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Advice please on orthotic prescription in case of PF

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Berms, Apr 9, 2008.

  1. Berms

    Berms Active Member


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    Hi all, just hoping someone may be able to help me with my orthotic management of a case of chronic plantar fasciitis.

    46yo lady, chronic p/f last 5 years (unsuccessfully managed so far), general a ligament laxity associated with systemic condition (she couldn't remember the name of the condition) excessive motion about both axes of the MidTarsal Joint and excessive rom of the 1st ray.... all leading to excessive pronation resting stance and during gait. Hallux valgus deformity also present with early degen of 1st MTP joint. She also has severe fat pad atrophy under the heels and plantar met area.

    However, when I line up the foot in "neutral" with the pt lying in the prone position, everything lines up? ie, no FF or RF alignment issues? But when I let go the foot shape becomes a mess. I took the cast and laid it on the table, and there is no forefoot to rearfoot abnormality to correct?

    My question is, what do I need to focus on with the orthotic prescription?

    Thanks for any advice.
    Adam.
     
  2. Re: Advice please on orthotic prescrition in case of PF

    My $0.02

    If she's got lig laxity from a systemic cause and the foot corrects into a good position just give her a neutral cast with no posting to capture the foot in its non-"mess" configuration. Or, if you think that she needs something a bit more substantial then pop a small rearfoot medial post on (depending on what a navicular drift / drop tells you about the planal dominance).

    I might be tempted to pop a cavity in the heel and stick something soft in there to compensate for the Fat pad atrophy as well. Correcting the biomechanics alone won't work if she's walking on bone...

    Regards
    Robert
     
  3. Ella Hurrell

    Ella Hurrell Active Member

    Re: Advice please on orthotic prescrition in case of PF

    I agree with Robert - you will probably benefit from adding some cushioning to allow for the fat pad atrophy.

    Just a thought but are you sure that plantar fasciitis is the correct diagnosis? Perhaps you could get an ultrasound scan or MRI to identify?

    Ella
     
  4. slaveboy

    slaveboy Member

    Re: Advice please on orthotic prescrition in case of PF

    What is the patients subtalar joint and hubsher test or fhl?
     
  5. Ian Linane

    Ian Linane Well-Known Member

    Re: Advice please on orthotic prescrition in case of PF

    Hi

    Think Roberts option is reasonable on what you describe so far with the options of a skive.

    Not sure what management issues you have taken yet but some thoughts if they help:

    What at the accessory movements like at the TCJ. Although the foot may be "messy" there may be limitation of TCJ movement that contribute to the tissue stress and inhibit recovery.

    Taking up Ellens point I have had 4 cases recently of long term "diagnosed PF". Whilst there may have been some involvement of the PF the greater areas of palpable discomfort was abductor hallucis. Deep tissue work to this area proved to be the resolution giver. ( with some orthoses in a couple of those cases)

    Cheers
    Ian
     
  6. David Smith

    David Smith Well-Known Member

    Re: Advice please on orthotic prescrition in case of PF

    Adam

    You wrote
    My answer is - Saggital plane progression. (probably)

    You don't give much info but does she have a cavus foot? does it have a flexible f/foot equinus? What is the relaxed "messy" position like exactly? What is her ankle dorsiflexion like- stiff or compliant? stiff I would expect, or compliant but restricted end RoM. Does the medial longitudinal arch continue to lower and extend after full hallux plantarflexion ie toe contact? IE does she have Functional hallux limitus. Are the Posterior muscle groups stiff or compliant? Does she have even hip levels? What positon is her pelvis in normal stance and gait. Does she stand with fully extended knees or flexed knees. Does she exhibit extensor substitution? ie does she use her EHL and EDL to dorsiflex the ankle?

    In people with lax ligaments it is my experience that many also have tight muscles and tendons. Therefore the joints are able to compensate for the muscle tightness, and do.

    Interventions, such as orthoses and mobilisations, need to address these criteria if they exist.

    I can say more about the prescription once you have answered the above.

    Cheers Dave
     
  7. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    Re: Advice please on orthotic prescrition in case of PF

    Only one thing to focus on: Reducing the force in the injured structure. Is Jacks test or the Hubschur maneuver easier standing on the orthotic than off the orthotic?
     
  8. Berms

    Berms Active Member

    Re: Advice please on orthotic prescrition in case of PF

    Hi Craig. Several people have also mentioned the "Jacks Test" and "Hubschur maneuver". I am not familiar with these tests, do you have any links/discussions describing what they are and how do perform them?

