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Biomechanics Pearls of Wisdom

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Robertisaacs, Nov 25, 2009.

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    As some may know I write a column for Pod now. I have an idea for a future entry if I can get enough help.

    I'd like to put together a compilation of Biomechanical "pearls of wisdom". By the wisdom of crowds principle and considering the sum of the experience and knowledge on this arena this could be a pretty special article if everybody chips in!

    So. In 30 words or thereabouts, if you could impart one piece of information and / or advice on biomechanics, what would it be?

    Please don't be shy. Pragmatic advice is as welcome as theoretical. All pearls will be credited to the author if you give your name, if not it will be credited to your avatar. Feel free to offer more than one. If we end up with more than the available word count I'll choose the best but I reckon I could get away with 20 - 25 gems of wisdom!

    Remembering the rather brilliant "5 truths of biomechanics" and "5 fallacies of biomechanics" threads I have great hopes for this!

    Many thanks
  2. Johnpod

    Johnpod Active Member

    It's all very well measuring fourteen and a half degrees, but it's a waste of time if you can only get six degrees of correction into the shoe
  3. Craig Payne

    Craig Payne Moderator

    Motion, position, alignment and posture do not hurt or damage tissues. The forces need to stop motion are what do the damage.
  4. Johnpod

    Johnpod Active Member

    Here's another...

    If you get bogged down in measurements and you are not sure what your lines mean or where you are going - ask the patient to stand. Step back a pace or two and look at your patient as a whole. Then reconsider - what needs to be done to straighten them up?
  5. Johnpod

    Johnpod Active Member

    And another.....

    Pain arises from structures at the end of their ROM (range of movement).
  6. 1. Biomechancial Dogma is dead . Every patient is different there is no normal.

    2. Your best Goniometer is your ear. Listen to your patients.
  7. Craig Payne

    Craig Payne Moderator

    10 degrees is NOT the normal range of motion for the ankle joint.
  8. Craig Payne

    Craig Payne Moderator

    Foot pronation and supination does NOT drive tibial internal and external motion - its the other way around.
  9. Blind enthusiasm and superstition are not a replacement for sound knowledge and understanding of anatomy and mechanical principles.

    Foot orthoses are generally inert, shaped pieces of plastic as such they can only directly effect the forces acting at the foot – orthoses interface. This is ultimately how foot orthoses “work”.

    Think in four dimensions, always.

    There are many theories and models of foot and lower extremity function and dysfunction. The human locomotor apparatus knows nothing of these, nor cares less.

    Podiatric biomechanics is not black and white, use all of the colours all of the time.
  10. blinda

    blinda MVP

    Like it.

    The foot actually stabilises (not a loose bag.....) whilst pronating as the fascia becomes taut, pulling joints together (reverse windlass).

    The foot can be maximally pronated and still have an arch.

    Movement does not cause damage - force does. Jumping off a building - hitting the ground hurts, not the falling!;)

  11. Ask not what podiatric biomechanics can do for you, ask what you can do for podiatric biomechanics.
  12. Just because you cast a foot in a certain position does not mean that the foot will adopt that position on top of the foot orthosis constructed from that cast.

    The world outside your window is rarely a hard, flat, level surface.

    People don't just walk or run in straight lines when wearing foot orthoses. Rather they may step, hop, skip and jump in any direction their hearts desire.
  13. Craig Payne

    Craig Payne Moderator

    The orthotic will do a really good job of holding the postive cast in the certain position you want it in!
  14. Griff

    Griff Moderator

    Identify what anatomical structure(s) hurts -> decide what forces are damaging it -> change those forces
  15. Craig Payne

    Craig Payne Moderator

    The only measurements that count are those where you can actually do something with the number
  16. Heres one for you Robert

    Pronation is not bad.

    Workout what hurts and reduce the load on it

    The foot will move on top of the orthotic it will not be fixed.

    Know the difference between shank dependent and shack independent orthotics.

    Think about the word BIOMECHANICS. Don´t forget the mechanics bit when reveiwing patient and considering what you want your orthotic to do.
  17. flipper

    flipper Member

    The "evil flat foot" is not necessarily a bad foot, and an orthotic will not permanently create the arch you desire.... So your child/patient can still participate in sports that involve running!
  18. alan murchison

    alan murchison Welcome New Poster

    Orthotics key into the auto-support mechanism of the foot and allow the foot to support itself
  19. Dikoson

    Dikoson Active Member

    If something hurts then something is generally wrong with it.

    Assume nothing, test everything and understand why there is a problem. Its all about the "why", if you dont know the "why" then stop!
  20. efuller

    efuller MVP

    Tissue stress rules!!!!!

