Article

The goals of this study were to determine if the muscle contributions to vertical
and fore-aft acceleration of the mass center differ between crouch gait and
unimpaired gait and if these muscle contributions change with crouch severity.
Examining muscle contributions to mass center acceleration provides insight into
the roles of individual muscles during gait and can provide guidance for
treatment planning. We calculated vertical and fore-aft accelerations using
musculoskeletal simulations of typically developing children and children with
cerebral palsy and crouch gait. Analysis of these simulations revealed that
during unimpaired gait the quadriceps produce large upward and backward
accelerations during early stance, whereas the ankle plantarflexors produce large
upward and forward accelerations later in stance. In contrast, during crouch
gait, the quadriceps and ankle plantarflexors produce large, opposing fore-aft
accelerations throughout stance. The quadriceps force required to accelerate the
mass center upward was significantly larger in crouch gait than in unimpaired
gait and increased with crouch severity. The gluteus medius accelerated the mass
center upward during midstance in unimpaired gait; however, during crouch gait
the upward acceleration produced by the gluteus medius was significantly reduced.
During unimpaired gait the quadriceps and ankle plantarflexors accelerate the
mass center at different times, efficiently modulating fore-aft accelerations.
However, during crouch gait, the quadriceps and ankle plantarflexors produce
fore-aft accelerations at the same time and the opposing fore-aft accelerations
generated by these muscles contribute to the inefficiency of crouch gait.
CI - Copyright (c) 2012 Elsevier B.V. All rights reserved.

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