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Correcting for genu varum without risking inversion sprain

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Joanne Moore, Sep 15, 2011.

  1. Joanne Moore

    Joanne Moore Member


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    Hi all,

    I have, what is very probably, a very basic bio question for you, so advance apologies given!


    I've just seen a patient compaining of bilateral medial knee pain, and an assortment of bilateral nerve (sharp/shooting) pain in both feet, with a history of inversion sprains again bilaterally.

    He has the following:

    Genu varum
    Gastroc and soleus equinis

    Is maximally pronated in stance
    Has tenderness in sinus tarsi bilaterally

    How do I reduce the tension in the sinus tarsi area without increasing his risk of further lateral ankle sprains?

    Can't wait to hear your suggestions,

    Joanne
     
  2. efuller

    efuller MVP

    Talliard in 1981 described sinus Tarsi syndrome. In that paper he noted that people with sinus tasrsi syndrome had absence of firing of the peroneals in gait. With injection of local anesthetic into the sinus tarsi normal peroneal activity returned. Talliard had a different explanation than mine. My explanation is that pain in the sinus tarsi is increased with peroneal activity (pronation moment). So, the person chooses to inhibit their peroneal muscles. So, when this person walks on uneven terrain, they will step on something that causes an unexpected inversion moment and the inhibited peroneals won't have time to respond before the sprain occurs. So, it's ok to increase supination moment in individuals with sinus tarsi pain, because you hope the decrease in pronation moment from the ground will allow normal peroneal activity to return.

    Sinus tarsi pain will often be present with tibial or genu varum. This is one of the important things taught by Root et al. You can't just look at the range of motion relationship of the calcaneus to the leg, you also have to relate the leg to the ground. However, with significant genu varum there will tend to be increased compression in the medial compartment of the knee. A varus heel wedge will tend to increase the compression of the medial compartment of the knee. So, be prepared to take the wedge out if knee pain increases with treatment of the sinus tarsi syndrome.

    Eric
     
  3. In addition to Eric's excellent response. I would check balance about the ankles and work on rehabilitation. Following ankle inversion sprains there is often a lag in reflexive peroneal firing and generally poor "balance" control. What is the source of the medial knee pain? Moreover, how old is the patient? Give me a tinkle at about 9.00 am tomorrow and we can have a chat about this one, if you like Joanne.
     
  4. davidh

    davidh Podiatry Arena Veteran

    Hi Joanne,

    Without seeing the patient I would have a stab at orthoses with 1/8th inch heel raises and 4 degs RF varus wedges, and, importantly, valgus FF wedges to help with the inversion sprain problem.

    Actually I wouldn't;), not without seeing the patient, but that's what springs to mind from your description.

    Also, bear in mind that chronic ankle inversion sprains almost always have a bunch of adhesions associated, usually adjacent to the lateral malleolus, and these will need some rehab, usually cross-frictional massage and stretching.

    General enquiry - general answer. Good luck with your patient.
     
  5. Maximum eversion height?
     
  6. davidh

    davidh Podiatry Arena Veteran

    Oh, I would probably go with something like 2 degrees, perhaps try some 5mm felt placed laterally to begin with.

    Haven't seen the patient remember, so this must all, of necessity, be vague.
     
  7. efuller

    efuller MVP

    The idea of measuring maximum eversion height is that you don't have to guess, or that you have some idea, of what amount of valgus wedge would be too much. In someone with Sinus tarsi pain (the uncompensated varus foot) any wedge might be too much.
     
  8. :good: My point exactly. I knew my previous post wouldn't go over your head, Eric. After all, it was you that first described this little clinical gem. Joanne and I discussed this earlier today on the telephone. Perhaps this test is worthy of further description so that those unfamiliar with it may bring it into their clinical work-up?
     
  9. efuller

    efuller MVP

    Are you talking about here or an article. Or both?

    Here

    The maximum eversion height test is one I devised after trying to understand what John Weed was teaching at CCPM. He was trying to relate how tibial varum, calcaneal range of motion and forefoot rearfoot relationship relates to the ground. He also was teaching that you should not evert the calcaneus further than it its range of motion allowed. There are many problems inherent in the approach that he used, but it is a very important concept.

    Background:
    There is a limit to eversion range of motion of the forefoot. One of the limits is the end of range of motion of the STJ when there is bone to bone contact of the lateral process of the talus when it hits the floor of the sinus tarsi. Another limit is when the lateral metatarsals become maximally dorsiflexed and their plantar ligaments become taugth (and there stiffness increases) The position of the forefoot, relative to the ground, varies from individual to individual.

    The test:
    Patient standing in angle and base of gait. Ask them to attempt to evert their foot without shifting their weigth to their other foot. Asking the patient to do both feet at the same time helps prevent the patient from cheating too much. Patients will also try to bring their knees closer together as this will tend to allow them to get the lateral forefoot higher off of the ground. When they are maximally everted, not the height of the lateral forefoot off of the ground. Some people will not be able to lift their lateral forefoot off of the ground and others can lift it more than an inch with many possibilities in between. Do not make a forefoot valgus wedge higher than this height as it will attempt to evert the forefoot farther than the range of motion allows. A wedge that is too large will create a discomfort of either high pressure under the lateral forefoot or pain in the sinus tarsi. It is conceivable that knee pain could develop as well.

    Eric
     
  10. davidh

    davidh Podiatry Arena Veteran

    My point exactly.

