Functional and radiographic consideration of lower limb malalignment in children and adolescents with idiopathic genu valgum.

Three-dimensional gait analysis is capable of assessing dynamic load characteristics and the resulting compensatory effects of lower limb malalignment, which are generally not reflected in static imaging. This study determined differences in gait parameters in the frontal and transverse plane between patients and controls in order to identify compensatory mechanisms, and to correlate radiographic measurements and gait parameters in a consecutive series of children with idiopathic genu valgum. Thirty-three patients (mean age 12.3 years) were retrospectively reviewed and compared to a healthy control group. Children with genu valgum demonstrated significantly decreased internal knee valgus moments, shifting into varus moments. Furthermore, significantly different transverse plane gait patterns (decreased external knee rotation, increased external hip rotation) were observed. These patterns showed a relevant influence on the frontal knee moments, with knee rotation and foot progression angle showing the highest predictive value for changes and possible compensation of frontal knee moments. The correlation between commonly used radiographic measurements (i.e., mechanical axis deviation) and findings of the gait analysis was only low. Besides showing decreased internal knee valgus moments, our results suggest that considerable compensatory gait mechanisms may be present in children with idiopathic genu valgum to reduce joint loading.