The effect of botulinum toxin type A injection into the gastrocnemius muscle on sit-to-stand transfer in children with spastic diplegic cerebral palsy

Abstract

Objective: To investigate the benefit of botulinum toxin type A injection into the ankle plantarflexor muscle on sit-to-stand transfer in children with spastic diplegic cerebral palsy. Design: Case-control study. Setting: Inpatients in a university-affiliated hospital. Subjects: Forty spastic diplegic children aged from 2 to 6 years (18 children with botulinum toxin type A injection into both gastrocnemius muscles as an experimental group and 14 children without injection as a control group). Main measures: Sit-to-stand transfer task was evaluated using a motion analyser (Vicon 370 MA with six infrared cameras). The tests were performed twice with a two-week interval. The changes in temporal, kinematic and kinetic parameters were investigated in each group. Results: In the control group there were no significant changes in any of the measured parameters between the tests. In the experimental group, total duration (s) of sit-to-stand transfer was shortened after injection (4.359 ± 2.49 to 2.899 ± 1.48, P < 0.05). The maximal angles (degrees) of pelvic and hip joints were reduced (28.889 ± 5.53 to 26.579 ± 3.73 and 90.789 ± 8.69 to 87.239 ± 8.76) and the initial angle of ankle dorsiflexion was increased (4.419 ± 6.16 to 7.089 ± 6.09) after injection (P < 0.05). The maximal moments (Nm/kg) of the hip and knee joints (0.449 ± 0.17 to 0.519 ± 0.21 and 0.139 ± 0.05 to 0.189 ± 0.14) were increased while that of the ankle joint was reduced (0.329 ± 0.09 to 0.289 ± 0.10) after injection (P < 0.05). Only the cases with greater reduction of spasticity showed an improvement on kinematic and kinetic parameters. Conclusion: Botulinum toxin type A injection into spastic ankle plantarflexors led to better accomplishment of sit-to-stand transfer in children with spastic diplegic cerebral palsy.