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Lateral STJ instability with restricted internal hip RoM

Discussion in 'Biomechanics, Sports and Foot orthoses' started by David Smith, Apr 21, 2016.

  1. David Smith

    David Smith Well-Known Member

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    Ok guys

    I have a customer with metatarsalgia due to increased FTC integral, i.e. extended time and increased force magnitude, applied by GRF on lesser MPJs thru stance phase. He has lateral STJ axes but not valgus forefeet, Low stiff 1st MPJs but pressure mat indicates little to no GRF sub 1st MPJ on either foot. Ankle equinus (-3dgs d/flexion but mobilised to +10dgs d/flexion) No LLD - but did have apparent short left leg before ankle mobs but after there was no LLD.
    He has been diagnosed with demyelinating and axonal neuropathy plus Parkinsons disease, which results in mild tonic contraction of the foot supinators and so in open chain the feet become maximally supinated but easily stretched out. After stretching out the foot remains in a neutral position for many minutes before slowly returning to the supinated position. In closed chain weight bearing resting stance the forefoot can be pronated but not enough to get the 1st MPJ weight bearing but not enough to get the 5th ray off the ground (remind me of the name of that test!?) The 5th ray is medium compliant to dorsiflexion.

    The lateral instability of the standing foot comes from a lateral STJ axes and the restricted hip internal RoM during contralateral swing. So therefore weight bearing in stance phase remains mainly on the 4 lesser MPJ's.

    So using orthoses I could accommodate the supinated foot position and add heel lifts but this might result in increased lateral instability and inversion sprains.

    I would prefer to laterally post thru rear to forefoot so the foot can pronate over to weight bear on the 1st MPJ and at the same time the increased pronation moments about the STJ keep the foot more stable thru stance. There would also be the advantage of the supinators being stretched out during stance and gait as opposed to encouraging the shortening of the supinators with a medially posted device.

    The problem here is that the hip has no internal rotation available past the position where the knee is straight ahead - so increased pronation moments at the stj of the stance leg and internal rotating moments about the tibia might result in pathological torsion in the knee and hip joints during the contralateral swing phase.

    I was thinking of using lateral posting (plus heel lifts) in a full length polyurethane device that would pronate the feet but at the same time be more forgiving in terms of knee torsion due to the compliance of the material allowing some standing leg external rotation at the mid to late contralateral swing phase and so reducing saggital plane progression perturbation and subsequent compensations such as toeing out, although in fact toeing out might be an advantage as this will increase functionally available internal hip RoM.

    Any thoughts here would be appreciated thanks.
  2. efuller

    efuller MVP

    You did not mention peroneal strength. A lot of your findings could be associated with peroneals that are weaker than the posterior tibial muscle around the STJ. There has to be adequate peroneal strength to perform the maximum eversion height test as I have described it in the past. Alternatively, you could also assess eversion range of motion available, in stance, by using a wedge under the lateral forefoot. A foot with a lateral STJ axis could just sit with very little pressure under the first met.

    If he has limited internal hip rotation one would expect that his foot will be abducted relative to the line of progression. The anatomical structures that cause the end of hip range of motion can contribute an external rotation moment to the leg relative to ground (from momentum of the body moving forward). However, this moment can be over come by a pronation moment at the STJ contributing to internal leg rotation relative to the ground. One behavioral adaptation to avoid the conflict of hip and STJ moments on the leg would be to walk with the foot more external in the transverse plane. So, I question whether hip range of motion has that much effect on STJ position or even moments.

    If the patients problem is lateral instability then you need to assess if the problem is lateral STJ axis, or peroneal weakness or both. If there is peroneal weakness you need to increase pronation moment from some other source. The easiest thing to do is add a valgus wedge under the foot. If there is not enough eversion range of motion that valgus wedge can cause sinus tarsi pain or too much load under the lateral forefoot. If the rearfoot and forefoot wedge don't work then you have to work higher up the leg with braces and or high top shoes.

    The lift does sound appropriate for the forefoot pain. Especially if there is an early heel off. An early heel off would be the same thing you said about increased force time integral on the forefoot.

