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Sandal for leprosy patient

Discussion in 'Biomechanics, Sports and Foot orthoses' started by maxants33, Aug 11, 2013.

  1. maxants33

    maxants33 Active Member


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    Hello
    I'm a pod student out in Nepal doing some research at a leprosy hospital. I've been asked if I can make some sandals for a patient who has leprosy, as the footwear that she has been provided with are inadequate for her unusually functioning feet. I'm keen to do a good job as she is at high risk of developing a heal ulcer on her left foot. I would like to check my ideas with the PodA community before I do anything. I must warn readers that I've only been able to briefly assess her, and due to that language barrier and sheer busyness of the hospital, get very limited info on her. She is soon to leave the in-patient department after being admitted for an ulcer on her right foot caused by a burn from a fire.

    Patient has bilateral leprosy induced plantar neuropathy.
    She has undergone tibialis posterior tendon transfer op for a dropped foot on her left foot (TibPost split in two and reattached to TibAnt and EDL tendons, with retraining of muscle to act as dorsiflexor, maybe some folks know this procedure already), also undertaken with achilies lengthening. Op done sometime this year.
    Problem is that the op has left her with 0 degrees plantarflexion, but something like 50 deg dorsiflexion (both passive and active RoMs).


    In gait her left foot sits aprox 5-10 deg dorsiflexed, always WBing on the calc, except at propulsion, when her forefoot briefly touches the ground, but does not appear to bear much, if any weight. The calc also everts quite substantially throughout stance (probs due to relocation of TibPost?).
    Left foot calc plantar surface is also looking quite tender, not yet preulcerative, but looks like its only a matter of time - especially given its the rice planting season here and everyone is working like mad.

    The right foot appears to have normal function.

    I feel she may really benefit from an anteriorly placed rocker bottom on her left sandal, to bring the forefoot into use and take weight off the calc late in gate.
    I would also like to put in an arch support and slight medial wedge in to reduce the excessive pronation.
    I've attached a simple diagram below.
    The only material to use here is Micro cellular rubber, which most of the sandals here are made from (except the straps!). There are several densities to use though. Untitled.jpg

    Its all a bit rough and ready, but really, its either I make her something or she goes on WBing on her calc exclusively and returns with an ulcer.
    Hope someone can help!
     
  2. Boots n all

    Boots n all Well-Known Member

    Because of the dorsiflexed position, you will need to supply a closed back, a single strap around the back will create and narrow band of pressure and most likely not last long, a fully closed back will distribute that pressure better and be more sustainable long term.

    l would also make the heel and sole a single wedge, micro cell will compress quickly with wear and the larger the heel area the less that will effect, this will also help in better distributing pressure at the planta aspect.

    l understand the material limitations, a SACH would be good, but due to resources available ? at least do a rocker heel.

    Hope that helps, good luck with it.
     
  3. maxants33

    maxants33 Active Member

    Thanks David! Great advice!
    I have another patient who needs footwear mods! this time a leprosy affected man who was discharged 3 days ago after being admitted with a grade 4 neuropathic ulcer on the styloid processes of his 5th met, he's back with an even bigger wound, looks like footwear may be implicated... I will post this ASAP, I have ideas but they are a bit crazy, as the man's common peroneal nerve seems completely shot - there is so much to address... I will post photos later today. Probs not much that can be done, but better to try than to not I figure....
     
  4. maxants33

    maxants33 Active Member

    Hello this is the other patient who needs some kind of footwear intervention. Any suggestions are welcome!!!


    He has severe leprosy induced peroneal neuropathy and grade 2 weakness in the respective muslce groups. His foot is inverted through out swing phase and clearly suffers form foot drop ( all the classic hip-hiking and extra knee flexion for clearance). Both feet suffer from plantar insensitivity.

