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Marker sets and models for the kinematic analysis of lower limbamputees

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  • Marker sets and models for the kinematic analysis of lower limbamputees

    Dear Biomech-L subscribers,

    I'm doing some work on the use of biomechanical models and marker sets
    to study the kinematics of lower limb amputees. My efforts were
    initially geared towards selecting an appropriate marker set for amputee
    analysis that could also be applied broadly to all patient groups and
    healthy subjects (as normative controls) to facilitate comparison, with
    both clinical and research applications in mind. This would comprise a
    standard configuration that could be built upon for specific
    applications that require additional segments/parameters to be analysed,
    but would ensure data collection uniformity as far as possible.

    A lit search I conducted brought up many studies on individual amputees
    or amputee cohorts using a variety of marker sets, although the majority
    appeared to be some form of Helen Hayes derivative. On the prosthetic
    side markers were commonly placed on mechanical centres of rotation
    where obvious (e.g. on single axis joints) or "estimated from the sound

    I was concerned about the appropriateness of the use of several of the
    common models and methods when analysing amputee function, particularly
    when directly comparing the function/movement of prosthetic and sound
    limbs. Examples of such applications would be comparing prosthetic gait
    to normative data, evaluating limb symmetry (is this appropriate
    anyway?! I'm doubtful in most cases, esp when it concerns unilateral
    amputees), and comparing components that function differently
    mechanically (e.g. 4-bar knee vs single axis knee, SACH foot vs foot
    with articulated ankle joint).

    I imagine it may be possible to achieve more reliable/valid results (and
    a system that may be applied more universally) with joint centres
    determined functionally, technical markers for tracking segmental
    movement and perhaps the addition of extra markers to monitor relative
    movement of the residual limb with respect to the socket (although I
    won't even attempt to touch on the issues of placement and treatment of
    soft tissue artefact here..). Regarding the selection/development of a
    model that will enable prosthetic components that have not been designed
    to reproduce natural segment movement to be adequately represented (e.g.
    SACH foot, running blades) and that will allow different limb alignments
    to be compared (where the neutral condition at joints may be altered by
    nature of the study) I am a little lost. I anticipate when I begin to
    consider the analysis of joint moments, torques and powers, which
    undoubtedly will open yet another can of worms, I will be even more so.

    I suspect that my idea of a universally applied base marker set and
    model may be unrealistic, even given an allowance for additional
    markers/segments for specific analyses, and that with amputee cohorts
    kinematic models will have to be more specifically geared towards the
    question that the analysis is required to answer.

    I would be very grateful if anyone has any thoughts or advice to share
    on the subject. I remember there was a very relevant presentation and
    discussion at the CMAS UKI annual meeting and conference in Edinburgh
    2009 - I am aware that there may be groups specifically looking into it
    and I was wondering if there have been any recent developments that I
    have not come across. I'll happily post a summary of replies - please
    let me know if you'd prefer not to appear in it!

    Many thanks

    Jenny Kent
    Higher Scientific Officer
    Centre for Human Performance, Rehabilitation and Sports Medicine
    DMRC Headley Court
    Epsom, Surrey