the adoption of the mathematically quantifiable concept of hallux dorsiflexion stiffness would help all of us better understand the biomechanical effects of this common condition on the foot and lower extremity.
     
  8. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    I think we had some discussion previously that we always considered functional hallux limitus as being present or absent, when in reality it probably exists as a continuum. What you are suggesting is that a 'functional hallux rigidus' is probably one end of the continuum.

    If we also reconceptulise functional hallux limitus as a temporary increase in first MPJ dorsiflexion stiffness, then a 'functional hallux rigidus' would be an extremely high temporary increase in dorsiflexion stiffness.

    I have seen several 'functional hallux rigidus's' lately and coincidently they all had really sore backs. The most notable was a participant in one of the Boot Camps ... everyone was practicising Jacks Test when I got called over to look at one .... it was physically impossible to dorsiflex the hallux while she was standing ... no one could lift it ---- she also walked with a gait that circumducted at the knee. On non-weightbearing, the dorsiflexion was fine. Using the material we had handy we massively inverted the heel and put on a big forefoot valgus post and the tuff guys could just get some dorsiflexion ....

    Since that experience, I have been more conscious of it existing and several I have seen all had back pain and all walked with a gait that circumducted at the 'knee'. Usuing the usual orthotic modifications only were able to make a small diffference.

    As Kevin, said, do we want to call this a 'functional hallux rigidus'? Maybe call it 'an extremely high increase in dorsiflexion stiffness during weightbearing'
     
  9. Sounds good to me Thanks Gents.
     
  10. drsarbes

    drsarbes Well-Known Member

    I still think it was a trick question!
     
  11. efuller

    efuller MVP

    I'd agree with the other posts and add..

    There is not only a continuum across people, there is a continuum in one person over time. You may be born with a foot type that has functional hallux limitus. This foot will have high compressive forces at the 1st mpj and attempt motion at the mpj. This will lead to cartiledge damage and osteophyte formation that converts the functional hallux limitus to a structural limitus. If the same forces are still present, this will lead to a structural hallux rigidus from further cartiledge damage and osteophyte formation.

    I'm one of those people where you will have extreme dificulty lifting the hallux off of the ground. I was looking at some basketball shoes I had in high school. There was wear under first met and hallux. The basketball shoes since then only had wear under the hallux. Yes, I know n=1. I have a foot just like my dad's. I didn't make it out of podiatry school in time to make him orthotics before he needed a Keller for his hallux rigidus.

    Cheers,

    Eric
     
  12. Lab Guy

    Lab Guy Well-Known Member

  13. drsarbes

    drsarbes Well-Known Member

    "I'm one of those people where you will have extreme dificulty lifting the hallux off of the ground."

    No need to lift the hallux off the ground, the rest of the foot needs to rise over the hallux.

    So Eric.....when did you graduate high school and why do you still have your basketball shoes?????
    haha

    Steve
     
  14. CraigT

    CraigT Well-Known Member

    I vote for Functional Hallux Stiffidus.
    Tell that to your patient without giggling.
     
  15. efuller

    efuller MVP

    If you can't lift it off of the ground, you can't pivot over the MPJ. I used them for canoeing. Those old Chuck Taylors were great on the court and in the river.

    Eric
     
  16. james clough DPM

    james clough DPM Active Member

    Clinically you can see that functional limitation of first MTPJ motion is a continuum of stiffness. If the first ray is unstabke enough, it will elevate sufficiently with weight bearing to restrict DF entirely of the first MTPJ. I have seen this many times. I dont see the point in burying ourselves with terminology. The point of all this restriction is that it is only functional, and always can be overcome, reliably. I agree with eric that these problems do worsen over time. If we are not identifying them, then how do we treat this? From what I see the first ray is usually treated as a by product of STJ and midfoot control, not as a distinct entity. Just out of curiosity what was the heel position of this patient with functional hallux rigidus?
     
  17. Hi James, What do you mean by this ?

    If you mean STJ neutral Ive no idea I don´t measure it, the patient did have a medially deviated STJ axis if that helps.
     