    -----BMX is described with his current sandals on ( see pics) which have a large lateral posting---- All that can be seen on non-sandal wearing is a fully inverted foot, much like the gait of a club foot child. I have video, but the internet is so poor
    here I cant seem to upload it....:wacko:

    At loading he lands very inverted on the lateral side of his foot, but with the midfoot/calc both contacting simultaneously (this is when I think the ulcer site is traumatized). This contact is followed by a rapid pronation of the STJ which brings the rest of the plantar aspect into contact with the ground. The interesting thing is that his ankle/ leg stops moving while this pronation occurs, its as if he stops gait and all forward motion to allow his STJ to pronate, forward motion resumes after plantar surface is loaded.

    Mid stance looks nice and even, but when the foot moves into propulsion, it appears that weight is being borne on the lateral forefoot (5th-3rd mets), with the hallux the first of the toes to leave the ground ( also seems to me that there may be some preulcerative lesions around his lat forfoot).

    In the photos, you can see the resting position and angle of his STJ, thats roughly the angle he's at throughout swing and the angle at which he contacts the ground with his mid foot.
    P1060925.JPG

    P1060924.JPG

    P1060922.JPG

    P1060923.JPG

    Any advice would be great, its quite scary to be a student and faced with such important cases. I've attached a provisional idea for a sandal, please let me know if you see any problems with it (strapps not included in my design, but would be there in real life!).


    Hope someone can advise!
    Many thanks
    Max

    P.S - sorry for posting such rubbish histories and descriptions, its just so busy here and there are so many barriers that prevent thorough assessment.

    P.S No.2 :

    Forgot to add to my diagram - lateral flaring on the sandal heel area! (dont know how much to add, probs try a few things)
     

    Attached Files:

  5. angermayer

    angermayer Member

    Hi Max,

    Hope you are enjoying the busy life of the hospital... Your design of the sandal, although extreme, may work (in my inexpeienced opionion). My only thought is to address the area of the current styloid process ulceration by either using a low density material underneath or slightly hollowing the insole... Also be careful not to attach the straps anywhere near it as it may bulge the insole up.

    Bear in mind friction forces and therefore do not go to extremes with heel hight. Foot held by straps alone will be difficult to control and may lead to blistering.

    Good luck in your craftsmanship

    Michal
     
  6. Boots n all

    Boots n all Well-Known Member

    Go for a closed back, you want to control the foot and avoid as best you can any heel movement.

    If the back finishes its distal edge where the strap is, this will create a dip in the insole where the styloid wound is , helping to off load.

    As to the foot invertion moment, l would agree with building the sole with a lateral flare, but looking at the wear on the sole and your description he is making heavy fore foot strike.

    Are both heels built up the same, does the client have an LLD??
     
  7. maxants33

    maxants33 Active Member

    Thanks Boots n all!
    I really appreciate your looking into this. I've added a closed back to my design. I did check him for an LLD, nothing significant, but I checked him by wiggling his legs and comparing malleoli. The RF (ulcer foot) is more built up around the heel, so shod, there is a bit of a LLD.

    After loading he does sort of 'shudder' onto his forefoot, but seems to do most of the WBing on the 5th-3rd mets. His 1st ray seems quite dorsiflexed. I'm unsure about the extra material under the 1st-2nd rays - to get them WBing - does this seems smart? That lateral forefoot seems at risk of ulceration so I'm keen to redistribute that lateral pressure. the thing is, his peroenus longus is shot, and its difficult to test the condition of his FHL due to the deformity and language barrier. Is it OK to move weight onto a metatarsal that maybe does not have that much active muscle support?
     
  8. Boots n all

    Boots n all Well-Known Member

    Because of the nature of your sandal l would be reluctant to lift under 1st-2nd, you may cause the clients foot to slide across to the lateral side, the straps may not be enough to hold the foot? in a shoe it would work.

    Try it, but be prepared to have a very close look at gait and make the judgement.

    As to heel build up, and it is hard to make this call without seeing gait, l would consider increase heel pitch for both, this will help get better heel contact and spread the load.

    Try a few ideas, be prepared to be wrong and adjust as you see fit, with micro cell you will see marks on the sole very quickly and this will guide you.

