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PhD thesis on skin movement

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  • PhD thesis on skin movement

    Dear BIOMCH-L readers,

    My colleague Rene van Weeren at the Faculty of Veterinary Medicine in
    Utrecht (Netherlands) has recently completed his PhD thesis concerning
    the effect of skin-movement in kinematic analysis of the horse. The
    thesis may be of interest to those who use kinematic data for
    biomechanical analysis. A number of copies is still available from the

    Dr. P.R. van Weeren
    Department of General and Large Animal Surgery
    Faculty of Veterinary Medicine
    University of Utrecht
    P.O. Box 80153
    3508 TD Utrecht, The Netherlands.

    A short summary:

    by P.R. van Weeren, ISBN 90-9003110-3

    Chapter 1 is a review of equine movement analysis, and a general
    introduction to the problem of skin movement.
    Chapter 2 describes a technique (subcutaneous LED's) for direct measu
    rement of bone movement in a walking horse. Results and regression
    models relating skin movement to joint angles are presented in chapter
    The LED's could not be used in the upper parts of the limbs, where the
    bones are covered by a thick layer of muscles. A new technique, based
    on transcutaneous pins with two markers attached, was developed.
    Results for the walk and trot are presented in chapters 4 and 5. In
    chapter 6, the skin movement patterns of horses with different size are
    compared. It was found that, after normalization to bone length, the
    time courses of skin movement in different individuals were very
    An algorithm to correct raw kinematic data for skin-movement errors is
    developed in chapter 7. In order to apply this method, one has to be
    able to predict skin movement in an arbitrary individual. Suitable
    regression models, based on previous measurements, are given in chapter
    The final chapter (9) shows how the correction method can be applied
    to measurements done with a (modified) CODA-3 system. After correcting
    the kinematic data for skin-movement errors it was found that the knee
    and tarsal joints of the horse move congruently, which confirmed the
    existence of a 'reciprocal apparatus' formed by the Peroneus Tertius and
    Gastrocnemius muscles. Previous attempts had always failed because of
    errors as large as 15 degrees in the knee joint angle.

    According to the tradition, the thesis is accompanied by a number of
    'propositions', of which the first two are:

    'There is a marked discrepancy between the accuracy of the equipment
    used for equine kinematic gait analysis and the care with which
    researchers interpret the error caused by skin displacement in gait

    'The accuracy and high standard of equine kinematic gait analysis before
    World War II may serve as an example to many contemporary researchers.'

    --Ton van den Bogert
    Dept. of Veterinary Anatomy
    University of Utrecht, The Netherlands.