  3. David Smith

    David Smith Well-Known Member

    Eric -
    I didn't test peroneal strength but the neurologists reports lower limb and foot muscle strength testing and does not mention peroneal or eversion weakness but does mention weakness in some toes e.g. right hallux dorsiflexion NB the right hallux plantarflexes in open chain and in swing phase he sometimes catches the toe on the ground.
  4. Trevor Prior

    Trevor Prior Active Member

    The influence of an external hip position (i.e. lack of internal rotation) is something I see a lot of. Effectively, the foot is unable to start pronating until the effect of the hip is lost post heel unweighting.

    I see three common loading patterns:

    1. cuboid, 5th met, 1st met
    2. cuboid, 1st met
    3. No medial load i.e. stays lateral / central ? this seems to be your case.

    I would agree with you about the risk of a proximal issue with increased lateral loading as the issue is the inability of the leg to allow the rotation.

    In my opinion, you have three options:
    1. A device which aims to spread the load across as much of the foot as possible which is what you described.
    2. It may actually be possible to provide some medial loading with a shaft pad but you would have to check this with an inshoe system to make sure you do not increase lateral instability following heel raise.
    3. If, as Eric indicates, the problem is lateral instability, then you have little choice other than to provide lateral posting / wedging whatever you wish to call it. However, in this instance, I would consider it compromised control ? what is required but probably will not allow less ab normal (or more normal) loading.

    Based on what you have said with the central met symptoms, I would probably start with option one.

    I will add one question as a tease ? is the lateral STJ axis position something the patient was born with or has it adapted because the external hip position has directed the motion of the foot?

  5. David Smith

    David Smith Well-Known Member

    Good to hear from you Trevor

    Yes you seemed to have understood my dilemma very well. I think I'll get this guy back in and review in terms of some of the suggestions you and Eric have made.

    I too often notice the lateral instability caused by restricted internal hip rotation but I don't know if this can alter the anatomical position of the STJ axis, obviously it will become more functionally lateral. The lateral STJ axes that I mention are observed in the open chain using Kevin Kirby's technique of determining STJ axis position. What mechanism are you thinking of that would change the anatomical position of the STJ axis?

    Cheers Dave
  6. Trevor Prior

    Trevor Prior Active Member

    An adaptive mechanism. In other words, if the foot functions in this manner for a period of years, what's to say it does not adapt to the position. How many children do you see with lateral instability / more cavoid foot type - instinctively, I would say less than we see in adults which, if this is the case, suggests adaptation.

    Does anyone know of any papers that may shed some light?

    In my opinion, hip function has a significant effect on foot function and is often not discussed. One reason lesser metatarsal ostoetomies can fail - if there is increased central loading due to the function of the leg and foot, trying to change the load locally with an osteotomy is destined to failure.
  7. efuller

    efuller MVP

    The axis position is determined by the shape of the articular facets of the talus and calcaneus. I don't see how you could change the position of the axis after bony maturity. I don't understand how the joint surfaces would adapt to an external hip position. So, I guess my vote is that people are born with their axis position.
  8. efuller

    efuller MVP

    I'm having a hard time seeing how foot function is dramatically affected by hip function. The vast majority of the time people do not get to their end of range of motion of the hip. When someone functions in the middle of their hip range of motion only muscle activation can impart internal or external moments to the tibia. When ever the muscles try to rotate the thigh, they will simultaneously be trying to rotate the pelvis/ torso. (Newton's third law for rotational motion) The torso is free to move in space and the thigh is more constrained by what is happening at the STJ and the ground.

    Also the knee is a very poor torque translator in the transverse plane. I like the notion that when the hip does impart significant transverse plane moment to the thigh, the person could choose to activate their lower leg muscles to rotate the lower leg in the same direction that the thigh is trying to go. When the lower leg muscles do this they would be tending to reduce transverse plane stress on the knee. When someone does that old test where you have someone stand and rotate their pelvis and look at foot motion/position, you should look at the peroneal and posterior tibial muscles tendons. You will see them contract.

