The influence of spasticity on goniometric range of motion measurement in children with cerebral palsy

Background Spasticity may introduce bias in passive range of motion (ROM) measurements in children with cerebral palsy. This study aimed to explore the impact of spasticity on the reliability and potential measurement bias of goniometric assessments of ankle dorsiflexion and knee extension in children with unilateral spastic cerebral palsy (USCP). Methods 32 children aged 6–17 years with USCP were recruited. ROM was assessed by two blinded investigators, using a two-axis goniometer. Spasticity was estimated using the Modified Ashworth Scale. Agreement between examiners was evaluated with Bland-Altman plots and paired t-tests. Inter-rater reliability was assessed using intraclass correlation coefficients (ICC). Results No statistically significant differences in examiner agreement of ROM were observed between the spastic and contralateral sides for ankle dorsiflexion (extended knee: mean difference 0.22°, 95% CI: − 2.53 to 2.09; flexed knee: 0.78°, 95% CI: − 3.57 to 2.01), knee extension (0.31°, 95% CI: − 1.63 to 1.01), or popliteal angle (0.50°, 95% CI: − 2.53 to 3.53). ICC indicated high inter-rater reliability. Conclusions These findings support the use of goniometry as a reliable tool for assessing joint mobility in clinical and research settings with results equally valid for measurements on a spastic and contralateral limb.