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Pes Cavus w/ Peroneal spasms

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Skiboot Dr, Feb 28, 2006.

  1. Skiboot Dr

    Skiboot Dr Member

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    I have a 26 y/o female patient (my wife) in good health, no systemic disorders and pes cavus foot. She is a runner who recently has been complaining of peroneal spasms at the proximal aspect of her leg...exacerbated with inversion/eversion/plantarflexion in open chain. I am a student and have been trying to find some associations with her foot type and symptoms. I originally thought of a possible coalition, i am awaiting radiographs. I am aware that she has an os peroneum and was also curious if that could be contributing to her pain. Prior to her spasms she complained on arch pain along the course of the PL near its insertion. She wears orthosis x 4 years.

    Just wanted to get some feedback on what you all may think and maybe some direction on places i can find more information/reading.

    thank you,
  2. Craig Payne

    Craig Payne Moderator

    It sound like a typical low supination resistance foot and/or laterally deviated subtalar joint axis --> peroneal muscles have to work harder --> symptoms. Use a lateral rearfoot wedge.
  3. I first described that peroneal muscle overuse may be treated with rearfoot valgus and forefoot valgus wedges over 16 years ago in my October 1989 Precision Intricast Newsletter, "Biomechanics of Peroneal Muscle Overuse" (Kirby KA: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997, pp. 177-178).

    Then, over 10 years ago, I described the biomechanics of peroneal tendinitis in my July 1995 Precision Intricast Newsletter, "Biomechanical Treatment of Peroneal Tendinitis" (Kirby KA: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997, pp. 187-188).

    Successful treatment of peroneal muscle overuse or peroneal tendinitis/tendinosus is based on the mechanical concept of subtalar joint axis location and subtalar joint rotational equilibrium which you may read about in the following papers:

    Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987.

    Kirby KA: Rotational equilibrium across the subtalar joint axis. JAPMA, 79: 1-14, 1989.

    Kirby KA: Biomechanics of the normal and abnormal foot. JAPMA, 90:30-34, 2000.

    Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001.
  4. Berms

    Berms Active Member

    I do not have access to the article Kevin has posted, although they do sound like a great source of information on the subject.

    I was just wondering what lateral r/f and f/f wedging would do to a symptomatic cavus foot type described at the beginning of this thread? Could it cause resultant pathology to other parts of the foot - plantar fascia strain? end range pronation - tissue stress? etc?

  5. First of all, trying to add subtalar joint (STJ) pronation moment to a foot by only using rearfoot valgus wedges is not near as efficient as using the same degree of wedge on the forefoot because of the STJ axis passes posteriorly through the posterior-lateral aspect of the heel and anteriorly through the medial aspect of the forefoot. Therefore, due to this natural angulation of the STJ axis from posterior-lateral to anterior-medial, the 5th metatarsal head will nearly always be the area on the plantar foot that has the longest moment arm for ground reaction force (GRF) to cause a STJ pronation moment. A rearfoot valgus wedge will do little, by itself, to eliminate symptoms since it has little, if any, moment arm for GRF to cause a STJ pronation moment. Therefore, forefoot valgus wedges are much more efficient at creating STJ pronation moment in the foot with peroneal muscle/tendon pathology since they have a much greater moment arm for GRF to cause a STJ pronation moment.

    Second, consider that in patients with posterior tibial (PT) tendinitis/dysfunction we use varus wedges in their shoes and within the design of their orthoses (e.g. medial heel skive) to add external STJ supination moment to their foot to decrease the PT muscle contractile activity and the internal STJ supination moment. Most of us with clinical experience in these matters know that adding varus heel and arch wedges under patient's feet works well at relieving PT symptoms for these patients.

    However, what about the patient has has excessive magnitudes of STJ supination moment acting on their foot during gait? How are they to prevent their foot from rolling into excessive inversion, or spraining their ankle, with every step???? They use their peroneal muscles since the peroneals are the only extrinsic muscles of the foot that have significant ability to cause a STJ pronation moment. Using the same logic that allows us to understand that varus wedges help PT muscle/tendon problems, we should now be able to understand that using valgus wedges should help peroneal muscle/tendon problems since valgus wedges increase the external STJ pronation moment.

    Let me take a little side step here to say something that seems so obvious to me but is not so obvious to the rest of the podiatric profession about the biomechanical theories that are taught in podiatry colleges. Does any theory of foot biomechanics that is currently taught in podiatry schools predict why valgus wedges help patients with peroneal muscle/tendon pathology???

