Article

The weight-bearing in-vivo kinematics and kinetics of the talocrural joint,
subtalar joint and joints of the foot were quantified using optical motion
analysis. Twelve healthy subjects were studied during level walking and
anticipated medial turns at self-selected pace. A multi-segment model of the foot
using skin-mounted marker triads tracked four foot segments: the hindfoot,
midfoot, lateral and medial forefoot. The lower leg and thigh were also tracked.
Motion between each of the segments could occur in three degrees of rotational
freedom, but only six inter-segmental motions were reported in this study: (1)
talocrural dorsi-plantar-flexion, (2) subtalar inversion-eversion, (3) frontal
plane hindfoot motion, (4) transverse plane hindfoot motion, (5) forefoot
supination-pronation twisting and (6) the height-to-length ratio of the medial
longitudinal arch. The motion at the subtalar joint during stance phase of
walking (eversion then inversion) was reversed during a turning task (inversion
then eversion). The external subtalar joint moment was also changed from a
moderate eversion moment during walking to a larger inversion moment during the
turn. The kinematics of the talocrural joint and the joints of the foot were
similar between these two tasks. During a medial turn, the subtalar joint may act
to maintain the motions in the foot and talocrural joint that occur during level
walking. This is occurring despite the conspicuously different trajectory of the
centre of mass of the body. This may allow the foot complex to maintain its
function of energy absorption followed by energy return during stance phase that
is best suited to level walking.
CI - Copyright 2009 Elsevier B.V. All rights reserved.

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