Quantitative gait analysis is an important clinical
tool for quantifying normal and pathological patterns
of locomotion, and has been shown to be useful
for prescription of treatment as well as in the
evaluation of the results of such treatment
(1,6,16,17). Typically, data acquired during a clinical
gait analysis include relative positions and orientations
of body segments, foot-floor reaction
forces, temporal-distance parameters, and phasic
activity of muscles of the lower extremities. Several
practical methods in current use provide relative
orientation of segments either directly or as a derived
parameter from measurements of relative position
of segments.