Test-Retest Reliability of Discrete Gait Parameters in Children With Cerebral Palsy

Objectives: To examine the test-retest reliability of discrete gait parameters in children with cerebral palsy (CP) in Gross ;Motor Function Classification System (GMFCS) levels I, II, and III; to calculate the measurement error between testing sessions of these parameters in the total sample and within GMFCS subgroups using the standard error of measurement; and to evaluate the minimal detectable change (MDC) to identify discrete gait parameters that are most sensitive to change in children with CP. Design: Test-retest reliability study. Setting: Rehabilitation facility with human movement laboratory. Participants: Ambulatory children with CP (N=28). Interventions: Not applicable. Main Outcome Measures: Intraclass correlation coefficients (ICCs), standard error of measurement, and MDC of discrete gait parameters. Results: Parameters measured in the sagittal plane and temporal-spatial parameters were highly reliable across all GMFCS levels (ICC range, .84-.97), while test-retest reliability in the frontal and transverse planes varied from poor to excellent (ICC range, .46-.91). Using MDC as a guide, hip and pelvis parameters in the transverse and frontal planes were least responsive for GMFCS levels I and III (MDC ranges, 8.3 degrees-18.0 degrees and 2.7 degrees-23.4 degrees, respectively), whereas ankle kinematics were the least responsive for level II (MDC range, 8.2 degrees-11.9 degrees). Reliability was dependent on mobility level, with children in GMFCS level III exhibiting greater test-retest variability overall. Conclusions: Our findings suggest that select discrete gait parameters measured using computerized gait analysis are reliable and potentially responsive measures of performance and can be used as outcome measures in intervention studies.