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choice of a reference posture is important when investigating rearfoot
motion in clinical populations. The reference posture used may affect
the magnitude of the peak angles and therefore may not enable comparison
of the rearfoot kinematics across different populations. This study
examined the relationship between the rearfoot frontal plane pattern
of motion and three reference postures during the stance phase of
walking in healthy and patellofemoral pain syndrome (PFPS) subjects.
The three reference postures investigated were: Relaxed Standing posture,
subtalar joint neutral position (STJN) and when the calcaneus and
the lower leg were vertically aligned (Vertical Alignment). The rearfoot
inversion/eversion during the stance phase was measured in 14 healthy
subjects and 13 subjects with diagnosed PFPS using three dimensional
motion analysis with the three different reference postures. The graphs
of rearfoot inversion/eversion motion were overlaid with the angle
at the rearfoot in the static posture and any intersection between
the static angle and rearfoot motion was noted. An ANOVA showed significant
differences in static posture between the groups for Relaxed Standing
(p = 0.01), and STJN (p = 0.02). For both groups, with Relaxed Standing
as a reference posture, the mean rearfoot pattern of motion did not
intersect the Relaxed Standing static angle during the stance phase.
The use of Vertical Alignment reference posture, however, showed an
intersection of this reference posture through the rearfoot pattern
of motion. The use of the Vertical Alignment reference posture also
generated a typical rearfoot motion pattern for both groups and therefore
it may be an appropriate reference posture for both healthy and PFPS
individuals.
KEY
WORDS: Vertical alignment, subtalar joint neutral position,
rearfoot motion, reference posture.
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