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Prescribing Orthoses: Has Tissue Stress Theory Supplanted Root Theory?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Apr 1, 2015.

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  1. drhunt1

    drhunt1 Well-Known Member

    "Tissue stress theory is currently the best method by which to design prescription foot orthoses for patients with mechanically based foot and lower extremity pathologies. In my opinion, tissue stress theory will eventually supplant the evaluation and treatment techniques advocated by Root and colleagues within the next decade."

    A leap of faith, and/or wishful thinking.
     
  2. Ian Linane

    Ian Linane Well-Known Member

    Hi Kevin
    Thanks for a succinct article on this as well as giving a nice historical perspective. Enjoyed it and found it valuable.
     
  3. drhunt1

    drhunt1 Well-Known Member

    Ian-remember that Dr. Root's body of contributions were a "work in progress", not an end point, but a beginning for deeper and greater understanding. It is up to those that followed him to expand and further define his work, not attempting to design a better mouse trap. I have gleaned a lot of useful information from Merton's work, only to fine tune those precepts as I deem necessary. I have yet to be able to use tissue stress theory to solve anything. Just my two cents.
     
  4. efuller

    efuller MVP

    When one uses a paradigm that is a "a work in progress" one should note which parts are helpful and which parts are not. The concept of a partially compensated varus is helpful. Intrinsic forefoot valgus posts are helpful. However, there is no coherence to the explanation of how orthotics work under neutral position theory.

    Have you ever tried? Matt, for someone who often admonishes others to keep an open mind......

    The recent discussion we had on lateral ankle instability is a good case. You seemed confused on whether a rearfoot varus was a cause of supination or not. Which is understandable as many are confused by the neutral position explanations of lateral instability.

    The cause of why some feet will have lateral ankle instability, while other feet will have pronation related problems is easily explained with understanding the inter-relationship of the STJ axis and the location of center of pressure under the foot.

    Eric
     
  5. Female 40 something squash player with chronic lateral ankle instability & orthoses that resolved the problem: lateral heel skive, external oblique rearfoot post, lots of medial arch fill etc- go figure why these worked... Hint: they didn't "bring the ground up to the foot and negate the need for compensation".
     

    Attached Files:

  6. Sinex

    Sinex Member

    Dr. Spooner why must the post be oblique? what shore is it? how deep was the heel cup? thank you
     
  7. Because by extending the post on the lateral side of the shell it increases the stiffness on the lateral portion of the shell (decrease the span length), increasing the orthoses reaction forces on the lateral side of the STJ axis, pulling the centre of pressure more laterally http://www.ncbi.nlm.nih.gov/pubmed/16988168 , thereby potentially increasing the external pronation moment acting about the STJ axis- the patient had chronic lateral ankle instability ViZ. the design intent of the orthoses was to increase the external pronation moment and/or decrease external supination moment acting about the rearfoot complex. It doesn't have to be oblique, it just helps. You could thicken the shell along the lateral border, put an external stiffener in- all would skin the cat similarly.


    Shore was 65 before it was applied according to the manufacturer- what was it when it had been applied to the orthosis?

    Heel cup height on which side? I think they were about 10mm all around.
     
  8. drhunt1

    drhunt1 Well-Known Member

    Really, Eric? You suggest I'm confused? When did I EVER write that a rear foot varus 'caused' supination? I didn't...so don't bother looking it up. It appears perhaps you should review my first video again, to get a better understanding. Also, please review my video that I created at a great expense to myself if you feel inclined for a refresher course:

    https://www.youtube.com/watch?v=7BSetRI_UH4&feature=youtu.be

    What I DID write, and what Dr. Root alluded to was that a high rear foot varus position places the patient at greater risk for inversion type sprains. GRF compensation for rear foot varus is PRONATION...however...what happens when the rear foot varus deformity is not compensated at the STJ? What is that called, Eric? Further, what happens when this patient's foot strikes the ground that is irregular and the foot is highly inverted at heel strike?
     
  9. Sinex

    Sinex Member

    Thank you so much
    Do you think we could also say that an externally oblique post promotes an external pronation moment whitin the stj for a duration superior than a not oblique post during walking? In other words, while the cop shifts ahead after the heel strike and rapidly moves away from a normal post, an oblique post could determine a supination moment control for more time.

    And one last thing; is it wrong to use a valgus extrinsic post or intrinsic rearfoot wedge for a case like this?
     
  10. I think what it does is increase the stiffness of the lateral side of the foot orthosis Which should draw the CoP relatively more laterally until heel lift

    You could use an extrinsic valgus rearfoot, or like I did here, an intrinsic lateral heel skive.
     
