Centre of pressure error with increasing gait velocity: The clinical impact on predicted inverse dynamics during gait in children with typical development.

Background: Centre of pressure (CoP) location error is common when predicting inverse dynamic parameters during gait. Tolerance levels of error have been previously reported. However, the clinical impact of gait velocity on CoP error has not been considered.

Research Question: What is the clinical impact of CoP error with increasing gait velocity on predicted inverse dynamic parameters during gait in children with typical development?

Methods: Three-dimensional kinematic and kinetic data were recorded at three self-selected velocities on children with typical development (walking, fast instructed walking and running). CoP location error was applied in 3 mm increments up to a maximum of 12 mm in an anteroposterior direction. Differences in maximum kinetic parameters between increments and gait velocities were assessed in conjunction with changes in GDI-kinetic.

Results: Relative error (difference expressed as a % of maximum moment) decreased at all joints as gait velocity increased. The GDI-kinetic was only clinically significant for the self-selected walking condition at 9 mm and 12 mm respectively.

Significance: The GDI-kinetic difference remained below the threshold for fast walking and running which suggested that CoP error of up to 12 mm in the 3D optoelectric / force plate configuration would be acceptable if subjects were assessed under these conditions.