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Uncompensated Forefoot Varus

Discussion in 'Biomechanics, Sports and Foot orthoses' started by RSThorogood, May 13, 2012.

  1. RSThorogood

    RSThorogood Member


    Members do not see these Ads. Sign Up.
    This is a call to anyone who can help with this issue.

    I'm a student pod and whilst on placement, a 17yo male presented with an uncompensated forefoot varus with tight posterior muscles (Gastroc, Calf & Hamstring) and an ankle equinus. During gait, he had excessive lateral contact throughout the stance phase of gait with late stance phase WB on the IPJ of the Hallux. During late stance phase and going into toe-off the patient had to internally rotate his knee to enable his Hallux to hit the ground for toe off. The patient's foot was so fixed that you had to apply an extremely large amount of force to lift the lateral side of his foot whilst WBing.

    Previously he had been prescribed orthotics that he liked and ended up growing out of. This orthotic seemed to be a custom midfoot device with minimum cast fill to contour the foot and enabling better pressure distribution. The orthotic also had an extrinsic medial post at the rearfoot. However, the orthotic quite worn and any other modifications may have been worn down.

    The patient was complaining of pain in the hip & knee joints since he had grown out of his old orthotics, and was asking for new ones.

    The Senior Pod and I casted the patient in a slightly everted position. The senior pod then wanted to prescribe a minimum cast fill midfoot device, with a lateral skive and 1st ray cutout. However, I'm not too sure how exactly the 1st ray cutout will aid in the patients gait, and was looking for some more explanation on this issue.

    Secondly, would a varus wedge under the forefoot be more appropriate in terms of bringing the ground up to the foot and hopefully reducing that internal rotation at the knee?

    Any help would be greatly appreciated. Thank you.
     
  2. efuller

    efuller MVP

    Welcome to the arena.

    First a definition. John Weed taught that an uncompensated rearfoot or forefoot varus was one where there was no motion of the STJ and the heel or forefoot was in varus. A partially compensated varus was where STJ was fully pronated and the medial forefoot did not fully load because there was not enough eversion range of motion available. A person with these foot types will often choose to plantar flex their first toe to get some load on the medial forefoot and hence you will often see a hallux hammer toe. These folks will also tend to walk with their foot abducted so that they can roll off the medial forefoot. To abduct the foot you will usually see the knee cap pointing externally. So there is an inconsistency in the presentation that you describe if this is really a not fully compensated varus foot.

    The wrong thing to do for a partially compensated varus foot is to add a forefoot valgus wedge. You are not going to get the medial forefoot to load with this treatment because there is not enough range of motion in the joints to get the medial forefoot down. The forefoot valgus wedge will just increase the load more on he lateral forefoot in the uncompensated, or partially compensated varus, foot. If your senior pod is willing to learn, you can demonstrate this to him by having the patient attempt to evert in stance. (I have learned from my students.) The partially compensated varus foot (I don't really like that terminology because it takes to long to type) will be unable to evert the foot without moving the top of the tibia toward the midline of the body. I call this the maximum eversion height test, and this test is described elsewhere on the arena.

    I'd agree that if you have an uncompensated varus foot that a forefoot varus wedge would be a better treatment.


    Eric
     
  3. David Smith

    David Smith Well-Known Member


    If the knee pain is due to abduction moments about it and the hip pain is really GT bursitis due to increased tension and tracking of the ITB as the knee adducts and internally rotates, then I would add a forefoot medial/varus post but with the 1st ray/mpj lowered depending on the status of the ray. If the 5th ray is low and stiff then lower the 5th ray and have less varus f/f post. Mobilise the foot and ankle joints, appropriate exercises for hip and ankle RoMs, strengthening and stretching.

    A valgus rearfoot post would tend to increase the abduction moments about the knee and hip and tend to increase pathological forces acting there. Also consider what tissue / structure is stopping the STJ everting and if you try to evert it more by using a lateral post then what trauma may occur to that tissue / structure?

    Regards Dave Smith
     
  4. Bill Bird

    Bill Bird Active Member

    Welcome to Pod Arena. It's addictive but worth it.

    All the above is very helpful but in answer to this specific question;

    "The Senior Pod and I casted the patient in a slightly everted position. The senior pod then wanted to prescribe a minimum cast fill midfoot device, with a lateral skive and 1st ray cutout. However, I'm not too sure how exactly the 1st ray cutout will aid in the patients gait, and was looking for some more explanation on this issue."

    A first ray cut out is usually used if the medial band of the Plantar facia, which inserts anterior to the 1MPJ, tightens when the hallux is dorsiflexed. This causes what is know as the windlass effect as first noticed by Hicks, 1954. By allowing the 1MPJ to drop down into the cutout at heel lift, the cutout releases the tightness of the medial band and allows the hallux to dorsiflex. This is why David asked you if the medial band tightened when the hallux was dorsiflexed.

    May not be the right thing to do in this case, but is a very useful tool in many other cases.
    Bill
     
  5. davidh

    davidh Podiatry Arena Veteran

    Hi, and welcome to the forum.