    Thats it for me, l am off overseas until September, there are plenty of others here to help you along the way, all the best!
     
  9. markjohconley

    markjohconley Well-Known Member

    Good on you David!
     
  10. efuller

    efuller MVP


    Wow, what a great learning environment. Have you read Kevin's rotational equilibrium article. Have you read my center of pressure article. Have read the classic Hicks article on the function of the muscles. These articles can give you the background to help understand the pathology that you are seeing.

    The posterior tibial transfer sounds more like a posterior tibial sacrifce to create a ligament that does not allow plantar flexion of the ankle joint. (in my opinion, a very questionable choice of surgery.) Is there still some dorsiflexion range of motion left.

    It sounds like you are on the right track with the idea that the problem is too much weight on the heel and the solution is to transfer that weight to the forefoot. The advice that you have on strapping/ uppers sounds good. The shape of the outersole is going to be dependent upon ankle dorsiflexion and angle of the tibia to the ground at toe off. If the person wants, is able to, take longer strides then If the person would like to take longer strides then a wedge under foot to keep the foot dorsiflexed with a rocker break proxiimal to the met heads. The angle of that break should not be so big that it demands plantar flexion of the ankle. I'm going to try and put that all together. At the heel the thickness of the outersole will be just enough to allow for a few months of wear (a minimal amount) The outersole will get progressively thicker to a point just behind the metatarsal heads. This will create the dorsiflexion angle for the foot bed of the top of the sandal. At the point just proximal to the metatarsal heads the midsole/outersole will start to get thinner. The angle between the flat surface of the proximal part of the outer sole (sagittal view) and the distal part could start at 10 degrees and then you could grind more of an angle after watching the patient walk. Of course, the rocker effect should be abandoned if the lack of sensation makes walking dangerous on the more unstable shoe. Without a rocker there is a very good chance of developing genu recruvatum

    I also like the idea of the varus heel wedge to counteract the loss of the posterior tibial muscle. As was already pointed out, when you stand on a varus heel wedge you will tend to slide from medial to lateral and there needs to be something that stops that slide. A heel cup, like an orthotic, within the sandal may do it. A heel counter may do it.

    Try and notice with your patients which muscles are still working and which muscles have 0 strength. And then observe the gait. You will get no better education on what the muscles do in gait.

    Good luck.
    Eric
     
  11. efuller

    efuller MVP

    The other article you need to be familiar with is Kevin Kirby's palpation of the location of the STJ axis. Knowing where the axis is can be helpful in understanding whether or not a forefoot varus wedge will be helpful in this patient. From your description it sounds like the peroneal muscles have no strength and this is why the foot is varus in swing. You should check this by looking at range of motion available of the rearfoot. Weight bearing you could try the Coleman block test to see how how much range of motion in the direction of eversion there actually is. (The maximum eversion height test won't work because there are no peroneal muscles.)

    The absence of peronus longus could be the reason that the first ray looks dorsiflexed.

    The position of the STJ axis is critical is that it determines what ground reaction force will attempt to do to the foot. The weight bearing part of the foot can move relative to the axis. If only post tib is acting the foot will supinate during swing and pull most of the foot to a position that is medial to the STJ axis. Then when the person attempts to bear weight the foot will be pushed into further inversion. The hitch you see in the gait may be an attempt for the person to "shake" the foot into a more pronated position so that ground reaction force will now create a pronation moment. I've seen a person with a laterally positioned axis that chose to forefoot strike to land first on the fifth met head so that the ground would pronate the foot. When he landed heel first, ground reaction force on the heel would tend to supinate him too much. Look at the hitch in gait ans see if he moves his leg from lateral to medial just before heel contact. This will create a medial to lateral component of force that will tend to pronate the STJ. It might help you to figure out why the STJ pronates after contact.

    A laterally deviated STJ axis will also tend to cause high loads on the lateral forefoot. That could be the cause of the ulcer and appearance that he only bears weight on the lateral forefoot. It could also be lack of eversion available. Or both a lateally deviated STJ axis and lack of eversion available.