  11. Jeff Root

    Jeff Root Well-Known Member

    Did the foot go to the ground or did the orthotic bring the ground up to the foot (see medial arch)? Clearly in this patient the orthotic GRF, especially in the medial arch prevented the arch from collapsing to the ground. And the device also reduced the pronatory compensation (degree of calcaneal eversion) in the rearfoot. Has tissue stress replaced this traditional Root Functional Orthotic approach. No.
    Jeff
     

    Attached Files:

  12. drhunt1

    drhunt1 Well-Known Member

    One of the great things about Simon placing me on ignore is that I can respond to his posts with the same flippant attitude as he did mine when I came back to posting here. First, after looking at his orthotics, I can safely write that those are ugly...flat out ugly orthotics that I would be embarrassed to distribute to any patient. Second, in his pics of the orthotics, he shows that he abducted the foot distal to the MTJ....why? He never offers an explanation. Third, he condescendingly states: "Hint: they didn't "bring the ground up to the foot...". Nor should they, if the patient didn't present with a significant or contributory forefoot varus deformity. However, one can tell from the pic of the patients' feet that she has a rear foot varus deformity that is either barely compensated or uncompensated...thus, this patient is predisposed to lateral instability issues, (can't quite tell, because Simon didn't provide a rear view comparing RCSP to NCSP). Here's a more complete set of jpegs to illustrate my point. In this patient I took a rear view comparing RCSP to NCSP, and am offering the lateral WB plain film radiograph. [notice the calcaneal bisection is not accurately drawn...but that's OK...because it functions as merely a reference line]. Her main problem is lateral instability from the rear foot...not from the fore foot necessarily. In the following video, hers is the second foot shown...yes, she has a forefoot varus deformity, (which is shown with reference lines), but her lateral instability is mainly from the rear foot.

    https://www.youtube.com/watch?v=O-5qHOOSaQs&feature=youtu.be
     
  13. Sinex

    Sinex Member

    Excuse me I think you mean "draw the CoP relatively more medially" right?
     
  14. No. Increasing the relative stiffness on the lateral side of the orthosis will increase the reaction forces on the lateral side of the orthosis as the rate of change of momentum between the foot and the orthosis will be higher where the interface is stiffer. All other things being equal, this will shift the centre of pressure towards the lateral side of the orthosis. In this case of chronic lateral ankle instability where the design intent is to increase STJ pronation moment this should be desirable- hence the foot orthoses were successful.
     
  15. Sinex

    Sinex Member

    It really makes sense now. Thank you for Your time.
     
  16. Andrea:

    I've been following your discussion with Simon and really can't add anything more to what Simon has already told you. The basis for designing optimum foot orthoses for patients is understanding what the abnormal forces and moments are which are causing the pathology and then use the foot orthosis to modify the reaction forces (i.e. ground reaction forces and orthosis reaction forces) acting on the plantar foot to reduce the magnitudes of these pathological forces and moments. This is the basis of Tissue Stress Theory which is reviewed in my article, Prescribing Orthoses: Has Tissue Stress Theory Supplanted Root Theory?

    The only thing I would do differently with the foot orthosis is to add a small valgus forefoot extension (e.g. 3 mm laterally under 5th metatarsal head skived down to 0 mm thickness 1st intermetatarsal space) which would then add the benefit of significantly increasing the external subtalar joint pronation moment during late midstance and propulsion. I treat quite a few tennis players (my office is next door to a large tennis club) and use forefoot extensions quite often in athletes who are involved in side-to-side sports such as tennis, basketball, etc.
     
  17. Simon:

    Were this patient's peroneals tonically active during standing? Looks like a very similar foot to the one that I used in my paper on SALRE to illustrate the peroneal tendon activity in feet with laterally deviated STJ axes.
     
  18. They did have a full length top-cover with valgus forefoot extension. I made these about 7 years ago. The patient came in to get new top-covers last month, I just quickly snapped a shot when I was mid-way through recovering them. So the picture was just the shells on my work bench, when finished they had 3mm eva full length with 3.5 degree valgus forefoot wedge 5-2 to sulcus.
     
  19. Good man, Dr. Spooner. I'm sure she was a happy lady. That is nearly exactly how I would treat her.:drinks
     
  20. Very much so.
     
  21. drhunt1

    drhunt1 Well-Known Member

    Less then two weeks away from my article being published on the cause of growing pains in children and the anatomic/pathologic link to RLS in adults, using Root biomechanics. Cheers!
     
