Variability and reproducibility of gait parameters in youth with cerebral palsy: Feasibility for multicenter motion...

Demonstrating instrumented gait analysis inter-evaluator reproducibility is essential to perform proper multicenter studies. Studies have evaluated inter-evaluator reproducibility but often were limited to highly experienced evaluators or assessed in healthy individuals only. The current study aimed at determining if introducing variability through evaluators with various years of gait analysis experience would lead to acceptable levels of reproducibility?

Three adolescent and one young adult with cerebral palsy were each evaluated by four out of ten evaluators with various years of marker-based gait analysis experience. Gait analysis was performed on a 10-m walkway at patients' preferred speed. The intraclass correlation coefficient (ICC), and the intrinsic (inter-trial) and extrinsic (inter-evaluator) variability of gait parameters were computed.

Ten evaluators from nine different motion analysis centers (average of 8.4 ± 10.4 years of gait analysis experience; min: 1 year; max: 33 years) participated in the study. For most joints, good to excellent (0.75 to 1 ICCs) reproducibility was reported. Error analysis revealed that the main source of variability was associated with evaluators and not patients' gait. Regression analysis showed that years of experience in a motion analysis center was not a significant predictor of mean inter-evaluator deviation (β= -0.002 ± 0.006; p = 0.659) or of its standard deviation (β= -0.002 ± 0.004; p = 0.650).

The result of the current project suggests that one year of marker-based gait analysis experience and reviewing of a procedure video prior to engaging in a study is sufficient to generate quality data.