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Human Joint Properties

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  • Human Joint Properties

    I am responding to Marina Koutchouk's request for information regarindg
    the stiffness and dampins of different human joints posted on Frduay 20

    In general I thing that most of the information is simply not available.
    There have been a number of single degree of freedom studies of
    individual joints -- mostly ankle, finger, wrist and elbow. Ian Hunter
    and I reviewed these in a CRC review in 1990.
    (Kearney, R.E. and I.W. Hunter, System identification of human joint
    dynamics. Critical Reviews in Biomedical Engineering, (1990) .18:55-8.).
    In general these studies show that:

    (1) Joint propoerties can be reasonably approximated by inertia,
    stiffness and damping for small perturbations under stationary operating

    (2) However, the damping and stiffness change dramatically with the
    operasting point and are particularly sensitive to changes in position
    and level of activations. Stiffness changes may be greater than an order
    of magnitude as these conditions vary through the physiological range.

    (3) The simple second order model DOES NOT hold when these parameters
    are changing rapidly as they do during active or passive movements

    (MacNeil, J.B., R.E. Kearney, and I.W. Hunter, Identification of
    time-varying biological systems from ensemble data. IEEE Trans. BME,
    (1992) .39:1213-1225.

    (Kirsch, R.E. and R.E. Kearney, Identification of time-varying stiffness
    dynamics of the human ankle during an imposed movement. Exp. Brain Res.,
    (1996) .In Press.

    (4) Reflex contirbutions, at least at the ankle, are very nonlinear and
    cannot bre thought of as simply increasing the stiffness or damping at
    the ankle (e.g. Kearney, R.E., R.B. Stein, and L. Parameswaran,
    Identification of intrinsic and reflex contributions to human ankle
    stiffness dynamics. IEEE Trans. BME, (1997)

    (5) Until now there have been relatively few studies of joint mechanics
    of larger joints (hip, knee, shoulder) or multiple degrees of freedom
    There is some very recent work in this direction: Gomi, H. and M.
    Kawato, Eqilibrium-point control hypothesis examined by measured arm
    stiffness during multi-joint movement. Science, (1996) 272:117-120.)

    Hope this information helps. Please contact me if you need more

    rob kearney
    Robert E Kearney, Ph.D. Eng.,
    Professor & Chair,
    Department of Biomedical Engineering,
    McGill University,
    3775 University Street,
    Montreal, Quebec, Canada H3A 2B4

    Tel : (514) 398-6737
    Fax : (514) 398-7461
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