Abstract: BACKGROUND: Genu valgus as a major deformity of children’s lower limbs may appear abnormal manifestations in the early stage of growth and development. However, the current research mainly focuses on the surgical treatment, and the research on the gait of children with genu valgus is relatively lacking.   
OBJECTIVE: To provide scientific basis for the early evaluation and treatment through the systematic analysis of the gait characteristics of children with genu valgus. 
METHODS: Fifty children with genu valgus and 50 healthy volunteers were selected. According to the occurrence of genu valgus, the subjects were divided into 3-6 years old and 7-12 years old. Three-dimensional gait analysis system was used to collect the kinematic, dynamic and spatiotemporal parameters of each subject. The gait parameters of children with genu valgus were compared with those of healthy children to summarize the gait characteristics. 
RESULTS AND CONCLUSION: (1) In terms of spatiotemporal parameters, the step length, forward velocity and step width of children with genu valgus decreased, while the single support time of children aged 7-12 increased. (2) In terms of kinematic parameters, the angle of foot pronated and genu valgus increased; the angle of tibia internal rotation increased; the maximum extension angle of hip joint decreased; and the angle of foot clearance decreased in children with genu valgus in stance phase; the maximum plantar flexion angle and the range of ankle joint flexion also decreased in children aged 7-12 years old. (3) In terms of dynamics, the ground reaction force in vertical direction decreased when the foot was off the ground; the maximum power of ankle and knee joint of children at the age of 3-6 decreased; and the moment of knee valgus decreased; the ground reaction force in vertical direction decreased and the power of hip joint decreased during the loading response period of children at the age of 7-12. (4) The results show that the walking efficiency and stability of children with genu valgus decreases, the lower limb propulsion ability decreases, and the line alignment is abnormal in ankle and knee joints. In children with knee valgus of low age, the compensatory abnormal movement of hip joint and the functional decline of lower limb muscle group are more obvious; in children with knee valgus of mature gait, the abnormal compensation of hip joint is reduced, but the abnormal line alignment of ankle and knee joint always exists. 

Key words: genu valgus, children, three-dimensional gait analysis, force line