OBJECTIVE: To determine the relationships between spasticity, strength, and the 
functional measures of gait and gross motor function in persons with spastic 
diplegia cerebral palsy (CP).
DESIGN: Retrospective, cross-sectional study.
SETTING: Hospital clinic.
PARTICIPANTS: Ninety-seven participants (49 boys, 48 girls; mean age+/-standard 
deviation, 9.11+/-4.8 y) with spastic diplegia CP were tested once.
INTERVENTIONS: Not applicable.
MAIN OUTCOME MEASURES: A KinCom dynamometer was used to objectively measure 
spasticity (ankle plantarflexors, knee flexors, hip adductors) and maximum 
strength (ankle dorsiflexors and plantarflexors, knee flexors and extensors, hip 
abductors and adductors). A gait analysis was conducted to evaluate linear 
variables (gait speed, stride length, cadence) and kinematic variables (ankle 
dorsiflexion, foot progression, knee and hip flexion, pelvic tilt at initial 
contact and ankle dorsiflexion, knee and hip flexion, pelvic tilt, trunk 
rotation range of motion) during gait. Gross motor function was measured using 
the Gross Motor Function Measure (GMFM-66) and separately, the GMFM walking, 
running & jumping dimension. Multiple linear regression analysis was used to 
determine the relationships between spasticity, strength, gait, and the GMFM 
(P<.05).
RESULTS: Spasticity did not account for a substantial amount of explained 
variance in gait and gross motor function (up to 8% for the GMFM walking, 
running & jumping dimension). Moderate to high correlations existed between 
strength and gait linear data and function, accounting for up to 69% of the 
explained variance (strength and GMFM-66, r2=.69).
CONCLUSIONS: For this cohort of participants with spastic diplegia CP who 
ambulated with or without an assistive device, strength was highly related to 
function and explained far more of the variance than spasticity. The results may 
not be generalized to those with more severe forms of CP.