BACKGROUND: Observational gait assessment is an important clinical approach to the evaluation of gait disorders. Quantitative gait analysis systems provide accurate information, but the high cost of these instruments makes observational analysis more affordable to clinical practice. OBJECTIVES: To develop an observational gait scale (OGS) for characterizing the gait of children with spastic cerebral palsy (SCP) and to evaluate its validity and reliability criteria in comparison with a computerized motion analysis system representing the gold standard for kinematic gait assessment. METHODS: Twenty-three videos of children with SCP (9.54 ± 2.22 years) were evaluated by four physical therapists using the OGS, in two sessions. Kinematic data from the ankle/foot complex, knee, hip and pelvis were obtained using the Qualisys Pro-reflex motion analysis system. To establish criterion validity and the intra- and inter-rater reliability, the observational data were compared with motion analysis data, between the two sessions and between the raters. The weighted kappa test was applied to analyze the concordance between the evaluations. RESULTS: The OGS presented very good validity for the knee (r=0.64, p<0.05) and good validity for the ankle/foot complex (r=0.59, p<0.05). The intra-rater reliability was very good for the ankle/foot complex (r=0.79, p<0.05), knee (r=0.77, p<0.05) and hip (r=0.73, p<0.05) and good for the pelvis (r=0.59, p<0.05). The inter-rater reliability was very good for the ankle/foot complex (r=0.68, p<0.05) and knee (r=0.65, p<0.05), and good for the hip (r=0.48, p<0.05). CONCLUSIONS: The OGS demonstrated good reliability and validity for the ankle/foot and knee observations. New observational strategies are needed to improve the psychometric properties of the items relating to the hip and pelvis.
gait; cerebral palsy; scales; reliability; validity