  9. Trevor Prior

    Trevor Prior Active Member

    This is an observation I have made on many occasion when looking at patients with inshoe analysis. Invariably, if there is an external hip position (i.e. the mid point is external), the load on the foot stays lateral until heel lift. Assuming most do not reach end point, then an external position will cause load laterally assuming no issues with knee or tibial rotation.

    Interestingly, another observation has been the relative position of the foot and angle of gait with an external hip position - the higher arch more classicially supinated feet tends to occur with less abduction of the foot, the flatter more classically pronated foot type have increased abduction. The latter often then demonstrate a functional genu valgum and an altered loading pattern dependant on the mobility of the foot.

    Having done more analysis using 3d kinematics, I see a fair number of patients with reduced tibial rotation and, invariably, they load laterally as well.
  10. By definition, STJ axis position is not only determined by the shape of the talar and calcaneal articular facets but also by the shape of the foot inferior to the STJ. For example, a medially deviated STJ axis will become less medially deviated after a medial displacement calcaneal osteotomy is performed for treatment of posterior tibial tendon dysfunction. In other words, since the plantar aspect of the foot is the reference for STJ axis spatial location, then any positional or structural change in the foot inferior to the STJ axis may affect STJ axis spatial location.

    STJ axis position may become more lateral with a more supinated foot, and STJ axis position may become more medial with a more pronated foot. STJ axis location is determined not only by genetics but by muscle activity, injuries and neuromuscular function.
  11. efuller

    efuller MVP

    I agree. Where we differ is what part of the foot we are looking at. Yes, if you have equal rearfeet and one foot has more of a mettaductus then that foot will have a more lateral position of the axis relative to its forefoot. I also agree that if you externally rotate the talus you will move the axis externally and make the axis more laterally positioned relative to the forefoot. However, where the axis is relative to the talus and calcaneus is determined by the shape of the articular facets. This assumes that the joint surfaces are compressed together and they cannot separate as in most weight bearing situations.

  12. efuller

    efuller MVP

    Trevor, that is very interesting. I haven't paid much attention to that. What knee issues or tibial rotation issues will change the lateral load?

    I see two causes of high lateral load. The first is lack of eversion range of motion. In this case the foot can't evert far enough to significantly load the medial forefoot. These people will often abduct their foot to be able to roll over their foot to get weight on the medial forefoot.

    The second cause of high lateral load is a laterally deviated STJ axis. At rest the force x distance from the medial side of the foot has to equal the force x distance from the lateral side of the foot. If the axis is lateral the lateral side of the foot has a smaller distance, so it must have a larger force. These feet will tend to use their peroneal muscles to evert their foot and create higher medial loads. Kevin made a good video of this type of foot when he was doing his fellowship.

    Trevor, do you use the maximum eversion height test? That test can separate those to foot types quite easily. Sometimes you see a lateral axis with a foot that has no eversion.

  13. Bruce Williams

    Bruce Williams Well-Known Member

    The only thing I would addis for u to consider using a sub Hallux digital pad to overcome the Hallux plantarflexion amd aid the peroneus longus in activity.
    Eric's right about peroneal weakness.
    Trevor's right about affecting the foot first and worrying about hips last. PHysio may assist this pts hip rotation one the foot issues are corrected.Nice summary on your part and a damn interesting case!
  14. Eric:

    I agree with your first two causes of high lateral loads but, for completeness sake, I need to add a third and fourth cause of high lateral loads: high lateral loads can occur in patients with excessive supination tone and/or spasm in their deep posterior muscle group and may also occur due to guarding for painful pronation related symptoms, such as in painful plantar fasciitis.
  15. Dave:

    I would make an orthosis with a lateral heel skive, flat rearfoot post and with a forefoot valgus extension of 3 mm EVA/korex under the 2nd through 5th metatarsal heads in order to increase the external STJ pronation moment during gait. This should be combined with a shoe with a relatively non-compressible lateral midsole to increase lateral shoe sole stability.

    I see no concern to worry about the knee or the hips in this patient. The patient will not be pronated too much by this device but will just become less supinated by it.