  18. james clough DPM

    james clough DPM Active Member

    What I am asking is for the RCSP. I am wondering if the rearfoot is very unstable in this individual, or how much the patient is medializing their weight bearing forces? If the axis is medially deviated then we know that there is a propensity to medialize or evert the heel. However in the context of the overall position of the heel, considering the frontal plane alignment of theleg, was the patient really everted?

    The reason I am asking this question is that I often see these forefoot issues without significant rearfoot eversion. The question of course is: Is the rearfoot 'driving' the forefoot or is the forefoot 'driving' the rearfoot. I dont think there is one answer to this question, always, I have seen what seems to be both, and in most individuals the problem is pervasive to the forefoot and the rearfoot. But not always, and what I am trying to understand with your patient is what is 'driving' the problem. This in my mind will allow us to find the best solution to the problem as well.

    I think we need to understand the pathology the best we can to find the best solution. Its the old adage , we need to make a diagnosis before we can prescribe a treatment.
     
  19. Amen Brother!!

    Hmmm.

    What is to "medialize" the weight bearing forces?

    What is an unstable rearfoot?

    How much will a RCSP measurement tell you given the intertester variability?

    I think I sort of see where you are coming from but you may need to clarify your terminology a bit.
     
  20. Hi Jim, welcome to Podiatry Arena.:welcome:

    I don't think the relaxed calcaneal stance position (RCSP) can be assumed to be a valid indicator of the amount of subtalar joint (STJ) pronation moment and/or STJ supination moment that is occurring during relaxed bipedal stance for the following reasons:

    1. The inter-examiner variation in drawing heel bisections is about +/- 5 degrees. Therefore, for one examiner, the calcaneus could be 5 degrees everted and for another examiner the same calcaneus on the same foot could be considered to be 1 degree inverted.

    2. The RCSP does not in any way take into account the spatial location of the STJ axis relative to the external and internal forces which are causing STJ pronation and supination moments across the STJ during relaxed bipedal stance. Without knowing the location, magnitude, point of application and direction of all the external forces relative to the STJ axis, we can't possibly know exactly what the net STJ moment is at any time during walking, standing or running.

    However, I do believe that the maximum pronation test and supination resistance tests (Kirby KA, Green DR: Evaluation and Nonoperative Management of Pes Valgus, pp. 295-327, in DeValentine, S.(ed), Foot and Ankle Disorders in Children. Churchill-Livingstone, New York, 1992.) can be very helpful in determining STJ moments. The maximum pronation test uses the heel bisection line to determine whether the patient is maximally pronated or not and can be a valuable indicator of whether there are excessive STJ pronation moments occurring or not as we found support for in our recent research (Pascual Huerta J, Ropa Moreno JM, Kirby KA: Static response of maximally pronated and nonmaximally pronated feet to frontal plane wedging of foot orthoses. JAPMA, 99:13-19, 2009). In addition, Payne and coworkers found that the supination resistance test was correlated to STJ axis location and body weight, which is a much better indicator of what STJ moments are occurring during relaxed bipedal stance than RCSP, by itself, could ever tell us (Payne C, Munteaunu S, Miller K: Position of the subtalar joint axis and resistance of the rearfoot to supination. JAPMA, 93(2):131-135, 2003).

    As far as the idea of the either the forefoot or rearfoot "driving" the other, both forefoot and rearfoot mechanically influence each other at all times during gait. Since the forefoot and rearfoot are attached to other, and this connection becomes mechanically much stiffer under weightbearing loads, then it would be best to simply say that the forefoot and rearfoot are mechanically dependent on each other. In other words, the forefoot doesn't drive the rearfoot with the rearfoot remaining passive any more than the rearfoot drives the forefoot with the forefoot remaining passive. Both the rearfoot and forefoot are exerting forces and moments on each other which will determine the ultimate position and motion of the foot at any instant of gait.

    Good to have you around, Jim. Hope you continue to contribute to our discussions.
     
