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Plantar hallux ulcer with posterior tibial tendon dysfuntion

Discussion in 'Diabetic Foot & Wound Management' started by MBel, Jan 7, 2015.

  1. MBel

    MBel Member


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    Hi All,
    Just wondering if anyone would be able to offer any advice regarding a pt. I have been seeing for the past few years that has a recurrent ulcer plantar to her hallux. We can get the ulcer heal, via use of a pneumatic walker or felt padding with a wound shoe. However when we transition from said offloading modalities to her pedorthic supplied footwear the area reulcerates. Pedothic footwear consists of sandals and closed in depth shoes with total contact orthotic, rockersoles with stiffened carbon plates.

    Pt. is 78 year old with long standing T2 diabetes requiring insulin, acute kidney failure in April 2012, current chronic kidney disease stage 3, hypertension, diabetic retinopathy. Most recent HbA1c in March 2014 was 7.5%

    She has peripheral neuropathy, adequate pedal vascular flow, functional hallux limitus, stage 2 posterior tibial tendon dysfunction with no pain. Foot has typical appearance of a PTTD stage 2 being abducted forefoot, collapsed midtarsal joint, minor talonavic bulge and calcaneus eversion. Ankle dorsiflexion causes abduction.

    She has been review via the regional orthopedic foot and ankle surgeon who performed an achillies lengthening procedure. This hasn’t been successful in helping prevent reulceraton.

    I have modified her orthotics multiple times to help reduce her midtarsal collapsing and plantar flex her 1st ray to alleviate her FHL. This failed as has a mortan’s extension.

    Compliance with offloading is overall good, however she does admit to not wearing any offloading device if needing to get out of bed at night.

    My current thought is offloading via an AFO? Any other advice would be much welcomed.

    Michael
     
  2. footplant

    footplant Active Member

    Hi Michael,

    Thanks for sharing this case. I have a diabetic orthotic clinic, so very interested, but this isn't an expert opinion by any means. I assume the ulcer is under the inter phalangeal joint of the hallux?

    From what you're describing I'd want to know whether you've tried increasing the angle of the rocker sole, or moving the apex proximally? For example, placing the apex at 60% of shoe length.

    Also, what kind of cover are you using with the foot orthosis? If a foot orthosis aiming to reduce mid foot collapse or aid 1st MPJ motion hasn't helped, have you tried a very soft orthosis with low density cover like poron. For example a 3-6mm thick 30 shore EVA base plus a 3-6mm poron cover?

    Finally, like you say I would think that the more invasive option of an AFO with a suitable footplate should be able to recreate the success of the pneumatic walker.

    Best wishes,

    Josh
     
  3. Ben Lovett

    Ben Lovett Active Member

    Hi Michael,
    Sounds like you’re on the right track but with the background of kidney disease and insulin controlled DM2 any pressure may be too much pressure for an area already damaged by ulceration.

    In my experience plantar 1st IPJ ulcers represent the most difficult to offload as the windlass mechanism will plantar-flex the hallux until balanced by the resulting ground reaction force. In some one with stage II PTTD this force will be very high due to the loss of the supination moment provided by Tibialis posterior.

    We’ve started tuning orthotics aimed at off-loading the 1st IPJ with an F-Scan in shoe plantar pressure analysis system and the results have been interesting.
    Not too surprisingly standard full contact EVA orthoses almost invariably increase the pressure at the 1st IPJ where there is a functional windlass mechanism due to their tendance to reduce 1st ray plantar-flexion. Met domes, lateral forefoot wedges, 2-5 met head support and long 1st ray cut outs all tend to help, but not necessarily consistently which is where the F-Scan really helps.

    From what you’ve described controlling the presumably large pronation moment is going to be key to de-tensioning the plantar fascia and reducing the hallux plantar flexion moment.