    In addition, the patient can always choose to walk more abducted to avoid the end range of internal motion of the hip if you pronate the foot more with the orthosis In addition, many people walk with their knee joints externally rotated as this patient probably already does. The only hip joint problems I see in patients with orthoses is when the orthoses over-supinate the foot and the gluteus medius/minimus insertional tendinitis/bursitis occurs at the greater trochanter (indeed, not true hip joint pathology, but in the hip joint region).

    Hope this helps.:drinks
  16. Trevor Prior

    Trevor Prior Active Member


    Thanks for this. I slept on this and the direction and range of motion of the joint itself is largely determined by the ligaments, generally the angle of the fibres. Thus, as these can adapt, if I were to place someone in a cast with stj inversion for a period, we know that this would limit the motion and alter function.

    As Kevin has indicated, there are things external to the joint that can affect the axis position. It is therefore not a leap of faith to infer that functioning with an external hip position has the potential to alter the dynamics of the joint, around which the ligaments adapt and the axis alters.

  17. Trevor:

    The direction and range of motion of a joint is determined by multiple factors:

    1. The three-dimensional morphology of the articular facets.
    2. The strength, spatial orientation, points of attachment of the ligaments within and external to the joint.
    3. The three-dimensional shapes of any intra-articular menisci that alter the contact properties of the articular facets (e.g. knee joint).
    4. The internal forces created by the muscles which cross the joint.
    5. The external forces from ground reaction force, gravitational force or inertial force.

    In order to alter the predominant axis of motion of a joint then at least one of these above factors must be altered. However, we must remember that there is not a single joint within the body that has a single, fixed, hinge-like axis. Even in the relatively constrained subtalar joint (STJ) , there is a constantly moving axis of rotation, which has often been described as a "bundle of axes" (Van Langelaan EJ: A kinematical analysis of the tarsal joints: An x-ray photogrammetric study. Acta Orthop. Scand., 54:Suppl. 204, 135-229, 1983).

    With this in mind, altering the transverse plane hip joint position during gait has the potential to alter the axis of rotation of the STJ, ankle joint, midtarsal joint, midfoot joints and MPJs due to the change in internal and external forces acting within and across these joints. Injury to the ligaments, tendons, bones, muscle or fascia, all of which produce the internal forces within a joint, also have the potential to cause a permanent change in axis location in any of these joints.

    For those also following along, one of the main points in understanding the above discussion is that it is the motion of the joint which determines the axis of rotation of the joint since no joint within the human body has a single, fixed axis of rotation which is hinge-like.
  18. Trevor Prior

    Trevor Prior Active Member

    Could not agree more. I believe that the actual function is the net result of the relative moments across the three planes within the foot and proximal to the foot. Thus, it should be possible to build a 'picture' of likely function and, in reverse, determine the effect of intervention. This of course would take a lot of work to validate but allow us to marry the various components of function such as structure, flexibility, strength, control etc.

  19. Obvs.

    The big issue here is the CNS and it's intervention with your intervention. As I say to many patients when discussing biomechanics: "of course this is all physics, but you are made of biology...sometimes the biology chooses to alter the physics being appled to it."
  20. Trevor Prior

    Trevor Prior Active Member

    I get those examples and, to be honest, I do not use the test that often. The reason being is I tend to use inshoe analysis when I have that foot type as I look at the loading pattern they exhibit as mentioned in a previous post.

    If there is reduced lateral forefoot contact, I apply lateral forefoot posting or equivalent. If there is 1st and 5th MTPJ loading I consider a met dome type pad and may extend this forward but with reduced material beneath the 5th. If they load laterally alone - this is the time I apply more lateral control. In these instances it is simply to try and stabilise the foot as they are usually quite severe. If I need more lateral stability on the first two examples, I may increase the lateral control. However, if I place any load through an area that I believe is functioning towards it's end range of motion (like the last example) I consider this as compromised control.

    Interestingly, for all of these foot types, I will have the lateral border of the orthoses relatively stiff to increase the moments. However, at present, I am experimenting with making the medial aspect more flexible if there is evidence of reduced tibial rotation to see if this can be encouraged. Whilst this should be easily achievable with cad cam / 3d printing / laser sintering it is not quite so easy to get the labs to do this at this stage and I need to review some of the outcomes.

