Abstract
The objective of this study was to determine the functional (gait) changes in a hemiparetic subject with lower extremity spasticity using force components of the ground reaction forces (GRFs) following injection of botulinum toxin A (BTXA). These data were used to complement the clinical findings resulting from physical examination. Ten trials of walking gait at a self-selected pace were analyzed pre-injection (PI), 1 week post-injection (1 PO), and 4 weeks post-injection (4 PO). Data were collected using a force platform mounted flush with a specially constructed walking surface at 1000 Hz. Ground reaction forces (GRFs) were plotted across the stance phase of gait and analyzed for functionally relevant changes in the subject's gait pattern.
The ground reaction forces showed improvement in the subject's gait at 1 PO. A reduction of plantar flexor spasticity and equinus toe-heel foot placement accompanied gains in propulsion from the affected limb at 1 PO. At 4 PO, the reduction of spasticity remained, but propulsion on the limb had ceased. The GRF data aided in the clinical determination of treatment efficacy. This study suggests that for patients with spastic deformities with plantar extension and attendant difficulties with gait that botulinum toxin injection can relieve the problems of plantar extension but may reduce or abolish gait propulsive force on the side of the injection due to muscle weakness. Further research on the relationship between the amount of botulinum toxin needed to produce gait improvement and the possible attendant leg weakness needs to be done to help establish the role of this treatment for spastic lower extremities. GRF analysis and full three-dimensional gait analysis is recommended for such studies.