MoCap-GM Metatarsal

Hi,

My goal is to lengthen the segments by either a scaling factor or to input specific measurements for the MT bones and analyze the output.

I am using AnyBody v6.0 with AMMR 1.6 I believe. I am changing the length of the Metatarsal3 (MT3) in the AAUHuman\FootGM\Seg.any file. The problem is, this file says “Not Loaded” at the top. However, when I comment out any part of the code within this file, I receive an error. I believe this is simply a bug with the code saying its “Not Loaded” when it actually is loaded.

Ignoring this, I have some other issues. When I do change the length, I simply scale it by length*1 or 1.5 etc. After loading my initial conditions, the model view still looks the same. The segment has not lengthened at all. Even if I do length3, there is no observable difference. From my understanding of the code, there should be an observable difference when loaded.

Also, after scaling the length and running inverse dynamic analyses, there is no change in the output on the “ExtensorDigitorumLongusToe3Tendon.” I would assume that lengthening the segment would change the force on it but it doesn’t seem to.

Please let me know if I am doing this correctly or not.

Thanks,
Chris

Dear Chris,

The first issue seems to be a bug in the modeling system. I could observe a similar behavior for some files, I forwarded the issue to our developers to analyze it.

About the Metatarsal scaling. This project is not trivial. The foot model uses a very complex scaling technique. I presented the model a couple of week s ago at the combined ORS meeting, here is the video re-recorded:

http://www.youtube.com/watch?v=joNnTVz8zuA&feature=c4-overview&list=UUbgDnEKXyYOETR_Nb6YdehA

Where do you exactly change the length?
Here are some questions to demonstrate the difficulty of the project.
How do you want to change the recorded pressure data to be applied to the longer metatarsal?
How do you want to change the recorded motion from motion capture to deal with the longer metatarsal?

Amir,

I am trying to analyze the stresses on the foot, specifically the metatarsals, based off of patient specific data. I assumed the best way to do this would be to manually enter the values in for the metatarsal lengths but it seems that this won’t work.

How would you recommend I do this? Would I have to create a foot model based off of patient specific measurements and input that into a software like MeshLab as seen here:
http://www.youtube.com/watch?v=BmB-88o8uYY&list=UUbgDnEKXyYOETR_Nb6YdehA
and then upload that into AnyBody to use?

What would you recommend?

Chris

Hi Chris,

sorry for the late answer.

The model uses a lot of measured input:

  • force plates
  • pressure plates
  • motion capture (28 markers on foot)
  • Surface scan of foot

If you have all of that data it is very easy to analyze a new subject. I understand that this is a huge effort to measure all of that, so we are working on models that require less measurements. I have some prototypes ready, but they are not released yet.

You can change also single values from the existing model, but if you make for example the metatarsal longer, the measured pressure data will not fit to the new foot geometry.
You could start by changing the scaling method:

  1. Change the FootScaling Law in the HumanModel file from LengthMassFatRBF to only LengthMassFat. (RBF is morphing using the surface scan):

    #include “<ANYBODY_PATH_BODY>Scaling\FootScaling\ScalingLengthMassFat.any”
    // #include “<ANYBODY_PATH_BODY>\Scaling\FootScaling/ScalingLengthMassFatRBF.any”

  2. Change the AnyMan file in the HumanModel file from AnyManRBF to only AnyMan:
    // #include “AnyManRBF.any”
    #include “AnyMan.any”

Now you can change the overall foot length in the AnyMan file.

Amir,

Thank you for your help.

A couple more questions:

-Is it possible to use a patient specific foot without using the force plate? Or would that defeat the purpose? I do not have access to a force plate.

-What program would you recommend to convert a CT to a .stl to use in AnyBody? And where in anybody do I upload this .stl?

-I am going through the Scaling tutorials (Lesson 3) and I am unable to download and save “Lesson3c.Main.any”. Is there a problem with the tutorial?

-Also, I made those changes in my file and I received an error
ERROR(SCR.PRS1) : C:/U…s/B…U/D…p/A…0/AMMR/A…n/Beta/M…t/S…g/RBFLandmarks.any(25) : ‘ScaleFunction’ : Object already declared at :
C:\Users\BME_RU\Desktop\AnyBody.6.0\AMMR\Body\AAUHuman\Scaling\FootScaling\ScalingLengthMassFat.any(212) : ‘ScaleFunction’

Thanks again,
Chris