Marker Sets

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1

Hi,

I have created several models using gait analysis data and have got some over-active muscles particularly at toe off. I was wondering if anyone else had had this problem and had any solutions for it! I appreciate that this could be a complex problem and there could be many explanations for it but I thought that any suggestions of simple things to try might be useful.

The marker set from the gait analysis data has four markers clustered on each lower limb segment rather than the marker sets I have seen previously, with markers placed on bony landmarks and one marker on the body segment. I have used the PosVelAcc optimisation on the GaitApplication2. Has anyone else used Gait Application2 with different marker sets?

The muscles that are over active are Gastrocnemius Lateralis, Medialis and Tibalis Anterior. To try and reduce the muscle forces across the ankle I then tried using an AnyReacForce for both the ankle plantar flexion and the eversion. However, although this does reduce the forces I still have an over-active Gastrocnemius Lateralis and Semitendinosus. I realise that using a AnyReacForce is not a ideal solution since it just bypasses that problem and I still end up with over-active muscles so this doesn’t completely help my problem.

Any suggestions gratefully received!

Catherine Manders

2

Hi Catherine,

Yes, we often see overloaded muscles exactly at toe-off, and the cases I can think of have been due to inaccurate GRF data just around this point in time. Do you have the possibility of visualizing the behaviour of the CoP during the stance phase in your model? If you have, please check what happens to it just around toe-off. My guess is that it migrates far away from the toes.

Best regards,
John

3

Thanks for your suggestion. Unfortunately that doesn’t seem to be the problem. My COP is underneath the ball of the foot as the toes leave the ground and the muscles have just return to normal activity at that point.

4

Hi Catherine,

I am will be traveling the next two weeks and cannot take a look at your model, but if you make a post over in the professional forum and upload your model there, then perhaps one of the supporters will have a look at it.

Best regards,
John