    All fun.

    Busy couple of days before I fly to Melbourne for a week for the conference and some other lectures so may have a hiatus.

  21. Trevor Prior

    Trevor Prior Active Member

    Originally Posted by Trevor Prior View Post
    I believe that the actual function is the net result of the relative moments across the three planes within the foot and proximal to the foot.

    Yep but the proximal function is not often discussed as it relates to STJ axis. I have seen few discussions (although accept I may have missed them) around proximal muscle and joint (exception of medial OA of the knee) problems that discuss how we apply the principles of STJ axis to managing the proximal complaints. The age old question as to ground up or body down. Often a combination but I believe they can be linked.

    Agreed which is why I like reviewing what the orthoses do both beneath the foot and proximally - accepting the limitations of any measuring system.
  22. But how are you measuring the in-vivo stress in the tissues? We may see the same kinematic pattern with and without orthoses, but that does not mean the internal stresses are the same- right?
  23. Trevor Prior

    Trevor Prior Active Member

    Well that is interesting. I know the studies say that orthoses do not change the kinematics but that is not what I see. I think this may be a combination of the changes are small in absolute terms but, probably more importantly, the changes are subject specific and thus not consistent and thus harder to demonstrate statistically.

    That the changes are not consistent might be an argument for not assessing. However, we accept that the effect of orthoses varies between individuals, why not the kinematics?

    You are of course correct, I cannot measure the internal stresses and my system does not provide joint moments - that is an expense I cannot afford / justify with the fees we are able to charge.

    However, I can look to see the way the plantar loading has changed and I can see if kinematic function has increased or decreased and then get some gauge of the relative benefit.

    We had patient on Monday who we had tried several orthoses options using inshoe analysis and it was difficult to really see an improvement with any of the options. However, she had a more mobile foot type and we provided her with the best of the options. She returned for feedback but also 3d analysis. The latter identified some control and restriction problems but the orthoses made no significant difference - you might say this is because they do not effect kinematics but I regularly see changes.

    Thus, I advised her that the issues were proximal, orthoses were unlikey to help her complaint (hip and gluteal). Her feedback - she feels more comfortable with the orthoses but little different to her pain.

    You might ask, quite reasonably, why did we just not try the orthoses and see - we could of course done that. However, she had previous opinions with mixed advice, the initial analysis led us to the devices most likely to help and then demonstrated the likely causes and some evidence that orthoses were not her answer. The analysis also makes recommendations for a rehab programme and key areas to target.

    I also accept that the process for designing the orthoses is not validated, it is a process we have used for more years than I care to remember and has proved successful in terms of symptom relief. If there is any keen researcher out there who would like to evaluate this further, i would be more than happy to collaborate with an open mind.

  24. However, the physics of biology is biomechanics. There is no electrical, hydrodynamic, acoustic nor mechanical process in biology that can't be explained using the principles of physics.

    Maybe better to say the following (especially to the sports injury patients? "You are a living animal with a central nervous system that may makes decisions that are not always best for the biomechanical well-being of your body's structural components. It is my job to heal the injuries that your central nervous system has chosen to provide you with by making those bad decisions.";)
  25. This is one of the reasons i like to see the individual subjects data presented in research papers.

    I generally agree with your process, I think it is the semantic interpretation where I sit more cautious than you appear to be. For example, your term "relative benefit"- lets say we see a decrease in hip internal rotation with an orthosis, how do we know that this is "beneficial" in this individual, at this time? Indeed, how do we know from the kinematics that this has not now placed one or more of the tissues around the hip outside of it's zone of optimal stress (ZOOS) and put that tissue at risk of injury?

    Again, how are we judging "an improvement"? Given that you agree that inter-subject variation is normal and expected, how can we say whether the pressure map data and / or the kinematic data is "improved" or worsened? Genuinely interested.

    So if I'm understanding correctly, if you do not see the kinematic change you are predicting with the foot orthoses, you assume that the issue is a due to proximal problems and that foot orthoses will be of little/ no benefit in such cases?

