Intrarater reliability of lower limb sagittal range-of-motion measures in children with spastic diplegia

In this study, 10 sagittal lower limb range-of-motion measures were conducted in a blinded fashion in 25 children with spastic diplegic cerebral palsy and in 25 age- and sex-matched controls. The participants comprised 22 males,mean age 10 years 8 months and 28 females, with mean age 9 years 8 months; age range 6 to 17 years. One paediatric physical therapist performed duplicate goniometric measures at zero time and 7 days later using the same sequence of measures, location, and time of day. Mean absolute differences for measures within one session ranged from 0.7 to 2.9degrees in controls and from 1 to 4.2degrees in children with spastic diplegia. Most intraclass correlation coefficients (ICCs) for intra-sessional measures were more than 0.90 in both groups. Measures between sessions were less reliable. Mean absolute differences between sessions were up to 7.1degrees for children with spastic diplegia and 8.6degrees for controls, with most ICCs being less than 0.80. Inter-sessional variation in measures was similar in both groups, suggesting that measurement variability is not influenced by the presence of spasticity. Averaging of two measures did not improve inter-sessional reliability compared with the use of a single measure. Dynamic measures (RI) were as reliable as passive measures (R2), but there were inter-sessional differences in calculations using R1 and R2 measures of up to 30degrees.