    I think you’re on the right track with an AFO as this would theoretically provide the greatest pronation control especially if combined with a medial heel skive. If it also incorporated a long 1st ray cut out and 3-4mm of support for the 2nd-5th met heads then the IPJ pressure might start to come down. I would certainly combine the AFO with a rocker sole shoe (how's her balance?) especially if the AFO's rigid at the ankle.
    Overall there are a lot of variables and finding the right combination is tricky without some way of measuring plantar pressures incurred in the device and footwear combination.
    Good luck
    Ben
     
  4. MBel

    MBel Member

    Hi Josh and Ben,
    Many thanks for you reply’s. Josh this pt. has had a few different orthotics over the past 3 years. Currently they have typical tri density orthotic, that being EVA base with poron/plasterzote liner. The rocker apex is approx. plantar to the metatarsal heads. Both orthotic and shoe modifications were done via a pedorthist. The orthotic could defiantly be improved to help reduce pronatory moment, mid tarsal collapse, plantar flexion of the 1st Ray and de-tensioning the plantar fascia for reduce force plantar to IPJ of the hallux. The pedorthist takes foot impressions semi-weightbearing in a foam box without plantar flexion the first ray or making sure the midtarsal isnt collapsing.

    Ben an F-Scan or pedar would most definitely be or great value. I have tried all of your orthotic modifications you listed with no luck. That is why I was thinking of going down the AFO track as this would reduce the pronatory moment the most.

    Would an AFO with a full length foot plate be of benefit in this instance?

    I was also wondering if any of the surgeon’s on podiatry-arena, are preforming any offloading procedures for chronic hallux ulcerations? Not necessarily with PTTD because like Ben said hallux ulcerations can be very challenging to offload.

    I will try and upload a photo of their current sandals/orthotics.

    Many thanks

    Michael
     
  5. MBel

    MBel Member

     

    Attached Files:

  6. Ben Lovett

    Ben Lovett Active Member

    Hi Michael,

    A fixed ankle, ridged foot plate AFO with a rocker soled shoe would be very similar to a pneumatic walker which you say you’ve had success with in the past, so this should be worth a go since you’ve already tested the concept. Locking the whole foot up essentially switches off the windlass mechanism that is the cause of the trouble in the first place.

    If you start with a ridged AFO an ankle hinge could be added in future if the rigid device causes problems and similarly the foot plate could be shortened and the 1st Ray cut out if it turned out that the rigid foot plate didn’t help.

    In terms of surgery a rotational / translational calcaneal osteotomy and FHL splicing to tib post should greatly reduce pronation moments and hence plantar fascia tension but her medical background may preclude this (I’m not a surgeon BTW). Shortening the 1st met or removing the proximal phalange would take the tension out of the plantar fascia of course but might hasten the development Adult Acquired Flat Foot. I suspect most surgeons would simply amputate the toe as this would carry the least chance of complications.
    Ben
     
  7. Ben Lovett

    Ben Lovett Active Member

    Just saw your photo of the orthotic. Hard to say from one view but I would say that there’s a fair chance it could be increasing plantar hallux pressure.

    Attached is an example from a patient with persistant bilateral plantar IPJ ulcers. The initial F-Scan run is the patient in his rocker soled shoes with no orthoses (godos2). The next run is with his orthotists manufactured total contact insoles (godos3 - as with your pedorthotist no attempt is made to allow for 1st ray function). The result is an increase in pressure time integral at the IPJ from 0.38 kg/cm2xSec with no insole to 0.45 with the insole on the right and from 0.55 to 0.81 on the left.

    I then ground out the 1st Ray, added a 2-5 platform , a 5° rear varus wedge and some heel raise godos 4 (he had pronounced ankle equinus) and got the plantar hallux pressure time integrals down to the point where the orthotic were at least not making things worse, however not much better either.

    I then tried to increase the pronation control of these devices by increasing the posterior aspect of the arch profile with some poron - godos5 (see photos) this made things worse again. I’m assuming this is because it applied pressure to the plantar fascia and therefor a plantar flexion moment at the 1st IPJ. In another patient with a less prominent plantar fascia the result might well have been different.