    Thanks.
     
  9. Berms

    Berms Active Member

    Re: Advice please on orthotic prescrition in case of PF

    Thanks David. Excuse my ignorance, but could you explain Saggital plane progression?


    Slightly cavus (but flexible) foot, ankle dorsiflexion adequate but less than 10deg, yes FHL (I think), Valgus knee position during stance, yes - significant extensor substitution....

    I have opted for a device which aims to reduce tissue stress, particularly on the plantar fascia, offload pressure on the 1st met head with cut out and reverse mortons ext 2-5, and a heel aperture with some additional padding for comfort/shock absorption.... How am I doing so far?
     
  10. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    Re: Advice please on orthotic prescrition in case of PF

    The simplest form* of the test is to have patient standing and you dorsiflex the hallus and estimate how hard it is. Then have them stand on the orthotic and do it again. Theoretically, if the test is easier, then there is potentailly less force going through the plantar fasica and the windlass establishes much easier.

    We got some data on people with unilateral plantar fasciitis and the force in Newtons to dorsiflex the hallux was substantially higher on the symptomatic side when compared to the asymptomatic side. This could have been the reason for the plantar fasciitis or it could be a consequence of the plantar fasciitis (the cross sectional nature of the study design does not allow a conclusion either way). Either way the forces were high and the intervention has to reduce it for them to get better.

    As an exercise, do Jacks test before and after putting on low dye tape .... the force needed to dorsiflex the hallux goes down to almost zero .... imagine what that does to the forces in the tissues.

    *We have refined the test to also look at the timing of those forces, but lets get into that another day
     
  11. David Smith

    David Smith Well-Known Member

    Adam

    The planes of the body can be imagined as saggital, coronal / frontal and transverse. These are called the cardinal planes (As I expect you know)
    The saggital plane is the one that is parallel to the normal direction of walking.
    Sagittal plane theory says that when saggital plane progression ie forward motion or Centre of Mass velocity is blocked by some anatomical or physiological condition then there may be some compensations in the closed kinetic chain (usually about the joints) that allows the continuation of forward motion. These compensations may cause pathology due to increased stress in the relevant tissues.

    Dananberg focuses on Functional hallux limitus as a major block to saggital plane progression and proposes that pronation is a primary compensation of FncHL. I and others including Dr Kevin Kirby do not think that FncHL is the primary cause of pronation rather that excessive lowering and extension of the MLA often due to pronation can result in FncHL. It is possible in my opinion that at this stage FncHL may be a cause of a secondary compensation resulting in additional pronation. The difference may be a result of perspective or relativity.


    To better understand these concepts read:

    Sagittal Plane Biomechanics HOWARD J. DANANBERG, DPM*(J Am Podiatr Med Assoc 90(1): 47-50, 2000)

    The Windlass Mechanism of the Foot A Mechanical Model to Explain Pathology
    ERIC A. FULLER, DPM*(J Am Podiatr Med Assoc 90(1):35-46, 2000)

    Plantar Fasciitis and the Windlass Mechanism: A Biomechanical Link to
    Clinical Practice Lori A. Bolgla; Terry R. Malone Journal of Athletic Training 2004;39(1):77–82


    THE MECHANICS OF THE FOOT II. THE PLANTAR APONEUROSIS AND THE ARCH
    BY J. H. HICKS

    Subtalar Joint Equilibrium and Tissue Stress Approach to Biomechanical Therapy of the Foot and Lower Extremity By Eric Fuller, DPM and Kevin A. Kirby, DPM

    A Study of the Elastic Properties of Plantar Fascia D. G. WRIGHT and D. C. RENNELS
    J Bone Joint Surg Am. 1964;46:482-492.

    Manipulation Method for the Treatment of Ankle Equinus Howard J. Dananberg, DPM* Jenna Shearstone, ATC†Michelle Guiliano, DPM‡(J Am Podiatr Med Assoc 90(8):385-389, 2000)

    Do a key word search for similar discussions in this Forum.


    Sounds OK, **ideal, some heel lifts would be good. Maybe a kinetic wedge. Mobilise the ankle if possible, give stretching exercises for posterior muscle groups. If you find the STJ axis is deviated medially you might want a medial skive. If there is a N/WB forefoot equinus I like to capture that in the cast and post it with a heel lift. (Or as I have an Amfit scanner, I scan it in a semi w/b position with extra presure on the Amfit pin to lift the heel and capture the f/f equinus.) Also post any apparent lld. Then at review see if it has altered and change as necessary. Refer to physio for proximal muscle tightness.
    I would try these things first without any medial posting as this may impede any pronation necessary to stop more proximal compensations. Remember pronation is only bad if it contributes to increased tissue stress that is likely to be pathological otherwise its normal an often optimal.