    Happy to lend a hand if I can.
  26. timharmey

    timharmey Active Member

    Hi Folks
    I just by observation have noted that lack of internal hip roation has a link to poor foot function.It is quite easy in most cases to improve hip function with simple stretches and strengthening , I think it is something that podiatrist should look out for more often, I have found it at the bottom of a few difficult cases ( I had nearly given up on podiatry arena I kept looking out for someone to raise lack of internal hip rotation)
    Last edited: Apr 28, 2016
  27. Trevor Prior

    Trevor Prior Active Member


    That is why I wanted you to come to clinic and I am looking forward to our workshop!!!!!

    Thanks for the thoughtful questions.
  28. If I had your system and a patient in front of me, what I should really like is to be able to load a database of age, gender, etc. matched individuals with and without the condition that my patient presented with to see where my patients kinematic data fits into the stored data.... interested? Now that's a big project, but worth carrying out. Series of PhD students...

    So, moving a kinematic variable within an individual towards a population mean is good, moving away from it is bad? I guess this is the bit that troubles me most. Given that variation is normal, why should trying to make kinematics of an individual more like the mean of a population be seen as positive?

    To quote Feiss (1909) regarding the use of averages and "normal" feet: "As earlier stated, one hundred cases are too few on which to base a fair average. But even if thousands of cases had been used it would be fallacious to reason that all feet in which the scaphoid tubercle is higher than the average, are normal, and all feet in which the tubercle is lower, are abnormal, because the average is obtained just as much from the figures below as from the figures above. Moreover, the chief point shown in the hundred cases is that there is marked variation in the height of the scaphoid in apparently healthy feet. Consequently, as the average is based on that variation, it has no significance further than what the term indicates, representing simply an average of normal variation. Such an average, therefore, cannot serve as a basis from which to estimate deformity. "

    Fast forward 100 years to quote Nester (2009): "Variation between people in foot kinematics is high and normal"

    Given this, using the mean as some sort of "ideal" target to aim toward seems a bit bizarre and rather pointless to me. What should be more useful would be if you could show that the kinematic variable(s) in question showed a dichotomy between unaffected and affected populations for a pathology of interest and then use your system to demonstrate which of these populations the individual subject "belonged to". However, I suspect that more often than not there will be no such dichotomy. Fairly simple project though: take individuals with a given pathology compare their kinematics with a group of un-injured, t-test the kinematics to see if the populations are discreet from one-another. That's really what your system is currently missing here- you've first got to demonstrate that the kinematics are different in the injured individuals versus the un-injured individuals for each specific pathology. Looking at the meta-analyses that Griff was part of, generally we only see medial tibial stress syndrome and anterior knee pain coming out as being predicted by static and dynamic foot posture- more work needed looking beyond the foot me thinks. Interesting...

    That's the key, we could do away with the population mean and it's standard deviation from your system and just look at changes in the individual in question and it wouldn't really make any difference to your current approach. While we don't need to compare to a population mean here, I sort of agree with you and sort of don't- I'll try to explain:

    Ten years or more ago I wrote: "Because the magnitude of stress in the tissues that restrain a joint at the ends of its range of motion is increased when the joint approaches that end range of motion, the magnitude of tissue stress in these restraining structures will necessarily decrease when the joint is functioning in its midrange position. With this in mind, any treatment approach that attempts to limit the extreme excursions of the subtalar joint rotational position and the subtalar joint spatial location, and that attempts to normalize their temporal movement patterns, should be capable of reducing tissue stress around the joint, thus improving symptoms caused by increased magnitudes of tissue stress." Simon K. Spooner and Kevin A. Kirby (2006) The Subtalar Joint Axis Locator. Journal of the American Podiatric Medical Association: May 2006, Vol. 96, No. 3, pp. 212-219.

    However, with ten years worth of reflection since I wrote that, I am not so sure...

    Lets assume we see a reduction in the excursion of a joint during a given function when an orthosis is placed under the foot. One might assume (as I did above) that the stresses in the restraining tissues will be reduced. However, what we are observing with our kinematics is that the motion has been arrested over a shorter distance, it does not tell us what has caused this reduced excursion.