    One of the most profound examples of how the Subtalar Joint Axis Location/Rotational Equilibirum (SALRE) Theory of Foot Function can help a clinician understand how the foot works so that they can design better orthosis therapy for their patients is in the example of the patient with pes cavus feet, metatarsus adductus or excessive rearfoot varus foot and also peroneal muscle/tendon pathology. The STJ Neutral Theory, as promoted for years by Root, Weed and Orien, (and still being promoted by many podiatric colleges both here in the US and abroad) did not have any mechanical explanation as to why peroneal tendinitis would occur in pes cavus, metatarsus adductus foot or excessive rearfoot varus feet.

    On the other hand, the SALRE theory easily predicts that the lateral STJ axis location seen in pes cavus, metatarsus adductus and excessive rearfoot varus would cause increased STJ supination moments that could lead to peroneal muscle/tendon pathology. The SALRE theory also nicely predicts that valgus forefoot and rearfoot wedges would help reduce the peroneal muscle contractile force during weightbearing activities since these valgus wedges add increased magnitudes of STJ pronation moment to the foot so that the peroneals do not need to contact so hard to add STJ pronation moment to the foot during weightbearing activities.

    Over the last 20 years I have been lecturing and writing on these subjects but still find it somewhat frustrating that this knowledge of the theory and practice behind how to properly treat peroneal muscle/tendon problems is not being taught at most podiatry colleges. Why not??!! It is so easy to treat peroneal pathology with valgus wedges, but this simple pain-relieving knowledge is probably only understood by about 5% of the podiatrists here in the US and probably not much more in other countries!!

    Maybe if I continue shouting from my soapbox for another 21 years (I'll be 70 by then), then the podiatry profession will begin to learn how simple it is to treat peroneal muscle/tendon pathology using the SALRE theory. I doubt I'll last that long......
  6. Ian Linane

    Ian Linane Well-Known Member

    Not sure if I am scatching the right spot here.

    I have found it quite common to have pes cavus foot types over load the lateral compartment and have tended to think of my rear foot treatment of this as a resister to increased supination rather than increasing a pronatory force (as per forefoot valgus wegde.)

    In these cases I have tended to pour the negative vertical. This usually means that the positive cast sits in an inverted position once it is let go of. To bring the heel vertical then often means an intrinsic forefoot balance platform is applied met 2-5, being deepest on the 5th. (equivalent to the forefootwedge???) Once this is done I then apply a lateral skive to the heel to resist the tendency of the over inversion.

    It certainly seems to have been helpul for many people. Of course in a case of the above with rigid plantarflexed 1st ray then a forefoot extension and met cut out has served beautifully.

    Successfully killing biomechanical terminolgy again :)> but hope it helps.

  7. efuller

    efuller MVP

    Two kinds of inverted rearfoot

    There are two kinds of feet that can have increased lateral forefoot loads, hence callus sub 4 and or 5th met heads. The laterally deviated axis foot will tend to supinate until its center of pressure is under the axis. If the axis is so far lateral (line drawn between center of heel and 3rd met head.) Roughly speaking half the weight has to be on one side of the axis and the other half on the other side of the axis. This will cause high loads on 4 and 5. The other kind of foot that is the classic Rootian varus foot. (Forefoot or rearfoot, it does not matter which.) This foot runs out of STJ motion before the medial forefoot can bear significant weight and hence the calluses sub 4 and 5.

    To tell the difference between them you have to try to pronate the STJ with either a block (Coleman block test) under the lateral forefoot or by having the patient use their peroneal muscles while standing. If there is range of motion in the direction of eversion, it's the laterally deviated axis foot, if not then it's a varus foot. One warning, you can have a laterally deviated axis foot that also has a varus. This is a hard one to treat, because a forefoot valgus wedge will try to evert the STJ farther than it can go and you get too mjuch load on the lateral column and possibly sinus tarsi pain.

    When I have patients use their peroneal muscles in stance, I look to see if there is range of eversion of the lateral forefoot off of the ground. Don't make your valgus forefoot wedge higher than this distance. I did once in my own foot and it hurt. I have mistakenly added too much forefoot valgus wedge in patients who came back with pain to dismiss this notion.

    By the way Ian, adding a pronation moment is the same as resisting supination. A negative pronation moment is a positive supination moment.

    This also highlights a problem with the Root et al, paradigm. Their explanation for the laterally devaited axis foot was that there was "forefoot influence" from a forefoot valgus. Which Ian and I see most of the time. However, some laterally deviated axis feet appear to have a forefoot varus and exhibit high lateral column and have eversion available. I won't go into the problems of forefoot to rearfoot measurement, but will just say that it is random.

    That cast that has a forefoot varus can still be used to get a forefoot valgus wedge to treat the peroneal tendonits. The cast can be balanced further everted than where it sits. This will also evert the heel cup of the orthosis, which will be a good thing for the laterally deviated axis foot.

    I like Ian's idea of adding a valgus heel skive to increase pronation moment.

