IntroductionTypically, children develop approximately 23 degrees of lateral tibiofibular torsion by puberty. 1 Some children such as those with DS, however, may not develop this typical amount of bony torsion. As it is difficult to predict whether a child will develop enough lateral tibiofibular torsion for normal gait, clinicians disagree as to whether or not to treat these children. 2 Treatment usually consists of serial casting or bracing during development. The purpose of this paper was to evaluate 1) whether children with DS exhibit significantly different moments about the lower leg than children without disabilities, and 2) whether the wearing of foot orthoses affected this moment.MethodologyEighteen 3-6 year old children with DS were evaluated using three dimensional motion analysis of the lower leg, 3 and three dimensional force plate data to calculate the moment about their lower legs during gait in sneakers alone, in sneakers and orthoses one week later, and again in sneakers and orthoses between 2 and 4 months later. These same data were also collected from 10 children without disabilities, within the same age range, wearing sneakers alone. The kinematic data were collected at 60 Hz using the Podiatric Telefactor Motion Analysis System. The kinetic data were collected on a PDP 11 minicomputer at 200 Hz using a Kistler Force plate. In addition, velocity data were collected on all subjects at 200 Hz using a custom built fishing reel type tachometer. The tibiofibular moment curves were compared qualitatively using visual analysis and statistically using ANCOVA with velocity as a covariate. In addition, the data were analyzed using a canonical correlation with 3 aspects of the moments entered as eigen values. These 3 dependent measures were peak internal and external moments during stance and phase of zero crossings during stance.ResultsA typical tibiofibular moment curve has an internal moment followed by an external moment with the zero crossing between 30% and 40% of stance (fig. 1). Using ANCOVA, neither peak moment amplitudes nor phase of zero crossing were significantly different for children with DS with or without wearing orthoses. The phase of zero crossing, however, was significantly different for children with DS (in all conditions) from the children without disabilities. Canonical correlation also differentiated between children with DS and those without disabilities (fig. 2). Furthermore, canonical correlation revealed that the group of children with DS were separable into 2 groups. After the period of accommodation, one group of children with DS (DAE) were no longer distinguishable from the children without disabilities (with these parameters) and the other group (DAI) continued to be distinguishable (fig. 2).DiscussionThe fact that the zero crossing phase was significantly different for children with DS (in all conditions) from the children without disabilities demonstrates that the moment about the lower leg is a parameter which can distinguish between children with and without DS. When viewed as one group using ANCOVA, in a univariate fashion, the sample of children with DS in sneakers did not distinguish themselves from those wearing orthoses. However, when using canonical correlation, a multivariate technique, it became apparent that the group with DS could be divided into 2 groups; those whose tibiofibular moment became more like that of children without disabilities and those who did not. We are continuing to collect data from more subjects with DS and to analyze other data from all the subjects in attempts to hypothesize predictive differences.