    We do know that forces drive motion and as you rightly note, it is the interplay between the internal and external joint moments which influence the position and motion of the segments of a joint and viz. it's excursion during function. What we hope when we see a reduction in the excursion of a joint in concert with a foot orthosis is that it is the modification of the external moment induced by the foot orthoses which has decelerated the segmental motion about the joint over a shorter distance. Thus reducing the internal stresses on the restraining tissues.

    However, it may well be that the tissues are simply now generating more internal moment ("braking force") to arrest the motion over a shorter distance and are thus being subjected to higher levels of stress. Kinematics in isolation cannot discern which is the case here. This adds to my concerns about comparing to a population mean. When you move your kinematic variable toward the population mean, how do you know you have not increased the tissue stress?

    The converse here is also true, we may see no change in the kinematics, but that does not mean that the internal stresses have not changed.
    There is more, but this post is long enough.

    Question to all: lets say we had a sinus tarsi syndrome foot caused by increased inter-osseous compression at the floor of the sinus tarsi. It has been discussed here many times that we need only to reduce the compression force at the floor of the sinus tarsi to obtain a positive clinical outcome and that this decrease in compression can be achieved without any observable change in kinematics. Can a decrease in compression be obtained without any observable change being seen on an in-shoe pressure system? I say it could, what say you?
  29. further thoughts... even if the observed reduction in the joint excursion is due to the change in the external moment, this does not necessarily equate with a reduction in tissue stress- try jumping out of a window and landing on a mattress versus jumping out of a window and landing on concrete... which, I guess brings us back to leg stiffness, joint excursion, tissue stress and the CNS...
  30. For the question Simon I think i agree that you could get the same readings or kinematic measurements.

    1 is guess the in shoe systems are not 100% accurate for many reasons.

    But just because you reduce the compression forces doesn't mean that you have to have kinematic changes. The reduction of compression forces will mean an increase in another force acting on the STJ which may mean where the forces are acting have changed but the kinematics maybe the same.

    Ie think net not individual forces
  31. Trevor Prior

    Trevor Prior Active Member

    This will be relatively short as I am preparing for my trip. We would need to have a longer discussion regarding the relative merits or not of population means but I do agree that we need to look at specific conditions to see how they vary to the population.

    Certainly, I am beginning to see some patterns that are more common and this would be good to study in greater detail. It does suggest that there can be more than one pattern of dysfunction that can contribute to the same pathology and this generally relates to the plane in which the majority of dysfunction occurs. What the 3d does allow, is a better insight into transverse plane rotation, particularly of the tibia and this is something that is very difficult to assess otherwise.

    Theoretically, it might be possible to reduce the load in the sinus tarsi without changing the plantar loading but, from my experience of assessing orthoses generally with this technique. If you do not change loading, it is generally because the driving forces from proximal dysfunction are too great - this might be an example where they could be enough to change the dynamics across the joint but not enough to change the loading of the foot. However, in this instance, you may well be transferring the load to another joint. An example here would be: Pt has sinus tarsi syndrome due to the load placed on the foot from proximal dysfunction. The intervention reduces the compressive load but not the plantar load as the driving force is too much. However, by the same token, it transfers the load to another joint such as the CCJ or met cuboid joint enough to make it symptomatic.

    As I mentioned before, I do not profess to have all of the answers, I am taking an approach to try and analyse why pathology may occur, all of the potential contributing factors and the broader effect of intervention.

    The holy grail is to achieve reduced load to manage injury without causing abnormal function elsewhere - I have yet to hear anyone provide the method by which they assess the effect their interventions have had elsewhere - other than it does not hurt.

    The journey is long but these are all steps towards a better understanding.
  32. Agreed, but we also must be aware of the limitations and be cautious that we do not take steps in the wrong direction. We can talk about this over a pint at Summer School, Trevor. Hope your travels are successful.