    From your foot description I agree that a forefoot varus wedge should help.
    I would have tried that first TBH, because without that the patient will still struggle to weightbear on the first ray, and the leg will tend to interally rotate as part of a compensatory mechanism.

    But without actually seeing the patient it's all kind of hypothetical.

    Bill (Bird) - I like your website!
     
  6. Jeff Root

    Jeff Root Well-Known Member

    Did you check the range of motion of the subtalar joint? You could be dealing with a combination of both forefoot and rearfoot varus. If the patient is compensating by abducting their foot and leg due to a lack of adequate eversion (an uncompensated or partially compensated forefoot varus and or a rearfoot varus) then an orthosis with intrinsic or extrinsic forefoot varus posting should help increase ground reaction force on the medial aspect of the forefoot. A varus forefoot extension added to the orthosis will increase the varus correction anterior to the distal aspect of the orthotic shell and can be very beneficial with this foot type. The extension can be sulcus length or full length.

    I would caution against a lateral heel skive if the patient doesn’t have a range of calcaneal eversion available. You can’t force the stj to pronate is there is no anatomical range of motion available. This will only make the heel cup less or uncomfortable. If the heel is functioning in a maximally pronated (maximally everted) position throughout the stance phase of gait, then what is the logic of a using lateral heel skive? You also mentioned equinus. Have you considered using a heel lift (unilateral or bilateral) to address the equinus? Is this patient's condition unilateral or bilateral? Is there a limb length discrepancy? Mild club foot? Congenital abducted talus?

    Jeff Root
     
  7. Dananberg

    Dananberg Active Member

    Very interesting foot type. My take on this is as follows. When equines exists, the peroneus longus is invariably inhibited. This is why he walks on the lateral side of his foot. In addition, there is a failure to adequately plantar flex the 1st ray and/or maintain its stiffness against ground reactive force. What results is a dorsiflexed 1st met, and a plantarflexed hallux used for medial column support. For this portion of the treatment process, manipulation of the ankle is ideal. Ankle joint dorsiflexion can easily be re-established as can peroneal facilitation via this technique.

    Midfoot rigidity, however, requires an additional form of care. I tend to post the forefoot to cast in varus, but c/o the 1st ray in the shell. I then add a forefoot extension as posted 1-5, but cut a kinetic wedge type depression into the top half of the forefoot extension sub 1st. It can be filled with poron, so the top surface is flush. This method effectively brings the ground to the foot, but permits 1st ray plantarflexion/hallux dorsiflexion to occur in a timely fashion. Over time, the varus component of the extension will need to be reduced as using the windlass to mobilize the remainder of the foot usually proves quite successful. Once adequate ROM of the midfoot exists and the patient can pronate the forefoot to 1st met ground contact, the extension can be eliminated.

    Howard
     
  8. cpoc103

    cpoc103 Active Member

    RST:- are you absolutely sure this pt has a varus forefoot, and not a supinatus.
    If was a supinatus this could be why your senior pod used a lat wedge, it sounds as if the pt has a lat avoidance. Is the equinus structural or functional? You said he had tight posterior compartments which could explain this aspect.
    If it is a supinatus then a medial wedge could potentially make this worse, as many have stated inc Craig Payne varus is quite rare and a fixed osseous problem!!
    Good luck

    Question everything knowledge is life!!

    Col.
     
  9. Sally Smillie

    Sally Smillie Active Member

    not really addressing the mechanics, there are much much better folk for that, but as an Aussie trained Pod now practising in the UK, I am intrigued by the very widespread use of 1st ray cut-outs over here. I use them sparingly, and I do suspect desperately over-used here.
    As for the forefoot wedge, it if is a forfeoot varus (osseous) a far less bulky and effective option is the instrinsic forefoot varus shell modification, done usually at the plaster stage of manufacture. It supports the foot in varus until later stance when it allows the 1st MPJ to plantarflex at late stance.
    Can I ask why did they not corrrect the tight posterior musculature which has such a strong influence on the gait and just look at the foot mechanics?
     
  10. efuller

    efuller MVP

    There is an interesting contradiction here. The intrinsic forefoot varus post will tend to raise the arch and when it raises the arch, depending on how the fill is added, it will tend to push up on the underside of the first ray (i.e. not allow first ray plantar flexion). This is dependent on there being a full width orthotic. An orthotic with part of the shell cut out under the first ray would theoretically have less of the problem.

    One of the first things that led me to question the neutral position biomechanics that I was taught in school was the explanation of how a forefoot varus intrinsic post works. Using just pure theory, the STJ should pronate as soon as the heel lifts off of the orthotic. However, clinically, this is not what my instructors were seeing. Their explanation was that the STJ was put in a more stable position and the same forces that would cause, without an orthotic, a compensation of pronation wouldn't cause STJ pronation with an orthotic. Later, I've come to the belief that the high arched device causes more muscular activity, especially in the posterior tibial muscle, and this is why you see resupination with high arched devices.

    Eric
     
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