    There are a lot of pearls that are negatives, ie don't think that.... If you are just starting out, remember the advice that tells you what to do. (This is an addition to the only useful measurements are ones that changes what you do.)

    Understand the relationship between the location of ground reaction force and the subtalar joint axis. You push lateral to the axis, the foot tends to pronate. You push medial to the axis, the foot to supinate.

    More advanced:
    Once you've found the anatomical structure that hurts, draw the free body diagram of that structure to understand how to reduce stress on that structure. Or take the advice of someone who has.

    Eric Fuller
  21. Ella Hurrell

    Ella Hurrell Active Member

  22. I come back from a hard day in the lab hoping for one or two posts, and here are 20!!!

    You guys rock! What a community!

    Keep em coming! At this rate it'll be a double column!
  23. "It is incomprehensible to me that a podiatrist would not want to devote their practice careers toward better understanding the biomechanics of the foot and lower extremity for the benefit of their patients when, in fact, the foot is the only part of the body to be regularly subjected to external forces that are possibly orders of magnitude greater than the body weight of the individual."

    Kevin A. Kirby, DPM 11/25/09
  24. Graham

    Graham RIP

    An Orthotic is meerrly a frame on which you dispense the prescription. If the frame is bent, why bother with a prescription
  25. Jeff Root

    Jeff Root Well-Known Member

    Only practice that which is supported by evidence. As a result, you will have a lot of free time to devote to things other than the practice of medicine!
  26. Graham

    Graham RIP

    If in doubt, Cut it out....the first ray that is:dizzy:
  27. Craig Payne

    Craig Payne Moderator

    Inverted foot orthoses can and do make some feet pronate more ... and the patient still gets better.
  28. Sammo

    Sammo Active Member

    I know it sounds a little basic but I am consistently surprised by some practitioners and students poor anatomy knowledge..

    "Know foot anatomy like the back of your.. um, foot."
  29. If you think you understand everything about foot mechanics and orthotics you have probably not asked the right questions of yourself or others.
  30. Craig Payne

    Craig Payne Moderator

    Is the Holy Grail of foot orthoses to treat pronatory pathologies as simple as overcoming the rearfoot inversion moment and lowering & smoothing the 1st MPJ dorsiflexion stiffness curve?
  31. I think it was eric who said this to me awhile ago in a post.

    Don´t worry about motion think of moments when considering joint moevement.

    or something like that
  32. I think that the Holy Grail of podiatric biomechanics is to be able to accurately predict and efficaciously prevent or treat mechanically induced pathologies of the foot and lower extremity. As we have already stated that forces cause pathology, not motion then the concept of "pronatory pathologies" is then a misnomer too. Moreover, pathology may be a result of forces which tend to cause supination, dorsiflexion, plantarflexion, inversion, eversion, abduction and adduction moments in addition to "pronatory" forces; pathology may also arise from forces which tend to result in compression, tension, shear and torsion. Thus, the Holy Grail of foot orthoses is simply to prescribe devices which allow all of the tissues of the foot to function within their zones of optimal stress and strain (ZOOSS).
  33. fatboy

    fatboy Active Member

    Sometimes marking (L)eft and (R)ight on devices isn't enough.
  34. "stiffness" seems to be the "new black" this season.
  35. The human body is a fantastic machine. It is designed to carry the genes from one place to another as efficiently and pain-free as it can, so that when it gets there, it can make new versions of those genes. The gait you see in your patients is the body's attempts at working with what it's got in the most efficient and pain-free way it can. Biomechanical function observed is a function of genotype + environment + (genotype x environment) + measurement error.
  36. Paul_UK

    Paul_UK Active Member

    Not as technical as others:

    "Remember the foot is connected to the rest of the body. If in doubt take a step back and look at the whole picture"

    "If in doubt ask. Don't be afraid to refer on to someone else"
  37. Love this one! You always make me laugh Fatboy. :drinks

    Ok, here's mine.

    "The more you learn, the less you'll know. Don't panic, that's meant to happen"

    "Never underestimate the effectiveness of sticking something soft and squashy under something painful"

    "If you treat your family you will end up regretting it!"

    and full credit to Ian Linane for...

    "Ask a question and you may seem a fool for a minute. Fail to ask and you will remain a fool forever"
  38. You will learn more from your mistakes than your success stories if you take the time to work out why your treatment plan did not work.
  39. efuller

    efuller MVP

    Any monkey can make an orthotic. You earn your money when figure out how to modify one to make it relieve symptoms better.

    You can lead a student/podiatrist to knowledge, but you can't make him drink.


  40. Johnpod

    Johnpod Active Member

    If you don't do it, you'll never be good at it.

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