  33. I believe that a reduction in sinus tarsi interosseous compression force would not be seen with in-shoe pressure analysis if the subtalar joint (STJ) supination moment was being generated from an internal source (e.g. posterior tibial muscle contractile activity) that would cause an increase in internal STJ supination moment. The posterior tibial (PT) muscle could just contract hard enough to add enough internal STJ supination moment to only reduce the interosseous sinus tarsi compression force without causing a STJ supination moment. However, if the reduction in sinus tarsi compression force was being caused by a foot orthosis which shifts ground reaction force (GRF) from lateral to medial on the plantar foot (i.e. a change in external force), the change in GRF patterns on the plantar foot should be easily detectable with an in-shoe pressure analysis system.

    The problem then is if one is only using an in-shoe pressure analysis system which doesn't measure shear forces, does not provide the spatial location of the GRF vector during gait and the STJ axis location is not known, then it would be impossible to reasonably predict whether the interosseous compression force within the sinus tarsi is being reduced, unless, of course, the foot is seen to supinate out of its maximally pronated position during gait.

    There are simply too many variables which are unknown to allow us to predict internal forces within the foot and lower extremity even within the most advanced biomechanics lab setting. That is why we must, as clinicians with our basic analysis tools, use the subjective comments of the patient combined with our gait analysis findings (i.e. kinematic data) to do our best to predict whether the mechanical interventions we are making for our patients are therapeutic, or are harmful.
  34. Tim:

    I see many patients with a lack of normal internal hip rotation that have relatively normal foot function. Why do you think a lack of normal internal hip rotation, let's say the patient can only get their knee joint axis to 10 degrees internally rotated relative to the frontal plane, would cause pathology or "poor foot function"?
  35. I'm so lucky to have had a great mentor. So, to sum up- regardless of the technology, we ultimately need to employ the change in symptoms as our outcome measure? Moreover, Trevor has suggested that if he see's no obvious change in the in-shoe pressure map nor any obvious change in the kinematics, then he does not employ foot orthoses therapy; your reponse seems to contradict this approach?
  36. Dr. Spooner, I believe you can hang your hat firmly on that statement since, as you stated earlier, we simply can't accurately predict internal forces using only in-shoe pressure analysis, pressure mats and/or 3D video analysis with skin markers. Subjective symptoms, therefore, will always be one of the key components in assessing the therapeutic benefits of foot orthoses, regardless of whether you are using expensive gait evaluation equipment or not.

    This then begs the question, how much do you really gain by using in-shoe pressure analysis and gait analysis systems when, in fact, the patient's subjective complaints are, by far, a much more important outcome measure in the clinical setting?
  37. Trevor Prior

    Trevor Prior Active Member

    To be fair what I said was, if there were no changes, then it is far less likely that orthoses will make any difference and I would be looking at managing in a different way. I also noted, that is rare for there to be no change at all.

  38. Yep, to be fair you did say that. What you haven't yet countered are the arguments I put forward as to why tissue stress cannot be evaluated by employing your system, nor why discontinuing foot orthosis therapy because you are not observing the kinematic nor the in-shoe pressure changes you expect may actually be counter-productive to the treatment of an individual... really interested now.
  39. timharmey

    timharmey Active Member

    it is not why , that I have thought about more the fact that they do., in my experince.I had some plantar fascia type pain much to my annoyance , treated it with orthotics, stretches etc, sort reduced in pain butnever went away, had a think talked to a physio and he noted I had some limited internal hip rotation in my hip, we worked out a few simple exercises and in about 3 hours all tha pain went.
    I have then looked out for it all the time and a lot of the time the foot that is problematic has limted internal hip rotation , then if there is no major hip pathology improving hip function along with orthotics/ stretches seem to help.I would thnk that loading laterially changes foot mechanics , and then walking in a way were you dont load laterially as well as having stronger gluts helps "improve" foot mechanics.
    Lots of people with limited hip function I would think have no problem ( I suppose I didnt till I got a bit older and fatter!).I t is not very scientific , just a pattern ,
    I have to be honest at first I was suprised but I see it so often I think that there is something to it .
  40. David Smith

    David Smith Well-Known Member

    Thanks Kevin

    This is consistent with my preferred treatment plan and I agree that foot placement abduction may be a required compensation.

    cheers Dave

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