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coupled motion/cross-talk

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  • coupled motion/cross-talk


    Recently (Clin Biomech 16 (2001) 455-458) Hof et al. identified
    'cross-talk' in the coupled cervical motion described by Feipel et al
    (Clin Biomech 14 (1999) 462-470) and subsequently suggested a more
    preferred Euler sequence that would minimize this 'cross-talk'.
    However, Hof stated that their recommendation would work for one
    sequence of motions, eg, flexion + axial rotation, (performed using a
    'dummy' head and neck) but would not work for a different sequence, eg,
    flexion + sidebending, of motions. Hof et al went on to conclude that
    'as long as no solution is available that can exclude cross-talk
    effects, any reported coupling effect in cervical spine motion should be
    interpreted with extreme caution'.

    I am investigating the 3D kinematics of the thoracic spine, and am
    particularly interested in the coupling patterns of sidebending and
    axial rotation. I would like to be able to describe with some degree of
    confidence what these patterns are knowing that the issue of
    'cross-talk' is ever present. Additionally, I would like to be able to
    explain the mathematical phenomenon that causes this problem.

    Hof el al has suggested that 'cross-talk' is a mathematical problem not
    related to measurement methodology but does not say what the
    mathematical problem is. So I am wondering if anyone in the
    biomechanics community can more precisely describe the mathematical
    problem (when using Euler angles) that causes 'cross-talk'?

    I will post all responses.

    Thank you.

    Gordon J. Alderink, PT, MS
    Program in Physical Therapy
    School of Health Professions
    319 Henry
    Grand Valley State University
    Allendale, MI 49401
    Phone: 616.331.2674
    Fax: 616.331.3350

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