  21. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    This brings back the issues in the thread on: Does the tibia drive the foot or does the foot drive the tibia?. How often have we heard bold statements like "Its the forefoot ... the forefoot drives the rearfoot" etc etc, when you know that they really have no idea if its teh case or not. It would be nice to the similar power equations using a methodology similar to the Belchamber one in that thread on foot v leg, thats gives us an idea where the driving force is coming from (ie rearfoot or forefoot) at different times of the stance phase (this is if it technically feasible).
     
  22. james clough DPM

    james clough DPM Active Member

    Robert, to answer your question of what do I mean to medialize. I suppose this term is used in the surgical world more so than the biomechanics world, but when we talk about medializing something we refer to moving in a medial direction. For instance, if we are doing a calcaneal osteotomy to correct for a flatfoot deformaity we will refer to medializing the heel or moving the heel more medial. The idea here is to bring the heel under the leg bisection. As the heel sits lateral to the leg bisection the patient will medialize their weight and roll off the medial side of their foot, creating medial column instability. The ability to supinate varies as the leg is too far medial. This also results in calcaneal eversion, the degree of this is determined by the leg position and the degree to which the STJ axis allows eversion to occur and soft tissue compliancy. I am not aware of any studies looking at what the effect of spatial orientation of the STJ axis is when this type of procedure is done. I can say however , that there is a change. You can see this clinically.
    Hi Kevin. glad to have this opportunity to communicate. We will all learn better by sharing our clinical observations. I believe they are the lens through which most of us understand the foot and practice medicine. To paraphrase Sig Hanson in a talk he recently gave to the Montana Podiatric Medical Association meeting, something to the effect of... I believe what I see and can observe and rely on this more to make my clinical decisions than the studies in the journals... . I would tend to see things the same way, after 25 years of looking at the foot critically, I have developed a lens through which I see foot function, mind you , that lens is largely based on the physical sciences and fundamental truths of mathematics. It certainly is great to have the research, whan present, but clincal observation will always lead the research. You must always first make the observation to be tested.

    I understand the STJ axis spatial relationships and what it is to tell us. This is useful in the context of the orthotic fabrication method, however, clinically I need to know if the heel is everted and the leg is sitting medial to the foot. As a surgeon, this is what I am looking for. When I do my rearfoot corrections I am looking for the degree of eversion of the heel relative to the degree of tibial varum or valgum, or genu varum or valgum. So my overall goal is usually to achieve a slight valgus alignment of the heel relative to the floor. I know this is also changing the spatial orientation of the STJ axis. Basically, your heel has less supination resistance at this point, correct?

    So, in the context of clinical evaluation and surgery in particular, I believe the frontal plane postion of the calcaneus still has relevance. The fact that we cannot produce the same values between testers does not reduce its clinical significance, in my opinion, it just points to the fact the there needs to be a better method of producing a calcaneal bisection that is standardized, so we are not all eye-balling this, this way we can share information which is more accurate.

    An unstable rearfoot, in my experience, has , almost a feather edge to it in the sense that you cannot prevent this foot from maximally pronating with dorsiflexion of the ankle. It is impossible in OKC to keep this foot near 'neutral ' position. In the context of this discussion I think the STJ axis would be very medially deviated and the heel would be displaced lateral to the bisection of the leg. The frontal plane postion of the heel will depend on the frontal plane position of the leg.

    There is a wide variation in the shape of the first met cuneiform joint clinically. Here I go with the surgical persective again, but I do a fair number of first met cun. fusions to repair bunion deformities, I see this in a lot of people without significant STJ axis deviation medially or at least minimal deviation medially, but very unstable first rays and hypermobility. So....in this case the first ray elevates and the rearfoot everts, but not necessarily until later in stance phase as the WB forces go over the forefoot is when calcaneal eversion increases. And it stays this way in FHL as the first ray cannot plantarflex and provide the 'lateralization' of weight and the initiation of STJ supination as a result of plantarflexion of the first ray. As a clinician this is what I see, a lot. As a clinical I see elevation of the first ray and FHL commonly in relative isolation when the STJ axis is fairly centralized on the heel. Am I splitting hairs here? Depends I suppose on perspective. I am seeing a lot of people get better clinically with addressing the first ray in relative isolation.
     
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