A non-linear, passive, model of the leg drop pendulum test: assessing changes in spastic cerebral palsy after vertical accelerations

Reports on the use of a passive, second order non-linear model of the leg drop pendulum test as a means of gaining insight into a therapeutic intervention in spastic cerebral palsy. Optimization techniques are used to adjust model parameters, such that model data fits actual data. Actual data is taken from a set of triplets, two of which have varying degrees of spastic cerebral palsy and one is without disability. The author compares five sets of data, one from the normal triplet and two each from the subjects with spasticity. Data from the subjects with spasticity is taken before and after vertical stimulation similar to that which one would receive while on horseback. The model parameters show several trends. First, stiffness and dampening coefficients are higher in the models of the disabled subjects´ data than the normal subjects. Second, these coefficients change, becoming more like the normal subject´s coefficients after vertical accelerations