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Congratulations to Prof. Hatze! After a fairly unprovocative period on
BIOMCH-L, something to stiffen the sinews (and, therefore, reduce those soft
tissue submotions!).
In response to points 1,2 and 5:
Neglecting other pursuits in musculo-skeletal biomechanics, in clnical gait
analysis the motion of the body refers to the
motion of body segments around joints. In that sense then, we describe the
skeletal motion, with the mean displacement of the soft-tissues in a steady
state, cyclical, activity being zero relative to the skeleton. Of course,
the sub-motion of the soft tissues may alter joint kinetics and
therefore the motion of the skeleton, though the size of these effects may
be
small in all but sporting activities.
In principal, we are able to perform a validation exercise of the
description of motion derived from surface markers without doing anything
too dreadful to the subject. I understand that some researchers are using a
texture matching technique between 2D projections of CT data and images from
dynamic biplanar
radiographs, to locate skeletal structure in 3D in treadmill walking.
They generate results with high levels of accuracy when compared to 3D
kinematics
computed from fiducial markers (a relatively
non-invasive gold standard, perhaps?) . Could we use such techniques to
verify the
use of surface markers to describe kinematics or calculate the magnitude of
our errors?
Of course, the accurate calculation of joint kinetics would still remain
elusive, particularly those parts derived from the inertial components.
Better, perhaps bespoke, anthropometric models are required. MRI is
providing some of that data, but the availability and cost of this
measurement may be probibitive to many laboratories. In
our laboratory, we use 3D ultrasound (optical tracking of a linear array
probe) to measure muscle morphology in the
static subject, for clinical purposes. It would be possible to make some
better estimates of the distribution of muscle volume and therefore muscle
mass using this technique. Also, we have performed some preliminary work
measuring bony
lengths (to within a few mm accuracy, we believe). With optically-guided
ultrasound, it should be possible to estimate joint centres and calculate
moment arms (in static conditions) without the skin and soft tissue spoiling
things (we haven't done this yet!).
Whether it's ultrasound and/or other techniques, motion analysis needs
local, relatively inexpensive, adjunctive methods to fill the
subject-specific knowledge gaps.
Adam Shortland PhD,
One Small Step Gait Laboratory,
Guy's Hospital
LONDON
UK
adam.shortland@virgin.net
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BIOMCH-L, something to stiffen the sinews (and, therefore, reduce those soft
tissue submotions!).
In response to points 1,2 and 5:
Neglecting other pursuits in musculo-skeletal biomechanics, in clnical gait
analysis the motion of the body refers to the
motion of body segments around joints. In that sense then, we describe the
skeletal motion, with the mean displacement of the soft-tissues in a steady
state, cyclical, activity being zero relative to the skeleton. Of course,
the sub-motion of the soft tissues may alter joint kinetics and
therefore the motion of the skeleton, though the size of these effects may
be
small in all but sporting activities.
In principal, we are able to perform a validation exercise of the
description of motion derived from surface markers without doing anything
too dreadful to the subject. I understand that some researchers are using a
texture matching technique between 2D projections of CT data and images from
dynamic biplanar
radiographs, to locate skeletal structure in 3D in treadmill walking.
They generate results with high levels of accuracy when compared to 3D
kinematics
computed from fiducial markers (a relatively
non-invasive gold standard, perhaps?) . Could we use such techniques to
verify the
use of surface markers to describe kinematics or calculate the magnitude of
our errors?
Of course, the accurate calculation of joint kinetics would still remain
elusive, particularly those parts derived from the inertial components.
Better, perhaps bespoke, anthropometric models are required. MRI is
providing some of that data, but the availability and cost of this
measurement may be probibitive to many laboratories. In
our laboratory, we use 3D ultrasound (optical tracking of a linear array
probe) to measure muscle morphology in the
static subject, for clinical purposes. It would be possible to make some
better estimates of the distribution of muscle volume and therefore muscle
mass using this technique. Also, we have performed some preliminary work
measuring bony
lengths (to within a few mm accuracy, we believe). With optically-guided
ultrasound, it should be possible to estimate joint centres and calculate
moment arms (in static conditions) without the skin and soft tissue spoiling
things (we haven't done this yet!).
Whether it's ultrasound and/or other techniques, motion analysis needs
local, relatively inexpensive, adjunctive methods to fill the
subject-specific knowledge gaps.
Adam Shortland PhD,
One Small Step Gait Laboratory,
Guy's Hospital
LONDON
UK
adam.shortland@virgin.net
---------------------------------------------------------------
To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl
For information and archives: http://isb.ri.ccf.org/biomch-l
---------------------------------------------------------------