Vertical Ground Reaction Forces in BKA and AB Children: A 3.5 Year Progress Report


How growth and development affects gait characteristics of below-knee amputee (BKA) and able-bodied (AB) children over time, is presently unknown. The purpose of this investigation was to compare the vertical ground reaction forces in BKA and AB children over a 3.5 year period. Height, mass, and force platform data were collected on 11 AB children (mean 8.4 years) and 3 BKA children (mean 7.4 years) during seven sessions held at 6 month intervals. The children walked across two adjacent plates at a constant speed (1.2 m/s ± 10%). Vertical force and time data were normalized to allow for inter-subject comparisons and 6 discrete variables were obtained from the vertical force-time curves. For this preliminary report, a paired T-test was used to determine whether significant differences existed for the variables between Sessions 1 and 7 (p less than 0.05). At the time of Session 7 the children were significantly taller and had greater mass when compared to those same results for Session 1. This growth appeared to have little affect on three of the variables (i.e., a local maximum, total impulse, total support time). However, a significant decrease in another local maximum and a slope variable and a significant increase in a local minimum occurred. It was speculated that the changes in these latter three variables were a result of the growth of the children and how it was related to the fixed walking speed used in the investigation. When the children were smaller it required greater stride frequency and/or stride length to attain the specified walking speed than when they were larger. This greater stride length and/or stride frequency could have the effect of increasing the magnitudes of the two variables.

Funding by the Variety Club of Southern Alberta Tent 61

Human Performance Laboratory University of Calgary. 2500 University Drive, N.W Calgary, Alberta. Canada T2N IN4