  22. These tonically active peroneals make sense using SALRE theory. However they don't make sense using STJ neutral theory and were never mentioned, to my recollection, in my classes taught by STJ neutral theorists. Any one ever hear of this idea that the peroneals must be tonically active in these laterally deviated STJ axis feet to prevent them from inverting their plantar forefoot from the ground when being taught by STJ neutral theorists?
     
  23. drhunt1

    drhunt1 Well-Known Member

    Take a closer look at the pic Simon posted. See the lesser digits actively flexed in order for the patient to gain support while in static stance? How is a valgus wedge going to reverse this? The patient is demonstrating flexor substitution in static stance, which indicates to me that hallux purchase is probably not adequate. A valgus wedge does nothing to treat this patient, and I'd love to have you explain why it does...using tissue stress theory in your explanation. Forget the peroneal complex...I'm more interested in the forefoot at this point.
     
  24. efuller

    efuller MVP

    There is nothing in your video that could not be learned from the fluoroscopy video. Your video nicely demonstrates that you should not put dark lettering on a dark background. What concepts did you think I needed a refresher on?

    You still appear confused. You are talking about how compensation for rearfoot varus is pronation. And you are talking about how an inverted heel will cause supination. Now if you used the concepts of center of pressure relative to location of the STJ axis you could explain both of those phenomenon. Joints move when there is a net joint moment or torque. When a joint "compensates" it is moving in response to moments applied to the joint.

    It is possible to have an inverted heel, that will have its center of pressure lateral to the STJ axis and it will pronate. If the heel were inverted far enough that the center of pressure under the heel was medial to the STJ axis you would get a supination moment from the pressure under the heel. It still may not supinate because there may be moments from other sources (peroneal muscles) so that there will be a net pronation moment about the STJ.

    When a foot strikes irregular ground, it will tend to move in the direction of the moment created by ground reaction force. When the irregular ground is more medial you get supination moment, when the irregular ground contacts more laterally you get a pronation moment. Matt, I bet you intuitively understand this. However, this is a better explanation of why certain motions occur.

    Eric
     
  25. drhunt1

    drhunt1 Well-Known Member

    First...I've NEVER seen those fluoroscopy videos. Can you provide me a link to them? Second, like I've written before, fluoroscopy imparts MASSIVE amounts of radiation onto the patient/subject, so while it may have been "acceptable" in the '80's, it is no longer that way. :deadhorse: Third, while those fluoroscopy videos are instructive for those individual patients, what about the variance in patient populations? No two feet are alike. In animation, one only needs to have the animator line up certain boney prominences and the depiction would be fairly accurate. That video is ground breaking on a number of levels. I've never seen the animated overlay performed before...it's a first...just like the STJ motion in the first video was groundbreaking...never seen that demonstrated before either. Thanks for recognizing the contribution I've made at a great expense to myself.

    A rear foot varus deformity that is not compensated remains inverted and is fully pronated. The peroneal tendon complex has no method of compensation to closed kinetic chain forces either from above or below, thus the patient is subject to supinatory injuries, ie., inversion type sprains. This is what Root discussed in Vol 2 on page 122 and 298. Hope this helps.
     
  26. Note also the activity of the lesser digit extensors, plantarflexing the lesser metatarsal heads in an attempt to increase GRF lateral to the subtalar joint axis and thus increasing the pronation moment about the STJ axis via GRF from the lateral met heads. By increasing the external dorsifexion moment under the lateral met heads with the valgus forefoot extension, the over-activity of the lesser digit extensors can be much reduced- instead of the internal moment provided via windlas and digital buckling. Anyway, the orthoses I prescribed were very much successful, so at the end of the day it doesn't really matter how they worked, or how they looked, the fact that they did completeley resolve the patients symptoms was more than enough for both me and the patient. Although, if I'd have followed a Root approach, I'd have ended up increasing the supination moment about the STJ axis and would have destroyed her ankle ligaments and peroneal tendons by now. Lucky for all that I'm not that naive.

    "Uncompensated", "partially compensated"; "compensated" can you enlighten as to the derivation of this bull****, Kevin?
     
  27. drhunt1

    drhunt1 Well-Known Member

    Could be a case of "even a blind squirrel finds an occasional nut". Those are NOT the extensors firing...those are the flexors...note the hammertoe second, as well. You "solved" the patients' complaints by stabilizing her rear foot, and I'm assuming by not allowing her to pronate to the end of ROM. And yes...it DOES matter how you achieved this...it is not an "end of the day" scenario. Tell this crowd how by using the Root method, you would've increased supinatory moments around the STJ. One only needs to take pics of the patient before and after application of the orthotic, preferably from behind in order to "prove" your point.
     