    Those are my thoughts anyway Adam, I expect there may be others who disagree though.

    Cheers Dave
     
  12. Adam and Colleagues:

    In patients that have proximal plantar fasciiitis (i.e. pain and tenderness plantar to the medial calcaneal tubercle), the two most common causes of this pain are excessive tensile forces within the plantar fascia and/or excessive compression forces caused by ground reaction force (GRF). I would suspect that in your patient, with the plantar fat pad atrophy, that certainly the compression forces that occur plantar to the heel from GRF during gait and/or during standing are a major cause of her continued symptoms.

    In order to reduce GRF plantar to the calcaneus, a well-cushioned foot orthosis (sometimes I will use a up to 6 mm of "Spenco" insole material as an orthosis topcover in these patients) along with using a "tight heel cup" to transfer force to the periphery of the plantar calcaneus will often be very helpful. I will order a plastazote #3 orthosis with the heel contact point made 3-4 mm thick with one to two layers of 3 mm Spenco topcovering material (3-6 mm total thickness). I will then grind the plantar heel of the orthosis into a "dell" or concavity, leaving the periphery of the plantar rearfoot post full thickness and the central plantar heel only 0.5 mm thickness. This "trampoline effect" of the orthosis heel cup reduces the thickness of the orthosis directly plantar to the symptomatic area while leaving the periphery of rearfoot post of the plantar calcaneus full thickness so that the GRF of the central calcaneus is reduced. AVIA uses a similar idea in their running shoes with their cantilever or anatomical cradle design.

    I also will make certain in patients like these that the patient never walks barefoot or without some sort of foot orthosis or heel cushioning under their heel. This is especially important since many people now have hardwood floors or tile floors in their homes and these harder flooring surfaces can cause injury to the plantar heel over time. I tell patients to sometimes even wear a rubber slipper shoe when taking a shower (I like the Crocs for that purpose) so that the heel is not irritated while standing on the tile floor of their shower. A favorite analagy I use for patients is as follows: what does your dentist tell you to do when you have a sore tooth?....don't chew on that side of your mouth! In much the same way, by not constantly irritating an inflamed heel by walking on it at home without adequate cushioning/support, their heel pain is likely to get better faster, just like a toothache will get better often if you don't constant chew using that tooth.

    As far as the tensile forces in the plantar fascia, the plantar fascia (i.e. central component of the plantar aponeurosis) will exert signficant tensile forces on the plantar calcaneus at its origin at the medial calcaneal tubercle during weightbearing activities. Therefore, one of the reasons that the plantar calcaneus is so commonly injured is that it is only area of the body that is subjected to a combination of such very large compression forces (from GRF) and very large tensile forces (from plantar fascia and plantar intrinsics).

    Research using cadavers and also mechanical modelling indicate that there is a direct correlation between the magnitude of tensile force within the plantar fascia and the magnitude of tensile force within the Achilles tendon. One cadaver study estimated the tensile force within the plantar fascia to be at 0.97 times the body weight of the individual. This means that for every 20 pounds of increased body weight, the plantar fascia will have approximately 20 more pounds of tensile force within it with each step.

    Plantar strapping (i.e. low-Dye strapping), foot orthoses with well-formed medial longitudinal arches and medial heel skives, and Achilles tendon stretching will all decrease the tensile forces within the plantar fascia which may also help with the pain of proximal plantar fasciitis. Wearing shoes with higher heel height differential will also tend to decrease the plantar fascial tensile force and relieve plantar heel pain but these shoes may also increase the GRF plantar to the calcaneus so that these shoes may not always help the pain in some individuals. I have also recently been finding that some patients respond to recalcitrant proximal plantar fasciitis by wearing spring heeled shoes (i.e. Z-coil shoes).These shoes seem to greatly reduce the GRF of heel impact during walking and minimize heel pain over time in some individuals. Unfortunately, these shoes cost about $200.00 (US Dollars).

    Hope this short analysis of the mechanics and treatment of proximal plantar fasciitis is of some benefit for you and your patients.
     
  13. Berms

    Berms Active Member

    Re: Advice please on orthotic prescrition in case of PF

    Thanks Craig.
     
  14. Berms

    Berms Active Member

    Thanks very much for the post Kevin - very informative.
     
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