Article

OBJECTIVE: To compare 3 different methods of measuring plantarflexor stiffness in
children with spastic diplegia cerebral palsy (CP) and children without
disability. DESIGN: Case-control study. SETTING: Human performance laboratory.
PARTICIPANTS: A retrospective analysis was conducted with children with spastic
diplegia (n=121; mean age, 8.4y) and children with typical development (TD)
(n=48; mean age, 9.7y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: An
isokinetic dynamometer was used to measure ankle plantarflexor stiffness at 10
degrees /s using 3 methods: (1) end-range method, which applied a linear slope to
the end of the torque-angle curve; (2) set-range method, which applied a linear
slope from 30 degrees to 10 degrees plantarflexion; and (3) a linear method,
which applied a slope only to the linear portion of the curve. RESULTS: Two-way
analysis of variance revealed significant main effects for group and stiffness
method. The end-range method showed no significant difference between groups for
plantarflexor stiffness (P=.62), the set-range method showed the CP group with
120% greater stiffness than the TD group (P<.046), and the linear method showed
the CP group with 35% greater stiffness than the TD group (P<.001). CONCLUSIONS:
The linear method appeared to resolve the issues with the previous methods;
applying a linear slope to a nonlinear curve or applying a linear slope to the
same range of motion for each child regardless of their range limitations. It is
clear that children with CP have limited range of motion; therefore, stiffness
occurs earlier in the range than would be expected for a typically developing
child. Using the linear method, children with CP were 35% stiffer in the ankle
plantarflexors than typically developing peers.
CI - Copyright (c) 2011 American Congress of Rehabilitation Medicine. Published by
Elsevier Inc. All rights reserved.

Langue : ANGLAIS