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This section presents the basic principles that enable the process
of Gait Analysis.
In general, it is assumed that
there are seven components that form the functional basis for gait.
1. Activation of the gait neuromuscular
system in the central nervous system.
2. Transmission of neural commands to the
peripheral nervous system.
3. Muscular involvement in producing
movement.
4. Generation of forces and moments at the
joints
5. Regulation of the joint forces and
moments.
6. Linear and angular displacement of the
body's segments
7. Generation of ground reaction forces
Only few of these components can be
measured. One can measure the external forces by utilizing force plates, pressure pads,
and various transducers. We can measure the movement by quantifying kinematics
parameters utilizing the APAS system to measure lengths, displacements, velocities and
accelerations. We can utilize the APAS Analog Module to measure EMG activity to allow some
estimation of muscular involvement, and Force Plates to measure ground reaction forces.
Since we cannot implant transducers into
the joints and measure muscular forces and moment directly, we must incorporate inverse
dynamics by measuring displacements of segments with simple mathematics to calculate
velocities and accelerations. Since the basic Newtonian equations allow us to
calculate forces by knowing mass and acceleration, we can estimate the forces and moments
at each body joint.
Only the anthropometry of the skeletal segments, the segment
displacements, the ground reaction forces and the electromyography can be measured
directly. Everything else must be calculated.
A detailed theoretical foundations are available at the
following URLs:
1. http://www.celos.psu.edu/kinematics/
2. http://www.cs.bsu.edu/~ykwon/kwon3d/theories.htm
We, at Ariel Dynamics, are using these theoretical mathematical
foundations to allow you, as the practitioner, to have the most state-of-the-art system
for the lowest cost possible. For $15,000 you can purchase the full system, including
the computer, the software and 2 high speed cameras!!! You can own the best gait system
for this cost. Check with Vicon, Motion Analysis, Qualysis, Elite, or Peak. You
will find that the minimum cost for less of a system is over $200,000.
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