have been used to record instantaneously
the three-dimensional joint rotation of
lower extremity. Accelerometers have also been
used for indirect measurement of angular displacements
of limbs (8,14,20). Interrupted light photography
has been used to derive sagittal plane motion
patterns (15,18) by monitoring reflective markers
placed on key anatomical locations. Cine film photography
(15,23) has been utilized to quantify the
motion patterns in three dimensions. Modern computer-
aided systems such as VICON (4) and SELSPOT
(2) provide accurate three-dimensional spatial
positions of reflective skin (surface) markers placed
on key anatomical sites on the lower extremities.
From these positional data, the relative angular rotation
of the individual body segments are derived
using analytical techniques based on a biomechanical
model of the lower extremity.