    I haven't seen the patient. Neither have you, neither has Dr Spooner. Joanne is clearly not experienced at treating this presentation.
    What you both seem to be highlighting, if you'll forgive me for saying, is a condition which the patient may or may not have.
     
  11. I think what both Dr Fuller and I are trying to highlight is that you shouldn't just bang a forefoot valgus wedge under a patient without assessing whether or not they might be able to tolerate it. That the maximum eversion height test is one way in which this might be assessed.

    "2 degrees 5mm"- "40... 45"

    http://www.youtube.com/watch?v=rafRwe52i38&feature=related
    http://www.youtube.com/watch?v=iqV3_J-andE&feature=related
    http://www.youtube.com/watch?v=lhrSfkqYXZ8&feature=related
    http://www.youtube.com/watch?v=rjBR2ngkWfI&feature=related
    http://www.youtube.com/watch?v=QlF9drU10II&feature=related

    Is it that time?
    http://www.youtube.com/watch?v=1ftnHoCdDDk&feature=related

    Brilliant.

    6-2, 6-love.
     
  12. admin

    admin Administrator Staff Member

  13. Joanne:

    This is an interesting patient with various mechanically-based pathologies that make it very difficult to treat one of the pathologies, without negatively affecting another coexisting pathology.

    With the limited information you have given us, I will try to go through each pathology so you know how each is mechanically produced.

    First of all, you stated that the patient has a genu varum deformity with medial knee pain. The most likely cause of this medial knee pain is medial knee osteoarthritis (OA). Medial knee OA can be caused by genu varum deformity due to excessive compression loading of the medial compartment of the knee. In addition, medial knee OA will also cause an increase in genu varum deformity due to loss of medial knee cartilage as the OA progresses. Unfortunately, for all of us trying to figure out what this patient has, without actually physically examining them ourselves, the exact cause of the medial knee pain is difficult, at best. You must remember that medial knee joint line pain may also be caused by medial collateral ligament sprain of the knee which, very commonly, is caused by excessive subtalar joint (STJ) pronation moments and excessive tensile force on the medial collateral ligament of the knee during weightbearing activities.

    Secondly, you noted that the patient was maximally pronated at the STJ with sinus tarsi pain. Sinus tarsi pain can occur in any patient that has a maximally pronated STJ but will more commonly occur in patients with medially deviated STJ axes due to the excessive magnitudes of compression forces between the lateral process of the talus and the floor of the sinus tarsi of the calcaneus (Kirby KA: Rotational equilibrium across the subtalar joint axis. JAPMA, 79: 1-14, 1989). Sinus tarsi compession forces may be reduced and sinus tarsi pain may be relieved with an anti-pronation foot orthosis and using shoes with higher heel-height differentials (shoes with higher heels). By the way, Joanne, it is unlikely that any tension within the sinus tarsi is the source of the pathology or pain in sinus tarsitis or sinus tarsi syndrome.

    Third, you noted that the patient has a history of inversion ankle sprains which may occur due to numerous etiologies including laterally deviated STJ axes, ligamentous instability from previous ankle sprains, weak peroneal muscles, inverted shoe soles, walking on uneven surfaces or poor ability to sense inversion motion of the ankle. Unfortunately, making an orthosis that increases the STJ supination moment to try and relieve the sinus tarsi pain may not only increase the risk of inversion ankle sprains but may also increase the pain from a preexisting medial knee OA. Therefore, this problem of treating one problem possibly causing another problem may be what happens with this patient when you start trying to treat them mechanically.

    I do have one idea for you. First of all, I suggest you have the patient purcahse a high top boot with at least a 1/2" heel height diffential to not only prevent further inversion ankle sprains but also to help relieve some of the compression force within the sinus tarsi. Next, make a good antipronation foot orthosis with a medial heel skive (Kirby KA: The medial heel skive technique: improving pronation control in foot orthoses. JAPMA, 82: 177-188, 1992), well formed medial arch and a slight valgus forefoot extension (start at about 3 mm thickness under 4th and 5th metatarsal heads). This orthosis should not only decrease the sinus tarsi compression force but also should not increase the lateral ankle instability.

    As far as the medial knee pain is concerned, you may need to see how it responds to the boot and orthosis since if the patient has medial knee OA then increasing varus support of the foot may exacerbate the medial knee pain, but if they have medial collateral ligament pain, then this same varus support may make the pain better.

    Hope my rather lengthy explanation helps explain how possessing a good knowledge of the etiologies of the many mechanically-based pathologies that the podiatrist sees daily in their patients, and how these pathologies can be effectively treated with mechanically-based treatments, will make you, and the others following along, much more effective podiatric physicians.
     
  14. Joanne Moore

    Joanne Moore Member

    To one and all of the contributors to this post.


    I can't overstate how grateful I am for your time, and effort in replying to my, and indeed all, Podiatry Arena queries. To have access to the world's leaders in this field is an incredible resource, and I can't quite believe that you would spend the time pondering, explaining, and debating issues which are black-and-white, and clear cut in your minds.

    I have the patient in question coming in this week, and plan on assessing his maximum eversion height, peroneal strength and single leg stance as suggested, and from there come up with a set of orthoses. I'll keep you posted if it be of any interest to you.

    I'm a million miles away from feeling confident with biomechanics, but this really gives me a hunger to study, question, test, and generally poke and prod a bit more!!

    Thank you all again.

    Joanne
     
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