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My new biomechanical model

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Robertisaacs, Sep 13, 2010.

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    Yep. I've made one. Everyone seems to have one. I felt left out.

    Sadly, not being the clever sod that my rt. hon. colleagues on this forum are, I can't come up with a theoretical model. Finite element analysis give me migraine. So I made a model in the physical sense. For teaching don'tcha know.

    Drumroll please....


    Like I said,its a biomechanics model. A model, made of wood and hinges, bungees and ropes, for use in teaching biomechanics to those who prefer kinesthetic learning (which in my experience is a LOT of people who struggle with biomechanics.)

    So, if I may, let me talk you through it.

    You can see the 5 struts representing the metatarsals. All individually hinged and connected at the toe end by a bungee with spacers to represent the IM ligaments. I tried to place them as anatomically accurately as I could, with the parabola at the proximal end and the 5th met flat to the floor. There is a paralell bar across the Mid tarsal area and a spirit level which works in frontal and sagittal planes to show what effect the windlass has on the sub talar joint (and vice versa)


    The 1st met is thicker and has a removable wedge to represent the stability at the base of the 1st met, with a toe at the other end which bends. If there is a mk 2 version it may have variably compressible wedges for the base of the 1st met.


    The first met. Mad the joint a little thicker to exaggerate the effect of the windlass (and because the head of the met IS thicker. The rope for the plantar apeuneurosis runs smooth under the met in grooves cut for the purpose (sesamoids).


    This is the bit I'm really proud of. A set of scales to measure the stress in the plantar apeuneurosis. Oh and the tension in the PA is adjustable to represent the differences in that structure in actual patients.


    So, apart from just playing with it, you can demonstrate all types of stuff on this thing. Change the base of the 1st met stability and see what that has on the stress in the PA. Change the height of the arch WITHOUT changing the PA tension (adjustable length remember) and measure the amount of stress which goes on when you dorsiflex the hallux to establish the windlass. Move the bag of sand which I use for body weight (not shown;)) medially or laterally on the mid tarsal area to represent the axial position and observe the effect THAT has on the PA stress, the stress to establish the windlass...

    Etc etc etc. I made this for a study day with a presentation on sagittal plane biomechanics but it's kept growing. I keep finding new stuff to put on it, and new stuff I can use it for. One day, there will be Mk 2 which will be far better.

    I've had a lot of fun, and learned a lot making it. Hopefully the people I inflict it on when teaching will find it useful!

    Whaddaya think?

  2. RobinP

    RobinP Well-Known Member

    I think the inflatable booster seat in the last picture was about as much use for your kids as it was for mine
  3. dannytso

    dannytso Welcome New Poster

    Wow I am very impressed at your project. Especially the scales to measure PA tension! Thank you very much for presenting this. In your next version, maybe go further back to the subtalar and ankle joint and add a mitered hinge model?
  4. Jeff Root

    Jeff Root Well-Known Member

    Only one problem with your model as far as I can see. Possible termites! ;)
  5. Robert:

    Here is a foot model I constructed about 5 years ago to demonstrate at one of the PFOLA meetings I lectured at.

    Pink rope=plantar ligaments

    Blue rope=central component of plantar aponeurosis

    Attached Files:

  6. Thanks all. Never fear Jeff, I fumigate my models regularly.

    Like yours Kevin. Very neat. Very diddy.

    The model of the ankle would not go well with that one, gets too fiddly. I have a very basic ankle model with an adjustable achillies tendon, a talo crural joint which works only in the sagittal plane and a sort of sub talar joint with the axis at 42 degrees and a bungee for joint stiffness. Its good for showing "escape pronation" and the effect of tightening the triceps surae on the sub talar joint.

    I'll upload a pic of that later if I get time ;-). And If you're REALLY lucky, I might do a short video of it next time I do any lecturing and send it round. Depends if I can get someone to hold the camera.

  7. I'll hold the camera for you in Portugal, just watching you trying to explain it during a security search at the airport will be worth it.:D

    P.S. I always enjoy seeing Kevin's minimalist footwear.
  8. Yeah....

    Perhaps a minature version? This thing is about 4 1/2 feet long and a bit odd. The first day will be full enough without an invigorating and thorough body cavity search to start it off!
  9. Paul Bowles

    Paul Bowles Well-Known Member

    Barefoot running they are not!

    Looking at these models you guys have done blows me away....what amazing dedication and time you invest into this, a credit to you.

    I must also add that I think you are all nuts, and these models and their manufacture just further confirm my suspicions ;)
  10. Don't get that idea just because of the models. The squirrels gave me a lot of help.:wacko:

    Thanks Paul.

    Had an idea for another SALRE one last night.
  11. blinda

    blinda MVP

    Sooo true :drinks
  12. This is the ankle one. Not useful for much besides simulating effects of equinus on the sub talar joint.

  13. Mechanical models, such as the one that Robert and I have made, are excellent methods by which to demonstrate how the human foot and lower extremity function mechanically. In fact, these types of models can be so helpful to those certain individuals that have difficulty understanding complex three-dimensional mechanical concepts, I feel they should be required for teaching departments at all podiatric medical schools.
  14. Ian Linane

    Ian Linane Well-Known Member

    Hi Robert
    Really good stuff. Having seen earlier versions they just get better.
  15. Thanks Ian, By linear progression I should be producing something like optimus prime in about 20 years.;)

    I'll wait for the call from the university but I won't hold my breath...:rolleyes:
  16. Sarah Byrne

    Sarah Byrne Member

    I can't wait to see the new model (on Saturdays course in Poole). As one of those "Certain Individuals"!!!!! that Mr Kirby mentions, I can confirm that they do really help. Thankyou to all of you clever folks for your time and effort in helping the rest of us to be less scared!
  17. Ian Linane

    Ian Linane Well-Known Member

    The other thing Rob is that every time I see yours it just seems to get bigger ;)
  18. Ian, Are you coming on to me?!?!

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