  28. Jeff Root

    Jeff Root Well-Known Member

    Kevin,

    Here is what Root et al wrote in Normal and Abnormal Function of the Foot (page 340-341):
    "Indirectly, a spastic peroneus longus muscle can also supinate the subtalar joint. A spastic peroneus longus muscle fixes the 1st ray in its most plantarflexed position, thus everting the forefoot relative to the rearfoot. The spasm also prevents supination from occurring around the longitudinal axis of the midtarsal joint. Therefore, only inversion at the subtalar joint can compensate for the everted forefoot position. Ground reaction against the 1st metatarsal head exerts a strong inversion force upon the rearfoot and easily overcomes the weak pronation force exerted by the peroneus longus muscle upon the subtalar joint. Thus, when the peroneus longus muscle becomes spastic, the entire foot supinates at the subtalar joint. This is the etiological factor that causes the pes cavus deformity associated with Charcot Marie Tooth's disease".

    Jeff

    Note: I edited the reference page number which was originally incorrect.
     
  29. In order for a "spastic peroneus longus" to supinate the foot, the force at it's insertion multiplied by it's lever arm to the STJ axis has to be greater than the force at the tendons cuboid pulley, multipied by it's lever arm to the STJ axis- is it ever? I think, Eric lectured on this some years ago. What kind of foot orthosis would your father have made for such a foot, Jeff?
     
  30. efuller

    efuller MVP



    In a laterally deviated axis foot there tends to be, in the absence of muscle activation, higher loads on the lateral forefoot. This occurs because in order to balance the sum of force x distance medial to the axis has to equal the sum of force x distance lateral to the axis. When the axis is lateraly positioned the distance to parts of the foot that are lateral to the axis is smaller so the forces have to be higher. When you have higher forces laterally there will tend to be discomfort on the lateral metatarsal heads and the only way one can decrease force on the metarsal heads is to increase force on the toes. Thats why you would see chronic flexor activity. However, we are only seeing a snapshot and we shouldn't jump to conclusions without seeing the patient.



    So, a valgus wedge that was big enough, would cause the STJ to pronate and with STJ pronation there is talar adduction. This would cause the STJ axis to become less laterallly positioned. This could allow increased pressures on the medial side of the foot and decreased pressures on the lateral side of the foot. This is how a valgus wedge could lead to reduced flexor activity.

    The nice thing about tissue stress is that you don't have to use vague and poorly defined terms like "gain support".

    Eric
     
  31. Simon:

    Perhaps you've misread or misinterpreted my post. I was not criticizing your orthosis treatment since you have done almost exactly what I would have done for this patient. I was just pointing out that the tonic peroneal activity seen in feet with laterally deviated STJ axes is predicted using SALRE theory but from what I remember of hearing from Drs. Root, Weed and other STJ neutral theorists, tonic peroneal muscle activity was not predicted using STJ neutral theory. That's all.:drinks
     
  32. Jeff Root

    Jeff Root Well-Known Member

    Simon, that would depend on the results of the individual patient's examination, including, but not limited to the ROM of the STJ and the severity of the spasm. The device would have had intrinsic forefoot valgus correction, which as I have mentioned before, can reduce the everted position of the forefoot in functional orthotic therapy due to reduced plantarflexion of the 1st ray.

    Jeff
     
  33. Great- However, in static stance this lady was firing her lesser digital extensors.
     
  34. Jeff Root

    Jeff Root Well-Known Member

    Any condition that causes eversion of the forefoot (increased plantarflexion of the 1st ray) and external rotation of the tibia and talus relative to foot, will result in abduction of the STJ axis. The laterally deviated or abducted STJ axis may be the result of the spasm.

    Jeff
     
  35. Not your post Kevin, another written by a cock.
     
  36. Hang on a minute she had an inverted postion of the forefoot on the rearfoot during forefoot to rearfoot testing with the subtalar joint in neutral... your father would have forefoot valgus posted that? She had a rearfoot varus- your father would have valgus posted that? Come on Jeff, give me a break- your father was good for his time, but he wasn't that good.
     
  37. Jeff Root

    Jeff Root Well-Known Member

    You were talking about your patient and not the condition that I described?
     
  38. Jeff Root

    Jeff Root Well-Known Member

    Simon,

    It appears to me that your patient has an inverted rearfoot. If the forefoot is parallel to the ground, then she would appear to have an everted forefoot to rearfoot relationship.

    Jeff
     
  39. So, rearfoot varus, forefoot varus- chronic lateral ankle instability; your father's model would have us post the orthoses how?
     
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