  8. In order to translate terminology from the Root et al paradigm to the terminology that Eric and I are using, a little explanation is due. The foot classification scheme that Eric and I are describing is based, not on subtalar joint (STJ) neutral, but rather on the spatial location of the STJ axis. Therefore, a laterally deviated STJ axis can occur with the following Root et al "deformities":

    Frontal plane:

    1. Increased rearfoot varus deformity.
    2. Increased forefoot valgus deformity.
    3. Increased plantarflexed first ray deformity.

    Transverse plane:

    1. Increased metatarsus adductus deformity.

    The lateral deviation of the STJ axis causes an increased magnitude of supination moment from ground reaction force acting on the plantar foot. In addition, the lateral deviation of the STJ axis will cause all the extrinsic muscles of the foot to have either an increased length of supination moment arm or a decreased length of pronation moment arm. And finally, the STJ rotaional effects from the tensile forces generated from active contraction of the intrinsic muscles and passive elongation of the ligaments of the foot will also tend to cause greater STJ supination moment and decreased STJ pronation moments.

    These concepts are not exactly new to podiatry. I first published these concepts nearly 19 years ago (Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987). Maybe they will eventually be widely taught......however, from personal experience, I have learned to not get too excited since I don't think many podiatrists have the mechanical aptitude or the desire to learn these concepts, so I won't hold my breath.

    I remember having a discussion with Eric Fuller about these concepts that we were thinking about and working on early on in the late 1980s when I was teaching at CCPM and he had just graduated from the CCPM biomechanics fellowship. I shared my frustration with him about the inability of the podiatry profession, at that time, to be able to understand what I thought were relatively simple mechanical concepts (Root theories were the only theories taught back then). I told him I thought it might be ten years before the concepts were widely taught in podiatry, at the rate they were being disseminated and understood by the podiatry profession at the time.

    Now, we are approaching 20 years after my first paper on the subject and I have guarded confidence that these ideas will be widely understood and put to use by the brighter mechanical minds worldwide within our profession. I believe that the chapter that Eric and I wrote for an upcoming book may help clarify our thoughts on these concepts and their clinical utility in the treatment of mechanically based pathologies of the foot and lower extremity.
  9. Mark Egan

    Mark Egan Active Member


    any results from the plain films? Also why has she developed these issues? the orthotics were prescribed for what reason? has she been wearing the same orthotics for 4 years ? has she had peroneal issues before?

    I would also like to hear from others re. the use of valgus control in orthotics. If anyone uses talo crural mobilisations and STJ mobilisations in an effort to increase the DOM QOM and ROM of said joints. Also what sort of adjustments are made to the MLA of devices to compensate for increased midfoot pronation.

  10. Atlas

    Atlas Well-Known Member

    When Craig enlightened me about this concept in boot camp 1, it finally explained to me that simply "strengthening peroneals" wasn't the total answer post sprain. As Craig said (don't quote me), having a laterally deviated axis in the first place, perhaps means that the peroneals were "strong" but "disadvantaged (mechanically)" to begin with. Moreover, there were other ways (ground up) to address the problem. The concept was and still is a a good one.

    But because this concept is so good, and because we all like to generalise and pidgeon-hole, the danger is that we all start to conclude that patient x has a laterally deviated STJ axis BECAUSE they sprained their ankle.
  11. It is much easier to increase the external subtalar joint (STJ) pronation moments with a valgus wedge under the heel and lateral forefoot than to get a patient to do peroneal strengthening exercises. However, both of these therapies, working together, give the best results.

    I don't think that the intelligent clinician will suddenly jump to the conclusion that just because they were taught that inversion ankle sprains may be caused by a laterally deviated STJ axis that they will then decide that all patients that suffer a inversion ankle sprain have a laterally deviated STJ axis. Does the intelligent clinician jump to the conclusion that just because he learned that tight calf muscles may cause plantar fasciitis, then they will think that all plantar fasciitis is caused by tight calf muscles? I think not. The intelligent clinician will reasonably understand that all the injuries they treat are.....multifactorial.

    However, the "uninspired" clinician who does not have the intellectual capability to comprehend basic mechanical principles or is too lazy to try to understand these basic mechanical principles may, very well, think that all patients that sprain their ankles have a laterally deviated STJ axis.

    Unfortunately, after having lectured for 20 years on biomechanics to thousands of podiatry students and podiatrists in six countries, it is obvious to me that about 1/3rd of the podiatry students/podiatrists have good mechanical intuition, 1/3rd have poor mechanical intuition, and the other third have fair mechanical intuition. About 5% of podiatry students/podiatrists have excellent mechanical intuition. I have no control over how a student will comprehend basic mechanical concepts. If they don't understand they must speak up or take the responsibility to do the extra work required to comprehend the subject. This is the cold-hard reality of professional education.

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