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  • Re: Ankle torque

    Here is a summary of all the answers I got concerning the ankle torque.
    The values I made reference in the first message were for the
    antero-posterior ankle stiffness when standing, that could be the
    reason for the differences in the values of the messages I have
    received.

    The reference of the paper where I got this information is:
    Ankle stiffness of standing humans in response to imperceptible
    perturbation: reflex and task-dependent components.
    By Richard C. Fitzpatrick et al.
    Journal of Physiology (1992), 454, pp.533-547.

    Thanks to all answerers


    -----Original Message-----

    I would like to get information about the torque that appears in
    the ankle joint during an inversion / eversion rotation of about 30
    degrees (ankle sprain). I just need an approximate value for a
    general adult population.

    I have found some information about ankle stiffness for the
    antero-posterior movement of the ankle. The value of the stiffness is
    between 400 and 800 (Nm/rad) for adult men, but I think I can not
    extrapolate this data for inversion / eversion rotation of the ankle.


    __________________________________________________ _________


    J. Marcus Hollis:

    We have found in our clinical studies of ankle laxity that you can
    easily
    get 30° of inversion with a 4 Nm moment without injury or discomfort.
    (The device we use actually measures the tibia-calcaneous motion or the
    motion of what we call the ANKLE JOINT COMPLEX. This will have greater
    mobility in inversion than just the ankle joint)

    Of course in all depends on the individual. The ankle stiffness varies
    greatly among individuals.

    J. Marcus Hollis, Ph.D.

    __________________________________________________ _________

    Ian Wright:

    Regarding ankle joint mechanical properties, check out:

    Chen, J., Siegler, S., and Schneck, C.D., 1988, "The three-dimensional
    kinematics and flexibility characteristics of the human ankle and
    subtalar
    joints- Part II: flexibility characteristics, Journal of Biomechanical
    Engineering, Vol. 110, pp. 374-385.

    __________________________________________________ _________

    Karol Galik:

    Check the folloowing article:

    "I. C. Wright, R.R. Neptune, A.J. van den Bogert, B. M. Nigg: The
    influence of foot positioning on ankle sprains: Journal of Biomechanics
    33
    (2000) pp. 513-519".

    Karol Galik
    PhD student at ME department
    University of Pittsburgh, PA
    412 624 9776 Phone
    kagst34@imap.pitt.edu


    __________________________________________________ _________

    Jim Funk:

    The question you ask is actually quite complicated. Have you
    investigated
    the automobile safety literature? Several papers have addressed this
    question in one form or another. However, many factors affect the
    stiffness of the ankle joint. For one thing, human volunteers have
    stiffer ankles than cadavers, even with relaxed muscles. Active muscle
    contraction would tend to further stiffen the ankle joint. Also, ankle
    stiffness increases when the joint is subjected to dynamic rotation
    compared to quasistatic rotation. Axial loading of the leg also
    stiffens
    the ankle joint in inversion/eversion and may affect the mode of injury.

    In addition, the precise definition of inversion-eversion must be
    addressed. For example, is the angle defined by the rotation of the
    calcaneus relative to the tibia or the forefoot relative to the tibia?
    Forefoot rotation relative to the calcaneus can be substantial. Also,
    ankle stiffness about the inversion/eversion axis increases when
    rotation
    about the other axes (dorsiflexion/plantarflexion and internal/external
    rotation axes) are constrained.

    Various papers have reported that injury (ligament tears or malleolar or

    fibula fractures) occurs at greater than 60 degrees inversion/eversion
    (Begeman et al., 1993), 30-35 degrees inversion/eversion (Parenteau et
    al., 1998), or less than 10 degrees inversion/eversion if injurious
    levels
    of axial loading are present (Funk et al., 2000). The moment at which
    injury occurs has been reported to be 34 Nm in inversion and 48 Nm in
    eversion (Parenteau et al., 1998). The stiffness of the ankle joint is
    non-linear, and increases at higher rotations. However, the value of
    400-800 Nm/rad is quite a bit higher than what is reported in the
    literature for untensed volunteers and cadavers subjected to quasistatic

    rotation without axial loading (Crandall et al., 1996; Petit et al.,
    1996;
    Jaffredo et al., 2000). Of course, all of these numbers may vary
    depending on the age, mass, and gender of the subject.

    Here are the references I used:

    Begeman, P., Balakrishnan, P., Levine, R., King, A., Dynamic Human Ankle

    Response to Inversion and Eversion, Proc 37th Stapp Car Crash Conf, SAE
    933115, pp. 83-93, 1993.

    Crandall, J.R., Portier, L., Petit, P., Hall, G.W., Bass, C.R., Klopp,
    G.S., Hurwitz, S.R., Pilkey, W.D., Trosseille, X., Tarriere, C., Lassau,

    J.-P. Biomechanical Response and Physical Properties of the Leg, Foot,
    and Ankle, Proc 40th Stapp Car Crash Conf, SAE paper 962424, pp.
    173-192,
    1996.

    Petit, P., Portier, L., Foret-Bruno, J.-Y., Trosseille, X., Parenteau,
    C.,
    Coltat, J.-C., Tarriere, C., Lassau, J.-P., Quasistatic Characterization

    of the Human Foot-Ankle Joints in a Simulated Tensed State and Updated
    Accidentological Data, Proc. Internation Research Conference on the
    Biomechanics of Impact (IRCOBI), pp. 363-376, 1996.

    Parenteau, C.S., Viano, D.C., Petit, P., "Biomechanical Properties of
    Human Cadaveric Ankle-Subtalar Joints in Quasi-static Loading," Journal
    of
    Biomechanical Engineering, Vol. 120, pp. 105-111, 1998.

    Funk, J.R., Tourret, L.J., George, S.E., Crandall, J.R., The Role of
    Axial Loading in Malleolar Fractures, Biomechanics Research, SP-1494,
    pp.
    9-21, Society of Automotive Engineers, SAE paper 2000-01-0155, 2000.

    Jaffredo, A.S., Potier, P., Robin, S., Le Coz, J.-Y., Lassau, J.-P.
    "Cadaver Lower Limb Dynamic Response in Inversion-Eversion," Proc.
    Internation Research Conference on the Biomechanics of Impact (IRCOBI),
    Montpelier, France, pp. 183-194, September 2000.

    Jim Funk
    Research Scientist
    Automobile Safety Laboratory
    University of Virginia
    1011 Linden Ave.
    Charlottesville, VA 22902
    Phone: (804) 296-7288
    Fax: (804) 296-3453

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