Standing balance in healthy boys and in children with Duchenne muscular dystrophy.

Balance in double stance was measured on a force platform with an X-Y Plotter (stabilograph) in 57 healthy boys aged 5 to 10 years and in 13 children with Duchenne muscular dystrophy (DMD), aged 6 to 15 years. Horizontal excursions of the center of gravity were measured in the anteroposterior (AP) and right-left (RL) planes. Measurements superimposed upon foot position tracings were compared with a potential excursion defined by the outer margin of foot position. Balancing ability was expressed as a ratio of measured excursion to potential maximal excursion. The objective was to determine whether a quantitative functional measure relating to muscle weakness and standing could be obtained. The mean ratio of AP excursions for healthy children was 0.5 (range 0.29 to 0.7); for dystrophic children 0.29 (range 0.07 to 0.57). The mean ratio of RL excursions for healthy children was 0.57 (range 0.23 to 0.77); for dystrophic children 0.36 (range 0.1 to 0.63). These ratios tended to increase with age in healthy children but decreased in those with dystrophy. DMD children have less ability to move the horizontal center of gravity within the base of support on double stance than their healthy peers of comparable age. Stabilography may be useful not only for assessing balance and documenting its deterioration but also for evaluating the effectiveness of treatment in DMD.