DynaKAD.

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Version 1.0, December 1998
Written by Richard Baker, richard.baker@greenpark.n-i.nhs.uk, based on original code by Laura Finney.


Requirements
============

This model will not work unless you have BodyBuilder version 3.51 build 116 or higher. You can check this by clicking |help|About BodyBuilder... from within BodyBuilder. Talk to your VICON supplier if you have an earlier version.


Disclaimer
==========

This model is distributed on the understanding that the author takes no responsibility for its use by others. Individual users must satisfy themselves of its reliability. Like most Gait Analysis Models there is no gold standard against which to compare its results and an assessment of its validity is essential subjective.

I suggest that it is best used as a training or quality assurance tool. It should not be used routinely to compensate for careless placing of thigh markers. If large corrections factors are routinely encountered then marker placement protocols should be reviewed. 


Introduction
============

This is a BodyBuilder model which will calculate a thigh rotation value to enter in the VCM based on the assumption that any varus/valgus signal which looks similar to the knee flexion/extension signal is an artefact of thigh wand mis-placement. It will not be reliable if the subject has true medio-lateral instability at the knee or if the subject exhibits a stiff knee gait (in either flexion or extension). 

It works on a .C3D file of a walk using the standard VCM marker set. It will work if there are gaps in the data but results are far more reliable with complete data.


Running the model
=================

To run the model open the .C3D file containing the trial you wish to analyse and select the DynaKAD.mod, DynaKAD.mkr and DynaKAD.mp files in the subject settings. Open the parameter file in BodyBuilder and modify the input parameters for the particular subject, all lengths are in millimetres. Run the model and the results will be in entered as output parameters in the parameter file. 

You can insert values of the $LVCMRotation and $RVCMRotation into the Thigh Rotation boxes on the Session window of the VCM and if you (re)process the data the corrected traces will be displayed. If you have used the KAD to determine the shank rotation then (to a good approximation) replace the shank rotation values using the equation:

       new shank rotation = old shank rotation - (old thigh rotation - new thigh rotation)

Static plantarflexion and foot rotation angles should only be affected to a limited degree.


Files
=====

The files are provided in read only format. I suggest they are left like this for reference. Obviously you are completely free to copy them and modify the copies.

DynaKAD.mkr	

Is a not essential, any .mkr file describing the standard VCM markerset will do.

DynaKAD.mp	

Is essential. There is a lot of comment to try and help you understand what the model is doing and what its limitations are. It may be easier to delete the comment lines for easier routine application once you are happy with this. It makes sense to
save a version of this along with the .C3D files for each subject.

DynaKAD.mod

This is based on CALIGULA.mod, a bodybuilder version of the VCM model which I have written and demonstrated to be virtually identical to the VCM model. It has comment lines describing how it functions, but these will need to be read in conjunction with the published paper describing the method.

DynaKAD.doc

This is a paper which has been accepted for publication in Human Movement Science. It gives full details of the theoretical basis for the model. It is in Microsoft Word 6.0 format.