    I’ve there for given up on trying to modify the TCIs and cast him for polypro devices with a medial heel skive, long 1st cut out and 2-5 extension. I haven’t issued these yet but will run them over the F-Scan when I do.

    Hope that's interesting even if it dosn't tell you where to go with your specific case.
    Ben
     

    Attached Files:

  8. footplant

    footplant Active Member

    Hi,

    Again, interesting discussion. Thanks for attaching the graphs. I don't have much experience with polypropylene foot orthoses in patients with ulceration. Just in terms of the picture of the sandals, I notice that there is a bit of heel-sole differential / pitch (15-20mm?) which I'd assume would move pressure anteriorly towards the hallux. The rocker sole also seems to be very minimal. Where I've had success in these cases has been with much larger rocker soles, and minimal or no pitch (or even negative pitch) which effectively moves pressure back to the mid foot (illustration at link below for reference). Provided that the tissues of the mid foot are able to take the pressure. But again, an AFO is an option especially with the PTTD.

    Best,

    Josh

    http://www.bapo.com/Framework/ResourceManagement/GetResourceObject.aspx?ResourceID=5c169360-34f3-4396-a7aa-57343bdaf4a6
     
  9. RobinP

    RobinP Well-Known Member

    The heel pitch will actually pull the centre of pressure toward the heel. If there is equinous present, this is a must as not accommodating the equinous will massively increase forefoot pressure.

    I would agree however, that the rocker sole is insufficient and would probably do better point loaded and further back. It is probably worthwhile looking at how good Windlass function actually is. More importantly, reverse windlass - ie load the 1st MPJ heavily and see how much plantar flexion of the hallux there is and how strong it is.

    In many cases, there may not be much reverse windlass function and you can simply use a thick Mortons extension effectively jamming up 1st ray movement and creating an artificial "rocker" inside the shoe. In combination with a very loaclised void/window/sink/aperture under the ulcerated area, you might get little enough pressure(and importantly friction) in the area to keep it healed.

    Not the first choice but sometime worth a shot before deciding to use an AFO/CROW
     
  10. footplant

    footplant Active Member

    Hi,

    Can you explain the pitch / movement of pressure for me? I thought that in the absence of reduced ankle joint range of motion increasing the pitch would move pressure forwards, and reducing it would move pressure backwards. I just looked around for papers but could only see the one below. It kind of backs up what I was thinking but it's looking at pretty high heels..

    Thanks,

    Josh

    http://www.sciencedirect.com/science/article/pii/S0958259204000781
     
  11. Ros Kidd

    Ros Kidd Active Member

    A recurrent ulcer in a diabetic patient raises the spectre of osteomyelitis and should be investigated. Whilst the HbA1c isn't "awful" it could be tighter. Perhaps a review by a High Risk Foot Clinic would be helpful.
    My 2c worth
    Ros
     
  12. MBel

    MBel Member

    Many thanks for all your replies. I totally agree that the rocker could be improved Josh and they would benefit from a different sole pitch. I have had several discussions with the pedorthist about rocker locations, apex and details. Not sure how clued up they are about rocker design.

    Thanks for the f-scan attachment Ben very interesting. I have used all of your orthotic modifications listed with no such luck. That being heel lift, aggressive rearfoot wedging, increasing arch profile, reverse mortans extension, cluffy wedge, mortans extension with depression for the IPJ.

    They have had an achillies lengthening procedure done and ankle dorsiflexion range is excellent.

    Ros thanks for your input. They have and are continually assessed for osteomyelitis as well as having a biopsy done to rule out any other pathology’s. I do consist of a minimal model HRFC, consisting of podiatrist, wound nurse and diabetes educator. We do have access to vascular surgeons and one regional orthopaedic foot and ankle surgeon. We don’t work as a team, which would be greatly beneficial. That is the way it works in many region areas of NSW, unfortunately.

    On a side note, the orthopaedic surgeon stated that they had good 1st MPJ ROM and suggested that they offload the area via an offloading corn pad from the chemist! I was a little dumbfounded from this suggestion?:wacko:
     
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