    So, if the laterally deviated STJ axis is causing the high lateral forefoot loads the valgus wedge is a really good idea. You could cut a hole in the valgus wedge under the ulcer to off weight that specific area.

    If there is no eversion available and an average or medial STJ axis location then a forefoot varus wedge might help. If there is a lateral axis a forefoot varus wedge will just cause him to roll his ankles into inversion. If you are not experienced in finding the axis, you could just see if he can stand on a temporary forefoot varus wedge. If he is unable to put any weight on it without falling down he has a lateral axis and the varus forefoot wedge will just makes things worse.

    Now, this guy might be a surgical candidate for a tendon transfer. If he has the range of motion available, a transfer of one of those now useless peroneal tendons to create a ligament that prevents STJ eversion could possibly be helpful.

    Good luck. Let me know if you want to expand on any of these ideas.
    Eric
     
  12. efuller

    efuller MVP

    Google "podiatry arena: maximum eversion height test" to see a thread that talks about how much wedge to add.

    Looking at the non weight bearing foot, in that much varus, I really want to put this guy into high tops. Really high top shoes that have an eversion angle on the rearfoot. That picture is really crying out for control from above the ankle. I just want to put some tape from around his heel and up the lateral side of the leg to pull the heel into inversion. If you only had the materials.
    Eric
     
  13. maxants33

    maxants33 Active Member

    Wow!! Thanks Eric! Your advice has been really useful, especially the use of rotational equilibrium, this seems quite important here. I've included your thoughts into my design - its also really useful for me as a student to better under stand what is going on in this patient.

    Unfortunately an above ankle device or high tops are not going to work here - due to the stigma that comes with them. He had been given a caliper type device in the past but discarded it due the thing people said to him. The leprosy stigma is such a huge obstacle to compliance here, most patients will only wear modified sandals or shoes.

    I also said to the surgeon here about a peroneal tendon being used to fix the foot in a more everted position, I'm guessing you mean from the 5th met or cuboid to the fibula?
    The surgeon was thinking about moving his tib-post across to the lateral forefoot or peroneal insertions. I dont like this idea, I imagine that retraining the tib-post to do a peroneal's job would be pretty difficult, there could be a risk of losing both lateral and medial muscle support if it failed also.
    Any thoughts on this?

    Foot wear designs submitted to the footwear dept, I leave Nepal in a week, so hopefully I will get to see some results (good or bad) before I go.

    I would definitely recommend leprosy work to other pods, I will be back and for longer. Its so challenging, but the sense of reward is very high!!
     
  14. efuller

    efuller MVP

    In regards to the surgical choice: It really depends on the ability of the relevant muscles to produce force and the available range of motion of the joints. If there is no peroneal strength then there is no loss in using that tendon. There is no point in doing the surgery unless the foot can evert to the point to get the medial forefoot to the ground. From what you have said, I would use a peronal tendon to go from the lateral maleolus to the body of the calcaneus to hold the STJ into eversion. If there is still any strength in peroneus brevis the patient would retaing the ability to shift force on the forefoot with motion of the midtarsal joint using post tib and peroneus brevis or longus. That will give them a bit better ability to balance. (Balance is the ability to shift the location of the center of pressure under the foot using muscles. Look at your foot as you stand on one foot and you can see the back and forth shift from the muscle activity.)

    If the posterior tib is used, retraining may not be the issue, but the ability for the tendon to slide. If it doesn't slide you are only creating a ligament. (As was seen with that other patient.) There may be some benefit to removing the deforming force of the posterior tibial muscle, but if you already have weak muscles destroying another doesn't seem right. Is the posterior tib the deforming force? From my vantage point, it seems that your surgeon seems to fixated on post tib transfer surgery. It is better to think about what the problem is and how to apply the forces that you want to fix the problem than to look at the published surgeries that exist. In this foot you want to increase eversion moment or create a more everted position. This can be done without cutting the posterior tibial muscle.

    Eric
     
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